Articles

Keywords: Pseudanabaena, cyanobacteria, complementary chromatic adaptation, microbial diversity, phylogeny, evolutionary diversification

Pseudanabaena species are poorly known filamentous bloom-forming cyanobacteria closely related to Limnothrix. We isolated 28 Pseudanabaena strains from the Baltic Sea (BS) and the Albufera de Valencia (AV; Spain). By combining phenotypic and genotypic approaches, the phylogeny, diversity and evolutionary diversification of these isolates were explored. Analysis of the in vivo absorption spectra of the Pseudanabaena strains revealed two coexisting pigmentation phenotypes: (i) phycocyanin-rich (PC-rich) strains and (ii) strains containing both PC and phycoerythrin (PE). Strains of the latter phenotype were all capable of complementary chromatic adaptation (CCA). About 65kb of the Pseudanabaena genomes were sequenced through a multilocus sequencing approach including the sequencing of the16 and 23S rRNA genes, the ribosomal intergenic spacer (IGS), internal transcribed spacer 1 (ITS-1), the cpcBA operon encoding PC and the IGS between cpcA and cpcB. In addition, the presence of nifH, one of the structural genes of nitrogenase, was investigated. Sequence analysis of ITS and cpcBA-IGS allowed the differentiation between Pseudanabaena isolates exhibiting high levels of microdiversity. This multilocus sequencing approach revealed specific clusters for the BS, the AV and a mixed cluster with strains from both ecosystems. The latter comprised exclusively CCA phenotypes. The phylogenies of the 16 and 23S rRNA genes are consistent, but analysis of other loci indicated the loss of substructure, suggesting that the recombination between these loci has occurred. Our preliminary results on population genetic analyses of the PC genes suggest an evolutionary diversification of Pseudanabaena through purifying selection.

Keywords: otolito, crecimiento reciente, condición, lubina, Dicentrarchus labrax, larvas, alimentación, validación.

Otolith growth and the value and properties of the Recent Otolith Growth Index (ROGI) were studied in sea bass (Dicentrarchus labrax L.) larvae that were reared for the first month of life with four different feeding regimes: fed, non-fed, late-feeding and late two-day fast. A marking experiment using alizarin complexone was previously carried out to validate increment deposition. Daily increment deposition was observed to take place from day two after hatching (DAH). The different feeding regimes did not significantly affect the periodicity of otolith increment deposition but did affect increment width. The ROGI was used as a tool for assessing feeding-induced differences in condition. Non-fed larvae had significantly smaller otoliths than fed larvae at the same age. In the late-feeding larvae (food available from 13 DAH), increment width increased progressively once food was supplied, and reached values similar to those for fed larvae after one week of feeding. Deprivation of food for two days in post-flexion larvae (in the fourth week of larval development) was reflected in the formation of progressively narrower increments which had still not returned to normal width two days after feeding was resumed. Our results show that the width of the outermost otolith increments reflect the past feeding history and that the ROGI can be used to distinguish well fed from suboptimally nourished larvae.

Keywords: Nephrops norvegicus; Inertial current; Ultradian rhythms; Cardiac rhythm; Locomotor rhythm; Deep-sea

Data on biological rhythms of the Norway lobster Nephrops norvegicus (L.) are compared with new findings on inertial currents, a non-photic geophysical hydrodynamic fluctuation. Laboratory experiments on animal endogenous cardiac activity and locomotor rhythms using individuals from the middle slope (400–600 m depth) of the Mediterranean Sea revealed a consistent proportion of ultradian 18-h animals (20.6% and 12.0% of the studied cases for cardiac and locomotor tests, respectively). This characteristic, not reported in similar experiments with individuals from shallower depths (20–200 m) in the Atlantic Ocean, was initially considered meaningless from an ecological point of view. However, a close comparison with in situ oceanographic measurements over 1 year revealed a clear relationship between inertial current fluctuations and the observed 18-h behavioural and physiological rhythms. We propose a novel scenario involving potential non-photic (i.e. hydrodynamic) modulation of Nephrops biorhythms, and suggest that this may provide a paradigm for other benthic species in deep-water areas.

Keywords: Feeding; Functional response; Gross growth efficiency; Growth; Polychaete larvae; Polydora ciliata

We studied the effect of food concentration on the feeding and growth rates of different larval developmental stages of the spionid polychaete Polydora ciliata. We estimated larval feeding rates as a function of food abundance by incubation experiments with two different preys, presented separately, the cryptophyte Rhodomonas salina (ESD = 9.7 µm) and the diatom T. weissflogii (ESD = 12.9 µm). Additionally, we determined larval growth rates and gross growth efficiencies (GGE) as a function of R. salina concentration. P. ciliata larvae exhibited a type II functional response. Clearance rates decreased continuously with increasing food concentration, and ingestion rates increased up to a food saturation concentration above which ingestion remained fairly constant. The food concentration at which feeding became saturated varied depending on the food type, from ca. 2 µg C mL− 1 when feeding on T. weissflogii to ca. 5 µg C mL− 1 when feeding on R. salina. The maximum carbon specific ingestion rates were very similar for both prey types and decreased with increasing larval size/age, from 0.67 d− 1 for early larvae to 0.45 d− 1 for late stage larvae. Growth rates as a function of food concentration (R. salina) followed a saturation curve; the maximum specific growth rate decreased slightly during larval development from 0.22 to 0.17 d− 1. Maximum growth rates were reached at food concentrations ranging from 2.5 to 1.4 µg C mL− 1 depending on larval size. The GGE, estimated as the slope of the regression equations relating specific growth rates versus specific ingestion rates, were 0.29 and 0.16 for early and intermediate larvae, respectively. The GGE, calculated specifically for each food level, decreased as the food concentration increased, from 0.53 to 0.33 for early larvae and from 0.27 to 0.20 for intermediate larval stages. From an ecological perspective, we suggest that there is a trade-off between larval feeding/growth kinetics and larval dispersal. Natural selection may favor that some meroplanktonic larvae, such as P. ciliata, present low filtration efficiency and low growth rates despite inhabiting environments with high food availability. This larval performance allows a planktonic development sufficiently long to ensure efficient larval dispersion.

Keywords: Protists; Carbon flux; Particle traps; Clone libraries; 18S rDNA

The importance of key taxonomic groups of eukaryotic phytoplankton as contributors to downward particle flux was evaluated near the European time-series station (ESTOC) in the eastern subtropical North Atlantic in March 2005. For the first time, previous termmolecularnext term (cloning and sequencing) techniques were used to compare plankton communities from various depths in the euphotic zone with clone libraries from surface-tethered particle traps. Analyses of 18S rDNA clone libraries revealed compositional differences between the phytoplankton assemblages in the photic zone and those retrieved from shallow particle traps below, suggesting that not all phytoplankton contribute equally to particle flux. Contrary to expectations, our study also showed that it is not diatoms, despite their high abundance in the water column, but rather small phytoplankton taxa that dominated sequences recovered from trap material. We provide here first observational evidence that large taxa with mineral tests may not necessarily contribute more to export production than do smaller taxa even if the former are abundant in the water column.

En el sudoeste de Andalucía, en Huelva, existe un extraño paisaje donde discurren aguas de color rojo. Es el río Tinto.

Keywords: Deep-sea crustaceans; Aristeus antennatus; Nephrops norvegicus; Muscle and hepatic biomarkers

Several biomarkers indicative of stress were characterised in the crustaceans Aristeus antennatus and Nephrops norvegicus sampled off the Barcelona coast (NW Mediterranean). The biomarkers selected were cholinesterase (ChE) activities in muscle; and catalase, glutathione reductase (GR), total glutathione peroxidase (t-GPX), DT-diaphorase (DT-D), glutathione S-transferases (GSTs) and carboxylesterases (CbEs) in hepatopancreas tissue. Lipid peroxidation (LP) levels and total protein yield (PY) were also determined in muscle and hepatopancreas tissues. The activities and levels are discussed in relation to species and season, and differences in these two factors were observed for most biomarkers. AChEs and pseudocholinesterases were present in the muscles of both crustaceans. Catalase and GST activities were higher in N. norvegicus, whereas GR and t-GPX activities varied according to the season. Hepatic CbE activities were similar in the two crustaceans, whereas LP levels and PY were different between species. Seasonality and species particularities are factors to consider when these crustaceans are used as sentinels.

1] A persistent gyre at the mouth of the Bay of Fundy results from a combination of tidal rectification and buoyancy forcing. Here we assess recent interannual variability in the strength of the gyre using data assimilative model simulations. Realistic hindcast representations of the gyre are considered during cruises in 2005, 2006, and 2007. Assimilation of shipboard and moored acoustic Doppler current profiler velocities is used to improve the skill of the simulations, as quantified by comparison with nonassimilated drifter trajectories. Our hindcasts suggest a weakening of the gyre system during May 2005. Retention of simulated passive particles in the gyre during that period was highly reduced. A recovery of the dense water pool in the deep part of the basin by June 2006 resulted in a return to particle retention characteristics similar to climatology. Retention estimates reached a maximum during May 2007 (subsurface) and June–July 2007 (near surface). Interannual variability in the strength of the gyre was primarily modulated by the stratification of the dense water pool inside the Grand Manan Basin. These changes in stratification were associated with mixing conditions the preceding fall–winter and/or advectively driven modification of water mass properties.

El deterioro de los ecosistemas marinos debido al calentamiento global, la sobrepesca y la contaminación ha resultado en alteraciones a escala global y regional. En ocasiones, esos cambios favorecen más a especies alóctonas que a las autóctonas.

An ensemble Kalman filter (EnKF) is used to assimilate data onto a non-linear chaotic model, coupling two kinds of variables. The first kind of variables of the system is characterized as large amplitude, slow, large scale, distributed in eight equally spaced locations around a circle. The second kind of variables are small amplitude, fast, and short scale, distributed in 256 equally spaced locations. Synthetic observations are obtained from the model and the observational error is proportional to their respective amplitudes. The performance of the EnKF is affected by differences in the spatial correlation scales of the variables being assimilated. This method allows the simultaneous assimilation of all the variables. The ensemble filter also allows assimilating only the large-scale variables, letting the small-scale variables to freely evolve. Assimilation of the large-scale variables together with a few small-scale variables significantly degrades the filter. These results are explained by the spurious correlations that arise from the sampled ensemble covariances. An alternative approach is to combine two different initialization techniques for the slow and fast variables. Here, the fast variables are initialized by restraining the evolution of the ensemble members, using a Newtonian relaxation toward the observed fast variables. Then, the usual ensemble analysis is used to assimilate the large-scale observations.

Keywords: Salinity; Temperature; Neural networks; Atlantic Ocean; Regression analysis; Argo

Linear and non-linear empirical models for salinity (S) are estimated from the Argo temperature (T) and salinity (delayed) data. This study focuses on the reconstruction of salinity in the upper 1200 m of the eastern North Atlantic Ocean, a region characterized by the presence of many different water masses. While previous studies have found it necessary to split this region by boxes to fit different polynomial models in each box, a unique model valid for the entire region is fitted here. Argo profiles are randomly distributed on two sets: one for fitting the models and one for testing them. Non-linear regressions are built using neural networks with a single hidden layer and the fitting data set is further divided into two subsets: one for adjusting the coefficients (training data) and one for early stopping of the fitting (validation data). Our results indicate that linear regressions perform better than the climatologic T–S relationship, but that non-linear regressions perform better than the linear ones. Non-linear training using a three-data subsets strategy successfully prevents overfitting even when networks with 90 neurons in the hidden layer are being trained. While the presence of local minima may complicate the generalization of non-linear models to new data, network committees (created by training the same network from different random initial weights) are shown to better reproduce the test data. Several predictors are tested, and the results show that geographical, or surface, information does provide significant information. These results highlight the potential applications of future satellite missions measuring sea-surface salinity to reconstruct, when combined with temperature profiles, vertical salinity profiles.

Keywords: Cystoseira; deep-water algae; population structure; growth; biodiversity; conservation; Mediterranean

Populations dominated by Cystoseira zosteroides, an endemic and threatened Mediterranean seaweed, colonize deep-water rocky habitats down to more than 50 m depth. Assemblages dominated by this species display high algal and invertebrate species richness. Algal biomass averages 1134 g dw m−2. Erect and turf algae account for only 25% of total algal dry weight, while encrusting corallines are responsible for the remaining 75%. Sponges, bryozoans and ascidians constitute the dominant sessile macrofauna. Cystoseira zosteroides is the dominant erect algae, with a mean biomass of 60.6 g dw m−2, and densities ranging from 4 to 7 plants m−2. The alien turf alga Womersleyella setacea has a biomass of 104.2 g dw m−2 and covers most of the understory substrate. The size-frequency distribution of C. zosteroides populations shows differences over time. Mean annual growth of the main axis is around 0.5 cm and mean annual mortality rate is lower than 2%. Recruitment was almost nil during the studied period of time (10 years). Processes structuring these deep-water Cystoseira stands must be driven by episodic disturbances, after-disturbance recruitment pulses, and long periods of steady growth that last at least 10 years. However, it is also possible that recruitment is irreversibly inhibited by the alien alga W. setacea in which case these old-growth stands are faced with extinction. The highly diversified assemblages and the low growth and low mortality rates of C. zosteroides indicate high vulnerability to natural and anthropogenic disturbances, and call for effective measures to ensure their conservation.

Prokaryotic extracellular enzymatic activity, abundance, heterotrophic production and respiration were determined in the meso- and bathypelagic (sub)tropical North Atlantic. While prokaryotic heterotrophic production (PHP) decreased from the lower euphotic layer to the bathypelagic waters by two orders of magnitude, prokaryotic abundance and cell-specific PHP decreased only by one order of magnitude. In contrast to cell-specific PHP, cell-specific extracellular enzymatic activity (alpha- and beta-glucosidase, leucine aminopeptidase, alkaline phosphatase) increased with depth as did cell-specific respiration rates. Cell-specific alkaline phosphatase activity increased from the intermediate water masses to the deep waters up to fivefold. Phosphate concentrations, however, varied only by a factor of two between the different water masses, indicating that phosphatase activity is not related to phosphate availability in the deep waters. Generally, cell-specific extracellular enzymatic activities were inversely related to cell-specific prokaryotic leucine incorporation. Thus, it is apparent that the utilization of deep ocean organic matter is linked to higher cell-specific extracellular enzymatic activity and respiration and lower cell-specific PHP than in surface waters.

The distribution of prokaryotic abundance (PA), respiratory activity (ETS), heterotrophic production (PHP), and suspended particulate (POM) and dissolved (DOM) organic matter was determined in the meso- and bathypelagic waters of the (sub)tropical North Atlantic. PA decreased by one order of magnitude from the lower euphotic zone to the bathypelagic waters, while ETS decreased by two and PHP by three orders of magnitude. On a section following the Mid-Atlantic Ridge from 35ºN to 5ºN, ETS below 1000-m depth increased southwards up to three-fold. This latitudinal gradient in the deep waters was paralleled by a six-fold increase in Particulate Organic Carbon (POC), whereas no trend was apparent in the DOM distribution. Significant correlations between POM and ETS were obtained in the water masses between 1000-m and 3000-m depth, the Antarctic Intermediate Water and the North East Atlantic Deep Water. A strong imbalance in the dark ocean was found between prokaryotic carbon demand (estimated through two different approaches) and the carbon sinking flux derived from sediment-trap records corrected with 230Th. The imbalance was greater when deeper in the water column, suggesting that the suspended carbon pool must account for most of the carbon deficit. Our results, together with other recent findings discussed in this paper, indicate that microbial life in the dark ocean is likely more dependent on slowly sinking or buoyant, laterally advected suspended particles than hitherto assumed.

The variability of picoplankton and nanoplankton autotrophic (A) and heterotrophic (H) communities was studied along a zonal gradient extending from the NW African shelf to 500 km offshore in two contrasting seasons of the year: early spring (spring) and summer (summer). Plankton abundance was significantly higher in summer than in spring. In particular, heterotrophic prokaryotes (HP) and Prochlorococcus (Proc) were an order of magnitude more abundant in summer, presumably due to a higher loading of dissolved organic matter and higher temperatures. The average ratio of A to H biomass was lower during the summer. Over the African shelf, picoplankton was lowest during summer, while both the autotrophic and heterotrophic nanoflagellates (ANF and HNF) showed the highest abundances. In contrast, in spring, the highest abundance of Picoeukaryotes (PE) and Synechococcus (Syn) was found over or close to the shelf. The offshore sampling sections intersected a complex area of strong mesoscale variability, which affected the plankton distribution. In summer, the entrainment of an upwelling filament around a cyclonic eddy provoked the increase of HP and Syn abundances by about one order of magnitude over the surrounding waters, while PE were more abundant over the core of the eddy (probably due to nutrient pumping). In spring, HP and Syn were more abundant at the boundaries of an anticyclonic eddy and in the filament (where PE also increased). Proc abundance increased up to one order of magnitude in the core of the eddy and in the eddy-oceanic waters front. ANF and HNF showed the highest abundances in the filament and the eddy. In summary, although seasonality affects the background variability in microplankton communities, the mesoscale variability found in the Canary Islands transition zone strongly modulates the patterns of distribution, abundances and changes in community structure, altering the A to H ratio and concomitantly playing a key role modifying the carbon pathways within the food web in the region.

Keywords: Transparent exopolymer particles · TEP · Bacterial productivity · Primary productivity · Carbon cycling · Size fractionation · Gulf of Aqaba

Variations in transparent exopolymer particles (TEP), bacterial biomass production (BP) and primary productivity (PP) were followed over 52 h at a deep water station in the Gulf of Aqaba (Eilat, Israel) during the spring, in April 2008. About 20 h after the start of the study, there was a short (~15 h) but intense storm event that probably caused a nutrient pulse and, subsequently, a brief outgrowth of diatoms in the euphotic layer. Concentrations of TEP and BP ranged from 23 to 228 µg gum xanthan equivalents l–1 and from 0.2 to 0.6 µg C l–1 h–1, respectively. Concentrations of TEP and BP were measured in unfiltered and in GF/C (1.2 µm)-prefiltered samples. Most of the TEP (59 ± 21% of total TEP, mean ± SD) were in the smaller (GF/C-filtered) size fraction (0.4–1.2 µm); however, after the crash of the diatom bloom, the majority of TEP were in the >1.2 µm size fraction. In the GF/C-filtered fraction, BP averaged 59 ± 12% and 93 ± 5% of total BP in the upper water column and from 300 m, respectively. Significant correlations were observed between TEP and BP, suggesting that active heterotrophic bacteria may have been associated with these particles. During the 3 d of our study, PP and BP in the euphotic zone averaged 480 and 225 mg C m–2 d–1, respectively, suggesting that about half or more of the primary produced carbon was metabolized by heterotrophic bacteria in the upper water column. Coincident with strong mixing caused by the storm, TEP concentrations decreased in the surface water and increased at depth. We suggest that TEP acted to link carbon flux between the primary producers and heterotrophic bacteria, and that the downward movement of TEP from the upper water layers may be an important process in transferring organic carbon to deeper waters of the Gulf of Aquaba. Sinking TEP could provide not only organic carbon substrates for associated bacteria but also form ‘hot spots’ of elevated microbial metabolism and nutrient cycling throughout the water column.

Keywords: Seamount; Meddies; Topographic interaction; Region of study 33.8–40.3°N; 26.8–14.2°W

During years 2003 and 2004 both Sedlo and Seine Seamounts, lying in the area of influence of the Mediterranean water outflow in the Northeast Atlantic, were investigated in the framework of the EU-funded project OASIS. Analysis of CTD data shows that the levels of major variability in temperature and salinity were confined to the upper ocean layer, which is subject to seasonal air–sea heat exchange, and to the Mediterranean Water (MW) level. In this paper we concentrate on the latter case and show that the variability observed resulted from Mediterranean water eddies (Meddies) colliding with the seamounts. Combined data from CTD surveys, current meter moorings, ship-mounted ADCP and satellite altimetry suggest that during the period of observations there was only one Meddy interacting with each of the seamounts. On Sedlo Seamount intensive interaction resulted in the loss by the Meddy of about 25% of the salt around the seamount, whereas on Seine the Meddy (or portion of it) escaped the seamount after performing several rotations around the summit without any significant interaction.

Mediterranean Water eddies (meddies) are thought to play an important climatic role. Nevertheless, their dynamics are not sufficiently known because of difficulties encountered in their observation. Though propagating below the main thermocline, a number of pieces of evidence of sea surface manifestation of meddies are collected. The present work is based on joint in situ and altimetry data analyses to prove that the meddies can be followed with remote sensing data for long periods of time. The in situ observations are based on data from an oceanographic cruise, which crossed three meddies, and reanalysis of historical data sets, including RAFOS floats paths. Suggested methodology permitted us to obtain uninterrupted tracks for several meddies for a period from several months to more than 2 years. It was found that the dynamically calm region to the north of the Azores current presents favorable conditions for meddy tracking. The meddy surface signal may become shattered and difficult to follow during interaction with a strong dynamic structures (the Azores current/surface vortexes) or peaking topography. Theoretical considerations support the observations and lead to the conclusion that the dynamic signature of meddies at the sea surface is an intrinsic property of meddy dynamics.

Planktonic food webs play an important role driving the environmental fate of persistent organic pollutants, and POP accumulation in phytoplankton has been previously studied for its importance as a first step in the aquatic food webs. However, little is known about the accumulation and cycling of organic pollutants between zooplankton and water. The present study shows the results of laboratory experiments on the bioconcentration (by passive uptake) of polycyclic aromatic hydrocarbons in phytoplankton (Rhodomonas salina) and accumulation in copepods (Paracartia(acartia) grani), by ingestion and diffusion. Both bioconcentration (BCF) and bioaccumulation (BAF) factors show significant correlation with the octanol−water partition coefficient (Kow) for phytoplankton and zooplankton. The BCF values for phytoplankton were 2 orders of magnitude higher than those for copepods. The analysis of fecal pellets shows that elimination by defecation is mainly significant for PAHs taken up from ingested phytoplankton but not due to passive uptake. However, the dominant elimination mechanisms are by far metabolism and diffusive depuration. Indeed, the mass balance suggests that metabolism of PAHs by copepods is a significant process that could play a role in the fate of PAHs in the water column. Uptake, depuration, eggestion, and ingestion rates increased with hydrophobicity of the chemical, while the metabolism rate was slightly higher for the less hydrophobic compounds. Passive partitioning dominated the accumulation of POPs in zooplankton. The derivation of all the uptake and loss rate constants for PAHs opens the door to future modeling studies of the role of zooplankton in PAH cycling in the marine environment.

Effects of temperature on aspects of the life cycle and physiology of the copepod Calanus helgolandicus (C. helgolandicus) were investigated in the laboratory. Development times (DTs) were determined for organisms reared individually at 9, 12 and 15°C under saturated food conditions. While animals were successfully reared from egg to adulthood at 12 and 15°C, at 9°C, all the individuals had died prior to entering NV. The cohorts were fed with a monoculture of Prorocentrum micans as food saturating conditions. The cohorts were fed with monocultures of Prorocentrum micans which should represent saturated food concentrations with a dinoflagellate diet used in many other experimental studies. However, the monoculture nature of the diet and/or the laboratory containment conditions may have caused the mortality rates encountered. Impacts of short-term temperature change on egg production (EP) and hatching success were also investigated over the course of 1 year on individuals collected from station L4 (Western English Channel) and incubated in the laboratory. DTs increased as temperature decreased, with longer DTs at comparable temperature with those in Thompson’s study [(1982) Growth and development of Pseudocalanus elongatus and Calanus sp. in the laboratory. J. Mar. Biol. Ass. UK, 62, 359–372.] Evidence is presented to suggest that in this other study a mix of Calanus finmarchicus and C. helgolandicus may have been used. Equiproportional development was observed for the nauplii, but no pattern was defined for the copepodites. At low temperatures, mortality rates in the incubations were higher, but adult condition factor was higher, the longer DTs allowed greater body mass to be accumulated. EP rate was correlated with temperature at station L4, but the short-term incubation temperature did not have a significant influence on EP when measured over a short timescale (24 h). Egg hatching success also did not differ between incubations with small temperature differences.

The impact of viruses and protists on bacterioplankton mortality was examined monthly during 2 years (May 2005–April 2007) in an oligotrophic coastal environment (NW Mediterranean Sea). We expected that in such type of system, (i) bacterial losses would be caused mainly by protists, and (ii) lysogeny would be an important type of virus–host interaction. During the study period, viruses and grazers together were responsible for 50.6 ± 40.1% day−1 of bacterial standing stock losses (BSS) and 59.7 ± 44.0% day−1 of bacterial production losses (BP). Over the first year (May 2005–April 2006), protists were the principal cause of bacterial mortality, removing 29.9 ± 20.4% day−1 of BSS and 33.9 ± 24.3% day−1 of BP, whereas viral lysis removed 13.5 ± 17.0% day−1 of BSS and 12.3 ± 12.3% day−1 of BP. During the second year (May 2006–April 2007), viruses caused comparable bacterial losses (29.2 ± 14.8% day−1 of BSS and 40.9 ± 20.7% day−1 of BP) to protists (28.6 ± 25.5% day−1 of BSS and 32.4 ± 20.0% day−1 of BP). In 37% of cases higher losses of BP due to viruses than due to protists were found. Lysogenic infection was detected in 11 of 24 samplings. Contrary to our expectations, lytic infections dominated over the two years, and viruses resulted to be a significant source of bacterial mortality in this oligotrophic site.

Keywords: Pocket beach; Catalan coast; Spain

Coastal planform studies are a relevant initial stage before launching detailed dynamic field experiments. The aim of this study is to define the planform characteristics of 72 Catalan pocket beaches, natural and man-made, and to determine their sheltering effect, embaymentization and their status of equilibrium. Planform measurements were performed on SIGPAC, 1:5000 orthophoto sets and wave climate was provided by Puertos del Estado (Wana model). Planform parameters were applied and coastal planview indexes were determined. The study shows that the Catalan pocket beaches display a wide range of indentation, suggesting that no single structural, tectonic or morphological control dominates their planform. The man-made pocket beaches typically display indentations which are smaller than those shown by natural pocket beaches. Headland spacing and beach area are positively correlated. The more indented bays are, the shorter their beaches become. Low-indented pocket beaches are the widest and the longest ones. Deep indentation contributes towards beach protection and energy dissipation which counteracts rip efficiency and inhibits the formation of mega-rips. Pocket beaches often show gradual and moderate alongshore changes in texture and beach morphology. One third of the Catalan pocket beaches are “sediment starved”, i.e., 60% and more of their embayed shorelines are deprived of beach sediments. Examination of the status of equilibrium demonstrates that most of the Catalan pocket beaches are in an unstable mode, with indentation ratios that are unrelated to the wave obliquity.

Eye development, optical properties and photomechanical responses were examined in embryos and hatchlings of the southern calamary, Sepioteuthis australis. This species occurs in shallow coastal waters in Australia and New Zealand, and the egg masses were collected in October and December 2004 from Great Oyster Bay, Tasmania. At the earliest developmental stage the eye of the squid was comprised of a hemispherical cup of undifferentiated neural retina, while presumptive iris cell layers and lentigenic precursor cells enclosed a posterior eye chamber. Differentiation of the proximal and distal processes was observed in correspondence with the cornea development and lens crystallization, and occurred before differentiation of the neural retina, which was complete prior to hatching. Longer photoreceptor distal processes were first observed just prior to hatching in the dorsal-posterior retina. After hatching, this difference was much more evident and higher photoreceptor density was found in the central retina. This indicates that the eye of S. australis at this age uses different retina areas for different visual tasks. Optical sensitivity and resolution suggest that juvenile S. australis are diurnal. This study also found functional photomechanical responses of visual screening pigment migration and pupil constriction in S. australis embryos, although complete functionality of the pupil at this stage was uncertain. However, the pupils of squid aged 2 days closed almost completely under bright conditions, showing that photomechanical responses were highly developed in the juvenile squid. These findings indicate that squid embryos are able to perceive visual stimulation, suggesting an early reliance on vision for survival after hatching.

Land–ocean transfer of sediment and organic matter along the Moroccan Atlantic margin (NW Africa) seems to have been very effective during the last 130 ka. In a marine core from this region, we found total organic carbon (TOC) values ranging from 0.3 to 1.7 dry wt% of bulk sediments. These relatively high values are fairly unusual, as the core was recovered from an open-ocean environment that is currently oligotrophic. In order to explain this trend, more typical of an upwelling eutrophic setting, three processes were evaluated: (1) in situ primary production associated with the extension of the Cape Ghir upwelling filament, (2) bottom water conditions that may favour organic carbon preservation and (3) lateral organic carbon advection. The site occasionally experienced more eutrophic conditions, especially during termination I; here, we recorded a relative high abundance of the planktonic foraminifer Globigerina bulloides, suggesting high primary production. However, given the absence of correlation between TOC and G. bulloides records, high TOC storage cannot be attributed exclusively to primary production. Preservation factors such as bottom water ventilation are also ruled out. Lateral TOC advection seems to be the most plausible process. Today, lateral advection and offshore transport of nutrients and organic matter characterize the study region. However, the triggering mechanisms deserve further investigation. Different controlling factors influencing the mobilization and advection of organic carbon from coastal upwelling sites to the deep basin are discussed. The correlation found between down-core TOC and sea-level changes suggests sea-level fluctuations as the most effective mechanism driving nepheloid layer detachment and seaward material transport.

Keywords: Seismic oceanography; Mediterranean Undercurrent; Thermohaline fine structure; Mixing; Entrainment; Temperature; Salinity; Amplitude

Seismic reflection profiling is applied to the study of large scale physical oceanographic processes in the Gulf of Cádiz and western Iberian coast, coinciding with the path of the Mediterranean Undercurrent. The multi-channel seismic reflection method provides clear images of thermohaline fine structure with a horizontal resolution approximately two orders of magnitude higher than CTD casting. The seismic data are compared with co-located historical oceanographic data. Three seismic reflectivity zones are identified: North Atlantic Central Water, Mediterranean Water and North Atlantic Deep Water. Seismic evidence for the path of the Mediterranean Undercurrent is found in the near-slope reflectivity patterns, with rising reflectors between about 500 and 1500 m. However, the core of the undercurrent is largely transparent. Seismic images show that central and, particularly, intermediate Mediterranean Waters have fine structure coherent over horizontal distances of several tens of kilometers. However, the intensity of the reflectors, and their horizontal coherence, decreases downstream. This change in seismic reflectivity is probably the result of diminished vertical thermohaline contrasts between adjacent water masses, so that double-diffusion processes become unable to sustain temperature and salinity staircases. Comparison of root-mean-square seismic amplitudes with temperature and salinity differences between the Mediterranean Undercurrent and the overlying central waters suggests a causal relationship between observed thermohaline fine structure and true seismic amplitudes. We estimate that, within this intermediate water stratum, impedance contrasts are mainly controlled by sound speed contrasts (a factor between 3.5 and 10 times larger than density contrasts), which are mainly controlled by temperature contrasts (a factor between 1.5 and 5 times larger than salinity contrasts).

Keywords: Microzooplankton, Phytoplankton, Ciliates, Dinoflagellates, Grazing, Impact

Mesozooplankton and 63–200 μm net-collected microzooplankton grazing on phytoplankton and protozoans was evaluated by 24-h incubations on a latitudinal transect in the Atlantic Ocean, from 35°N to 38°S (AMT-15; September–October 2004). The sampling area comprised contrasting ecosystems, including upwelling zones and oligotrophic subtropical gyres. Grazing impacts of mesozooplankton and 63–200 μm microzooplankton on total chlorophyll a (Chl a), >5 μm Chl a, ciliates, and dinoflagellates were low for both zooplankton size fractions, always removing<1.5% of the standing stocks of these groups. Grazing had a slightly greater impact upon primary production (up to 10% of primary production consumed daily), although on most occasions grazing removed<1% of primary production per day. To account for the reduction of micrograzers by predators in the experimental bottles and the consequent reduction of grazing pressure, the data were corrected with knowledge on the decrease of microzooplankton during incubations and global estimates of microzooplankton grazing. The corrected grazing rates for mesozooplankton ranged from 4% to 28% of the primary production consumed daily, and from 1% to 2% of the standing stock of Chl a removed every day. The 63–200 μm microzooplankton corrected grazing impact was always<5% of the primary production and standing stock consumed per day. The corrected grazing activity of 63–200 μm microzooplankton and mesozooplankton rendered daily rations ranging from 3% to 38% of the body carbon consumed daily, not sufficient for basal metabolism in most of the areas studied. Finally, the data on mesozooplankton grazing on primary production confirm the recent hypothesis of a decline of the relative importance of mesozooplankton grazing on primary producers with increasing primary production [Calbet, A., 2001. Mesozooplankton grazing effect on primary production: a global comparative analysis in marine ecosystems. Limnology and Oceanography 46, 1824–1830].

Molt directament relacionada amb l’efecte d’hivernacle i, per tant, amb el canvi climàtic, la conferència d’Eva Calvo s’ocupà dels oceans com a grans segrestadors de diòxid de carboni

Continuous monitoring of water-column and near-bottom hydrosedimentary processes in the Mediterranean Sea over the last 15 years has resulted in a novel view of the functioning of this land-locked sea. Destratification of the water column and fast, dense, organic-matter-rich, and sediment-laden near-bottom currents occurring in late winter to early spring efficiently transfer matter and energy from the continental shelf and the upper ocean layers to the deep basin. These currents, known as dense shelf water cascading (DSWC), have been repeatedly measured by moored instrumentation during concurrent field experiments in the Gulf of Lion (northwestern Mediterranean Sea) and the Adriatic Sea (central Mediterranean). Physical oceanography observations made in the eastern Mediterranean in the early 1990s, together with observations of large-scale bed forms on the shelf floor, indicate that this phenomenon also occurs in the Aegean Sea (eastern Mediterranean) where it impacts the neighboring deep basins. The source areas of DSWC are the northernmost shelves of the Mediterranean Sea. Due to their location and inland topography, they are more exposed to the cold, persistent, intense northerly winter winds that cool shelf (and offshore) waters enough to make them denser than underlying waters, thus triggering their sinking once a density threshold is reached. It has also been observed that low river discharge on these shelves favors late winter-early spring cascading as shelf waters become denser than they would be under high river discharge. While offshore convection cells bring only “blue water” to the deep basin, DSWC events carry huge amounts of organic and inorganic substances as they scour the shelf and slope seafloor while sinking. Cascades of DSW may last for several weeks, and cascading waters sink continually deeper until they find their density equilibrium level, which changes from year to year. It has been observed that particularly intense DSWC events that carry shelf waters to the deepest parts of the western Mediterranean basin occur at subdecadal frequency. The influence of seafloor topography on the path followed by DSWC is best illustrated by submarine canyons. At specific locations, canyons are the main conduits for the cascading shelf waters, and from this developed the concept of “flushing submarine canyons.” If the volume of cascading waters in a given event is too large, the canyons may be unable to accommodate it, and, therefore, those waters may escape from the canyons—especially where they are less entrenched. It has been also observed that DSW may cascade as sheet flows, sweeping continental slopes along tens of kilometers or more before spreading over the deep basin. The findings reported in this paper are just the tip of the iceberg in terms of the consequences of DSWC on deep-water mass formation and on the deep ecosystem of the Mediterranean Sea. As cascades often occur simultaneously with spring phytoplankton blooms in the various Mediterranean regions, there is no doubt that their role as a natural mechanism for carbon sequestration from the shallow ocean layers will demand the attention of the scientific community in the coming years.

Keywords: Megabenthos; Invertebrates; Continental Slope; Trophic Guilds; Labile Organic Matter; Submarine Canyons

The distribution of megabenthic epifauna (invertebrates) in the Balearic Basin (western Mediterranean) has been analyzed at depths between 427 and 2265 m after compiling samplings performed in 1985–1992 and 2007–2008 with an OTSB-14 bottom trawl. 84 epibenthic taxa of invertebrates (excluded decapod crustaceans) were collected. Epibenthic assemblages were organized in five groups (n-MDS analyses) as a function of increasing depth: upper slope assemblage, U, hauls between 427 and 660 m; middle slope assemblages M1 and M2, hauls between 663–876 m and 864–1412 m, respectively; lower slope assemblages L1 and L2, hauls between 1488–1789 m and 1798–2265 m, respectively). We found significant differences in assemblage composition between all depth-adjacent pairs of groups. Trends in the distribution of biomass vs. depth and within assemblages varied when hauls taken over insular were compared to those over mainland slopes. Over insular slopes we found (n-MDS) only four distinct depth assemblages, with significant differences between all depth-adjacent group pairs, except between L1 and L2. Over the mainland slope, two peaks of biomass situated at U (427–660 m) and at L1 (1488–1789 m) were clearly identified, attributable to the echinoid Brissopsis lyrifera and holothurian Molpadia musculus at U and to the synallactid holothurian Mesothuria intestinalis at L1. The distribution of biomass vs. depth on insular slopes did not follow this pattern, showing no significant biomass peak below 1000 m and a total biomass an order of magnitude lower than adjacent to the mainland. After compiling available environmental data over the mainland slope off Barcelona, we found coincidence between the peak biomass of Mesothuria intestinalis and: i) a significant increase of labile OM (%OrgC, C/N, hydrolizable aminoacids–EHAA, and the EHAA/THAA-total hydrolizable aminoacids-ratio) over 1600 m; and ii) an increase of turbidity and T at 1500–1600 m in February 2008. We suggest that such OM inputs must likely be associated to the formation of nepheloid layers close to submarine canyons, probably associated with oceanographic processes in deep water masses in the area. This would explain why aggregations of M. intestinalis were linked to the mainland part of the Balearic basin, with highest densities located south of canyons. If hotspots of biomass as cited here for M. intestinalis are regulated by factors such as river inputs, both natural climatic changes (e.g. changes in rainfall regimes) and human impact (e.g. river damming) may affect deep-Mediterranean communities below 1000 m.

Keywords: deep sea, trawl comparison, diversity, decapod crustaceans, fishes, Aristeus antennatus, OTSB

A series of 57 (600-750 m) and 32 (1184-1320 m) hauls were compiled to compare data from four trawl types in analyses of the species composition and diversity of deep benthopelagic fish and decapods off the Catalonian coasts (western Mediterranean). Two 1-warp trawls (OTSB-14 and MTS-25) and two 2-warp trawls (a commercial trawl [CT] and a GOC73) were used, from hauls performed between 1988 and 2007 were compiled. At 600-750 m the OTSB-14 hauls were separated in multi-dimensional scaling (MDS) from hauls performed with MTS-25, CT, and GOC73. Ordination of hauls along DIM1 of MDS was significantly correlated (Spearman’s r) with mesh size at codend, bridle length, and vertical opening of trawls. When CT and GOC73 were compared with MTS-25, the most dissimilar species were Aristeus antennatus, Galeus melastomus and Trachyrhynchus scabrus. A particular case was A. antennatus, with a significantly higher abundance in MTS-25 catches than the rest of the trawls. At 1200-1300 m the OTSB-14 and MTS-25 hauls were segregated in MDS analysis. DIM2 was correlated with the sampling period (month), indicating a temporal effect on haul composition. At 1200-300 m the main dissimilarities between OTSB-14 and MTS-25 were marked by Alepocephalus rostratus and A. antennatus (caught with MTS-25), and by Cataetyx alleni, the Notacanthidae Notacanthus bonapartei and Polyacanthonotus rissoanus, and Plesionika acanthonotus (caught with OTSB-14). As a conclusion, OTSB-14 showed a significantly higher abundance in catches than MTS-25, CT and GOC73, and a higher S (number of species) and J (equitability) than MTS-25. On the lower slope seasonality influenced trawl comparisons; however, it is likely that MTS-25, with higher vertical height than OTSB-14, caught the benthopelagic fish A. rostratus more efficiently, explaining the higher biomass from MTS-25 there. MTS-25 positively selected A. antennatus, in parallel to a negative catchability for other species.

Keywords: Trophic relationships; Shelf-slope break; Plankton–benthos coupling; Zooplankton daily migrations; Predator–prey distribution; Hake; Mesopelagic communities

Short spatio–temporal variations in the feeding intensity and the diet of the European hake, Merluccius merluccius, together with the abundance of their potential prey were studied between August 2003 and June 2004 at two locations, northwest (Sóller) and south (Cabrera), off the island of Mallorca (Balearic Islands, Western Mediterranean) at depths between 150 and 750 m. The two areas present different oceanographic conditions. Hake was mainly distributed along the shelf-slope break and the upper slope (between 166 and 350 m) where recruits (TL<18 cm) were dominant. The hake's diet varied as a function of size. Recruits fed mainly on micronektonic prey, and the diet was influenced primarily by seasonality, with two dietary patterns (identified by MDS analyses) corresponding to August–September 2003 (summer) and to November 2003/February–April 2004 (autumn–winter). The summer pattern was consistent with a thermally stratified water column, while November and April were consistent with homogenized temperature and salinity throughout all the water column. The main prey of recruits were the euphausiid Meganyctiphanes norvegica and the midwater fish Maurolicus muelleri in autumn–winter and myctophids (mainly Ceratoscopelus maderensis) in summer. In contrast to recruits, the geographic factor (NW vs. S) was the main factor influencing the diets of post-recruits (TL between 18 and 21.9 cm) and adults (TLgreater-or-equal, slanted22 cm). Hake recruits (and to a lesser extent post-recruits) and their preferred prey occupied different depth ranges during daylight periods. Meganyctiphanes norvegica and Ceratoscopelus maderensis were, for instance, distributed as much as 500 m deeper than hake that had eaten them. All these trends were especially obvious at NW, an area with a more abrupt slope and with a greater influence by northern winter intermediate water (WIW) inflow in early spring than the S area. These factors probably enhanced micronekton aggregation in April, when feeding intensity (stomach fullness) increased among recruits and post-recruits only at NW. All these factors may have a crucial role in the diet, distribution and probably recruitment success of small hake. Biological factors were also important in trophic shifts in the diet and feeding of hake. Multi-linear regression models pointed to a trend of higher fullness with higher hepato-somatic index (HSI). Therefore greater food consumption by hake may enhance its metabolic condition. Within the framework of shelf-break and slope ecology, we show how the ‘boundary’ mesopelagic community inhabiting the middle slope sustains the trophic requirements of hake, a species distributed at shallower depths along the shelf-slope break. Mesopelagic euphausiids and myctophids are often found in the diets of shelf-break fish. Because the boundary mesopelagic community is distributed worldwide, the high levels of fish biomass often found at shelf-slope breaks could be sustained trophically by deeper, offshore mesopelagic communities, an inverse energy transfer from deep to shallow-water marine ecosystems.

For depths ranging between 650 and 1700 m we have compared recent (2007–2008) to older (from 1988 to 1992) data, searching for previous termlong-term changesnext term in the distribution, abundance and previous termcompositionnext term of deep megafauna (fish and decapods) off the central Catalonian coasts (western Mediterranean). Overall, in the depth interval between 600 and 1100 m, we found higher abundance of fish in 1988–1992 than in 2007, a decrease simultaneous with an increase of decapod crustaceans. Older and more recent haul replicates (after 20 years) had similar assemblage previous termcompositionnext term in the depth range 1300–1700 m, whereas we found significant previous termchangesnext term at 1000 m. previous termDiversitynext term of fish was greater in 1988–1992 than in 2007, while previous termdiversitynext term of decapod crustaceans increased between the two periods. Thus, there was a reorganization in benthopelagic communities, rather than a loss of biodiversity. This was in agreement with previous termlong-term changesnext term described for previous termdiversitynext term of (neritic) zooplankton in the western Mediterranean. We found a dominance of plankton-suprabenthos feeders (e.g. fish such as Lepidion lepidion, Hymenocephalus italicus and Alepocephalus rostratus; the decapods Plesionika spp. and Sergestes arcticus) in 1988–1992. In 2007 by contrast, dominance of plankton-suprabenthos feeders decreased, and assemblages were increasingly composed of benthos-feeding decapods (e.g. Aristeus antennatus, Pontophilus norvegicus and some hermit crabs) preying for instance on polychaetes. These results coincided with low/negative North Atlantic Oscillation index (NAO) in 2007 and in the period immediately before (2004–2006) 2007 (increase of benthos feeders), and with high average NAO in 1988–1992 (decrease of benthos feeders, which in turn may enhance abundance of plankton feeders). The benthic decapod Calocaris macandreae and suprabenthos (small crustaceans, mostly peracarids, living on and just beneath the sediment surface) are key prey in food webs off Catalonian margins, acting as links between surface oceanographic processes and abundance of benthopelagic predators. A conceptual model is presented relating previous termchangesnext term in climatic conditions with previous termchangesnext term in deep-sea, benthic-suprabenthic food webs. Calocari macandreae was more abundant in 2007, after 3 years of negative NAO. Under negative/low NAO, rainfall and river discharges increase in the NW Mediterranean, which may enhance advective food inputs for macrobenthos. This fits well with the higher abundance of benthos feeders in 2007, as well as with the significant deepening of decapod crustacean assemblages in that same period. Suprabenthos, being short-lived and annual species, were more abundant under positive NAO conditions (1988–1992), probably enhancing the abundance or aggregation of suprabenthic/pelagic feeders.

Keywords: Food-web modelling · Ecopath with Ecosim · Fishing impacts · Environmental factors · Ecosystem indicators · Adriatic Sea · Mediterranean

We used a process-oriented model (Ecosim) to characterize changes in marine resources in the north-central (NC) Adriatic Sea (Mediterranean) from 1975 to 2002, and to explore the extent to which these changes were driven by trophic interactions, environment and fishing. Fishing efforts and fishing mortalities were used to drive the ecosystem model, and available biomass and catch data were compared to the model predictions. We calibrated and assessed the fit of the model using the sum of the squared deviations of the observed and predicted biomass values. Trophodynamic indicators were then calculated and used to analyse changes to the ecosystem. Trophic interactions, fishing, and environmental conditions were important driving factors of the ecosystem. Predictions from the model adequately matched observed biomass and catch data for each year. Observed trends and predicted data for biomasses decreased with time for several species, including Norway lobster, hake, red mullets, flatfish, and anchovy. The environmental functions resulting from the fitting procedure predicted that primary production and nutrients increased beyond the baseline from 1975 level, and then showed a decrease. They were negatively correlated with mean sea surface temperature and positively correlated with the Mediterranean Oscillation Index. Our results suggested that the NC Adriatic ecosystem became more degraded over time due to expanding fishing effort, bottom-up effects, and climatic anomalies. Possible mechanisms involved are discussed. Comparing our findings with descriptions of the south Catalan Sea ecosystem showed certain similarities between these 2 Mediterranean ecosystems and revealed unique features of the Adriatic Sea.

Keywords: Food-web model; Ecopath with Ecosim; Trophodynamic indicators; Ecosystem structure; Ecosystem functioning; Keystone species; Transfer efficiency; Western Mediterranean

We analysed changes in the ecological roles of species, trophic structure and ecosystem functioning using four standardized mass-balance models of the South Catalan Sea (North-western Mediterranean). Models represented the ecosystem during the late 1970s, mid 1990s, early 2000s, and a simulated no-fishing scenario. The underlying hypothesis was that ecosystem models should quantitatively capture the increasing exploitation in the ecosystem from the 1970s to 2000s, as well as differences between the exploited and non-exploited scenarios. Biomass showed a general decrease, while there was an increase in biomass at lower trophic levels (TL) from the 1970s to 2000s. The efficiency of energy transfer (TE) from lower to higher TLs significantly increased with time. The ecosystem during the 1990s showed higher biomass and flows than during the 1970s and 2000s due to an increase in small pelagic fish biomass (especially sardines). Exploited food webs also showed similarities in terms of general structure and functioning due to high intensity of fishing already in the 1970s. This intensity was highlighted with low trophic levels in the catch, high consumption of production by fisheries, medium to high primary production required to sustain the catches and high losses in secondary production due to fishing. Significant differences on ecosystem structure and functioning were highlighted between the exploited and no-fishing scenarios. Biomass of higher TLs increased under the no-fishing scenario and the mean trophic level of the community and the fish/invertebrate biomass ratios were substantially lower in exploited food webs. The efficiency of energy transfer (TE) from lower to higher TLs was lower under the no-fishing scenario, and it showed a continuous decrease with increasing TL. Marine mammals, large hake, anglerfish and large pelagic fish were identified as keystone species of the ecosystem when there was no fishing, while their ecological importance notably decreased under the exploited periods. On the contrary, the importance of small-sized organisms such as benthic invertebrates and small pelagic fish was higher in exploited food webs.

Keywords: Computer Applications; Fisheries Science; Natural Resource Management

This is the second edition of a book that reviews current and future computer trends in fisheries science applications. The first edition was published 10 years ago. Individuals have been quick to realize the potential of computers in fisheries and scientists continue to take advantage of the rapidly advancing tools and technology. This book provides a valuable sampling of contemporary applications and in some cases compares recent developments to the status of the situation 10 years ago. In many cases perspectives are presented by the same authors that contributed to the first edition. Scientists will have an opportunity to evaluate the suitability of different computer technology applications to their particular research situation thereby taking advantage of the experience of others.

Keywords: Parasquilla ferussaci, Stomatopoda, Western Mediterranean, Gulf of Cadiz

New records of Parasquilla ferussaci (Roux, 1830) (Crustacea, Stomatopoda) from the Eastern Atlantic and Western Mediterranean.- We report the occurrence of the little known stomatopod Parasquilla ferussaci on the Atlantic and Mediterranean coasts of the Iberian peninsula. Documentation is based on three specimens captured off Isla Cristina (Huelva) in the Gulf of Cadiz, off Fuengirola (Málaga) in the Alboran Sea and off Gavà (Barcelona) in the North-Western Mediterranean. These reports fill the distribution gap between Eastern Central Atlantic reports and previous Mediterranean reports east of the Balearic Islands.

Keywords: climatic anomalies , summer lengthening , energetic constraints , benthic suspension feeders, extreme events

Summer conditions in the Mediterranean Sea are characterized by high temperatures and low food availability. This leads to “summer dormancy” in many benthic suspension feeders due to energetic constraints. Analysis of the most recent 33-year temperature time series demonstrated enhanced stratification due to global warming, which produced a ≈40% lengthening of summer conditions. Many biological processes are expected to be affected by this trend, culminating in such events as mass mortality of invertebrates. Climatic anomalies concomitant with the occurrence of these events represent prolonged exposure to warmer summer conditions coupled with reduced food resources. Simulation of the effects of these conditions on a model organism demonstrated a biomass loss of >35%. Losses of this magnitude result in mortality similar to that noted in field observations during mass mortality events. These results indicate that temperature anomalies are the underlying cause of the events, with energetic constraints serving as the main triggering mechanism.

Keywords: Sub-mesoscale, Filaments, Altimetry, Mediterranean circulation, Lagrangian dynamics

Transport and mixing properties of surface currents can be detected from altimetric data by both Eulerian and Lagrangian diagnostics. In contrast with Eulerian diagnostics, Lagrangian tools like the local Lyapunov exponents have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether this theoretical advantage is of practical interest in real-data, mesoscale and sub-mesoscale analysis, because of the uncertainties and resolution of altimetric products, and the non-passive nature of biogeochemical tracers. Here we compare the ability of standard Eulerian diagnostics and the finite-size Lyapunov exponent in detecting instantaneous and climatological transport and mixing properties in the south-western Mediterranean. By comparing with sea-surface temperature patterns, we find that the two approaches provide similar results for slowly evolving eddies like the first Alboran gyre. However, the Lyapunov exponent is also able to predict the (sub-)mesoscale filamentary processes occurring along the Algerian current and above the Balearic Abyssal Plain. Such filaments are also observed, with some mismatch, in sea-surface temperature patterns. Climatologies of Lyapunov exponents do not show any compact relation with other Eulerian diagnostics, unveiling a different structure even at the basin scale. We conclude that filamentation dynamics can be detected by reprocessing available altimetric data with Lagrangian tools, giving insight into (sub-)mesoscale stirring processes relevant to tracer observations and complementing traditional Eulerian diagnostics.

Known as ESA’s ‘Water Mission’, SMOS will improve our understanding of Earth’s water cycle, providing much-needed data for modelling of the weather and climate, and increasing the skill in numerical weather and climate prediction.

MIRAS is more than just the payload of SMOS. It is a radio telescope pointed towards Earth, an instrument that has challenged the fundamental theories of radio astronomy, and made a major contribution to science even before being launched.

Keywords: Phytoplankton · Protists · Nutrients · Stoichiometry · Light response · Sea ice · Beaufort Sea · Arctic

Between autumn 2003 and summer 2004, the icebreaker CCGS ‘Amundsen’ occupied a station in Franklin Bay, Beaufort Sea. Two microcosm experiments were carried out in spring, while the water column was covered by sea ice, to test whether phytoplankton assemblages sampled from ice-covered (spring) surface waters would be able to bloom when exposed to increased light and to what extent this bloom would be limited by light or nutrients. Two additional experiments were carried out during a sea-ice free period in summer. For the spring experiments (April 2004), surface water collected through an ice hole was distributed into 10 l Nalgene bottles and subjected to different photosynthetically available radiation (PAR; 5 to 60 µmol photons m–2 s–1) and nutrient addition treatments. A similar setup was repeated in July and August 2004. In the spring experiments, chlorophyll a (chl a) concentration showed an initial decline, probably reflecting a combination of autotrophic cell losses and photoacclimation effects. After about 2 wk, chl a started to increase exponentially at PAR above 10 µmol photons m–2 s–1, due to the proliferation of autotrophic nanoflagellates. In summer, chl a increased immediately after enclosure, mainly due to diatom (Thalassiosira/Porosira) growth. In spring, nutrient addition had no effect on the net rate of chl a accumulation, while phytoplankton increased faster and reached higher biomass in the nutrient-amended bottles in summer. The relationships between nutrient consumption and production of chl a and particulate organic matter in our experiments suggested an important utilization of dissolved organic nutrients.

Keywords: Mesopelagic macrofauna; Suprabenthos; Stable isotopes analysis; Temporal variations; Environmental factors; Western Mediterranean

The trophodynamics of mesopelagic (macrozooplankton/micronekton) and benthic boundary layer (suprabenthos=hyperbenthos) faunas from the Algerian Basin were characterized on a seasonal scale through stable carbon and nitrogen isotopic analyses of a total of 34 species and two broad taxa (Copepoda and Cumacea). This is the first study simultaneously focused on trophodynamics of deep-sea zooplankton and suprabenthos. Samples were collected southeast of Mallorca (Algerian Basin, Western Mediterranean), on the continental slope close to Cabrera Archipelago, at 650–780 m depths, ca. bi-monthly between August 2003 and June 2004. Mean δ13C values of suprabenthos ranged from −21.1‰ (Munnopsurus atlanticus) to −16.7‰ (Cyclaspis longicaudata). Values of δ15N ranged from 2.8‰ (Lepechinella manco) to 9.9‰ (larvae of Gnathia sp.). The stable isotope ratios of suprabenthic fauna displayed a continuum of values, confirming a wide spectrum of feeding guilds (from filter feeders/surface deposit feeders to predators). According to the available information on diets for suprabenthic species, the highest annual mean δ15N values were found for the hematophagous isopod Gnathia sp. parasite on fish (represented by Praniza larvae) and carnivorous amphipods (e.g. Rhachotropis spp., Nicippe tumida) consuming copepods, and the lowest δ15N values were found for two cumaceans (Cyclaspis longicaudata and Platysympus typicus) feeding on detritus. Assuming a 15N-enrichment factor of 2.5‰ and deposit feeders as baseline, we found three trophic levels in suprabenthic food webs. δ13C ranges were particularly wide among deposit feeders (ranging from −21.8% to −17.3‰) and omnivores (from −20.5% to −18.8‰), suggesting exploitation of particulate organic matter (POM) of different characteristics. Our isotopic analyses revealed lower ranges of δ13C and δ15N for macrozooplankton/micronekton, compared with suprabenthos. δ13C values of zooplankton taxa ranged from −21.1‰ (the hyperiid Phrosina semilunata) to −19.9‰ (the decapod Pasiphaea multidentata), while δ15N values ranged from 3.9‰ (P. semilunata) to 7.5‰ (P. multidentata). Among zooplankton, more enriched δ15N values were found among carnivores (e.g. the fish Cyclothone spp. and Pasiphaea multidentata) preying on copepods, hyperiids, euphausiids and small fish. The lowest δ15N values were found for hyperiids that feed on the mucus nets of salps (e.g. Vibilia armata). After contrasting isotope analysis with dietary data, we conclude there were two trophic levels among zooplankton/micronekton. Strong correlation between the mean annual δ15N and δ13C values was found for zooplankton (R2=0.7), but not for suprabenthos, which suggests a single source of carbon for plankton. We found a general seasonal trend for δ13C enrichment from late autumn (November) to late winter–spring (February–April) for both suprabenthos and zooplankton. The δ13C enrichment in February–April was correlated in zooplankton with higher surface chlorophyll a concentration 1 month before sampling. As evidenced by δ13C–δ15N correlations, the response of zooplankton to the peak of surface primary production was almost immediate (an increase of δ13C–δ15N correlations in February), and stronger than for suprabenthos. The response among suprabenthos was weak, with slight increase in δ13C–δ15N relationships in April–June.

Keywords: Suprabenthos (Hyperbenthos); Assemblage Dynamics; Stable Isotopes; Seasonal Variations; Environmental Factors; Mediterranean; Coastal Muddy Bottoms

The trophodynamics of suprabenthic fauna were analyzed in the Gulf of Castellammare (North-western Sicily, Italy) at depths ranging between 40 and 80 m. Variations in species abundance and biomass together with changes in nitrogen and carbon stable isotope composition were explored at a seasonal scale, from November 2004 to June 2005. Suprabenthos showed maximum biomass and abundance from late winter to summer, while minimum values were found in autumn. The highest abundances of mysids and copepods occurred in March, 1 month after the peak of primary production. Amphipod abundance was higher in summer, likely due to a relative increase in organic matter in the sediments. Statistical analysis provided evidence for separation of sample abundances as a function of season. The best match between suprabenthos abundance and environmental variables was found with Chlorophyll a recorded 3 months before the sampling. Stable isotope analyses suggest a relatively complex food web in the Gulf of Castellammare with several potential food sources. Some suprabenthic species (i.e. mysids and copepods) exhibited depleted values of δ13C, indicating a planktonic source of nutrition. Cumaceans and amphipods displayed more enriched δ13C values, pointing to more detritivorous behaviour. A third group with intermediate δ13C values comprised species with a mixed diet (e.g. Ampelisca spp., Apherusa vexatrix and Harpinia spp.). Assuming a 15N-enrichment of ca. 2.54‰ between consumers and their diet, at least two trophic levels can be distinctly identified: (1) filter feeders/grazers (mysids, copepods), suspension/deposit feeders (Ampelisca spp., A. vexatrix, small Goneplax rhomboides) and omnivores, alternatively feeding on detritus and small invertebrates such as meiobenthos (the cumacean Leucon mediterraneus or the amphipod Westwoodilla rectirostris); (2) carnivores on small crustaceans and zooplankton (the amphipod Harpinia spp., the gobiid fish Lesuerigobius suerii and the decapod Philocheras bispinosus). Seasonal changes in isotopic composition occurred for the dominant suprabenthic species. This may result from diet shifts associated with changes in the availability of different food sources and/or from change in the primary sources of organic matter that are particularly variable in coastal environments.

Feeding habits of blackmouth catshark Galeus melastomus and velvet belly lantern shark Etmopterus spinax were studied throughout the Spanish Mediterranean, from the Alboran Sea to the Gulf of Lion, between 400 and 790 m depth. Diets were studied taking into account size and depth differences. Included within the trophic guild of non-migratory macroplankton feeders, both species preferably exploited mesopelagic resources (mainly natantian decapods, euphausiids, mesopelagic fish and cephalopods). G. melastomus mostly preyed on decapod crustaceans (46% in terms of IRI), with cephalopods, euphausiids and mesopelagic fish as a secondary prey item. The diet of E. spinax was composed primarily of mesopelagic fish (61.4% in terms of IRI), with decapod crustaceans and cephalopods of secondary importance. Both species showed ontogenetic changes in their diets: small blackmouth catshark specimens (between 150 and 350 mm total length) mainly consumed cephalopods, medium size individuals (351–450 mm TL) consumed decapod crustaceans, while larger specimens (larger than 451 mm TL) seemed to be more generalist-feeders. Smaller specimens of E. spinax (150–250 mm TL) mostly fed on small crustaceans and cephalopods, whilst an increase in the consumption of mesopelagic fish (mycthophids and Stomiiformes) was detected in larger individuals (251–450 mm TL). Diet of G. melastomus also changed throughout the narrow depth range explored, mainly consumed euphausiids and mesopelagic fish between 400 and 500 m depth, whilst preferably exploiting natantian decapods and cephalopods below 500 m of depth. However, this trend may be correlated to the larger-deeper trend found for this species. Slight but not significant differences were found in E. spinax diet by depth, with euphausiids mainly consumed at lower depths (400–500 m). In a multispecies MDS analysis, diets of G. melastomus and E. spinax were separated and the anosim test proved evidence for significant differences in the diets of the two species (R = 0.25; P = 0.05), mainly attributed to the stronger pelagic habits of E. spinax in comparison with G. melastomus. Low overlap (by Schoener Index) also occurred when comparing specimens of the same size range. In general, the higher occurrence of benthic prey in the diet of G. melastomus (i.e. the brachyuran crab Geryon longipes, the thalassinid shrimp Calocaris macandrae) than in E. spinax pointed to a stronger pelagic behavior for the velvet belly lantern shark. Both multivariate analysis and the Levins Index pointed to a narrow niche breadth for the two sharks. A trend of increasing fullness was found for both species in the highly productive areas of the Alboran Sea and Vera Gulf, probably related to higher resource availability, enhanced by local upwellings.

Keywords: feeding ecology; stable isotopes; trawl ban; Arnoglossus laterna; Mediterranean Sea

This study assesses the effects of bottom trawling on the feeding ecology of the scaldfish Arnoglossus laterna, by contrasting diets in an untrawled area and in two trawled areas off northern Sicily (western Mediterranean): the Gulf of Castellammare (which hosts a 200 km2 no-trawl area) and the gulfs of Termini Imerese and Sant\'Agata. Scaldfish were collected in May–June 2005 using a commercial otter trawler between 40 and 80 m on muddy bottoms. Our data show that scaldfish is a selective feeder and consumes similar prey items in the three gulfs, although between-site differences in the relative prey abundance in the stomachs were detected. In the three gulfs scaldfish fed mainly on the crab Goneplax rhomboides and on the fish Lesueurigobius suerii, but there was an increase in the consumption of L. suerii and the shrimp Alpheus glaber in the trawled areas. Ontogenetic changes were evident in the diet of scaldfish, with juveniles preying mainly upon suprabenthic species, e.g. mysids and small decapods. While significant differences occurred in the diet of juveniles among all areas due to natural spatial variability, variations in the diet of adults, which feed on benthic prey, occurred between untrawled and trawled areas. These variations were clearly due to trawling disturbance, and no significant difference was detected in the diet of adults between the two trawled areas. On the contrary, the trophic level (δ15N values) of scaldfish did not vary between trawled and untrawled areas and between juveniles and adults. Changes in the source of carbon, as detected by δ13C values, were evident between juveniles and adults, evidencing a shift from a suprabenthic (juveniles) to a benthic (adults) diet.

Keywords: Kryptoperidinium foliaceum; binucleate; cell cycle; cysts; dinoflagellate; endosymbiont; life history; sexual reproduction

Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus of diatom origin. However, it is unknown whether the binucleate condition is permanent or not and how the diatom nucleus behaves during the life history processes. In this sense, it is also unknown if there is a sexual cycle or a resting stage during the life history of this species, two key aspects necessary to understand the life history strategy of this dinoflagellate. To answer these questions, life history and cell cycle studies were performed with the following results: (i) Kryptoperidinium foliaceum has a sexual cycle and in the dinoflagellate strains studied, the binucleate condition is permanent. Sexuality in the host was confirmed by the presence of fusing gamete pairs and planozygotes in clonal cultures (revealing homothallism), but signs of meiosis in the endosymbiont were not observed. The endosymbiont nucleus likely fuses first, because fusing gamete pairs were found to have two dinoflagellate nuclei but only one endosymbiont nucleus. After complete gamete fusion, the planozygotes had apparently normal endosymbiont and dinoflagellate nuclei. (ii) Asexual division studies using flow cytometry showed that the S phase in the endosymbiont (diatom) nucleus starts 6–8 h later than in the host nucleus, but there was no evidence of mitosis in the former. (iii) Sexual and asexual cysts were formed in culture. Neither cysts from natural samples nor those formed in culture exhibited a dormancy period before germination.

Keywords: Aperture synthesis, Imaging, Microwave radiometry, Remote sensing, Water cycle

SMOS (Soil Moisture and Ocean Salinity, European Space Agency) is the first satellite mission addressing the challenge of measuring sea surface salinity and moisture of land from space. It uses an L-band microwave interferometric radiometer with aperture synthesis (MIRAS) that generates brightness temperature images, from which both geophysical variables are derived. This paper presents the principles of operation of the instrument and the algorithmic approach implemented for the retrieval of salinity from MIRAS observations. The retrieval of salinity requires very demanding performances of the instrument in terms of calibration and stability. This text includes material from an article published in the ESA Bulletin in February 2009 [1] and a paper to appear in the Proceedings of IEEE in November 2009 [2]. The latter contains many relevant references not included here.

Initiated in2002, HydroChanges (HC) is one of the eigth international programs supported by CIESM. It consist in a network of accurate autonomous SBE37 CTDs deployed in selected Mediterranean key-sites, with a typical 1.hr sampling interval. In order to make deployments/recoveries as easy as possible, even from small ships, the CTDs are generally set on short moorings, so that they sample at 10-20 m above the seafloor, most often associated with a current-meter. Moorings are serviced locally by individual partners every 1-2 years. Altrouugh the primary goal of HC is to monitor long-term variability, we illustrate in this paper the relevance of HC strategy also for accurately detecting, characterizing and monitoring effects of Dense Water Formation (DWF) precesses in the western basin of the Med.

Keywords: Biodiesel; Dinoflagellates; Karlodinium veneficum; Lipids; Microalgae

Microalgae are microscopic heterotrophic–autotrophic photosynthesizing organisms with enormous potential as a source of biofuel. Dinoflagellates, a class of microalgae, contain large amounts of high-quality lipids, the principal component of fatty acid methyl esters. The biotic characteristics of the dinoflagellate species Karlodinium veneficum include a growth rate of 0.14 day−1, a wet biomass of 16.4 g/L, a growth period of approximately 30 days, and an approximate 97% increase in fatty acid content during the transition from exponential phase to stationary phase. These parameters make K. veneficum a suitable choice as a bioresource for biodiesel production. Similarly, two other species were also determined to be appropriate for biodiesel production: the Dinophyceae Alexandrium andersoni and the Raphidophyte Heterosigma akashiwo.

Keywords: Inversion algorithm, SMOS, salinity

As part of the preparation for the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite mission, empirical sea-surface emissivity (forward) models have been used to retrieve sea-surface salinity from L-band brightness-temperature (T B) measurements. However, the salinity inversion is not straightforward, and substantial effort is required to define the most appropriate cost function. Various Bayesian-based configurations of the cost function are examined, depending on whether a priori information is used in the inversion. A sensitivity analysis of T B to several geophysical parameters has been performed and has shown that the instrument has low sensitivity to the parameters that modulate the T B (including salinity). The SMOS end-to-end simulator is used to test the accuracy of different cost-function configurations. Currently, the general opinion in the SMOS community is that a partially constrained cost function, in which the salinity constraint is effectively removed, is the most appropriate for salinity retrieval. The purpose of this letter is to show that we found no evidence that such a configuration performs better than a fully constrained or a nonconstrained one. Moreover, in contrast to previous results, we found that the fully constrained inversion does not converge to the reference or auxiliary salinity value and produces the most accurate salinity retrievals of the tested configurations. Therefore, such a configuration should not be disregarded for future tests.

Keywords: Alfacs Bay; Fiberglass; Filter feeding; Gut content; Mediterranean Sea; Mytilus galloprovincialis

Alfacs Bay is a N.W. Mediterranean estuary important for mussel (Mytilus galloprovincialis) aquaculture. During studies at the site, fiberglass particles were detected. The presence of fiberglass occurred naturally in the water throughout the study period (November 2006 to July 2007). An investigation was undertaken into its role in the feeding behavior of the local mussels. Fiberglass was present in all types of mussel samples. Rejection, which we would have expected for the whole study period, was only evident during the second season studied. To our knowledge, this is the first report of the ingestion of fiberglass by a marine organism. Our novel finding indicates the need to investigate fiberglass ingestion by marine organisms at different levels of the food web and the possible implications for human health and the health of the organisms themselves. In addition, we propose the use of mussels as sentinel organisms to monitor fiberglass contamination in marine ecosystems.

Keywords: erosive features; Mediterranean Outflow Water; Gulf of Cadiz; continental slope; contourites; neotectonics; Quaternary

Contourite depositional systems have been the focus of much recent research, but still relatively little is known about contourite erosive features and their associated processes. Based on multibeam bathymetry, side-scan imagery and different resolution seismic records, a detailed description and classification of the major erosive submarine valley features of the Contourite Depositional System of the Gulf of Cadiz middle slope is presented for the first time. Four types of erosive features have been differentiated, including contourite moats, contourite channels, marginal valleys and large isolated furrows, and interpreted in terms of their tectonic and oceanographic implications during the Quaternary. The study of the distribution and characteristics of erosive features is essential to better understand the present and past interaction of the Mediterranean Outflow Water (MOW) with the middle slope seafloor, and allows us to propose a new and more precise scheme for the MOW circulation patterns. This scheme includes a main along-slope circulation responsible for the excavation of the contourite moat and channels, and a secondary down-slope circulation responsible for the erosion of marginal valleys and isolated furrows. Three evolutionary stages have been observed in the development of the erosive system during the Quaternary, that can be related to changes in the distribution and splitting of the MOW as a consequence of the segmentation of the NE–SW diapiric ridges by neotectonic effects: 1) Early Pleistocene to Mid-Pleistocene: linear diapiric ridges; 2) Mid-Pleistocene to Late Pleistocene: diapiric reactivation and 3) Late Pleistocene to Holocene: main recent phase of diapiric ridges segmentation and rotation. This study provides important regional clues for establishing the evolution of the erosive features in relation with neotectonic effects, and represents a good example of the potential of erosive features as evidences for the reconstruction of the paleoceanography and recent tectonic changes.

A detailed regional characterization of the physiography, morphology and sedimentary systems of the Central Bransfield Basin (CBB) was carried out using swath bathymetry and high- and very high-resolution seismic profiles. The basin margins show continental shelves with numerous glacial troughs, and continental slopes where relatively wide and flat slope platforms represent the middle domain in an atypical physiographic scenario in glaciated margins. Although the CBB is tectonically active, most of the morphologic features are sedimentary in origin, and can be classified into four sedimentary systems: (1) glacial-glaciomarine, composed of erosional surfaces, glacial troughs, furrows and draping sheets; (2) slope-basin, formed by trough mouth fans, slope aprons, the Gebra-Magia instability complex and turbidity systems; (3) seabed fluid outflow system composed of pockmark fields; and (4) contourite, composed of drifts and moats. The sedimentary systems show a clear zonation from shelf to basin and their dynamics reflects the complex interplay among glacial, glaciomarine, marine and oceanographic processes involved in the entire shelf-to-basin sediment distribution. The CBB morphology is primarily controlled by glacial/interglacial cyclicity and physiography and to a lesser extent by tectonics and oceanography. These factors have affected the South Shetland Islands (SSI) and Antarctic Peninsula (AP) margins differently, creating a relatively starved SSI margin and a more constructional AP margin. They have also created two entire sediment-dispersal domains: the shelf-to-slope, which records the glaciation history of the CBB; and the lower slope-to-basin, which records the imprint of local factors. This study provides a 'source-to-sink' sedimentary scheme for glaciated margins, which may be applied to the basin research in other margins, based on the characterization of sedimentary systems, their boundaries and the linkages among them. This approach proves to be adequate for the identification of global and local factors governing the CBB and may therefore be applied to other study areas.

Keywords: disturbance; effects of climate change; marine biodiversity; mortality outbreak

Late in summer 2003, extensive mass mortality of at least 25 rocky benthic macro-invertebrate species (mainly gorgonians and sponges) was observed in the entire Northwestern (NW) Mediterranean region, affecting several thousand kilometers of coastline. We were able to characterize the mortality event by studying six areas covering the main regions of the NW Mediterranean basin. The degree of impact on each study area was quantified at 49 sites by estimating the proportion of colonies affected in populations of several gorgonian species compared with reference data obtained in years without mortality signs. According to these data, the western areas (Catalan coast and Balearic Islands) were the least affected, while the central areas (Provence coast and Corsica-Sardinia) showed a moderate impact. The northernmost and eastern areas (Gulf of Genoa and Gulf of Naples) displayed the highest impact, with almost 80% of gorgonian colonies affected. The heat wave of 2003 in Europe caused an anomalous warming of seawater, which reached the highest temperatures ever recorded in the studied regions, between 1 and 3 °C above the climatic values (mean and maximum). Because this exceptional warming was observed in the depth ranges most affected by the mortality, it seems likely that the 2003 anomalous temperature played a key role in the observed mortality event. A correlation analysis between temperature conditions and degree of impact seems to support this hypothesis. Under the present climate warming trend, new mass mortality events may occur in the near future, possibly driving a major biodiversity crisis in the Mediterranean Sea.

Keywords: Bacterial activity · Bacterial production · Central Atlantic · Nutrient supply · Primary production · Water column stability · Mediterranean mesocosms

Growing evidence of inorganic nutrient limitation on oceanic bacteria suggests a global dependence of bacterial activity and production on rates of nutrient supply. The present study examined whether surface bacterial abundance is significantly related to water column stability, and whether bacterial activity and growth rate are related to the rate of diffusive supply of inorganic nutrients to the mixed layer in the Central Atlantic during 2 meridional cruises. The 2 cruises were run under very different oceanic conditions, with relatively low values of bacterial activity in spring 1995 and relatively higher values in fall 1995. We obtained depth-resolved data in the second cruise and found that the integrated value of bacterial production was also related to the rate of nutrient supply, while integrated particulate primary production and chlorophyll concentration were not. There was also no relationship between particulate primary production and bacterial production. The relationship between nutrient supply and integrated bacterial production was tested with data from a mesocosm experiment showing a good fit to the pattern obtained in the Atlantic. Average bacterial production was ~21% of primary production in the Central Atlantic, with values ranging between 5 and 100%, and higher values in the tropical areas. The demonstration of a direct relationship between nutrient supply and bacterial activity helps to explain a relatively large bacterial biomass as compared to phytoplankton biomass, a low bacterial growth efficiency, and a high bacterial carbon demand relative to contemporaneous primary production often measured in the open ocean, as well as the accumulation of dissolved organic carbon (DOC) observed in nutrient-limited oligotrophic seas.

Mesopelagic prokaryotic communities have often been assumed to be relatively inactive in comparison to those from epipelagic waters, and therefore unresponsive to the presence of nearby upwelled waters. We have studied the zonal (shelf-ocean), latitudinal, and depth (epipelagic–mesopelagic) variability of microbial assemblages in the NW Africa–Canary Islands coastal-transition zone (CTZ). Vertical profiles of bacterial bulk and single-cell activity through the epi- and mesopelagic waters were combined with point measurements of bacterial respiration, leucine-to-carbon conversion factors and leucine-to-thymidine incorporation ratios. The overall picture that emerges from our study is that prokaryotes in the mesopelagic zone of this area are less abundant than in the epipelagic but have comparable levels of activity. The relationship between prokaryotes and heterotrophic nanoflagellates, their main predators, remains constant throughout the water column, further contradicting the assumption that deep ocean bacterial communities are mostly inactive. Both bulk and single-cell activity showed clear differences between stations, with higher mesopelagic activities closer to the shelf or affected by upwelling features. We also tested whether differences in microbial function between stations could be related to differences in bacterial community structure, and conclude that bacterial communities are very similar at similar depths in the deep ocean, even if the stations present order-of-magnitude differences in bacterial function.

Keywords: acclimation; cost-benefit; photosynthesis; phytoplankton; resource-allocation

Background: A key current issue in pelagic ecosystem modelling is obtaining better representations of the growth of phytoplankton so as to increase our understanding of the links between climate change and ocean biogeochemistry. Aims: Here we explore the use of cost-benefit analysis within the context of assessing the optimal distribution of resources for maximizing phytoplankton growth. Methods: We focus on capital and running costs by revisiting some of John Raven\'s cost-benefit analyses of chloroplast structure/function relations. Then, we describe a general framework for application of cost-benefit considerations in models of phytoplankton growth. Conclusions: Key to applying optimality criteria to phytoplankton growth models is quantifying the costs and benefits of alternative acclimation strategies. Costs include (1) capital costs of the structural and functional components of the cell, (2) running costs of CO2 fixation, nutrient acquisition, biosynthesis and repair, (3) opportunity costs for exploiting variability in the environment, and (4) taxes imposed by losses associated with transport to unfavourable environments, grazers and parasites. On short timescales of phytoplankton blooms, benefits can be assessed through influences on net growth rate, which can be increased by maximising resource gain (r-strategy) or minimizing losses (K-strategy). On longer timescales from years to millennia, the benefit is survival.

La conferència de Josep Maria Gili va mostrar la gran biodiversitat marina antàrtica, una de les grans sorpreses que han tingut els naturalistes en els darrers anys, però també s’hi van comentar els riscos derivats del canvi climàtic que posen en perill aquesta extraordinària mena d’ecosistemes

Keywords: Atlantic bluefin tuna * eggs * jellyfish larvae * Mediterranean * spawning period * Thunnus thynnus

For the first time, tuna spawning in a transport cage being towed from the western Mediterranean spawning ground to a fattening facility off the coast of northeastern Spain was examined during the 2008 fishing season. Daylight and night surface plankton samples were collected using bongo nets located in front of and behind the transport cage. The results for the different time intervals revealed clear and massive nocturnal spawning from 03:00 to 05:00, when the rear bongo was completely jammed with eggs (up to 250 000–300 000 eggs per 1000 m3). Egg size and morphology were consistent with the features of Thunnus thynnus eggs, and identification was confirmed by genetic analysis. Microscopic examination showed the eggs to be in the very early developmental stages. Spawning took place every night over the entire journey. The study showed that neither captivity nor handling/environmental changes along the route inhibited T. thynnus spawning to a very precise biological clock. The study also revealed the diel temporal concurrence of T. thynnus spawning and jellyfish larvae at the sea surface.

Keywords: Episodic meteorological forcing · Coastal osmotrophic plankton · Waves · Terrestrial runoff · Sediment resuspension · Nutrients · Time series · NW Mediterranean

In temperate coastal zones, episodic meteorological forcing can have a strong impact on the classical seasonal phytoplankton succession. Episodes of continental runoff and wind storms involve nutrient enrichment and turbulence, 2 factors that can promote primary production and alter the planktonic community species composition and size structure. We determined the joint influence of these 2 variables on the osmotrophic plankton of an oligotrophic NW Mediterranean open bay. We used an 8 yr long time series of monthly physical, chemical and biological water-column parameters, and we looked for correlations between these and several meteorological and physical high-frequency time series through cross-correlation analyses. Influence of river runoff in this particular location was found to be very important for phytoplankton dynamics, whereas no immediate response of bacterioplankton was detected. Resuspension events caused by waves had a secondary importance. Cross correlations allowed defining a sequence of responses to these types of forcing, from changes in water turbidity and salinity, to increases in phytoplankton and bacteria abundances through nutrient enrichments. The maximum response of the ecosystem in terms of chlorophyll a concentration lagged nutrient enrichment events by about 1 wk. A more detailed analysis was performed between June 2003 and June 2004, a period characterised by an intense drought in summer and by 6 strong meteorological events afterwards. The increase in the frequency of meteorological events during this period drove the system from heterotrophy to autotrophy. Our data stress the importance of episodic meteorological events in coastal planktonic communities.

The effects of turbulent motion on planktonic organisms have mainly been studied in the laboratory with devices capable of generating controlled turbulent conditions. Owing to technical and logistical difficulties, thorough assessments of hydrodynamics in such experiments are not routinely made. In this study, we examined the suitability of two widely used systems to generate isotropic, homogeneous, and stationary turbulence in laboratory containers: oscillating grid devices with large stroke length and relatively low frequencies of oscillation and orbital shaker tables. Turbulent kinetic energy dissipation rates were estimated from velocity measurements made with acoustic Doppler velocimeters. Both systems were shown to generate isotropic conditions in a relatively broad range of dissipation rates. Grid-stirred tanks produce homogeneous turbulence in both the horizontal and vertical dimensions, as long as stroke length is comparable to the height of the container. Turbulence in orbital shakers is not completely homogeneous, as it depends on the distance to the wall and to the surface. Empirical models are derived as a tool for the calculation of dissipation rates in the two systems within the ranges and conditions examined in this study.

A year-long series of monthly experiments with laboratory enclosures were conducted with water from Blanes Bay (NW Mediterranean) to analyse the change in the short-time response of the osmotrophic planktonic community to simulated turbulence and nutrient input events. Both experimental factors triggered a relative increase of biomass in the enclosures, in terms of chlorophyll a, bacteria and particulate organic matter. Ratios of particulate organic nitrogen to phosphorus became lower in the water than in the sediment, although turbulence partially smoothed out this difference. Initial physico-chemical conditions significantly influenced the short-time responses to experimental forcing. The response to turbulence, in terms of chlorophyll a, was maximum in spring. The response to nutrient enrichment was found to be seasonal, and was correlated with photoperiod and temperature, and also in situ nitrate and silicate concentrations and Secchi depth, which are proxies of recent inputs of nutrients resulting from episodes of resuspension and river discharge. This study shows robust qualitative regularities in the response of the osmotrophic planktonic community to episodes of turbulence and nutrient enrichment, with quantitative variability throughout the year, depending mostly on the recent record of hydrodynamic forcing.

Keywords: Parapenaeus longirostris, reproduction, fishery, spatio-temporal variations, hydrography, bottom characteristics, prey availability

The deep-water rose shrimp Parapenaeus longirostris is a demersal decapod crustacean that is commercially exploited by trawl fleets. The present work compares its population dynamics, biology and condition in two locations (southern and north-western Mallorca in the Balearic Islands, western Mediterranean, separated by a distance of 120 km) with different environmental conditions and explores the relationships between the species and certain environmental factors. Six multidisciplinary bimonthly surveys were carried out during 2003 and 2004 in these two locations (between 150 and 750 m depth) in order to collect data on the demersal species with bottom trawl, the hydrography (temperature and salinity) with CTD casts, and trophic resources (zooplankton in the water column and suprabenthos with Bongo net and Macer-GIROQ sledge respectively) and sediments with a Shipeck dredge. The trawl fleets from both locations were monitored by monthly on board sampling and daily landings obtained from sales bills. Additional data was obtained from other trawl surveys. Temporal differences were detected both annually, with a decreasing trend over the last years in species abundance, and seasonally, in the biological indexes analysed. Bathymetric differences were also found in abundance, mean length, sex-ratio and condition of females. There were clear differences between the two locations studied, with higher abundance, condition and mean length and a lower length at first maturity for females in the north-western location. Trophic conditions could act as a link between geo-physical and biological changes. These short spatio-temporal differences could be due to the higher productivity found at this location, with higher density of preferred prey for the studied species together with adequate seafloor topography, sediment composition and hydrographical characteristics.

Keywords: Sand–mud transition; Ebro continental shelf; Wave energy; Bed shear stress

An extensive dataset of sediment grain size and wave conditions in the Ebro Delta (NW Mediterranean) is used to verify the local scale applicability of the work of George and Hill (George, D.A., Hill, P.S., 2008. Wave climate, sediment supply and the depth of the sand–mud transition: a global survey. Mar. Geol., 254, 121–128) on the definition of the sand–mud transition (SMT). The proposal of using either a mean grain size of 63 μm or a mud content of 25% to define the presence of the sand–mud transition was locally verified (96% well-classified of a total of 382 samples). However, determining the depth of the sand–mud transition (hSMT) based only on the wave height shows several practical and conceptual inconsistencies that could be partially solved by including the wave period into the equation. On the Ebro Delta shelf, the use of the across-shelf distribution of skin friction accurately predicts the hSMT.

Keywords: Alexandrium minutum; Gonyostomum semen; Harmful algal blooms; Karenia brevis; Microcystis aeruginosa; Pseudonitzschia; Rhamnolipids

Biosurfactants have been suggested as a method to control harmful algal blooms (HABs), but warrant further and more in-depth investigation. Here we have investigated the algicidal effect of a biosurfactant produced by the bacterium Pseudomonas aeruginosa on five diverse marine and freshwater HAB species that have not been tested previously. These include Alexandrium minutum (Dinophycaee), Karenia brevis (Dinophyceae), Pseudonitzschia sp. (Bacillariophyceae), in marine ecosystems, and Gonyostomum semen (Raphidophyceae) and Microcystis aeruginosa (Cyanophyecae) in freshwater. We examined not only lethal but also sub-lethal effects of the biosurfactant. In addition, the effect of the biosurfactant on Daphnia was tested. Our conclusions were that very low biosurfactant concentrations (5 μg mL−1) decreased both the photosynthesis efficiency and the cell viability and that higher concentrations (50 μg mL−1) had lethal effects in four of the five HAB species tested. The low concentrations employed in this study and the diversity of HAB genera tested suggest that biosurfactants may be used to either control initial algal blooms without causing negative side effect to the ecosystem, or to provoke lethal effects when necessary.

Keywords: Dilution technique · Phytoplankton growth · Microzooplankton grazing · Coupling · Monte-Carlo simulation

Phytoplankton distribution is relatively constant in large areas of the surface ocean. In order to maintain this apparent stability, phytoplankton production and losses have to be balanced. Indeed, growth (μo) and grazing (g) rates obtained simultaneously with the dilution technique are often tightly coupled. One problem with this approach is that growth and grazing are not independent in the ecological model on which the method is based (net growth rate = μo – g). We evaluated to which extent this methodological artefact may influence the correlation between μo and g estimated using the dilution technique. Following a Monte-Carlo approach, we show that the methodological correlation can be substantial depending on: (1) the % error in the measurement of the state variable ND (e.g. chlorophyll a) and (2) the range (± SD) of the μo and g considered. As long as the error of ND is small (< 10%), the measured correlation between growth and grazing closely reflects a true ecological relationship. For large errors, the dilution technique can yield a substantial correlation between both variables, regardless of their ecological relation. The influence of this methodological correlation decreases as the range of growth and grazing rate values increases. We developed a procedure to evaluate the ecological versus the methodological nature of the correlation observed between μo and g. The application of this procedure to a data set obtained from a coastal site revealed that the high correlation observed (rS = 0.881, p < 0.0001) reflected a true ecological relationship.

The seismic reflection profile is the convolution of the seismic acquisition impulse response and the target impedance contrasts. In the ocean, these contrasts are mainly determined by the widths and gradients of the temperature transitions between the different water masses. Hence seismic oceanography profiles are sensitive to the frequency bandwidth of the seismic acquisition system. We tested a novel seismic source that allowed us to simultaneously profile the ocean with differing impulse responses. We show that frequencies ∼20 Hz are best to delineate large impedance contrasts that occur over a vertical scale of several tens of meters whereas frequencies ∼80 Hz image the boundaries of layers of around 10 m. We demonstrate a towed acquisition system that can operate from a research vessel to give a bandwidth from 10 to 120 Hz that could, if required, be modified to provide frequencies up to 200 Hz.

Keywords: Biliary PAHs; FACs; FF method; Teleost fish; NW Mediterranean; Ecological parameters

The fixed wavelength fluoresce (FF) method was used to estimate the levels of fluorescent aromatic compounds (FACs) in the bile of fourteen fish species of commercial and/or ecological interest. Sampling was carried out in the NW Mediterranean at depths ranging from 50 to 1000 m during four seasonal cruises. During the summer sampling period, some species were also collected from another site (Vilanova fishing grounds) for comparison. Baseline levels of the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, pyrene and benzo[a]pyrene were measured. Some seasonality was observed, with reduced FF levels in summer and no differences among sites, consistent with sediment PAH levels. We discuss our results in relation to fish phylogeny, season, depth, diet, trophic level and swimming capacity. Overall FF levels indicated differences among species; the suprabenthic feeders from shallow and deep communities, and Mullus barbatus in particular, displayed elevated FF values and are potential candidates for additional monitoring studies.

Keywords: sediment traps; organic carbon; biogenic silica; faecal pellets; particle fluxes; phytoplankton bloom

Downward particle fluxes were collected on two sites on the Antarctic continental shelf (407 m to 491 m depth) during 30 days in the austral spring and summer 2003–2004. The sampling period included the onset and demise of a phytoplankton bloom and the occurrence of a storm. The calm period previous to the storm enabled the phytoplankton to flourish and set conditions for a bloom. The storm enhanced mixing, production and particle aggregation that increased the transport of organic matter to the seabed. The wind-induced particle pulse represented 53% (306 mg OC m− 2 and 826 mg bSi m− 2) of the total mass flux collected during the study period at midwater column (179 m depth). Close to the seabed (28 m above the seafloor) the sample corresponding to the period of the highest flux in the upper trap was lost; however, high OC and bSi fluxes (279 mg OC m− 2 and 901 mg bSi m− 2) were still collected three days after. These fluxes were 42% and 30% of the respective fluxes collected at this depth throughout the study. Diatom aggregates and faecal pellets were the main vehicles for the transport of organic matter. Faecal pellets and foraminifera tests were ubiquitous in the traps; however, ellipsoidal faecal pellets were only present in the deeper traps where in some periods were more abundant than the faecal strings. Comparatively smaller particle fluxes than in other Antarctic settings during the same season were found and the differences attributed to the denser sea ice coverage (> 60%) observed during the present study. The chemical quality and the magnitude of the particle fluxes suggest that the phytoplankton bloom and the storm developed at least over a 75 km long area. The coincidence of these events produced in three days organic carbon and biogenic silica pulses over an area of at least 805 km2 of the continental shelf that may have amounted 85 to 225 tons and 308 to 725 tons, respectively. The occurrence of storms (> 15 m s− 1) during the spring–summer season in the last 20 years averaged 12 events per season, suggesting that the action of the wind could be very important in the development of organic matter-rich “green mats” on the sea floor.

This paper analyzes the spatial time series of surface chlorophyll (Chl) from the Sea viewing Wide Field of view Sensor and sea level anomaly (SLA) from altimetry satellite data from July 2002 to December 2007 in order to characterize the influence of the regional circulation on the phytoplankton biomass in the Balearic Sea. Correlations between Chl and SLA at seasonal and interannual time scales were examined using the singular value decomposition (SVD) method of the cross covariance matrix between Chl and SLA. Both seasonal cycles are negatively correlated in the whole basin, indicating that the nutrient availability in the surface layer for biological uptake is associated with the changes in the water column stratification. The coupled patterns, by applying the SVD method to Chl and SLA deviations from their seasonal cycles, identify three distinct biological responses to the circulation. The first pattern (explaining 70% of the covariance between Chl and SLA) indicates Chl enhancements around the Balearic Islands related to the Balearic current reinforced by the Northern current. The second pattern (12% of the covariance) shows that the peninsular coast is rather isolated from the regional surface circulation and its behavior is determined by the Ebro river discharges and land runoff. The third pattern (9%) represents higher Chl values along the peninsular slope and lower Chl around the Balearic Islands linked to the Northern current crossing the Ibiza channel without feeding the Baleric current.

Keywords: Epifauna; Functional traits; Fishing effort; Ecosystem-based management; NW Mediterranean

Selecting indicators of the response of the benthic community to fishing effort restrictions is important for testing the efficacy of management actions that seek to minimise ecosystem degradation. Components of epifaunal communities are sensitive to trawling, and concordant measurements of trawling effort can be used to establish a link between response and impact variables. Trawling effort on Mediterranean fishing grounds can be assessed, but the lack of data from communities inhabiting these areas makes establishing the response–impact relationship difficult. This study addresses this challenge by investigating benthic communities from the NW Mediterranean subjected to a gradient of fishing effort, and confirms that indicators based on functional components of epibenthos can be a useful tool to describe the response of communities to disturbance across habitat types.

Keywords: NW Mediterranean, Soil organic matter, Têt inner shelf, BIT index, Wet storm, Dry storm

River floods and storm waves are major processes for the dispersal and deposition of terrestrial organic matter (OM) in river-dominated coastal areas. A “wet storm” is connected to a flood with a high river discharge, while a “dry storm” is not associated with a flood. To better understand the sedimentation dynamics of terrestrial OM, especially soil OM, at the land–ocean interface during wet and dry storms, we studied sediment trap and core material collected on the Têt inner shelf (NW Mediterranean) using multiple organic proxies in combination with hydrodynamic parameters. The proportion of soil OM to the total OM in the trap material calculated based on the BIT (Branched and Isoprenoid Tetraether) index was higher during both wet (~40%) and dry (~30%) storms than during non-storm periods (~10%). However, only surface sediments (1-cm thick layers) recovered after December wet and moderate storms in 2003 showed enhanced soil OM percentages compared to the deeper sediments deposited during the last century. Given that the wet storm eroded 4-cm of seabed at the study site, flood-induced fresh soil OM was not deposited on the Têt inner shelf during the wet storm. However, the following moderate storm caused resuspension of floodassociated soil OM which was previously trapped nearshore. Accordingly soil OM was transported to the Têt inner shelf and stored there until the dry storm occurred.

This work investigates the ability of modelling seismic oceanography experiments by using underwater acoustic propagation equations. Seismic oceanography tries to retrieve the fine structure of the ocean water masses by processing the acoustic waves reflected in the low-contrast interfaces of fronts, eddies, internal waves or thermohaline intrusions. Since the reflectivity of such interfaces is of order 10-3-10-4, the absorption capability of the numerical boundaries becomes crucial. Complex Frequency Shifted offers a better alternative to classical Perfectly Matched Layer formulation, but has not yet been extended to acoustic equations. Here, first- and second-order Complex Frequency Shifted Perfectly Matched Layers equations are proposed which can provide reflection coefficients of order 10-5. Therefore, a numerical Finite-Difference Time-Domain (FDTD) scheme combined with the proposed CFS-PML equations is able to model such experiments.

Keywords: Gas hydrates; GIS; Heat flow; Fluid flow; Mud volcanoes; Gulf of Cadiz

This paper presents a computational model for mapping the regional 3D distribution in which seafloor gas hydrates would be stable, that is carried out in a Geographical Information System (GIS) environment. The construction of the model is comprised of three primary steps, namely: (1) the construction of surfaces for the various variables based on available 3D data (seafloor temperature, geothermal gradient and depth-pressure); (2) the calculation of the gas function equilibrium functions for the various hydrocarbon compositions reported from hydrate and sediment samples; and (3) the calculation of the thickness of the hydrate stability zone. The solution is based on a transcendental function, which is solved iteratively in a GIS environment. The model has been applied in the northernmost continental slope of the Gulf of Cadiz, an area where an abundant supply for hydrate formation, such as extensive hydrocarbon seeps, diapirs and fault structures, is combined with deep undercurrents and a complex seafloor morphology. In the Gulf of Cadiz, the model depicts the distribution of the base of the gas hydrate stability zone for both biogenic and thermogenic gas compositions, and explains the geometry and distribution of geological structures derived from gas venting in the Tasyo Field (Gulf of Cadiz) and the generation of BSR levels on the upper continental slope.

Towing gears are known to produce several kinds of effects on benthic ecosystems. As small organisms and benthic species with faster growth rates and shorter life histories can withstand the fishing mortality and benefit from reduced competition or predation, trawl fishing can enhance their proliferation. Thus, trawl fishing can lead to biomass loss and production increase, since smaller specimens are more productive than bigger ones. In the present study we evaluate the effects, if any, of trawling on benthic crustacean macrofaunal production rates. Sampling was carried out in two neighbouring sites in the central Adriatic Sea (central Mediterranean), one affected by fishing activity and one not. Production and production/biomass (P/B) ratio of 13 species of peracarid and eucarid crustaceans were estimated using the Hynes size-frequency method. Estimates measured at both sites were compared in order to test the hypothesis that higher production and P/B values should occur in the fished area rather than in the unfished one. Our results indicated that the effects on the species are more complex than expected in regard to this hypothesis, and that they depend on the ecological and behavioural characteristics of the selected species. Las artes de pesca de arrastre pueden tener varios tipos de efectos sobre los ecosistemas bénticos. Considerando que los organismos pequeños y las especies bénticas con mayores tasas de crecimiento y menores expectativas de vida pueden soportar la mortalidad por pesca y beneficiarse de una reducción en la competencia o depredación, la pesca de arrastre puede propiciar su proliferación y, por ende, resultar en una pérdida de biomasa y un incremento en producción, ya que las especies de menor talla son más productivas que las de mayor tamaño. En el presente estudio se evalúan los efectos, si es que los hay, de la pesca de arrastre sobre las tasas de producción de la macrofauna béntica. Los muestreos se realizaron en dos sitios adyacentes en la parte central del Mar Adriático (Mediterráneo central), uno impactado por actividad de pesca y otro no. Se estimaron la producción y la razón producción/biomasa (P/B) de 13 especies de crustáceos peracáridos y eucáridos mediante el método de frecuencia de tallas de Hynes. Las estimaciones para ambios sitios se compararon para probar la hipótesis de que los valores de producción y P/B deberían de ser mayores en la zona de pesca que en la zona de exclusión a la pesca. Los resultados indican que los efectos sobre las especies son más complejos que los esperados en relación a esta hipótesis, y que dependen de las características ecológicas y el comportamiento de las especies seleccionadas.

Les proliferacions de dinoflagel·lades semblen estar relacionades sovint amb certa estabilitat de la columna d’aigua. Experiments de laboratori han mostrat que la turbulència de petita escala pot disminuir-ne la taxa de creixement i inhibir-ne la divisió cel·lular, juntament amb un augment de la mida i dels continguts d’ADN i ARN. L’objectiu de la present Tesis Doctoral fou explorar els efectes directes de la turbulència de petita escala en processos fisiològics relacionats amb el cicle cel·lular i de vida, i investigar els mecanismes pels quals aquest factor ambiental interfereix en la biologia de les dinoflagel·lades per contribuir així a la comprensió del desenvolupament de llurs proliferacions. Es va evidenciar que el cicle cel·lular de la dinoflagel·lada Alexandrium minutum es va aturar transitòriament en la fase G2/M. Les investigacions del possible mecanisme d’interferència per part de la turbulència varen considerar la hipòtesis d’una alteració del sistema microtubular implicat en la dinomitosi, la participació dels receptors de rianodina en la via de mecanotransducció activada per aquest estímul, i l’existència d’una expressió gènica diferencial. La turbulència va modular també la concentració cel·lular de toxines i de DMSP, la formació de cists d’ecdisi. i la infecció de l’endoparàsit Parvilucifera sinerae en dinoflagel·lades. La infectivitat va disminuir en condicions d’agitació i l’encistament asexual no va constituir un mecanisme útil per a la seva prevenció. També es va avaluar l’adequació de diversos sistemes experimentals per a generar turbulència en el laboratori. L’agitador orbital és el més idoni per a estudis fisiològics amb dinoflagel·lades, ja que tot el cultiu és exposat a la turbulència i les cèl·lules no se’n poden escapar. La present tesis doctoral conclou que les dinoflagel·lades prefereixen condicions de calma en la columna d’aigua, ja que la seva fisiologia és sensible a les situacions de mescla intensa.

Keywords: Alexandrium minutum; cell cycle; Coulter Counter; dinoflagellates; flow cytometry; G2/Mitosis; mortality; small-scale turbulence

Decreased net population growth rates and cellular abundances have been observed in dinoflagellate species exposed to small-scale turbulence. Here, we investigated whether these effects were caused by alterations in the cell cycle and/or by cell mortality and, in turn, whether these two mechanisms depended on the duration of exposure to turbulence. The study was conducted on the toxic dinoflagellate Alexandrium minutum Halim, with the same experimental design and setup used in previous studies to allow direct comparison among results. A combination of microscopy and Coulter Counter measurements allowed us to detect cell mortality, based on the biovolume of broken cells and thecae. The turbulence applied during the exponential growth phase caused an immediate transitory arrest in the G2/M phase, but significant mortality did not occur. This finding suggests that high intensities of small-scale turbulence can alter the cell division, likely affecting the correct chromosome segregation during the dinomitosis. When shaking persisted for >4 d, mortality signals and presence of anomalously swollen cells appeared, hinting at the activation of mechanisms that induce programmed cell death. Our study suggests that the sensitivity of dinoflagellates to turbulence may drive these organisms to find the most favorable (calm) conditions to complete their division cycle.

In the Mediterranean, the standard fisheries management measures have been based mainly on effort limitation, minimum landing sizes for certain species and minimum mesh sizes. However, these measures will neither provide on their own full protection to all ecosystems attributes in need of protection, nor will guarantee sustainable fisheries. This chapter deals with new directions and ideas in the assessment and management of exploited marine resources in the Mediterranean, which must allow the future development of ecosystem approaches to fisheries management. It is argued here that fisheries assessment and management in the Mediterranean should consider not only traditional factors such as abundance and biomass of exploited resources and fishing effort, but also other relevant factors that have not been considered or properly addressed before, such as the identification and protection of essential fish habitats and benthic communities, the management of river outflows, the monitoring and management of recreational uses in coastal zones, the evaluation of the reproductive potential and physiological condition of exploited fishes and the consideration of climate change impacts. This chapter recommends a number of measures that will make possible a move from the traditional non-adaptive management, which tended to consider just those species of commercial importance, towards an adaptive system that incorporates explicit consideration of the broader marine environment issues.

Keywords: Antarctica - Sea pen - Pennatulacea - Octocorallia - Malacobelemnon - New species

The pennatulacean genus Malacobelemnon has previously been considered to be distributed in the Western Indian and western Pacific Oceans, with one described species and another possible undescribed species from South Africa. An undescribed shallow-water species attributable to this Kophobelemnidae genus has been collected from the Antarctic region (King George, South Shetland Islands). The present paper reports this discovery, providing the description and illustrations of the new species, Malacobelemnon daytoni n. sp. Some of the characters previously considered in the genus Malacobelemnon should be slightly modified to include the new Antarctic species. The general colony shape, the distribution of siphonozooids, number of longitudinal autozooids rows, and the length and shape of the section of axis are the main characters used to distinguish the new species from the other in the genus M. stephensoni Tixier-Durivault 1965. From a bathymetric point of view, Malacobelemnon daytoni n. sp. is one of the shallowest pennatulacean species recorded, being an important contribution to the shallow-water Antarctic fauna

During the spring and summer of 2003, the small-scale spatial distribution of fish larvae was analysed in and around the Medes Islands marine protected area (MPA). High specific richness was found during both seasons, which is when most coastal fish species spawn in the NW Mediterranean. Despite the small dimensions of the area, well-defined larval fish patterns were found. Larvae from pelagic eggs were located farther from the adult habitat than those from demersal eggs; however, there were exceptions, which highlight the influence of larval behaviour and pelagic larval duration. Inside the reserve, there was both a high diversity index and a high abundance of shorefish larvae in relation to the high abundance of adults and a possible retention of larvae in the MPA. Although there was a great variability both in species composition and abundance between periods, the sampling station assemblages were similar. Factors such as habitat and spawning location of adults, and the role of the MPA seem to determine the stability of the larval distribution patterns in time. The importance of small-scale approaches is highlighted to understand the fish larval spatial distributions.

The influence of organic nutrients on the evolution of Pseudo-nitzschia delicatissima cultures was investigated in an enrichment experiment with high-molecular-weight dissolved organic matter (HMWDOM) and in an uptake assay with 15N-ammonium and 15N-urea. HMWDOM was extracted from seawater collected at a nearby shore station during the decline of a diatom bloom. Four incubations were prepared: L1/5+DOM (P. delicatissima grown in L1 growth medium with 1/5 of the nitrate concentration of standard L1), (L1-N)+DOM (L1 without nitrate, i.e. nitrogen-deficient treatment), L1-DOM (control culture without added DOM) and BV+DOM (bacterial and viral control, free of microalgae). Incubations were carried out for 10 days. Chlorophyll a concentrations differed after day 4 and reached higher levels in the L1-DOM incubation by the end of the experiment; however, similar growth rates were observed in all incubations (1.64 ± 0.05 divisions day–1). The persistently lower cellular chlorophyll content in (L1-N)+DOM during the experiment was consistent with N limitation conditions. The data suggested that the nitrogen needed for the growth of (L1-N)+DOM cells might have originated from the DOM. Based on the results of 15N uptake assays, it was concluded that P. delicatissima more readily acquires ammonium than urea. Nevertheless, under low N conditions, P. delicatissima may use urea as an alternative N source, and comparable photosynthetic rates are attained on either substrate. Taken together, our results suggest a positive effect of organic nutrients on the growth of P. delicatissima.

Alexandrium catenella was grown in semi-continuous cultures in L1 growth-medium enriched with concentrated dissolved organic matter (DOM) from a diatom bloom. In medium with full nitrate (880 µM), the average growth rate was 0.32 ± 0.01 day–1 (L1, control without added DOM). Adding natural marine dissolved organic nitrogen (DON) at levels of 20–30 µM above background (10 µM) led to a higher growth rate (L1+DOM, 0.40 ± 0.00 day–1). In medium with lower nitrate level (175 µM) and higher DON (L1/5+DOM treatment), both dissolved inorganic nitrogen and DON were used, leading to the highest growth rates (0.43 ± 0.03 day–1). In medium without nitrate [(L1-N)+DOM treatment], the low ammonium concentrations observed throughout the experiment (<1 µM) as well as the uptake kinetics of A. catenella could not have supported the observed growth rates, leading us to conclude that DON was directly used by this organism, rather than using N remineralized by bacteria (from DON). The decrease of bacteria in DOM enriched bioassays could point to a nutrient limitation and competition with A. catenella for organic matter. Viruses likely contributed as an additional factor to keep the bacterial population from becoming dominant.

Keywords: organic and inorganic matter; experimental research; harmful algal blooms (HABs); microalgae nutrition

Samples were collected during one annual cycle (April 2007–March 2008) at Alfacs Bay (NW Mediterranean Sea) central station in order to assess the influence of organic nutrients in the growth of the microalgae assemblage, with special reference to Pseudo-nitzschia spp. This potentially toxic diatom forms natural and recurrent blooms in the study area. To assess further the relationship between Pseudo-nitzschia spp. and nutrients an enrichment experiment with high molecular weight dissolved organic matter (HMWDOM) was performed with field samples obtained during a Pseudo-nitzschia spp. bloom. HMWDOM was extracted from water collected at Alfacs Bay. Five bioassays were prepared: N + P (seawater with addition of nitrate and phosphate), DOM (addition of HMWDOM), (−N + P) + DOM (nitrogen deficient, with addition of phosphate and HMWDOM), (N + P) + DOM (addition of nitrate, phosphate and HMWDOM), seawater control (without added nutrients), and B + DOM (control of bacteria, without microalgae). The experiment was run in batch mode over 4 days. Results from the field study revealed that the concentrations of organic nutrients mostly surpassed the inorganic pool. Pseudo-nitzschia spp. was the most frequent and abundant taxa of the microalgae community. The micro-planktonic assemblage was arranged according to a seasonal factor (ANOSIM and cluster analysis). DON, nitrate and silicate were the most important abiotic parameters contributing to the dissimilarities between seasons (SIMPER analysis) and thereby potentially influencing the seasonal distribution of microalgae in the representative station. In the experimental investigation, Pseudo-nitzschia cells increased by the end of the experiment in the DOM bioassay but no respective increase was observed for chlorophyll a. This could point to an acquisition of nutrients through the DOM fraction that would conjointly reduce the need of chlorophyll a. The data obtained suggest that organic nutrients may exert an important role in the development of microalgae, including Pseudo-nitzschia spp., in the selected location.

Keywords: Androstenedione metabolism; Bolinus brandaris; Hexaplex trunculus; 5α-reductase; 17β-HSD; Tributyltin; Triphenyltin; Testosterone

A comparative study was performed to assess the metabolism of the androgen precursor androstenedione (AD) in two gastropod species from the Muricidae family: Bolinus brandaris and Hexaplex trunculus. AD was mainly converted to 5α-dihydrotestosterone by microsomal fractions isolated from Bolinus brandaris, whereas it was primarily metabolized to testosterone by Hexaplex trunculus. Sex differences in the metabolism of AD were only detected in Bolinus brandaris and attributed to higher 5α-reductase activity in males. Thereafter, the effect of the organotin compounds, tributyltin (TBT) and triphenyltin (TPT), on the metabolism of AD was investigated. A significant interference was only detected in females, and differences between the modes of action of the two compounds were observed: TPT was a strong inhibitor of 5α-reductase activity in B. brandaris at a concentration as low as 100 nM whereas only TBT (10 µM) altered the metabolism of AD in H. trunculus by increasing the activity 17β-hydroxysteroid dehydrogenase (17β-HSD). Thus, this work shows that the metabolism of the androgen precursor AD strongly differs among gastropod species, both in terms of activity and metabolic profile, and further demonstrates the ability of TBT and TPT to interfere with key enzymatic pathways involved in androgen synthesis.

Keywords: Inverse model - WOCE A16N section - nutrients - neutral density - water mass - interdecadal changes - ocean descriptor

We propose a simple polynomial expression for neutral density and nutrients as a function of potential temperature, pressure and salinity. The expression is applied to the 1988 North Atlantic A16N WOCE meridional section and the polynomial coefficients are calculated using an inverse technique. The resulting polynomials show good skill in reproducing the nutrients and density structure, as verified through an analysis of variance (ANOVA) test. The large-scale changes in the polynomial coefficients occur between equatorial (E), tropical (T), subtropical (ST), and subpolar (SP) waters. The temperature and pressure coefficients experience substantial changes at all transitions (E-T, T-ST, and ST-SP), while the salinity ones only have major variations at the T-ST transition. Mesoscale-like oscillations occur all along the section but are relatively small, except between about 40 and 50°N, in a region of rough bottom topography. The density field is reconstructed using individual and group coefficients, and the contribution of each coefficient is identified. The method is also applied to analyze the neutral density distribution in a nearly identical 2003 section, removing near-surface density values that may be related to different warming/cooling of the surface layer. The results show close resemblances but also some significant variations, which are discussed in terms of interdecadal variability. Hence, we argue that the set of calculated coefficients provides good integral descriptors for the vertical structure of the ocean.

Keywords: Ocean circulation, Intermediate water, Density currents, Atlantic Ocean, Africa

In this article, historical and climatological datasets are used to investigate the seasonal northward propagation of Antarctic Intermediate Waters (AAIW) along the eastern margin of the North Atlantic subtropical gyre. A cluster analysis for data north of 26°N shows the presence of a substantial number of hydrographic stations with AAIW characteristics that stretch northeast along the African slope. This water mass extends north during fall, as shown both through the comparison of actual and climatological data, and by applying a mixing analysis to normal-to-shore seasonal sections at both 28.5° and 32°N. The mixing analysis is further used with several fall cruises between 32° and 36°N, and shows that at these latitudes the core of AAIW propagates along the 27.5 isoneutral with contributions that reach as much as 50% at 32.5°N. An idealized Sverdrup-type model is used in combination with climatological hydrographic and wind data to examine what forces this eastern boundary propagation. It is found that column stretching, initiated in the tropical North Atlantic, is the dominant term in the vorticity balance of the AAIW stratum, capable of sustaining a winter–spring–summer northward transport of about 3-4 Sv (1 Sv ≡ 106 m3 s−1) that reaches as far north as the Canary Archipelago (28°N). In fall, this transport may continue beyond 28°N, sustained by a near-slope meridional stretching of this water stratum. AAIW probably fades away in the northeastern region as the result of several processes, specially enhanced double diffusion with surrounding waters and interaction with Mediterranean water lenses.

Keywords: Ecosystem model; Top-down; Bottom-up; Fishing impact; Trophic interaction; Environmental forcing; Ecopath with Ecosim; Climate effects

Fishing mortality and primary production (or proxy for) were used to drive the dynamics of fish assemblages in 9 trophodynamic models of contrasting marine ecosystems. Historical trends in abundance were reconstructed by fitting model predictions to observations from stock assessments and fisheries independent survey data. The model fitting exercise derives values for otherwise unknown parameters that specify the relative strength of trophic interactions and, in some instances, a time series anomaly for changes in primary production. We measured how much better or worse were model predictions when bottom-up forcing by primary production were added to top-down forcing by fishing. Searching for cross system patterns, the relative contribution of fishing and changes in primary production, mediated through trophic interactions, are evaluated for the ecosystems as a whole and for selected similar species in different ecosystems. The analysis provides a simple qualitative way to explain which forcing factors have most influence on modeled dynamics. Both fishing and primary production forcing were required to obtain the best model fits to data. Fishing effects more strongly influenced 6 of 9 of the ecosystems, but primary production was more often found to be the main factor influencing the selected pelagic and demersal fish stock trends. Examination of sensitivity to ecological and model parameters suggests that the results are the product of complex food-web interactions rather than simple deterministic responses of the models.

Keywords: functional diversity, grazing rates, MAST-4, MAST-1C, prey preference, uncultured flagellates

Aquatic assemblages of heterotrophic protists are very diverse and formed primarily by organisms that remain uncultured. Thus, a critical issue is assigning a functional role to this unknown biota. Here we measured grazing rates of uncultured protists in natural assemblages (detected by fluorescent in situ hybridization (FISH)), and investigated their prey preference over several bacterial tracers in short-term ingestion experiments. These included fluorescently labeled bacteria (FLB) and two strains of the Roseobacter lineage and the family Flavobacteriaceae, of various cell sizes, which were offered alive and detected by catalyzed reporter deposition-FISH after the ingestion. We obtained grazing rates of the globally distributed and uncultured marine stramenopiles groups 4 and 1 (MAST-4 and MAST-1C) flagellates. Using FLB, the grazing rate of MAST-4 was somewhat lower than whole community rates, consistent with its small size. MAST-4 preferred live bacteria, and clearance rates with these tracers were up to 2nl per predatr per h. On the other hand, grazing rates of MAST-1C differed strongly depending on the tracer prey used, and these differences could not be explained by cell viability. Highest rates were obtained using FLB whereas the flavobacteria strain was hardly ingested. Possible explanations would be that the small flavobacteria cells were outside the effective size range of edible prey, or that MAST-1C selects against this particular strain. Our original dual FISH protocol applied to grazing experiments reveals important functional differences between distinct uncultured protists and offers the possibility to disentangle the complexity of microbial food webs.

Keywords: alternative splicing; brain; fish mode; GPR54; Kiss1r; kisspeptin; kisspeptin receptor; kisspeptin-1 receptor; neuroendocrinology; puberty; Senegalese sole; Solea senegalensis; teleost

The KISSPEPTIN-1 receptor (KISS1R) and its ligands (KISSPEPTINS) are implicated in the regulation of the onset of puberty. We report the coding region and genomic structure of the kiss1r gene of a modern teleost, the Senegalese sole (Ss). Ss kiss1r cDNA contained an opening frame of 1137 bp, which results in a predicted 378 amino acid protein. Searching genomic databases allowed the identification of kiss1r orthologues in six new species belonging to three vertebrate groups and established the evolutionary relationships of all KISS1R sequences available to date. Analysis of Ss kiss1r revealed for the first time in any vertebrate KISS1R gene the presence of features that are characteristic of a mechanism of alternative splicing. This was confirmed by the identification of two transcripts, Ss kiss1r_v1 and Ss kiss1r_v2. The latter, arising from intron III retention, contained a 27 codons insert in transmembrane region 4 with two stop codons, suggesting it may lead to a truncated protein. The mRNA of the two variants was differently expressed in several tissues. In the brain, levels of the Ss kiss1r_v1 were higher than those of Ss kiss1r_v2. In the gonads, the opposite was observed. Both isoforms exhibited changes depending on sex and maturity stage. The presence of two variants may help to explain some discrepancies observed in past studies regarding KISS1R expression during puberty. Thus, the existence of alternative splicing for the KISS1R gene may contribute to our understanding of the many physiological functions suspected to be mediated by KISSPEPTIN-KISS1R signaling.

The physiological condition of larval Antarctic krill was investigated during asutral autumn 2004 and winter 2006 in the Lazarev Sea. Teh condition of larvae was quantified in both seasons by determining their body length (BL), dry weight (DW), elemental and biochemical composition, stomach content analysis, and rates of metabolism and growth. Overall the larvae in autumn were in better condition under the ice than in open water, and for those under the ice, conditions decreased from autumn to winter. Thus, growth rates of furcilia larvae in open water in autumn were similar to winter values under the ice (mean, 0.0008 mm d-1), whereas autumn under-ice values were higher (0.015 mm d-1). Equivalent larval stages in winter had up to 30% shorter BL and 70% lower DW than in autumn. Mean respiration rates of winter larvae were 43% lower than of autumn larvae. However, their ammonium excretion rates doubled in winter from 0.03 to 0.06 Nh4 DW-1 h-1, resulting in mean O: N ratios of 46 in autumn and 15 in winter. Thus, differing metabolic substrates were used between autumn and winter, which supports a degree of flexibility for overwintering of larval krill. The larvae were eating small copepods (Oithona spp.) and protozoans, as well as autotrophic food under the ice. The interplay between under-ice topography, apparent current speed under sea ice, and the swimming ability of larval krill is probably critical to whether larval krill can maintain position and exploit suitable feeding areas under the ice.

Keywords: Seamount dynamics TaylorCones Sedlo Seamount Vortexpair

Observations from a five-mooring array deployed in the vicinity of Sedlo Seamount over a 4-month period, together with supporting hydrographic and underway ADCP measurements, are described. Sedlo Seamount is an elongated, intermediate depth seamount with three separate peaks, rising from 2200 m water depth to summit peaks between 950 and 780 m depth, located at 40°20′N, 26°40W. Currents measured in depth range 750 and 820 m- the layer close to the summit depth of the shallowest southeast peak- showed a mean anti-cyclonic flow around the seamount, with residual current velocities of 2-5 cm s-1. Significant mesoscale variability was present at this level, and this is attributed to the weak and variable background impinging flow. Stronger, more persistent currents were found at the summit mooring as a result of tidal rectification and some weak amplification. Below 1300 m, currents were extremely weak, even close to the seabed. Time series of relative vorticity for the depth layer 750-820 m showed persistent anti-cyclonic vorticity except for two periods of cyclonic vorticity. A mean relative vorticity of -0.06f (f=the local Coriolis frequency) was calculated from a triangle of current meters located at the flanks of the seamount. Modelling results confirmed that anti-cyclonic flow above the seamount was likely due to Taylor Cone generation driven by a combination of steady impinging and tidally rectified flow. The closed circulation pattern over the seamount was found to extend to not, vert, similar150 m above the summit level, consistent with simple idealised theory and the supporting hydrographic observations. At shallower depths (<500 m) model simulations predicted a predominantly cyclonic recirculation most likely controlled by topographic steering along the zonal axis of the seamount. There was some indication of flow reversal at these depths from Acoustic Doppler Current Profiler (ADCP) measurements carried out at one hydrographic survey. The model results were in good agreement with observations at the seamount summit, but were unable to reproduce the mesoscale variability patterns recorded in shallower layers. Kinetic energy patterns derived from the model revealed high variability in the oceanic far field downstream of the seamount summit probably as a result of complex flow interaction along the chain of seamount peaks. Possible impacts of the flow dynamics on the biological functioning at Sedlo Seamount and its surroundings are discussed.

Keywords: Macroecology - Pelagic copepods - Large scale distribution - Mediterranean Sea - Centropages

The Mediterranean Sea is located in a crossroad of mid-latitude and subtropical climatic modes that enhance contrasting environmental conditions over both latitudinal and longitudinal ranges. Here, we show that the large-scale environmental forcing is reflected in the basin scale trends of the adult population of the calanoid copepod Centropages typicus. The species is distributed over the whole Mediterranean basin, and maximal abundances were found in the north-western basin associated to oceanic fronts, and in the Adriatic Sea associated to shallow and semi enclosed waters. The peak of main abundances of C. typicus correlates with the latitudinal temperature gradient and the highest seasonal abundances occurred in spring within the 14–18°C temperature window. Such thermal cline may define the latitudinal geographic region where C. typicus seasonally dominates the >200 μm-sized spring copepod community in the Mediterranean Sea. The approach used here is generally applicable to investigate the large-scale spatial patterns of other planktonic organisms and to identify favourable environmental windows for population development.

Keywords: connectance, food webs, indirect effects, inverse Jacobian matrix, linkage density, press perturbation, specialization

The prediction of the effects of disturbances in natural systems is limited by the general lack of knowledge on the strength of species interactions, i.e., the effect of one species on the population growth rate of another, and by the uncertainty of the effects that may be manifested via indirect pathways within the food web. Here we explored the consequences of changes in species populations for the remaining species within nine exceptionally well-characterized empirical food webs, for which, unlike the vast majority of other published webs, feeding links have been fully quantified. Using the inverse of the Jacobian matrix, we found that perturbations to species with few connections have larger net effects (considering both direct and indirect pathways between two species) on the rest of the food web than do disturbances to species that are highly connected. For 40% of predator–prey links, predators had positive net effects on prey populations, due to the predominance of indirect interactions. Our results highlight the fundamental, but often counterintuitive, role of indirect effects for the maintenance of food web complexity and biodiversity.

Ongoing declines in production of the world\'s fisheries may have serious ecological and socioeconomic consequences. As a result, a number of international efforts have sought to improve management and prevent overexploitation, while helping to maintain biodiversity and a sustainable food supply. Although these initiatives have received broad acceptance, the extent to which corrective measures have been implemented and are effective remains largely unknown. We used a survey approach, validated with empirical data, and enquiries to over 13,000 fisheries experts (of which 1,188 responded) to assess the current effectiveness of fisheries management regimes worldwide; for each of those regimes, we also calculated the probable sustainability of reported catches to determine how management affects fisheries sustainability. Our survey shows that 7% of all coastal states undergo rigorous scientific assessment for the generation of management policies, 1.4% also have a participatory and transparent processes to convert scientific recommendations into policy, and 0.95% also provide for robust mechanisms to ensure the compliance with regulations; none is also free of the effects of excess fishing capacity, subsidies, or access to foreign fishing. A comparison of fisheries management attributes with the sustainability of reported fisheries catches indicated that the conversion of scientific advice into policy, through a participatory and transparent process, is at the core of achieving fisheries sustainability, regardless of other attributes of the fisheries. Our results illustrate the great vulnerability of the world\'s fisheries and the urgent need to meet well-identified guidelines for sustainable management; they also provide a baseline against which future changes can be quantified.

Keywords: Sea Surface Salinity Model error covariances Ensemble modelling Regional ocean modelling Wind stress forcing Eastern subtropical North-Atlantic Ocean

Motivated by the imminent launches of two Sea Surface Salinity (SSS) satellite missions, this paper investigates salinity error covariances due to wind stress uncertainties in a regional simulation of the eastern North-Atlantic Ocean from 2000 to 2006. This work follows the study by Mourre et al. (2008), which concluded that the wind stress forcing was the main source of SSS model error in this region. The present study is based on ensemble simulations that start from the same initial conditions but are driven by different wind stresses. The error modes of the wind stress forcing field are approximated by the variability modes of the wind stress. Our results indicate that the surface salinity ensemble spread has an average value over the modelling domain of around 0.1 psu. Under the influence of model dynamics, the largest spreads are found in areas of significant SSS advection. The surface salinity spread also experiences a significant temporal variability at seasonal and interannual scales. The periods of error growth have a duration around 3-4 months. Horizontal SSS error correlation distances are inhomogeneous and anisotropic due to ocean dynamics. They are larger than 100 km almost everywhere in the domain, and can extend over 400 km along the path of the main surface currents. In addition, salinity and temperature anomalies induced by the wind stress forcing are not confined to the surface layers, but propagate into the ocean interior under the influence of vertical dynamical processes. Vertical salinity error correlation distances from the surface are locally larger than the annual maximum mixed layer depth. In areas where subduction occurs, the vertical correlation radii exceed 500 m. According to these results, it is expected that satellite SSS data assimilation in this region will be challenging because (i) the magnitude of the SSS model error is of the same order as the accuracy of the observations, and (ii) the horizontal SSS error correlation scales are comparable to the spatial resolution of satellite SSS products. On the positive side, the temporal resolution of satellite SSS data is finer than the time scale of SSS model error growth.

Keywords: Estrogen; Estradiol-17β; Aromatase; cyp19a; Aromatase inhibitor; Fadrozole; Androgen; 17α-methyldihydrotestosterone; Cyproterone acetate; Tamoxifen; Sex differentiation; Androgen receptor

The objective of this study was to contribute to our understanding of the role of sex steroids in fish sex differentiation and male maturation. Sexually undifferentiated sea bass were administered 17α-methyldihydrotestosterone (MDHT), estradiol-17β (E2), fadrozole (Fz), cyproterone acetate (CPA) or tamoxifen (Tx). MDHT produced 100% males whereas E2 and Tx resulted in 100% females. Fz produced 95% males while CPA did not alter sex ratios. E2 treatment did not affect gonadal aromatase (cyp19a) expression levels, supporting the possibility that the feminizing effect of exogenous E2 are not directly related to cyp19a regulation. Both MDHT and Fz decreased cyp19a expression. Moreover, androgen receptor (ar) expression levels increased during development in all but the MDHT group, suggesting that early exposure to an androgen down-regulates subsequent ar expression in males and that Fz does not interact with the androgen receptor. Together, these observations indicate that although MDHT and Fz result in a similar phenotype, the molecular pathways involved are likely different, and show that Fz masculinization is the consequence of inhibited ovarian differentiation rather than of a direct androgenic effect. Further, since CPA did not alter sex ratios when administered during the period of highest androgen sensitivity, we suggest that androgens are not required for initial testicular differentiation in the previous seabass. MDHT and Fz did not alter the number of precocious males but reduced and increased, respectively, their gonadosomatic index (GSI). In addition, Fz had lasting effects on the GSI of precocious and non-precocious males, probably due to alterations of estrogen function in the testis.

Keywords: Ocean turbulence, Wavelets, Coherent Vortex Extraction, Microcanonical Multifractal Formalism

It has been often argued that oceanic turbulence is similar to 2D turbulence; they share many properties and more particularly they seem to be driven by the dynamics of coherent vortices over large scales. For this reason, the application of techniques based on the extraction of coherent vortices as the Coherent Vortex Extraction (CVE) seems a natural choice for the description of ocean data. In this paper we will discuss on the properties of oceanic turbulence under the perspective of the Microcanonical Multifractal Formalism (MMF), and specifically for the description of altimetry data. We will see that MMF gives a good description of the geometry and statistical properties of altimetry data. We will show that a direct application of CVE on altimetry data has a rather low performance in comparison to other systems, which we justify as a consequence of the inhomogeneous character of ocean turbulence. We also show that a MMF-based separation criterion improves the standard CVE and allows to mitigate these problems. The results are discussed in the perspective of a cascade-based description of ocean turbulence.

Keywords: tissues, starvation, condition, Sardina pilchardus, Engraulis encrasicolus, Atherina presbyter, Paralichthys orbignyanus.

In some routine studies of larval condition based on RNA:DNA ratios, heads and/or guts are removed for further age and feeding analysis. Also, during capture larvae are often found with their eyes missing. In this work we analysed tissues effects (muscle, head, eye, gut and the whole larvae) on RNA:DNA ratios from different species (Sardina pilchardus, Engraulis encrasicolus, Atherina presbyter and Paralichthys orbignyanus) in different developmental stages and from different locations. For all species and development phases, it was shown that RNA:DNA ratios in the head were significantly lower than in muscle or gut. The comparison of RNA:DNA ratios of head with or without eyes did not show significant differences. In a comparison of results from muscle from two tail sections, RNA:DNA ratios were higher for the anterior section in Sardina pilchardus and Engraulis encrasicolus larvae. Caution is needed when RNA:DNA ratios are compared with other studies employing different dissection protocols. For the species studied we propose conversion factors to be applied to RNA:DNA ratio data when different body sections are analysed. We discuss the most appropriate tissues for assessing nutritional condition in fish larvae, based on trends in concentrations of nucleic acids and ratios during starvation experiments.

Keywords: Cold water corals · Submarine canyons · ROVs · Manned submersible · Population density · Spatial statistic · Spatial patterns · Patch size

The occurrence and density of 3 cold-water coral (CWC) species (Madrepora oculata, Lophelia pertusa and Dendrophyllia cornigera) were investigated in the Cap de Creus canyon (northwestern Mediterranean) by conducting and analysing 22 video survey transects. Species distribution patterns were also investigated at 3 spatial extents (km, 100s of m and m) across 3 of the transects using spatial statistics. Additionally, the locations of snagged benthic long-line fishing gear were logged across these 3 transects. Video surveys were carried out by both remotely operated vehicles (ROVs) and the JAGO manned submersible. CWCs were present in 15 of the 22 survey transects, predominantly those covering areas with hard substrate (boulders or hardrock outcrops). M. oculata was the most abundant CWC species in the survey transects, whereas L. pertusa and D. cornigera were much more sparsely distributed, with only isolated colonies observed in the majority of transects. M. oculata showed a significant contagious distribution pattern across the analysed transects, with several scales of spatial pattern and patch size being detected, whereas L. pertusa and D. cornigera were not found in sufficient numbers to apply spatial statistics. Different covariance patterns were found across the transects between snagged fishing gear and the presence of M. oculata. Further investigation of this relationship and the level of hazard posed by long-line fishing to M. oculata colonies is required prior to development of a protective management strategy.

Keywords: Shelf to basin sediment transport; Downward particle fluxes; Storms; Dense shelf-water cascading; Northwestern Mediterranean; Gulf of Lions

Downward particle fluxes and hydrodynamics in the northwestern Mediterranean basin were measured by a sediment trap and a current meter deployed at 2350 m depth, 250 m above bottom, from November 2003 to April 2005. During the winter of 2003–2004 there were high river discharges, two strong E–SE storms and several moderate storms and short periods of moderate dense shelf-water cascading during which dense shelf water did not reach the deep basin. Downward particle fluxes at the basin site were low during most of this winter but increased above one order of magnitude as a consequence of the strong storm and moderate cascading event that occurred in late February 2004. During the winter of 2004–2005, neither important river floods nor strong storms occurred but there were very intense and persistent dense shelf-water cascading events from February to April 2005. Dense shelf water, mixed with offshore convection water, reached the basin site in early March 2005, increasing downward particle fluxes by more than two orders of magnitude for more than 1 month. These observations indicate that events of significant sediment transport to the northwestern Mediterranean basin can be caused by severe winter E–SE storms associated with moderate cascading events or by exceptionally intense and persistent dense shelf-water cascading episodes alone. On the other hand, river floods, severe storms during water column stratification conditions (without cascading) and moderate storms concurrent with moderate dense shelf-water cascading did not generate sediment transport events able to reach the basin.

Keywords: Palinuridae; Decapoda; Rapid radiation; Tethys

Molecular data can aid in the resolution of conflicting hypotheses generated through difficulties in the interpretation of morphological data and/or an incomplete fossil record. Moreover, the reconstruction of phylogenetic relationships using molecular data may help to trace back the origin of morphological innovations which had a major impact on the radiation of a taxonomical group. In this work, different nuclear (18S, 28S, and H3) and mitochondrial (16S and COI) gene regions were sequenced in a total of 35 Achelatan species to test conflicting hypotheses of evolutionary relationships within the Achelata infraorder and solve the taxonomic disagreements in the group. The combined molecular dataset strongly supports the hypothesis that Achelata is a monophyletic group composed of two main families: Palinuridae and Scyllaridae. Synaxidae is found to be a polyphyletic group, which should be included within Palinuridae. Consequently, our results indicate that the origin of the stridulating organ occurred only once during Achelata evolution. Finally, the two main clades found within the Scyllaridae are in agreement with previous inferences based on adult morphological data. The dating of divergence of Achelata obtained with a relaxed-clock model is compatible with previous hypotheses of a Triassic origin of the Achelata.

Background Molecular tools may help to uncover closely related and still diverging species from a wide variety of taxa and provide insight into the mechanisms, pace and geography of marine speciation. There is a certain controversy on the phylogeography and speciation modes of species-groups with an Eastern Atlantic-Western Indian Ocean distribution, with previous studies suggesting that older events (Miocene) and/or more recent (Pleistocene) oceanographic processes could have influenced the phylogeny of marine taxa. The spiny lobster genus Palinurus allows for testing among speciation hypotheses, since it has a particular distribution with two groups of three species each in the Northeastern Atlantic (P. elephas, P. mauritanicus and P. charlestoni) and Southeastern Atlantic and Southwestern Indian Oceans (P. gilchristi, P. delagoae and P. barbarae). In the present study, we obtain a more complete understanding of the phylogenetic relationships among these species through a combined dataset with both nuclear and mitochondrial markers, by testing alternative hypotheses on both the mutation rate and tree topology under the recently developed approximate Bayesian computation (ABC) methods. Results Our analyses support a North-to-South speciation pattern in Palinurus with all the South-African species forming a monophyletic clade nested within the Northern Hemisphere species. Coalescent-based ABC methods allowed us to reject the previously proposed hypothesis of a Middle Miocene speciation event related with the closure of the Tethyan Seaway. Instead, divergence times obtained for Palinurus species using the combined mtDNA-microsatellite dataset and standard mutation rates for mtDNA agree with known glaciation-related processes occurring during the last 2 my. Conclusion The Palinurus speciation pattern is a typical example of a series of rapid speciation events occurring within a group, with very short branches separating different species. Our results support the hypothesis that recent climate change-related oceanographic processes have influenced the phylogeny of marine taxa, with most Palinurus species originating during the last two million years. The present study highlights the value of new coalescent-based statistical methods such as ABC for testing different speciation hypotheses using molecular data.

Keywords: nisto, Scyllarus pygmaeus, S. arctus.

In 1885, Sarato created Nisto as a new genus of slipper lobster and assigned two species to his taxon, namely Nisto laevis and N. asper. Bouvier later regarded these two species as post-larval stages of Scyllarus arctus (Linnaeus, 1758). This viewpoint of two post-larval stages has been accepted and retained, including being cited in the most recent scyllarid literature. The discovery of N. laevis and N. asper specimens in the reference collection of the Natural History Museum, London and the capture of three nisto-stage individuals, one in the north-western Mediterranean Sea and two in the Gulf of Cádiz (eastern Atlantic Ocean) have facilitated a historical review into the post-larval stages of S. arctus, as well as new detailed morphological descriptions. From the present study, it has been possible to describe and illustrate the nisto stages of S. arctus and S. pygmaeus (Bate, 1888) and to resolve the true identities of N. laevis and N. asper by DNA analysis. Accordingly, N. laevis has been identified as the nisto stage of S. pygmaeus and N. asper as that of S. arctus.

Keywords: Transparent exopolymer particles · Particle colonization · Bacteria · FISH · Turbulence · Nutrients · Mesocosms

We examined bacterial colonization of transparent exopolymeric particles (TEP) in nutrient-manipulated mesocosms subjected to different turbulence intensities. We quantified heterotrophic bacterial abundance, production and diversity using fluorescence in situ hybridization (FISH). The abundance of attached bacteria increased significantly with TEP size in all treatments. The slope values of the number of bacteria scaled with TEP size varied from 1.15 on Day 1 to 2.04 on Day 11 in still and turbulent tanks, respectively. Comparison between these slopes indicated that the number of attached bacteria for a given TEP diameter was higher under turbulence. The addition of nutrients and turbulence in mesocosms neither supported higher bacterial abundance nor resulted in a correlation between bacterial concentrations and TEP. However, in enriched turbulent tanks, the number of attached bacteria was higher and was linked to rapid TEP formation after the diatom bloom. This was accompanied by higher bacterial production (1.21 µmol C l–1 d–1 at the intermediate level of turbulence on Day 9), which was positively related to TEP. These correlations highlight the finding that higher bacterial productivity was due to a larger fraction of attached bacteria (up to 56.4%). Changes in bacterial production occurred with simultaneous changes in the community structure, i.e. the percentages of the Cytophaga-Flavobacteria-Bacteroides cluster increased significantly. By Day 9, this cluster became the dominant group of bacteria attached to TEP (85 and 90%, respectively at intermediate and high levels of turbulence). Among the marine heterotrophic bacterioplankton, this phylum is known to be common as attached bacteria. Therefore, it seems that the added nutrients and subsequent TEP production can be used by bacteria more efficiently under turbulent conditions through a shift in group-specific composition towards more attached bacteria with higher production rates.

Keywords: fluid seepage; deep-towed side-scan sonar; sub-bottom profiler; carbonate; mound; mud diapir

Our analysis of geoacoustic data from the Middle American margin provides an insight into the formation and evolution mechanisms of mound structures observed on the continental slope offshore Costa Rica. Based on high-resolution deep-towed sidescan sonar and sub-bottom profiler (SBP) data six different mound and fluid seepage structures at the Hongo mound field are characterized in detail. The Hongo mound field is located on the lower continental slope offshore Nicoya peninsula in the prolongation of the subducting Nicoya fracture zone. The mounds have oval to circular shapes with diameters of 500–1600 m and relief heights of 60–100 m. High backscatter anomalies near the mound summits indicate carbonate precipitation and focused fluid seepage activity within the last 10 ka. The data do not show evidence for mud extrusions and the structures were probably formed by a combination of carbonate precipitation and mud diapirism. Based on seismic stratigraphy analysis, mud diapirism is at least active since 42.5–57 ka and average vertical growth rates vary between 6–24 cm/ka. However, if diapirism represents the dominant mound evolution mechanism, mound heights of 80 m point to much older mound ages of 330–1330 ka.

A novel heterotrophic, marine, strictly aerobic, motile bacterium was isolated from the Red Sea at a depth of 1 m. Analysis of its 16S rRNA gene sequence, retrieved from the whole-genome sequence, showed that this bacterium was most closely related to the genera Oleispira, Oceanobacter and Thalassolituus, each of which contains a single species, within the class Gammaproteobacteria. Phenotypic, genotypic and phylogenetic analyses supported the creation of a novel genus and species to accommodate this bacterium, for which the name Bermanella marisrubri gen. nov., sp. nov. is proposed. The type strain of Bermanella marisrubri is RED65T (=CECT 7074T =CCUG 52064T). The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequence and the genome sequence of strain RED65T are AY136131 and AAQH00000000, respectively. A scanning electron micrograph of cells of strain RED65T and maximum-parsimony and maximum-likelihood phylogenetic trees based on almost-complete 16S rRNA gene sequences of strain RED65T and closely related species are available as supplementary figures with the online version of this paper.

Keywords: statistical physics, nonlinear dynamics, fractals, cascade processes

Complex systems are abundant in our natural environment. In linear systems, the equations of their dynamics can be very difficult to solve, but if they cannot be described with a single characteristic scale, at least they can be described by a set of few characteristic scales that are totally decoupled from each other. However, this takes on a completely different flavour in non-linear systems, where scales are coupled and appropriate multiscale analysis is in order. This is the case of complex systems and, more particularly, scale invariant systems. In these, the approach to their solution is different, and it usually involves a multiscale basis. In this context, wavelets are one of the most used representation paradigms. The research context of complex systems and, particularly, scale invariant systems and multifractals has been in constant evolution over the last few years. Theoretical advances, either statistical (stochastic processes and probability distributions) or geometrical (function analysis and measure theory), along with fancy signal-processing algorithms suited to scale invariant data (and additionally handling aliasing, discretization and other artefacts of experimental data), have originated new tools for multifractal characterization of systems. While ten years ago the only methods available were statistical, by the start of this thesis project, development of geometrical methods had begun (most notably, the microcanonical multifractal formalism (MMF)). Geometrical methods have a clear advantage over statistical methods: they characterize each point of the system and thus they permit new applications such as reconstruction and prediction of signals, i.e., not only statistical characterization. Additionally, geometrical methods provide statistical characterization with much less need of data than statistical methods. In the present thesis, we have worked on the generalization and improvement of MMF, as well as its applications to the inference and forecasting of systems that follow a cascade process. In particular, we have described applications to two very different systems: stock-market series and ocean turbulence. The representation of the signal as a microcanonical cascade plays a crucial role in these applications. This representation can be achieved with one particular wavelet called optimal wavelet. The most relevant theoretical achievements are the regularization of diverging multifractal measures, the establishment of the bridge between multiplicative variables in microcanonical cascade processes and local singularity exponents, and the design of accurate and robust measure of wavelet optimality for a given dataset. To achieve this, we have introduced a new formalism, that of microcanonical cascades, that marries the cascade formalisms with MMF. Regarding the developed applications, on stock-market time series, we have inferred the distribution of future returns conditioned by the cascade and we have shown that a prediction based on this inference improves that of an ARIMA model. From the distribution of future returns, future volatility and value-at-risk can be reliably forecasted. On ocean data we have characterized dynamical aspects from optimal wavelet cascade analysis. In particular, we have observed that anomalies in the cascade of sea surface temperature show particular points of heat transfer between structures at different scales in the zones of wind-driven currents, also in the gyres. Both understanding -- combined with appropriate modelling -- of dynamics and design of inference/forecasting algorithms have crucial importance for the anticipation of changes in natural phenomena. In this context, the chain formed by the three steps followed during the thesis, namely multifractal characterization first, then obtaining of the optimal wavelet and finally design of inference algorithms, summarizes the direction we have followed to tackle the study of econometric time series and ocean maps.

Keywords: Multifractal; Multiplicative cascade; Turbulence modeling

Recent developments in microcanonical multifractal formalism have lead to a sensible improvement in the numerical techniques for the determination of the multifractal characteristics of real signals. With the aid of these techniques, we have found empirical evidence of a common multifractal signature in six very different systems, ranging from stock market time series to sea surface temperature records. These systems are not only found to be multifractal, but their singularity spectra are coincident. We propose an explanation of this striking coincidence in terms of a cascade process and analyze its consequences.

Keywords: Optimal wavelet - Cascade processes - Microcanonical multifractal formalism - Time series forecasting

Cascade processes have been used to model many different self-similar systems, as they are able to accurately describe most of their global statistical properties. The so-called optimal wavelet basis allows to achieve a geometrical representation of the cascade process-named microcanonical cascade- that describes the behavior of local quantities and thus it helps to reveal the underlying dynamics of the system. In this context, we study the benefits of using the optimal wavelet in contrast to other wavelets when used to define cascade variables, and we provide an optimality degree estimator that is appropriate to determine the closest-to-optimal wavelet in real data. Particularizing the analysis to stock market series, we show that they can be represented by microcanonical cascades in both the logarithm of the price and the volatility. Also, as a promising application in forecasting, we derive the distribution of the value of next point of the series conditioned to the knowledge of past points and the cascade structure, i.e., the stochastic kernel of the cascade process.

Keywords: Stress, Surface layer, Wind, Instrumentation/sensors, Ocean circulation

Scatterometers estimate the relative atmosphere–ocean motion at spatially high resolution and provide accurate inertial-scale ocean wind forcing information, which is crucial for many ocean, atmosphere, and climate applications. An empirical scatterometer ocean stress (SOS) product is estimated and validated using available statistical information. A triple collocation dataset of scatterometer, and moored buoy and numerical weather prediction (NWP) observations together with two commonly used surface layer (SL) models are used to characterize the SOS. First, a comparison between the two SL models is performed. Although their roughness length and the stability parameterizations differ somewhat, the two models show little differences in terms of stress estimation. Second, a triple collocation exercise is conducted to assess the true and error variances explained by the observations and the SL models. The results show that the uncertainty in the NWP dataset is generally larger than in the buoy and scatterometer wind/stress datasets, but it depends on the spatial scales of interest. The triple collocation analysis also shows that scatterometer winds are as close to real winds as to equivalent neutral winds, provided that the appropriate scaling is used. An explanation for this duality is that the small stability effects found in the analysis are masked by the uncertainty in SL models and their inputs. The triple collocation analysis shows that scatterometer winds can be straightforwardly and reliably transformed to wind stress. This opens the door for the development of wind stress swath (level 2) and gridded (level 3) products for the Advanced Scatterometer (ASCAT) on board Meterological Operation (MetOp) and for further geophysical development.

We focus here on microbial respiration and its potential enhancement by organic-carbon injection via Deep and Intermediate Water formation in the western Mediterranean Sea. Electron transport system (ETS) activities of the nanoplankton and microplankton in the intermediate and deep water from this area show unexpected enhancement. Since ETS is a proxy for respiration these measurements indicate elevated respiration in these waters. In addition, they suggest horizontal transport of organic-carbon rich water-masses. In the western Mediterranean Sea the metabolic rates below 1,500 m were greater than rates at the same depths in the Atlantic. When all the profiles were corrected to the same temperature and normalized by the metabolic rate at 200 m, the Western Mediterranean rates were greater than rates from the same depths in both the Atlantic and equatorial Pacific Oceans. They also exceeded rates predicted from sediment traps. Furthermore they were not consistent with organic matter being supplied via rapidly sinking particulate material. Instead, they may be supported by dissolved organic carbon (DOC) transported to depth by eddies (van Haren et al., 2006), wintertime deepwater convection, or the type of wintertime cold-water cascading recently observed in the canyons on the Catalan-Occitan continental shelf and slope (Canals et al., 2006; Font et al., 2007).

Most pennate diatoms are allogamous, and various types of mating systems have been described. In Pseudo-nitzschia, reproductive stages have been identified in some species, and it is generally accepted that the genus is mainly heterothallic. Here we report homothallic auxosporulation of Pseudo-nitzschia brasiliana Lundholm, Hasle et G. A. Fryxell. To our knowledge, this is the first verified description of homothallic sexual reproduction in the genus. Auxospore formation was observed in all 16 subclones derived from three initial clonal cultures of P. brasiliana. Pairing was followed by production of two gametes per gametangium, which fused to give two zygotes. Each zygote (early auxospore) was initially spherical and adhered to one girdle band of the parental frustule. The two auxospores tended to expand parallel to each other and perpendicular to the parental frustule. Elongation was synchronous, slightly asynchronous, or totally asynchronous. The entire process of sexual reproduction, from gamete formation to the appearance of the initial vegetative cells, took 2–4 d. The occurrence of sex in a homothallic species seems an advantageous life strategy for this species in that any encounter between cells of the right size class is potentially sexual.

Keywords: Pseudo-nitzschia, Pseudo-nitzschia delicatissima, Cryptic species, Auxospores, Internal transcribed spacer, Diatom, Morphology, Growth rate, New species

Several strains of Pseudo-nitzschia delicatissima were isolated from the northwestern Mediterranean Sea and compared using light and electron microscopy, phylogenetic analyses of internal transcribed spacer rDNA, together with studies of their mating system, estimations of growth rates and reduction in cell size with time. Morphological and phylogenetic analyses identified all strains as Pseudo-nitzschia delicatissima, but in the phylogenetic analyses they fell into two genetically distinct clades. Studies of fine structural morphological characteristics by electron microscopy did not allow discrimination of the two clades. Mating experiments showed successful sexualisation among strains of clade B/1; whereas, mating attempts in clade A/2 and between clade A/2 and clade B/1 were unsuccessful under the examined laboratory conditions. The morphological characteristics of the daughter generations F1 and F2 were analyzed and abnormalities in the F2 generation described. We describe for the first time the rapid size reduction in the F2 generation. Culture studies showed physiological differences between the two clades; strains from clade A/2 showed a tendency for higher growth rates and slower reduction in cell size than strains from clade B/1. Morphological and phylogenetic studies comparing strains from different parts of the world showed P. delicatissima as a cryptic species complex comprising at least two different genotypes, both apparently cosmopolitan. The two genotypes were shown to occur sympatrically in the Mediterranean Sea, and we hypothesize that the genotypes were most likely separated by reproductive barriers associated with sexualisation occurring at different temperatures and hence different seasons. The molecular and physiological differences allow us to describe one of the genotypes, clade B/1, as a new species, Pseudo-nitzschia arenysensis sp. nov. Differences in growth capabilities of the cultures were observed in relation to cell size and physiological status and showed a nonlinear relationship between cell size and growth. Possibly, such capability plays a key role in the occurrence and dynamics of phytoplankton algae.

Two decades of intensive research have provided compelling evidence for a link between biodiversity and ecosystem functioning (B-EF). Whereas early B-EF research concentrated on species richness and single processes, recent studies have investigated different measures of both biodiversity and ecosystem functioning, such as functional diversity and joint metrics of multiple processes. There is also a shift from viewing assemblages in terms of their contribution to particular processes toward placing them within a wider food web context. We review how the responses and predictors in B-EF experiments are quantified and how biodiversity effects are shaped by multitrophic interactions. Further, we discuss how B-EF metrics and food web relations could be addressed simultaneously. We conclude that addressing traits, multiple processes and food web interactions is needed to capture the mechanisms that underlie B-EF relations in natural assemblages.

Mesoscale oceanic vortex dipoles are stable coherent vortex structures formed by two closely packed regions of opposite sign vertical vorticity. The authors investigate periodic oscillations in the vortices that make barotropic and baroclinic dipoles depart from a complete steady state. These oscillations are a pair of vortex Rossby waves (VRWs) and are numerically simulated using a three-dimensional, Boussinesq, and f-plane model. The evolution of balanced (void of inertia-gravity waves), static, and inertially stable dipoles is examined under different initial conditions. These initial conditions include the vortex potential vorticity (PV) geometry, initial distance between vortices, and PV extrema. The numerical results show that each VRW is an oscillation with azimuthal wave number 2 that amplifies preferentially at two vortex locations and has an angular phase speed of the same sign as the vortex vertical vorticity. The VRWs in the dipole (dipole VRWs) imply an oscillation in the dipole speed of displacement and, in baroclinic dipoles, interchange between kinetic and potential energy as well. In the absence of any external forcing, the amplitude, periodicity, and phase speed of the dipole VRWs depend on the initial conditions, especially on the PV extrema, vortex geometry, and initial distance between vortices. It is found that steady dipoles are possible but their steadiness is not robust in the sense that any small perturbation will cause the development of VRWs.

Molecular surveys of marine picoeukaryotes have revealed a large number of sequences unrelated to cultured organisms, such as those forming the marine stramenopile (MAST)-4 clade. Recent FISH (fluorescent in situ hybridization) data have shown that MAST-4 cells are uncultured heterotrophic flagellates of 2–3 μm in size that have a global distribution in non-polar marine waters. However, FISH is time-consuming and hard to apply to the many samples generated during oceanographic cruises, so we developed a real-time quantitative polymerase chain reaction (Q-PCR) protocol to determine rapidly the abundance of this group using environmental DNA. We designed a primer set targeting the 18S rRNA genes (rDNA) of MAST-4 and optimized and calibrated the Q-PCR protocol using a plasmid with the target sequence as insert. The Q-PCR was then applied to quantify MAST-4 rDNA molecules along three marine transects, longitudinal in the Indian Ocean, latitudinal in the Drake Passage and coastal–offshore in the Mediterranean Sea, and to a temporal study in a Mediterranean Sea coastal station. MAST-4 was detected in all samples processed (averaged abundances between 500 and 1000 rDNA molecules ml−1) except in mesopelagic and Antarctic samples, where it was virtually absent. In general, it was more abundant in the coast than offshore and in the deep chlorophyll maximum than at surface. A comparison of Q-PCR and FISH signals in well-controlled microbial incubations indicated that MAST-4 cells have around 30 copies of the rDNA operon. This Q-PCR assay quickly yielded quantitative data of uncultured MAST-4 cells and confirmed their wide distribution and putative ecological importance.

Keywords: Phytoplankton · Photosynthesis · Photo-acclimation · Individual-based · Modelling

In this study, we present a new model of acclimation to light under nutrient-replete conditions based on the photo-acclimation model by Geider et al. (1998; Limnol Oceanogr 43:679–694). Rather than being solely carbon (C)-based, the new model employs the cell as the basic unit, which makes it more amenable for application in individual-based (Lagrangian) modelling approaches. The model differentiates between a functional C pool which also contains nitrogen (N) and an energy reserve pool which does not contain N. The cell-specific light-saturated photosynthetic rate is assumed to scale with the size of the functional pool, and the light-limited photosynthetic rate with the cellular chlorophyll content. Through the explicit inclusion of a C (energy) storage pool, an improved regulatory term for chlorophyll synthesis, and the addition of an optional acceleratory term, the dynamics of the model in comparison to the original model could be improved. This is demonstrated by observations during a light-shift experiment on the diatom Skeletonema costatum.

Keywords: Salinity retrieval, SMOS, Inversion scheme, Cost function, Auxiliary data

The Soil Moisture and Ocean Salinity mission will provide from 2009 onwards sea surface salinity maps over the oceans. In this paper the issues related to the assessment of an optimum configuration of the salinity retrieval cost function will be described

Keywords: Sardinella aurita · Spawning · Eggs · Larvae · Circulation · Retention · Northwestern Mediterranean

In the last 20 yr, an increasing abundance and northward expansion of Sardinella aurita has been reported in the western Mediterranean. The present study characterizes the spawning habitat of S. aurita at the northern limit of their geographic distribution and determines the hydrodynamic conditions that could control their northward expansion in the western Mediterranean. Data along the Catalan shelf and slope were obtained in 4 oceanographic cruises conducted in the summers of 2003 and 2004. A clear preference for spawning in coastal areas shallower than 100 m was determined, with larvae showing a wider distribution extending offshore up to the position of the 150 m isobath. The greatest abundance of eggs and larvae was found in the southern half of the area on the wide shelf near the mouth of the Ebro River. This zone was characterized by high values of surface chlorophyll a in association with relatively low salinity waters from the Ebro River. In the northern part of the area, a thermal front across the shelf, with higher sea surface temperatures on its southern side, marked the northern limit of egg and larvae distribution. The northern side of this front was under the direct influence of the shelf–slope current, advecting slope waters from the north, while its southern side was dominated by coastal water. Larvae carried by coastal waters tended to concentrate near the convergence associated with the front. Thus, the thermal front retains and concentrates S. aurita larvae, and could represent one of the limiting factors for the expansion of the species towards the north.

Keywords: Zooplankton; Larvae; Polycyclic aromatic hydrocarbons; Feeding; Narcosis

Short-term (24 h) exposure experiments have been conducted to determine the effects of two environmental relevant polycyclic aromatic hydrocarbons (PAHs), naphthalene (NAPH) and dimethylnaphthalene (C2-NAPH), on the naupliar and adult stages of the marine cyclopoid copepod Oithona davisae. To resemble more realistic conditions, those exposure experiments were conducted under the presence of food. The naupliar stages evidenced lower tolerance to PAH exposure regarding narcotic and lethal effects than adults. Copepod feeding activity showed to be very sensitive to the presence of the studied PAHs, detrimental effects occurring at toxic concentrations ca. 2–3 fold lower than for narcotic effects. In addition we report PAH-mediated changes in cell size and growth rate of the prey item, the heterotrophic dinoflagellate Oxyrrhis marina, that could indirectly affect copepod feeding and help explain hormesis-like responses in our feeding experiments. The feeding activity of copepods is very sensitive to the direct and indirect (prey-viability mediated) effects of polycyclic aromatic hydrocarbons.

Marine seismic data display laterally coherent reflectivity from the water column that is attributed to fine scale oceanic layering. The amplitude of the different reflections is the expression of acoustic impedance contrasts between neighbouring water masses, and therefore water reflectivity maps the ocean's vertical sound speed and density (i.e., temperature and salinity) variations. Here we determine the relative contribution of each parameter by computing the temperature and salinity partial derivatives of sound speed and density, and using them to estimate reflection coefficients from a real oceanographic dataset. The results show that the mean contribution of density variations is 5-10%, while 90-95% is due to sound speed variations. On average, 80% of reflectivity comes from temperature contrasts. Salinity contribution averages 20%, but it is highly variable and reaches up to 40% in regions prone to diffusive convection such as the top of the Mediterranean Undercurrent in the Gulf of Cadiz.

A laboratory grazing experiment was conducted with the aim of quantifying the sulfur assimilation by a herbivore protist feeding on a dimethylsulfoniopropionate (DMSP)-containing phytoplankter. When supplied with dissolved 35S-DMSP, cultures of an axenic strain of the diatom Thalassiosira pseudonana took up 60–95% of the added radioisotope and accumulated it untransformed in the cytoplasm. Radiolabelled diatom cells were offered as prey to the heterotrophic dinoflagellate Oxyrrhis marina. After 32 h in the dark, all the prey had been grazed and digested, leaving only radiolabelled O. marina in the grazing bottles and thus providing an estimate of the percentage of DMSP-sulfur retained by the predator. Subsequent precipitation with cold trichloroacetic acid (TCA) provided the fraction of retained DMSP-S that had been assimilated into the micrograzer macromolecules. In parallel incubations with predator and dissolved 35S-DMSP only (no prey), O. marina (and their closely associated bacteria) took up the radiolabelled substrate osmotrophically to an activity of 0.04 dpm cell−1 and assimilated it all into macromolecules. By correcting grazing 35S-DMSP assimilation for osmotrophic 35S-DMSP assimilation, and comparing it with the ingested radioisotope, the percentage of ingested DMSP-sulfur retained and assimilated by the predator was determined to be 32 ± 4%. This is the first study that provides direct evidence that ingestion of a DMSP-containing prey supplies structural sulfur to a herbivore protist and that quantifies this assimilative supply at one-third of ingested DMSP.

Keywords: DGGE · SAR11 · Microdiversity · Primers · Methodology

Although SAR11 is usually the dominant bacterial group in most marine ecosystems when analyzed with clone libraries and fluorescence in situ hybridization, it is often not retrieved in studies where denaturing gradient gel electrophoresis (DGGE) has been used. We analyzed the microdiversity of SAR11 in Blanes Bay (NW Mediterranean) and we suggest that the high evenness of multiple microdiverse phylotypes, none of which being particularly dominant, is the probable reason for this methodological discrepancy. We used seeding experiments in which different amounts of 2 SAR11-affiliated clones were mixed with DNA from an environmental sample obtained from the Blanes Bay Microbial Observatory. Two primer sets differing at 2 base positions produced DGGE images that varied in their SAR11 detection threshold concentration. Our results show that primer mismatches and/or the presence of faint bands due to microdiversity could explain why SAR11 is frequently not retrieved from DGGE gels.

We present a 1-yr (2005–2006) record of organic carbon (OC) and total nitrogen (TN) contents and their isotopic ratios (d13COC and d15N) in sinking particles from the western Gulf of Lions. Maximum OC and TN fluxes recorded in January 2006 and March–April 2006 were associated with negative near-bottom temperature anomalies. This reveals large inputs of resuspended organic matter from the shelf basinwards to depths >1500 m by dense shelf-water cascading. The first pulse of organic matter had low d13COC (-25.5‰) and N:C (0.08) and high d15N (6.6‰) values, indicative of the arrival of organic matter of terrestrial origin. In contrast, the second pulse had high d13COC (-21.9‰) and N:C (0.15) and extremely low d15N (0.0‰) values, indicative of the transfer of organic matter with higher marine contribution. Though downslope export of organic matter from the adjacent shelf predominated, particles escaping from surface waters remained an important source of organic matter during low-energy and low-flux periods and especially during summer conditions, with significant contribution of N2 fixation to organic matter export. Overall, our results suggest the export of organic matter from different sources to the deep Mediterranean basin, which in turn might alter within a couple of months the quality of the sedimentary organic matter deposited on the sea floor and thus the dynamics of the deep ecosystems.

We demonstrate here results showing that bottom-up and top-down control mechanisms can operate simultaneously and in concert in marine microbial food webs, controlling prokaryote diversity by a combination of viral lysis and substrate limitation. Models in microbial ecology predict that a shift in the type of bacterial growth rate limitation is expected to have a major effect on species composition within the community of bacterial hosts, with a subsequent shift in the composition of the viral community. Only moderate effects would, however, be expected in the absolute number of coexisting virus–host pairs. We investigated these relationships in nutrient-manipulated systems, under simulated in situ conditions. There was a strong correlation in the clustering of the viral and bacterial community data supporting the existence of an important link between the bacterial and viral communities. As predicted, the total number of viral populations was the same in all treatments, while the composition of the viral community varied. Our results support the theoretical prediction that there is one control mechanism for the number of niches for coexisting virus–host pairs (top-down control), and another mechanism that controls which virus–host pairs occupy these niches (bottom-up control).

Keywords: Eddy corridor; Long-lived eddies; Eddies demography; Eddy tracking; Northeastern subtropical Atlantic

We report, from remote sensing and in situ observations, a new type of permanent structure in the eastern subtropical Atlantic Ocean, that we call the “Canary Eddy Corridor”. The phenomenon, is a zonal long-lived (>3 months) mesoscale eddy corridor, whose source is the flow perturbation of the Canary Current and the Trade Winds at the Canary Islands. The latitudinal range of the corridor spans 22°N–29°N and extends from the Canaries to at least 32ºW, near the mid-Atlantic. This is the main region of long-lived westward-propagating eddies in the subtropical northeast Atlantic. From a age-distribution study we observe that at least 10% of mesoscale eddies in this region are long-lived, with a dominance of anticyclones over cyclones. Another four westward-propagating eddy corridors were also detected: two small corridors north and south of the Azores Front; a small zonal corridor located near 31ºN, south of the island of Madeira; and a small corridor located near the Cape Blanc giant filament. The existence of these corridors may change, at least for the northeastern subtropical Atlantic, the general idea that mesoscale eddies are disorganized, ubiquitous structures in the ocean. The Canary Eddy Corridor constitutes a direct zonal pathway that conveys water mass- and biogeochemical properties offshore from the Canary Island/Northwest Africa upwelling system, and may be seen as a recurrent offshore pump of organic matter and carbon to the oligotrophic ocean interior. Estimates of volume and mass transport indicate that Canary Eddy Corridor westward transport is more than one-fourth of the southward transport of the Canary Current. The westward transport of kinetic energy by the eddies of the Canary Corridor is as important as the southward transport by the Canary Current. The total primary production related to the Corridor may be as high as the total primary production of the northwest Africa upwelling system for the same latitude range.

Keywords: Biological patterns - Mediterranean - Deep-sea - Biodiversity - Fishes - Crustaceans - Ecological indicators - Trophic level - Precautionary Principle

The Mediterranean Sea is a relatively deep, closed sea with high rates of fisheries exploitation. In recent years fishing activity has tended to shift towards deeper depths. At the same time, the Mediterranean displays some rather special hydrographic and biogeographic conditions. The present paper reviews the present state of knowledge of the fisheries, biology, and ecology of the deep-sea fish and crustacean species in the Mediterranean dwelling below 1,000 m with potential economic interest, placing special emphasis on the western basin, for which more data are available, as a basis for future studies of the ecology, biodiversity, and effects of climate change and exploitation in this zone. This review reveals that mediterranean deep-sea fishes and crustaceans employ highly conservative ecological strategies, and hence the low fecundity and low metabolic rates in a stable environment like the deep-sea make these populations highly vulnerable. Moreover, ripe females of the main species mentioned here concentrate in the deepest portions of their distribution ranges. Deep-sea fish and crustaceans have high trophic levels and low to medium omnivory index values. The ecological indices discussed here, in combination with the limited knowledge of deep-sea ecosystems, clearly call for an approach based on the Precautionary Principle.

We performed a multidisciplinary study characterizing the relationships between hydrodynamic conditions (currents and water masses) and the presence and abundance of the deep-water rose shrimp Aristeus antennatus in a submarine canyon (Blanes canyon in the NW Mediterranean Sea). This species is heavily commercially exploited and is the main target species of a bottom trawl fishery. Seasonal fluctuations in landings are attributed to spatio-temporal movements by this species associated with submarine canyons in the study area. Despite the economic importance of this species and the decreases in catches in the area in recent years, few studies have provided significant insight into the environmental conditions driving shrimp distribution. We therefore measured daily A. antennatus catches over the course of an entire year and analyzed this time series in terms of daily average temperature, salinity, mean kinetic energy (MKE), and eddy kinetic energy (EKE) values using generalized additive models and decision trees. A. antennatus was captured between 600 and 900 m in the Blanes canyon, depths that include Levantine Intermediate Water (LIW) and the underlying Western Mediterranean Deep Water (WMDW). The greatest catches were associated with relatively salty waters (38.5–38.6), low MKE values (6 and 9 cm2 s−2) and moderate EKE values (10 and 20 cm2 s−2). Deep-water rose shrimp occurrence appears to be driven in a non-linear manner by environmental conditions including local temperature. A. antennatus appears to prefer relatively salty (LIW) waters and low currents (MKE) with moderate variability (EKE).

Keywords: nnelida Polychaeta • deep sea • speciation • systematics • taxonomy

Sediment traps were placed in the water column both inside and in the vicinity of three northwestern Mediterranean submarine canyons. The sediment traps with 12 rotary collectors were deployed on mooring lines 30 and 500 m above the sea floor, and were sampled fortnightly. Polychaete worms (Anelida) and hydromedusae (Cnidaria) were the most abundant zoological taxa captured. Whereas hydromedusae and three of the polychaete species were clearly planktonic organisms, 16 polychaete species were adult benthic forms without special adaptations for swimming, and sometimes also had a large biomass. Four of the 19 polychaete species are described as new species: Aricidea (Allia) longisetosa sp. nov., Paradoneis hirsuta sp. nov., Ophelina margaleffi sp. nov., and Exogone (Parexogone) canyonincolae sp. nov. The rich collection of polychaetes obtained leads us to postulate that these animals are supported by a continuous flux of organic matter, and that they are adapted to the rigorous physical conditions that may occur between the seafloor and the bottom water.

Keywords: Maritime Antarctic lakes - Bacterioplankton - 16S rRNA gene - Denaturing gradient gel electrophoresis - Hope Bay (Antarctic Peninsula) - Potter Peninsula (King George Island)

The bacterioplankton assemblages of eight maritime Antarctic lakes with a wide range of trophic status and geographic span (six lakes from Hope Bay, Antarctic Peninsula and two from Potter Peninsula, King George Island) were described using denaturing gradient gel electrophoresis and band sequencing during two consecutive austral summers (2003–2004). Analyses of the gels identified a total of 230 bands spread across 57 different positions. Among those bands, 14 were shared between lakes from Hope Bay and Potter Peninsula, 17 were observed only in particular lakes, and 17 were registered both years in the same lake. We successfully reamplified and sequenced 43 bands located in 36 different positions belonging to Bacteroidetes, Actinobacteria, Betaproteobacteria and Cyanobacteria. The closest matches for 63% of the sequenced bands were from Antarctic or from other cold environment clones and sequences already in the databases, suggesting the widespread dominance of microbial communities adapted to cold habitats. The results of the multivariate analyses (Cluster Analysis and CCA) indicated that the nutrient status of the lake influences the bacterioplankton assemblages.

Keywords: Ecosystem indicators; Fishing/environmental impact; Trophic model; Southern Benguela; Southern Humboldt; Western Mediterranean

Previously, standardized snap-shot models of the Southern Benguela (1980–1989), Southern Humboldt (1992) and Southern Catalan Sea (1994) ecosystems were examined and found to facilitate assessment of ecosystem characteristics related to the gradient in exploitation status of the ecosystems; highest level of exploitation in the South Catalan Sea (North-western Mediterranean), high in the Southern Humboldt and lower in the Southern Benguela. Subsequently, these models were calibrated and fitted using available catch, fishing effort/mortality and abundance data series and incorporated environmental and internal drivers. This study furthers the previous comparative analyses by comparing changes in ecosystem structure using a selection of ecosystem indicators from the calibrated models and assessing how these indicators change over time in these three contrasting ecosystems. Indicators examined include community turnover rates (production/biomass), trophic level of landings and the community, biodiversity indicators, ratios of predatory/forage fish and pelagic/demersal fish biomass, catch ratios, and network analysis indicators. Using the set of model-derived indicators, the three ecosystems were ranked in terms of exploitation level. This ranking was performed using the values of these indicators in recent years (ecosystem state) as well as their trends over time (ecosystem trend). The non-parametric Kruskal–Wallis and Median tests were used to test for significance of the difference between indicators from the three ecosystems in the last 5 years of the simulation to compare present ecosystem states. We compared the slope of the lineal trend and its significance between ecosystems using the generalized least-squares regression taking auto-correlation into consideration to analyse ecosystem trends. The indicators that capture better the high impacts of fishing prevalent in the Mediterranean and Humboldt ecosystems, and the more conservative exploitation of the Southern Benguela, are the fish/invertebrates biomass and catch ratio, the demersal/pelagic fish biomass and catch ratio (depending on the ecosystem and the fishery being developed), flows to detritus, and the mean trophic level of the community (when large, poorly quantified groups such as zooplankton and detritus are excluded). This study suggests that the best option for classifying ecosystems according to the impact of fishing is to consider a broad range of indicators to understand how and why an ecosystem is responding to particular environmental or fishing drivers (or more likely a combination of these). Our results highlight the importance of including indicators capturing trends over time as well as recent ecosystem states. We also identified 23 pairs of indicators that correlated similarly in the three ecosystems (they showed a significant correlation with same sign). Further comparisons may contribute towards generalization of this list, progressing towards a better understanding of the behaviour of previous ecological indicators.

Keywords: Dimethylsulfide · Dimethylsulfoniopropionate · Sulfur · Food web · Primary production · Bacterial production · Respiration · Mediterranean

The contribution of dimethylsulfoniopropionate (DMSP) to the fluxes of carbon and sulfur through phytoplankton and bacterioplankton was investigated throughout an annual cycle in the Blanes Bay Microbial Observatory (coastal NW Mediterranean). DMSP accounted for 0.3 to 7% of biovolume-estimated phytoplankton carbon and 4 to 93% of calculated phytoplankton sulfur, with higher contributions in ‘summer’ (highly irradiated, oligotrophic waters, May to September) and lower in ‘winter’ (October to April). DMSP biosynthesis rates accounted for 0.8 to 7% of carbon fixation and 11 to 88% of sulfur assimilation through primary production, with slightly higher shares in summer. Upon release from the algal cells, DMSP supplied 0.5 to 6% of the total carbon demand of heterotrophic bacteria, and 3 to 100% of the sulfur demand over the year. Uncertainties associated with these calculations are due to a scarce knowledge of C:S ratios in marine bacteria. Bacterial DMSP-sulfur assimilation (measured with 35S-DMSP) was positively correlated with bacterial heterotrophic production rates (measured with 3H-leucine). In summer waters, characterized by higher ratios of particulate DMSP to chlorophyll a (DMSP p:chl a), DMSP-sulfur assimilation by bacteria was higher and contributed a larger share of the bacterial sulfur demand. We propose that the DMSP:chl a ratio is a good indicator of the relative role of DMSP in the carbon and sulfur fluxes through the first levels of the planktonic food web.

Keywords: Signal processing Empirical mode decomposition Intrinsic mode functions Alfacs Bay Mediterranean Sea Local phase

Time series of meteorological and hydrographic variables were analyzed using Huang’s Empirical Mode Decomposition (EMD) to ascertain the relationships among climatic forcings and the hydrographic behavior in an estuarine bay. The EMD method allowed us to separate the different characteristic oscillation patterns (or modes) of a 14 year-long time series of weekly hydrographic (water temperature and salinity) and meteorological (air temperature, pressure, wind and precipitation) data from Alfacs Bay (Ebre delta, NW Mediterranean). In order to explore the relations between couples of oscillation modes from different series, we developed a correlation index based on the phase differences between these modes. Common characteristic modes in the studied series are a seasonal pattern and an interannual oscillation. The comparison between series of meteorological and hydrographic variables shows significant correlations of two modes (of 1 year and 2-3 year periods, respectively) of water temperature with the corresponding two modes of air temperature and air pressure. There were also significant positive correlations between wind speed and water temperature. The use of EMD allowed to discover a strong connection between stratification and the use of irrigation channels in the bay; in addition, with the help of this method we can propose a common meteorological forcing mechanism for the observed patterns of variability. Those findings would have been impossible to guess by use of classical Fourier methods, and gives a demonstration of the power of EMD in climatic series analysis.

Keywords: Nereis diversicolor; Scrobicularia plana; Biomarkers; Marsh areas

The polychaete worm Nereis diversicolor and the clam Scrobicularia plana were collected from several sites, affected by different types of contamination, in a littoral enclosure in the SW Spain (Caño Sancti-Petri and Rio San Pedro). N. diversicolor was present in 6 sampling sites whereas S. plana in 4 of them. The aim of our study was to relate several pollution biomarkers to chemical sources (metals and organic pollutants e.g. PCB, PAH) in these species, thereby confirming their adequacy as sentinels for this habitat. The biomarkers surveyed in the two invertebrates were the activities of the antioxidant enzyme catalase (CAT), the phase II detoxifying enzyme glutathione S-transferase (GST) and the neurotoxicity marker acetylcholinesterase (AChE). Metallothionein (MT) levels were measured as a biomarker of exposure to metals. The results suggested a different response in the two sediment-dwelling organisms, the sediment-eating polychaete and the water-filtering clam, probably as a consequence of different contamination exposures. The results also suggested that samples from the “Caño Sancti-Petri” were exposed to biologically active compounds that altered some of their biochemical responses. Of all the biomarkers tested, AChE was the most sensitive one and N. diversicolor the potentially most robust sentinel in this ecosystem. In this low to moderately polluted environment, the biochemical approach better reflected temporal trends than site-related differences although it was also able to detect punctual chemical insults.

Submarine canyons are regarded as a sink for pollutants. In order to determine if this theory applied to deep-sea species from an important fishing ground (the Blanes submarine canyon) located in the NW Mediterranean, we sampled the commercial fish Phycis blennoides and Micromesistius poutassou and the crustacean Aristeus antennatus. Specimens were sampled inside and outside (in the open continental slope) the submarine canyon; both are regarded as potentially affected by exposure to different anthropogenic chemicals. Several pollution biomarkers in muscle (activity of cholinesterases) and liver/hepatopancreas (catalase, glutathione S-transferases, carboxylesterases, ethoxyresorufin O-deethylase in fish or mixed function oxygenase (MFO)-related reductases in crustacean, and lipid peroxidation levels) were measured. Chemical analysis of the persistent organic pollutants, namely polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) was also performed on the fish and crustacean muscle. Biomarker activities and levels were discussed in relation to pollutant exposure, habitat, and parameters including sex, size, and species. Biochemical responses and chemical analysis of PCBs evidenced interspecies differences as well as sex and size-related ones, mainly in A. antennatus. An indication of higher exposure to pollutants inside the canyon was observed, which was more clearly reflected in the fish than in the crustacean. However, further research is required to confirm this observation.

Keywords: Shelf- and slope-dwelling species; NW Mediterranean; Hepatic biomarkers; Diet; Ecological variables

Nine fish species of commercial interest from six teleost families and two species of elasmobranchs were selected for characterisation of hepatic biomarkers used in early-warning assessment of pollutant exposure. The sampling was carried out in front of the Barcelona coast (NW Mediterranean) during December 2006 at shelf (53 m) and slope (660 m) depths. The enzymes considered included the antioxidant defence catalase (CAT) and glutathione reductase (GR), phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST). Protein yield (PY) was used as a general marker of hepatic protein synthesis. Significant interspecies differences were evidenced, although each marker varied independently. Enzymatic activities in teleosts were higher than in elasmobranchs; they were very low in Scyliorhinus canicula (mainly a benthic feeder), but not so low in Galeus melastomus (pelagic feeder). In relation to depth, shallow water, shelf-living species had higher metabolic activities. Trophic variables were significantly related to PY and EROD activity, and were especially high in benthic/suprabenthic feeders. Trophic level (deduced from stable isotopy) and stomach fullness were associated with all hepatic markers, except GR. Swimming capacity was related to all hepatic enzymes. Our findings can be applied, not only from the perspective of conservation ecology regarding pollution, but also in fisheries, due to the economic interest of the species involved.

Photosynthetic picoplankton (PPP), particularly picocyanobacteria (PCya), are known to be a major component of phytoplankton in oligotrophic waters. We investigated the dynamics of PPP and heterotrophic bacteria (HBact) in Lake Tanganyika during the dry and rainy seasons of 2004 to 2007, in the two basins of this large lake. Flow cytometry analyses showed that PPP was mainly composed by PCya of the phycoerythrin-rich Synechococcus type, with maximal abundances (2.3 x 104–8.2 x 105 cells mL–1) found in the mixolimnion (10–20 m depth). PPP biomass integrated over the water column depth ranged between 0.41 and 3.09 g C m–2, with maximal values in the south basin during the dry season (2.28 ± 0.62 g C m–2 on average). The contribution of PPP to total phytoplankton biomass ranged from 41 to 99%, with highest values in the south basin in the dry season. Cellular measurements by image analysis of epifluorescence microscopy images showed a significant increase of the cell volume of the PCya during this period. Flow cytometry also allowed enumeration of photosynthetic picoeukaryotes. Assuming a conversion factor of 530 fg C cell–1, they contributed on average to 6% to PPP biomass, except during the dry season in the south basin, where their contribution increased to up to 20% of PPP biomass. Integrated over a 100-m water column depth, PCya biomass was on average 1.4 times higher than HBact biomass. This study establishes reference values for the biomass contribution of this part of the microbial food web, covering for the first time, spatial (different sites), vertical (profiles at different depths) and seasonal variations on a multi-year basis. The results strengthen the view of a major role of PPP in the pelagic food web of large tropical Lake Tanganyika.

Keywords: bacterial biomass • bacterial production • microbial food web • large tropical lake • Lake Tanganyika

1. Abundance and bacterial production (BP) of heterotrophic bacteria (HBact) were measured in the north and south basins of Lake Tanganyika, East Africa, during seasonal sampling series between 2002 and 2007. The major objective of the study was to assess whether BP can supplement phytoplankton particulate primary production (particulate PP) in the pelagic waters, and whether BP and particulate PP are related in this large lake. HBact were enumerated in the 0–100 m surface layer by epifluorescence microscopy and flow cytometry; BP was quantified using 3H-thymidine incorporation, usually in three mixolimnion layers (0–40, 40–60 and 60–100 m). 2. Flow cytometry allowed three subpopulations to be distinguished: low nucleic acid content bacteria (LNA), high nucleic acid content bacteria (HNA) and Synechococcus-like picocyanobacteria (PCya). The proportion of HNA was on average 67% of total bacterial abundance, and tended to increase with depth. HBact abundance was between 1.2 × 105 and 4.8 × 106 cells mL−1, and was maximal in the 0–40 m layer (i.e. roughly, the euphotic layer). Using a single conversion factor of 15 fg C cell−1, estimated from biovolume measurements, average HBact biomass (integrated over a 100-m water column depth) was 1.89 ± 1.05 g C m−2. 3. Significant differences in BP appeared between seasons, especially in the south basin. The range of BP integrated over the 0–100 m layer was 93–735 mg C m−2 day−1, and overlapped with the range of particulate PP (150–1687 mg C m−2 day−1) measured in the same period of time at the same sites. 4. Depth-integrated BP was significantly correlated to particulate PP and chlorophyll-a, and BP in the euphotic layer was on average 25% of PP. 5. These results suggest that HBact contribute substantially to the particulate organic carbon available to consumers in Lake Tanganyika, and that BP may be sustained by phytoplankton-derived organic carbon in the pelagic waters.

Keywords: Phytoplankton, Aerobic anoxygenic photoheterotroph, Bacterial, Fast repetition rate fluorometry, Chlorophyll a, Nutrient limitation, Gulf of Aqaba

Bioassay experiments were performed to identify how growth of key groups within the microbial community was simultaneously limited by nutrient (nitrogen and phosphorus) availability during spring in the Gulf of Aqaba’s oceanic waters. Measurements of chlorophyll a (chl a) concentration and fast repetition rate (FRR) fluorescence generally demonstrated that growth of obligate phototrophic phytoplankton was co-limited by N and P and growth of facultative aerobic anoxygenic photoheterotropic (AAP) bacteria was limited by N. Phytoplankton exhibited an increase in chl a biomass over 24 to 48 h upon relief of nutrient limitation. This response coincided with an increase in photosystem II (PSII) photochemical efficiency (Fv/Fm), but was preceded (within 24 h) by a decrease in effective absorption cross-section (σPSII) and electron turnover time (τ). A similar response for τ and bacterio-chl a was observed for the AAPs. Consistent with the up-regulation of PSII activity with FRR fluorescence were observations of newly synthesized PSII reaction centers via low temperature (77K) fluorescence spectroscopy for addition of N (and N + P). Flow cytometry revealed that the chl a and thus FRR fluorescence responses were partly driven by the picophytoplankton (<10 µm) community, and in particular Synechococcus. Productivity of obligate heterotrophic bacteria exhibited the greatest increase in response to a natural (deep water) treatment, but only a small increase in response to N and P addition, demonstrating the importance of additional substrates (most likely dissolved organic carbon) in moderating the heterotrophs. These data support previous observations that the microbial community response (autotrophy relative to heterotrophy) is critically dependent upon the nature of transient nutrient enrichment.

Keywords: ARGO, Level 3 , Soil Moisture and Ocean Salinity (SMOS) , coastal effects , sea-surface salinity (SSS)

The Soil Moisture and Ocean Salinity (SMOS) Mission is the second of the European Space Agency's Living Planet Program Earth Explorer Opportunity Missions, and it is scheduled for launch in July 2009. Its objective is to provide global and frequent soil-moisture and sea-surface-salinity (SSS) maps. SMOS' single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) sensor, an L-band 2-D aperture-synthesis interferometric radiometer. For the SSS, the output products of SMOS, at Level 3, will have global coverage and an accuracy of 0.1-0.4 psu (practical salinity units) over 100 times 100-200 times 200 km2 in 10-30 days. During the last few years, several studies have pointed out the necessity of combining auxiliary data with the MIRAS-measured brightness temperature to provide the required accuracy. In this paper, we propose and test two techniques to include auxiliary data in the SMOS SSS retrieval algorithm. Aiming at this, pseudo-SMOS Level-3 products have been generated according to the following steps: 1) A North Atlantic configuration of the NEMO-OPA ocean model has been run to provide consistent geophysical parameters; 2) the SMOS end-to-end processor simulator has been used to compute the brightness temperatures as measured by the MIRAS; 3) the SMOS Level-2 processor simulator has been applied to retrieve SSS values for each point and overpass; and 4) Level-2 data have been temporally and spatially averaged to synthesize Level-3 products. In order to assess the impact of the proximity to the coast at Level 3, and the effect of these techniques on it, two different zones have been simulated: the first one in open ocean and the second one in a coastal region, near the Canary Islands (Spain) where SMOS and Aquarius CAL/VAL activities are foreseen. Performance exhibits a clear improvement at Level 2 using the techniques proposed; at Level 3, a smaller effect has been recorded. Coastal proximity has been found to affect the retrieva- l of up to 150 and 300 km from the coast, at Levels 2 and 3, respectively. Results for both scenarios are presented and discussed.

Keywords: Specific affinity · Nutrients · P limitation · Degradable organic carbon · Mesocosm · Blanes Bay · NW Mediterranean

Availability of phosphate for phytoplankton and bacteria and of glucose for bacteria was studied in mesocosms using NW Mediterranean coastal water with added phosphate, glucose, or a combination of both. We observed an initial increase of bacterial production in all mesocosms, a continuous increase of particulate P only in the P-enriched mesocosms, and a greater accumulation of dissolved organic C in the glucose-enriched mesocosms compared to those enriched by both glucose and P. This suggests that the water used was initially P-starved with a certain pool of degradable organic C available for bacteria. Specific phosphate affinities indicated a P limitation for the bacterial community in all mesocosms. Specific glucose affinities were different between the mesocosms but much lower than the theoretical maximum predicted from the diffusion-limited model. This suggests that the glucose pool was not a strong controlling factor of bacterial growth. In the P-enriched mesocosms, it is indicated that the extent of P limitation shifted from highest to lowest, while the available pool of glucose steadily decreased during the experiment. The explanation suggested for these observations is that phosphate regeneration was enhanced in the plankton food web, by which bacterial carbon demand became higher than the degradable organic C produced in the P-enriched mesocosms.

Keywords: Crambe crambe · Life history · Long-term studies · Modular animals · Population dynamics

Demographic data play a central role in determining the overall dynamics of species and forecasting the effects of global change. We examined a decadal pattern of population dynamics and its underlying mechanisms in a population of the encrusting sponge Crambe crambe. A photographic series monitored yearly for 14 yr (1993 to 2007) was analyzed. A total of 133 genets and 157 ramets were individually identified and followed over 14 yr to record their fates: survivorship, partial mortality, recruitment via larvae, asexual events (fission and fusion), and growth. The number of genets varied little over time; their survival was high and differed significantly with size class (52, 82, and 100% for size classes 0–250, 250–700, and >700 mm2, respectively), while recruitment via larvae was very low. Overall, the population was characterized by the inputs and outputs of asexual ramets. Patterns of partial mortality were (1) significantly related to size and (2) did not differ significantly among years, and (3) no patch >500 mm2 suffered any type of mortality. We give the first evidence that net growth over more than a decade was close to zero for the larger specimens, while the smallest specimens exhibited the highest growth rates, quadrupling in size over 14 yr. Low mortality combined with the slow growth of large specimens indicates that C. crambe may live for several decades. This study provides rigorous baseline information necessary to uncover general patterns in the demography of marine sessile species and better predict the long-term fate of populations.

In the latest years, multifractal analysis has been applied to image analysis. The multifractal framework takes advantage of multiscaling properties of images to decompose them as a collection of different fractal components, each one associated to a singularity exponent (an exponent characterizing the way in which that part of the image evolves under changes in scale). One of those components, characterized by the least possible exponent, seems to be the most informative about the whole image. Very recently it has been proposed an algorithm to reconstruct the image from this component, just using physical information conveyed by it. In this paper, we will show that the same algorithm can be used to assess the relevance of the other fractal parts of the image.

Nowadays Earth observation satellites provide information about many relevant variables of the ocean-climate system, such as temperature, moisture, aerosols, etc. However, to retrieve the velocity field, which is the most relevant dynamical variable, is still a technological challenge, specially in the case of oceans. New processing techniques, emerged from the theory of turbulent flows, have come to assist us in this task. In this paper, we show that multifractal techniques applied to new Sea Surface Temperature satellite products opens the way to build maps of ocean currents with unprecedented accuracy. With the application of singularity analysis, we show that global ocean circulation patterns can be retrieved in a daily basis. We compare these results with high-quality altimetry-derived geostrophic velocities, finding a quite good correspondence of the observed patterns both qualitatively and quantitatively; and this is done for the first time on a global basis, even for less active areas. The implications of this findings from the perspective both of theory and of operational applications are discussed.

A field of sediment undulations has been mapped in the Llobregat River prodelta. Similar features had been recognized in other prodeltas and interpreted either as deformation or sedimentay structures. Therefore, proper interpretationof these undulations is neededfor correct risk assessment. We evaluate the characteristics of the sediment undulations in order to detrmine the most likely process for the origin of these structures. These characteristics indicate that the sediment undulations on the Llobregat River prodelta do not result from sediment deformation. Their identificaitonas sediment waves implies that such features do not pose a major hazard for further offshore development

Keywords: Bacterial heterotrophic production · Grazing rates · Temperature · Antarctic waters

Narrow annual ranges of temperature characterize polar waters. Consequently, small increases in temperature could significantly affect the metabolic processes of marine microorganisms. We investigated the response of bacterial heterotrophic production (BHP) and grazing rates to small temperature changes in 3 zones near the western Antarctic Peninsula—Bransfield and Gerlache Straits, and Bellingshausen Sea—during December 2002. We performed 8 grazing experiments with water samples collected from depths where chlorophyll a (chl a) concentration was maximum, and incubated the samples at ambient temperature and at –1, 1, 2 and 5°C. We expected that grazing would increase in parallel with BHP at increasing temperatures; however, temperature differentially affected these 2 microbial activities. Thus, grazing rates increased maximally at temperatures ≤2°C, except in 1 station in the Gerlache Strait, while BHP increased maximally at temperatures ≥2°C, except in 1 station in the Bellingshausen Sea. The percentage of grazed bacteria to BHP at the highest experimental temperatures was low (56 ± 19%) in the Gerlache Strait, high (395 ± 137%) in the Bransfield Strait and approximately balanced (97 ± 24%) in the Bellingshausen Sea. This suggests that differential microbial processes in each zone at increasing temperatures will also depend on the autochthonous community. The present study contributes to the understanding of the variability of polar biogeochemical fluxes, and may aid in predicting the response of microorganisms in future scenarios with local and seasonal changes in temperature.

Published algorithms were employed to convert SeaWiFS images of normalized water-leaving-radiance to absorption images of CDOM (chromophoric dissolved organic matter). The best performing algorithm was employed to produce decadal time-series of CDOM monthly composites from 1998 through 2007. Deficits in CDOM absorption coefficient for surface waters across the shelf over the summer were then acquired relative to the uniformly mixed waters prior to and following stratification (spring and fall, respectively). Estimates were attained of the photochemical oxidation of carbon to CO2 on and beyond the shelf of the Middle Atlantic Bight. Approximately 3-7 × 1010 g C as CO2 were estimated to be produced via photooxidation of CDOM over the summertime, highlighting the significance of CDOM photochemistry and pointing out the importance of CO2 photoproduction at a global scale. In principle, this approach could be applied to global ocean color data.

Keywords: Dinophysis spp. · Cell cycle · In situ division rate · Mitotic index · Cell maximum · Modelling approach

This study explores vertical heterogeneities of in situ division rates (μ) of 3 species of Dinophysis and discusses its implications in modelling the population dynamics of these species. Based on a post-mitotic index approach, estimates of μ from vertical net-haul (integrated) samples (μint) were compared with those from a single depth (oceanographic bottle samples) (μz) at the cell maximum during 2 daily cell cycle studies in the Galician Rías Baixas (NW Spain). Additionally, vertical profiles of μz were obtained during a field survey in Ría de Vigo. A 2-fold difference was observed between estimates of μz from the cell maxima and μint from integrated samples under stratified conditions. Differences were much larger when the minimum estimates of μ values from different depths (μmin) were compared within single vertical profiles. An exponential growth model was applied to simulate the dynamics of a D. acuminata population during a daily cycle in June 1994. Results show that actively dividing cells of a target species may be restricted to narrow layers of the water column. Estimates of μ at different relevant depths during cell cycle studies may be key to determining whether if increased numbers of a target species are due to in situ growth or to the balance of imports and exports.

Keywords: Vitamin A; Vitamin E; Cephalopoda; Cuttlefish; Squid; Octopus

The present study was designed to provide a look at the vitamin content of the early stages of cephalopods as an approach to their vitamin requirements in culture. Vitamin A and E profiles of the European cuttlefish Sepia officinalis, European squid Loligo vulgaris and common octopus Octopus vulgaris laboratory hatchlings and wild juveniles were analyzed. In addition, for O. vulgaris we determined vitamin A and E profiles of mature ovaries and eggs at different stages of development, and followed their possible dietary effects during the first month of paralarval rearing. We also analyzed vitamin A and E content of the live prey, i.e. Artemia nauplii, Maja brachydactyla hatchling crab zoeae and the mysidacean shrimp Leptomysis buergii. In the octopus ovaries and eggs, the vitamin A and E concentrations remained globally higher compared to paralarvae and wild juveniles. The vitamin A content in early stages of cephalopods was not much different from that observed in other marine molluscs and fish larvae and is expected to come from the carotenoid pool of their crustacean prey. Relatively high content of vitamin E was observed in the octopus ovaries, eggs, hatchlings and juveniles of the three cephalopod species analyzed. These levels are probably related to the high percentage of long chain polyunsaturated fatty acids (PUFA) that are particularly high in paralarval and juvenile cephalopods. The vitamin E content of the natural prey, M. brachydactyla and L. buergii, seemed to match or exceed the dietary needs of the three species of cephalopods analyzed. The vitamin E content of the Artemia-fed O. vulgaris increased during the rearing period and the content of the one month of age paralarvae did not differ from the content in wild octopus juveniles, suggesting that this prey may provide sufficient tocopherol for the young octopuses.

The effect of submesoscale balanced (void of waves) vertical velocity on initially steady nutrient-phytoplankton-zooplankton (NPZ) distributions is investigated numerically. First, steady vertical NPZ profiles, continuous but not continuously differentiable at several depths, are found as analytical solutions to the NPZ equations in the absence of flow. These solutions admit numerical equivalents that are continuously differentiable in the numerical sense, here meaning convergence of the vertical derivative with respect to increasing vertical resolution. These NPZ solutions require, however, large vertical resolutions, with a grid size of few centimeters, to be properly discretisized. The ecological model is next coupled to a nonhydrostatic Boussinesq f plane physical model that explicitly conserves potential vorticity on isopycnals. Then the NPZ solutions are used as steady initial ecosystem conditions to investigate the role of submesoscale balanced vertical velocity in forcing NPZ anomalies in an idealized case of a baroclinic unstable jet. The results show that the baroclinic flow rapidly develops balanced vertical velocity that in turn favors NPZ anomalies. A large cancelation between the local change and the horizontal advection occurs in the ecosystem variables. This particularly occurs for zooplankton anomalies that therefore behave as better passive tracers of the horizontal flow than phytoplankton anomalies. However, once phytoplankton and zooplankton anomalies develop locally, forced by vertical velocity, they are horizontally advected away from the upwelling or downwelling regions so that spatial distributions of vertical velocity and ecological fields become eventually uncorrelated.

Keywords: AARS; Bio-physical interaction; Calanus finmarchicus; Enzyme activity; Growth; Labrador Sea; Zooplankton; Production

Surface distribution (0–100 m) of zooplankton biomass and specific aminoacyl-tRNA synthetases (AARS) activity, as a proxy of structural growth, were assessed during winter 2002 and spring 2004 in the Labrador Sea. Two fronts formed by strong boundary currents, several anticyclonic eddies and a cyclonic eddy were studied. The spatial contrasts observed in seawater temperature, salinity and fluorescence, associated with those mesoscale structures, affected the distributions of both zooplankton biomass and specific AARS activity, particularly those of the smaller individuals. Production rates of large organisms (200–1000 μm) were significantly related to microzooplankton biomass (63–200 μm), suggesting a cascade effect from hydrography through microzooplankton to large zooplankton. Water masses defined the biomass distribution of the three dominant species: Calanus glacialis was restricted to cold waters on the shelves while Calanus hyperboreus and Calanus finmarchicus were widespread from Canada to Greenland. Zooplankton production was up to ten-fold higher inside anticyclonic eddies than in the surrounding waters. The recent warming tendency observed in the Labrador Sea will likely generate weaker convection and less energetic mesoscale eddies. This may lead to a decrease in zooplankton growth and production in the Labrador basin.

El Niño-Southern Oscillation (ENSO) properties can be modulated by many factors; most previous studies have focused on physical aspects of the climate system in the tropical Pacific. Ocean biology-induced feedback (OBF) onto physics and bio-climate coupling have been the subject of much recent interest, revealing striking model dependence and even conflicting results. Current satellite data are able to resolve the space-time structure of oceanic signals both in biology and physics, providing an opportunity for quantifying their relationships. Here we use the biological signature from satellite ocean color data to estimate interannual variability of the attenuation depth of solar radiation (Hp), a field linking ocean biology and physics. We then apply a singular value decomposition (SVD) analysis to interannual Hp and sea surface temperature (SST) anomaly fields to derive an empirical Hp model which is incorporated in a hybrid coupled ocean-atmosphere model of the tropical Pacific to represent the OBF. It is shown that the OBF can have significant effects on ENSO behaviors, including its amplitude, oscillation periods and seasonal phase locking.