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marins renovables

Keywords: Pasiphaea sivado · Pasiphaea multidentata · Ontogeny · Vertical migratory rhythms · Continental slope · Light intensity · Photoperiod length · Behavioural activity .

Vertical migratory rhythms of the western Mediterranean congeneric benthopelagic glass shrimps Pasiphaea sivado and P. multidentata were studied at depths of 400 to 430 m in relation to light intensity cycles (i.e. light regimes) in 2 different seasons: close to the autumn equinox (October) and to the summer solstice (June). Catches were considered a proxy of animal density close to the bottom and sampling was performed with consecutive epibenthic trawl hauls. These were continuously repeated over 4 d in order to determine the frequency and timing of species presence on the bottom. The density of animals present on the seabed at the time of the haul was estimated. In both P. sivado and P. multidentata marked diel differences in density were found which were correlated to variability in diel light intensity. While P. sivado was mostly captured at daytime in both seasons, regardless of size, P. multidentata only showed this pattern in the case of juveniles, i.e. individuals with carapace length <30 mm. Adult P. multidentata were mainly present on the bottom during the night, thus showing an apparent phase inversion in their movement patterns. This modification of diel behaviour can be interpreted as the result of differential habitat use with size/age. The comparison of present results with previous field studies illustrates that while P. sivado and juvenile P. multidentata perform actual vertical migrations, adults of the latter species undertake epibenthic movements along the bottom.

The morphological characteristics of the eyes and the retinae of lanternfish larvae of Lampanyctus crocodilus, Benthosema glaciale, and Myctophum punctatum were analyzed in pre-flexion, flexion, and post-flexion stages. Pre-flexion larvae of L. crocodilus, the species with the shallowest depth distribution, had spherical eyes located antero-laterally on a strongly laterally-compressed head, suggesting a forward binocular visual field. B. glaciale and M. punctatum larvae live deeper in the water column and had eyes elongated in the dorsal-ventral plane. The eyes of B. glaciale were prominent, projecting slightly outward from a laterally-compressed head, suggesting a strongly laterally-directed visual field. M. punctaum had stalked elongated eyes projecting from a dorso-ventrally flattened head. The eyes can be freely rotated allowing lateral, anterior and dorsally-directed vision. A prominent choroidal gland was situated beneath the ventral portion of the eye in M. punctatum and B. glaciale, while a smaller gland was present in the dorsal and ventral portions of the eye of L. crocodilus. In pre-flexion stage larvae, the retina of all three species was differentiated with numerous rod photoreceptors in the peripheral retinal areas and fewer cone photoreceptors mainly distributed in the central retina. This distribution suggests concomitant enhancement of scotopic sensitivity in the vertical visual plane and improved photopic acuity in the lateral and forward visual directions. The concurrent development of cones and rods, as observed in the pre-flexion stage of myctophid larvae, is consistent with meeting the special demands of visual planktivory in sub-surface waters. During larval development a gradual increase of ROS length was also accompanied by a progressive loss of cones that were almost totally absent in post-flexion larvae. This can be interpreted as an adaptive response to an impending deep mesopelagic adult life.

Keywords: cell proliferation rates; condition; Dicentrarchus labrax larvae; metabolic enzymes; RNA:DNA.

Six condition indices based on RNA, total soluble protein and two metabolic enzymes [lactate dehydrogenase (LDH) and citrate synthase (CS)] were analysed in muscle tissue of individual larvae, post-flexion reared sea bass Dicentrarchus labrax using DNA and total soluble protein as standards for size. In addition, the effect of 2 days of food deprivation on the cell proliferation rates was assessed. The RNA:DNA best reflected short-term changes in feeding conditions. If standardized by DNA content, LDH activity was a better indicator of condition than any other index but RNA:DNA. Further, the analysis of cell proliferation rates in muscle from 26 day-old larvae proved useful in distinguishing continuously fed larvae from individuals subjected to 2 days of fast.

Keywords: Octopus vulgaris; Cephalopoda; Paralarval rearing; Nutrition; Biochemistry.

Due to the high mortality rates and poor growth generally observed in Octopus vulgaris paralarval rearing experiments, it was decided to organize a working group in order to formulate recommendations to tackle this problem. Over a dozen scientists representing the most active current research groups related to this subject attended the meeting in Vigo, Spain, in November 2005. The aim of this working group was to determine the bottlenecks that prevent success in paralarval rearing, define the most appropriate rearing conditions, and identify required future research. This paper describes rearing techniques for the O. vulgaris paralarvae used by the different research participant teams, with regard to tank systems, feeding environment, and diets (Artemia, crustacean zoeae, sandeel flakes, copepods, etc.). Additionally, it includes other related themes such as the culture of Artemia and copepods, organisms that are commonly used in paralarval rearing. When embarking on O. vulgaris rearing it is advised to use prey rich in DHA (docosaenoic acid, 22:6n-3) and EPA (eicosapentaenoic acid, 20:5n-3), and with high DHA/EPA ratio. Such prey could be enriched Artemia, accompanied or not by crustacean zoeae or any microdiet. It is also recommended that, in future studies, values of growth and survival rates are recorded at the beginning of the benthic phase, in order to compare them to successful previous studies. Dry weight and DHA/EPA ratio of paralarvae may also be good criteria to define paralarval viability and evaluate success of the rearing system. It is further concluded that the nutritional aspect is the most important factor influencing larval mortality. Certain lipids (phospholipids, cholesterol, and polyunsaturated fatty acids), amino acids (lysine, leucine and arginine), and essential elements (e.g. copper) play a relevant role in the larval nutrition. It is believed that the PUFA content, especially DHA and EPA, constitutes one of the basic nutritional requirements. Regarding new research lines, no standardized system for paralarval rearing exists, and it is essential to make progress on this issue. Research on nutritional requirements is considered an area of highest priority, especially the development of a specific enrichment for Artemia, the search for alternative live preys, and the development of suitable formulated diets.

Keywords: effort dynamics, game theory, fisheries bioeconomics, simulation models, red shrimp, Northwestern Mediterranean..

Red shrimp, Aristeus antennatus (Risso, 1816) is one of the most important resources for the bottom-trawl fleets in the northwestern Mediterranean, in terms of both landings and economic value. A simple bioeconomic model introducing Game Theory for the prediction of effort dynamics at vessel level is proposed. The game is performed by the twelve vessels exploiting red shrimp in Blanes. Within the game, two solutions are performed: non-cooperation and cooperation.b The first is proposed as a realistic method for the prediction of individual effort strategies and the second is used to illustrate the potential profitability of the analysed fishery. The effort strategy for each vessel is the number of fishing days per year and their objective is profit maximisation, individual profits for the non-cooperative solution and total profits for the cooperative one. In the present analysis, strategic conflicts arise from the differences between vessels in technical efficiency (catchability coefficient) and economic efficiency (defined here). The ten-year and 1000-iteration stochastic simulations performed for the two effort solutions show that the best strategy from both an economic and a conservationist perspective is homogeneous effort cooperation. However, the results under non-cooperation are more similar to the observed data on effort strategies and landings.

Keywords: Game theory / Stochastic simulation / Bioeconomic model /Mediterranean fisheries / Aristeus antennatus.

GAMEFISTO simulation model is presented as a tool to improve the small scale fisheries bioeconomic simulation techniques. The main novelty of the current model is the implementation of game theoretic techniques for forecasting the fishing effort trends and consequently, the fish population levels and the economic outcome, including landings, income and net profits. The model assigns individual fishing strategies to individual vessels according to their technical characteristics. The fishermen within a fishing fleet exploiting a single stock are assumed to be the decision agents, who share not only a fish population (modelled through stock externality) but also a market, through an offer-demand function (market externality). Mediterranean fisheries need to be analysed at vessel level due to the heterogeneity of its fishing fleets. A ten year simulation on red shrimp, Aristeus antennatus, is presented as an application of the presented GAMEFISTO model

Keywords: Animal welfare, Animal ethics, Capture, Cephalopods, Cuttlefish, Handling, Housing, Nautilus, Octopus, Squid.

When using cephalopods as experimental animals, a number of factors, including morality, quality of information derived from experiments, and public perception, drives the motivation to consider welfare issues. Refinement of methods and techniques is a major step in ensuring protection of cephalopod welfare in both laboratory and field studies. To this end, existing literature that provides details of methods used in the collection, handling, maintenance, and culture of a range of cephalopods is a useful starting point when refining and justifying decisions about animal welfare. This review collates recent literature in which authors have used cephalopods as experimental animals, revealing the extent of use and diversity of cephalopod species and techniques. It also highlights several major issues when considering cephalopod welfare; how little is known about disease in cephalopods and its relationship to senescence and also how to define objective endpoints when animals are stressed or dying as a result of the experiment.

Keywords: Ichthyoplankton, Larvae, Spawning, Circulation, Western Mediterranean.

The demographic structure of the early stages of anchovy (E. encrasicolus) and round sardinella (S. aurita) in the southern Catalan sea in June 2005 were analysed and results discussed based on the hydrographic situation. Contrasting to previous Studies, distribution patterns showed an important overlap, with most of the larvae of both species located between the coast and the 200 m isobath (horizontal pattern) and between the surface and 30 m (vertical pattern).

Keywords: Small pelagic fish; Spawning habitats; Distribution; Ecology; Recruitment; Modeling; NW Mediterranean; Review.

In the NW Mediterranean Sea, anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are the most important small pelagic fish in terms of biomass and commercial interest. Round sardinella (Sardinella aurita) and Sprat (Sprattus sprattus) are also present in this region. This paper provides a general insight into the ecology of these species through a revision of the information available in an environmental context and in relation to exploitation features. Spawning habitats of the two main species, anchovy and sardine, are clearly differentiated based on water mass characteristics reducing the overlapping between their early developmental stages. Larval distribution is also related to major productivity mechanisms of the respective spawning seasons. In spite of the different environmental regimes in which larvae of these species develop, growth rates are fairly similar. Trophic modeling highlights the important ecological role of small pelagic fish in North Western Mediterranean ecosystems. This review points out the gaps in knowledge necessary to understand the dynamics of small pelagic fish in the region and to progress towards a precautionary and adaptive management

The Mediterranean is globally considered an oligotrophic sea. However, there are some places or certain seasons in which mechanisms that enhance fertility may occur. These mechanisms and related processes are especially relevant when they take place during the period of larval development. This study analyzes how environmental conditions occurring in the NW Mediterranean, at local and seasonal scales, contribute to determine the temporal and spatial patterns of fish reproductive activity in the region. The structure of the bathymetry, types of bottoms, diversity of adult fish habitats, as well as mechanisms conditioning the primary production of the region determine the location of spawning, whereas physical processes (e.g., shelf-slope density front and associated current, continental water inflows, winter mixing, stratification of the water column) determine the final distribution patterns of fish eggs and larvae. High larval concentrations occur over the edge of the continental shelf in relation to the presence of the shelf-slope front and its associated convergence. However, this pattern is subject to considerable spatio-temporal variability, due to frontal mesoscale activity. High larval abundance can also be observed near the coast in zones with topographic irregularities that can greatly modify circulation favouring penetration of slope waters into the shelf. Finally, larvae of large pelagic migratory species are mainly distributed in areas under the influence of recent Atlantic Water (AW) and near the frontal system between these inflowing AW and the more saline waters of the northern basin. A pronounced seasonal variability regarding both the number of species and the number of fish larvae in the plankton can be observed throughout the year. The two dominant species, sardine and anchovy, have non-overlapping spawning periods, autumn–winter and spring–summer, respectively. The diversity of feeding patterns as well as the fact that different fish species have different spawning periods might reduce inter- and intra-specific competition for food resources in this area. Most NW Mediterranean fish reproduce during the spring–summer stratification period, when the phytoplankton biomass values at the upper layers of the water column are lower than in winter. The development of the Deep Chlorophyll Maximum in this period and the high zooplankton biomass associated to it offers an important food source for the larvae. Additionally, during this period the inputs of continental waters in certain areas are one of the fertilization mechanisms of surface waters and some species, as anchovy, takes advantage of this situation. Autumn–winter is the period with lower ichthyoplankton diversity, being dominated by sardine, which reproduces on the continental shelf. The mixing of the water column during winter is one of the mechanisms that enhances productivity on continental shelves. Moreover, there are no intense currents on the shelf and the circulation is usually.

Keywords: anchovy larvae, continental waters, Engraulis encrasicolus, Mediterranean, transport.

The Gulf of Lions is one of the main anchovy (Engraulis encrasicolus) spawning areas in the NW Mediterranean. During the spring, low-salinity surface water from the outflow of the Rhoˆne is advected by the shelf-slope current along the continental slope off the Catalan coast. In June 2000, a Lagrangian experiment tracking these low-salinity surface waters was conducted to assess the importance of this transport mechanism for anchovy larvae and to determine the suitability of the tracked surface waters for survival of anchovy larvae. The experiment consisted of sampling the tracked water parcel for 10 days with three drifters launched at the core of the shelf-slope current where low-salinity surface waters were detected. The survey was completed by sampling the surrounding waters. Anchovy larvae from the spawning area in the Gulf of Lions were advected towards the south in the lowsalinity waters. The size increase of anchovy larvae throughout the Lagrangian tracking closely followed the general growth rate calculated by otolith analysis (0.65 mm day)1). However, advection by the current was not the only mechanism of anchovy larval transport. A series of anticyclonic eddies, originated in the Gulf of Lions and advected southwards, seemed to play a complementary role in the transport of larvae from the spawning ground towards the nursery areas. These eddies not only contributed to larval transport but also prevented their dispersion. These transport and aggregation mechanisms may be important for anchovy populations along the Catalan coast and require further study.

Keywords: Prestige oil spill, Mytilus galloprovincialis, Tetraselmis sp., water-accommodated fraction, biomarkers..

The activity of the antioxidant defences catalase (CAT, EC 1.11.1.6), glutathione peroxidase (t-GPX, EC 1.11.1.9), glutathione reductase (GR, EC 1.6.4.2), phase II glutathione S-transferase (GST, EC 2.5.1.18) along with the NADPH-dependent cytochrome c (CYP) reductase (EC 1.6.2.4), NADH-dependent cytochrome c reductase (EC 1.6.2.2), and NADH-dependent ferricyanide (b5) reductase (EC 1.18.1.1) was determined in the digestive gland of mussels Mytilus galloprovincialis fed with Tetraselmis sp. pre-exposed to the water accommodated fraction of the Prestige oil. Mussel gills were also used for measuring acetylcholinesterase activity (AChE, EC 3.1.1.7) and lipid peroxidation (LP) as an indication of neurotoxicity and oxidative stress damage respectively. Bioaccumulation of the selected polycyclic aromatic hydrocarbons (2 to 6 rings PAHs) in mussels after 2, 4, 7 and 10 days of exposure did not show any significant trend; the 2-3 ring PAHs were best represented (51%). A significant (p<0.05) bioaccumulation in exposed mussels was only observed for some alkylated 2-3 ring PAHs. Biochemical antioxidant responses (CAT, t-GPX and GR) significantly increased over time, regardless of exposure, whereas NADH-dependent reductases and LP were affected, regardless of the length of exposure. However, due to the low solubility of the Prestige crude, the PAH levels reached in exposed mussels were not sufficient to cause a clearly associated biochemical response.

Keywords: Alboran Sea; Ichtyoplankton distributions; Physical-biological coupling; Mesoscale; High frequency variability.

This work analyses a multidisciplinary data set including hydrological and meteorological data, satellite images, and fish larvae abundance from a high-frequency experiment conducted along a north–south transect across the Western Alboran Sea anticyclonic gyre. Four consecutive occupations of the transect, crossing the frontal area, evidenced the high-frequency variability of hydrological structures and its influence on the latitudinal and vertical distribution of fish larvae in a period of a few days. The influence of dynamical processes on fish larvae depends on the location of the spawning as well as on the larval fish position in the water column. Wind induced upwelling and/or the southward drift of the Atlantic current transport larvae of neritic species, such as Sardina pilchardus and Engraulis encrasicolus to open sea areas. At the same time, these events bring about alterations in the latitudinal and vertical distributions of mesopelagic fish larvae. The species with a relatively surface distribution, as Ceratoscopelus maderensis, were transported and accumulated to the south of the Atlantic Jet (AJ), while those with a deeper distribution in the water column, as Maurolicus muelleri or Benthosema glaciale, would be upwelled and concentrated to the north. This study shows that it is difficult to extract conclusions about the mean or preferential distributions of fish larvae when one single/synoptic survey is considered and that time evolution of hydrological structures has to be considered in order to conclude.

Keywords: Early life, Loliginidae, Embryo, Growth, Statolith.

Statolith size and growth was used to determine the influence of abiotic factors on the growth of Loligo vulgaris and Sepioteuthis australis embryos. Recently spawned egg masses collected from the field were incubated in the laboratory under different levels of light intensity, photoperiod, or short periods of low salinity (30&). Double tetracycline staining was used to follow statolith growth. In L. vulgaris constant light conditions produced significantly slower growth in the embryonic statoliths and embryos held at summer photoperiod had slower statolith growth than those held at winter photoperiods. However once they hatched out there was no evidence that photoperiod affected statolith growth. After hatching, in all photoperiods statolith growth rates decreased in comparison with late embryonic rates. In S. australis embryos, differences between the high and medium light intensities for summer and intermediate photoperiods were found, suggesting that under summer incubation temperature, longer daylengths at medium light intensity favoured higher statolith growth for this species. In comparison to controls, slower statolith growth in S. australis embryos due to low salinity only occurred when exposed for 72 h. Comparison with previous studies indicates that temperature seems to be the main abiotic factor influencing statolith growth during early stages, however, interactions among all abiotic factors needs to be determined as well as the unknown influence of other isolated factors, e.g., oxygen concentration within the egg mass