Articles

113 documents.
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Villarino E., J.R. Watson, B. Jönsson, J.M. Gasol, G. Salazar, S.G. Acinas, M. Estrada, R. Massana, R. Logares, C.R. Giner, M.C. Pernice, M.P. Olivar, L. Citores, J. Corell, N. Rodríguez-Ezpeleta, J.L. Acuña, A. Molina-Ramírez, I. González-Gordillo, A. Cózar, E. Martí, J.A. Cuesta, S. Agustí, E. Fraile-Nuez, C.M. Duarte, X. Irigoien, G. Chust
Nature Communications, 9, 142, 1-13. DOI: 10.1038/s41467-017-02535-8 (BibTeX: villarino.etal.2018)
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Figueroa R.I., M. Estrada, E. Garcés
Harmful Algae, 73, 44-57. DOI: 10.1016/j.hal.2018.01.006 (BibTeX: figueroa.etal.2018a)
Resum: Veure
In coastal and offshore waters, Harmful Algal Blooms (HABs) currently threaten the well-being of coastal countries. These events, which can be localized or involve wide-ranging areas, pose risks to human health, marine ecosystems, and economic resources, such as tourism, fisheries, and aquaculture. Dynamics of HABs vary from one site to another, depending on the hydrographic and ecological conditions. The challenge in investigating HABs is that they are caused by organisms from multiple algal classes, each with its own unique features, including different life histories. The complete algal life cycle has been determined in <1% of the described species, although elucidation of the life cycles of bloom-forming species is essential in developing preventative measures. The knowledge obtained thus far has confirmed the complexity of the algal life cycle, which is composed of discrete life stages whose morphology, ecological niche (plankton/benthos), function, and lifespan vary. The factors that trigger transitions between the different stages in nature are mostly unknown, but it is clear that an understanding of this process provides the key to effectively forecasting bloom recurrence, maintenance, and decline. Planktonic stages constitute an ephemeral phase of the life cycle of most species whereas resistant, benthic stages enable a species to withstand adverse conditions for prolonged periods, thus providing dormant reservoirs for eventual blooms and facilitating organismal dispersal. Here we review current knowledge of the life cycle strategies of major groups of HAB producers in marine and brackish waters. Rather than providing a comprehensive discussion, the objective was to highlight several of the research milestones that have changed our understanding of the plasticity and frequency of the different life cycle stages as well as the transitions between them. We also discuss the relevance of benthic and planktonic forms and their implications for HAB dynamics.
Paraules clau: Harmful algal species, Life history, Harmful algal blooms, Environmental and physiological factors, Resting stages, Management, Models
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Nunes S., M. Latasa, J.M. Gasol, M. Estrada
Marine Ecology Progress Series, 592, 57-75. DOI: 10.3354/meps12493 (BibTeX: nunes.etal.2018)
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Dall’Osto M., J. Ovadnevaite, M. Paglione, D.C.S. Beddows, D. Ceburnis, C. Cree, P. Cortés, M. Zamanillo, S.O. Nunes, G.L. Pérez, E. Ortega-Retuerta, M. Emelianov, D. Vaqué, C. Marrasé, M. Estrada, M.M. Sala, M. Vidal, M.F. Fitzsimons, R. Beale, R. Airs, M. Rinaldi, S. Decesari, M.C. Facchini, R.M. Harrison, C. O’Dowd, R. Simó
Scientific Reports, 7, 6047, 1-10. DOI: 10.1038/s41598-017-06188-x (BibTeX: dallosto.etal.2017a)
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Lara E., D. Vaqué, E.L. Sà, J.A. Boras, A. Gomes, E. Borull, C. Díez-Vives, E. Teira, M.C. Pernice, F.C. García, I. Forn, Y.M. Castillo, A. Peiró, G. Salazar, X.A.G. Morán, R. Massana, T.S. Catalá, G.M. Luna, S. Agustí, M. Estrada, J.M. Gasol, C.M. Duarte
Science Advances, 3, 9, 1-12. DOI: 10.1126/sciadv.1602565 (BibTeX: lara.etal.2017)
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Marín I., S. Nunes, E.D. Sánchez-Pérez, F.L. Aparicio, M. Estrada, C. Marrasé, T. Moreno, T. Wagener, X. Querol, F. Peters
Science of The Total Environment, 574, 553-568. DOI: 10.1016/j.scitotenv.2016.09.005 (BibTeX: marin.etal.2016a)
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Marañón E., W.M. Balch, P. Cermeño, N. González, C. Sobrino, A. Fernández, M. Huete-Ortega, D.C. López-Sandoval, M. Delgado, M. Estrada, M. Álvarez, E. Fernández-Guallart, C. Pelejero
Limnology and Oceanography, 61, 4, 1345-1357. DOI: 10.1002/lno.10295 (BibTeX: maranon.etal.2016)
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Jewson D., A. Kuwata, Ll. Cros, J.-M. Fortuño, M. Estrada
Scientia Marina, 80, S1, 89-96. DOI: 10.3989/scimar.04331.06C (BibTeX: jewson.etal.2016a)
Resum: Veure
Minidiscus comicus is a marine centric diatom that has cells with diameters as small as 1.9 μm, which brings it close to the lower limit of diatom cell size and also near to the lower limit of photosynthetic eukaryote cells. One of the questions that this raises is whether the cycle of size decline and size restoration used by most diatoms to time their life cycle can operate in such small cells. In samples collected from the western Mediterranean during 2009, M. comicus cells were found with diameters ranging from 1.9 to 6.0 μm. The larger cells were initial cells after size restoration, and these still had the valves of their parent cells attached, making it possible to determine the diameter of the threshold below which size restoration could be induced (3.1 μm). During size decline, M. comicus cell shape changed from discoid to spherical. This adaptation helped to reduce and even halt the rate of cell volume decrease, allowing cells to continue to use diameter decline as a clocking mechanism. The results show how adaptable the diatom cell wall can be, in spite of its rigid appearance.
Paraules clau: Marine diatom, Minidiscus comicus, size change, size limit, size restoration, diatomea marina, cambio de tamaño, tamaño límite, tamaño de restauración
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Solé J., E. García-Ladona, J. Piera, M. Estrada
Scientia Marina, 80S1, 129-137. DOI: 10.3989/scimar.04271.18A (BibTeX: sole.etal.2016k)
Resum: Veure
Phytoplankton blooms are events of production and accumulation of phytoplankton biomass that influence ecosystem dynamics and may also have effects on socio-economic activities. Among the biological factors that affect bloom dynamics, prey selection by zooplankton may play an important role. Here we consider the initial state of development of an algal bloom and analyse how a reduced grazing pressure can allow an algal species with a lower intrinsic growth rate than a competitor to become dominant. We use a simple model with two microalgal species and one zooplankton grazer to derive general relationships between phytoplankton growth and zooplankton grazing. These relationships are applied to two common grazing response functions in order to deduce the mathematical constraints that the parameters of these functions must obey to allow the dominance of the lower growth rate competitor. To assess the usefulness of the deduced relationships in a more general framework, the results are applied in the context of a multispecies ecosystem model (ERSEM).
Paraules clau: algal blooms; plankton; prey selection; grazing functions; multispecies model; mathematical constraints.
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Estrada M., M. Delgado, D. Blasco, M. Latasa, A.M.Cabello, V. Benítez-Barrios, E. Fraile-Nuez, P. Mozetič, M. Vidal
Plos One. Open acces, 11, 3, DOI: 10.1371/journal.pone.0151699 (BibTeX: estrada.etal.2016a)
Resum: Veure
We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal component assemblage), including several pennate taxa, Planktoniella sol, Hemiaulus hauckii and Pseudo-nitzschia spp., in the divergence regions. Our findings indicate that consistent assemblages of co-occurring phytoplankton taxa can be identified and that their distribution is best explained by a combination in different degrees of both environmental and historical influences.
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Gasol J.M., C. Cardelús, X.A.G. Morán, V. Balagué, I. Forn, C. Marrasé, R. Massana, C. Pedrós-Alió, M.M. Sala, R. Simó, D. Vaqué, M. Estrada
Scientia Marina, 80, S1, 63-77. DOI: 10.3989/scimar.04480.06E (BibTeX: gasol.etal.2016a)
Resum: Veure
We carried out monthly photosynthesis-irradiance (P-E) experiments with the 14C-method for 12 years (2003–2014) to determine the photosynthetic parameters and primary production of surface phytoplankton in the Blanes Bay Microbial Observatory, a coastal sampling station in the NW Mediterranean Sea. Our goal was to obtain seasonal trends and to establish the basis for detecting future changes of primary production in this oligotrophic area. The maximal photosynthetic rate PBmax ranged 30-fold (0.5-15 mg C mg Chl a–1 h–1), averaged 3.7 mg C mg Chl a–1 h–1 (±0.25 SE) and was highest in August and lowest in April and December. We only observed photoinhibition twice. The initial or light-limited slope of the P-E relationship, αB, was low, averaging 0.007 mg C mg Chl a–1 h–1 (μmol photons m–2 s–1)–1 (±0.001 SE, range 0.001-0.045) and showed the lowest values in spring (April-June). The light saturation parameter or saturation irradiance, EK, averaged 711 μmol photons m–2 s–1 (±58.4 SE) and tended to be higher in spring and lower in winter. Phytoplankton assemblages were typically dominated by picoeukaryotes in early winter, diatoms in late autumn and late winter, dinoflagellates in spring and cyanobacteria in summer. Total particulate primary production averaged 1.45 mg C m–3 h–1 (±0.13 SE) with highest values in winter (up to 8.50 mg C m–3 h–1) and lowest values in summer (summer average, 0.30 mg C m–3 h–1), while chlorophyll-specific primary production averaged 2.49 mg C mg Chl a–1 h–1 (±0.19, SE) and peaked in summer (up to 12.0 mg C mg Chl a–1 h–1 in August). 14C-determined phytoplankton growth rates varied between ca. 0.3 d–1 in winter and 0.5 d–1 in summer and were within 60-80% of the maximal rates of growth, based on PBmax. Chlorophyll a was a good predictor of primary production only in the winter and autumn. Seasonality appeared to explain most of the variability in the studied variables, while phytoplankton composition played a minor role. Daily integrated primary production was fairly constant throughout the year: similar to previous oxygen-based estimates in winter but considerably lower than these in summer. The difference between 14C- and oxygen-based estimates of primary production could be explained by community respiration. Annually integrated primary production amounted to a rather modest 48 g C m–2 yr–1 (equivalent to 130 mg C m–2 d–1). Although no interannual patterns were detected, our work soundly establishes the seasonal trends for the coastal NW Mediterranean, therefore setting the basis for future detection of change.
Paraules clau: Coastal time-series station, primary production, seasonality, photosynthetic parameters, PBmax, αB, estacion costera a largo término, producción primaria, estacionalidad, parámetros fotosintéticos
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Fuentes-Lema A., C. Sobrino, N. González, M. Estrada, P.J. Neale
Marine Ecology Progress Series, 535, 47-61. DOI: 10.3354/meps11414 (BibTeX: fuenteslema.etal.2015a)
Resum: Veure
This study shows the effects of solar UVR on the photosynthetic parameters and the production of both particulate and dissolved organic carbon (POC and DOC, respectively) of phytoplankton assemblages from oligotrophic areas of the southeastern Indian Ocean. Samples from the 20% PAR depth were incubated on deck under different intensities of 2 different light regimes: full solar radiation (PAR+UVR) and excluding UVR (PAR). Phytoplankton production was measured by the 14C method, obtaining size-fractionated POC (0.2, 2 and 20 µm), total POC and DOC. POC values were fit to a photosynthesis-irradiance (P-E) model that includes photoinhibition. Phytoplankton populations under PAR+UVR had a 10% lower maximum photosynthetic rate (PsB) and an 86% higher sensitivity to inhibition (β) than populations incubated under only PAR exposures. For some stations, cells larger than 2 µm showed higher PsB and photosynthetic efficiency (measured as the P-E slope, α) than smaller cells, but no significant differences were found for β. In contrast, DOC production was significantly higher under PAR+UVR than under PAR exposures and did not follow the P-E model used for fitting POC. The analysis of the P-E values for DOC production showed that values remained constant under PAR intensities but increased with increasing irradiance in the presence of UVR. In some cases, inhibition of DOC production at high irradiances was also observed. These results demonstrate the relevance of UVR irradiance as an environmental driver for phytoplanktonic DOC production in oligotrophic waters and reinforce the important role of UVR on the physiology and ecology of tropical plankton.
Paraules clau: Ultraviolet radiation, Phytoplankton, POC, DOC, P-E curve, Photoinhibition, Indian Ocean
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Gomes A., J.M. Gasol, M. Estrada, L. Franco-Vidal, L. Díaz-Pérez, I. Ferrera, X.A.G. Morán
Deep-Sea Research. Part I: Oceanographic Research Papers, 96, 59-68. DOI: 10.1016/j.dsr.2014.11.007 (BibTeX: gomes.etal.2015)
Resum: Veure
The response of planktonic heterotrophic prokaryotes to the NW Mediterranean winter–spring offshore phytoplankton bloom was assessed in 3 cruises conducted in March, April–May and September 2009. Bulk measurements of phytoplankton and bacterioplankton biomass and production were complemented with an insight into bacterial physiological structure by single-cell analysis of nucleic acid content [low (LNA) vs. high (HNA)] and membrane integrity (“Live” vs. “Dead” cells). Bacterial production empirical conversion factors (0.82±0.25 SE kg C mol leucine−1) were almost always well below the theoretical value. Major differences in most microbial variables were found among the 3 periods, which varied from extremely high phytoplankton biomass and production during the bloom in March (>1 g C m−2 d−1 primary production) to typically oligotrophic conditions during September stratification (<200 mg C m−2 d−1). In both these periods bacterial production was ~30 mg C m−2 d−1 while very large bacterial production (mean 228, with some stations exceeding 500 mg C m−2 d−1) but low biomass was observed during the April–May post-bloom phase. The contribution of HNA (30–67%) and “Live” cells (47–97%) were temporally opposite in the study periods, with maxima in March and September, respectively. Different relationships were found between physiological structure and bottom-up variables, with HNA bacteria apparently more responsive to phytoplankton only during the bloom, coinciding with larger average cell sizes of LNA bacteria. Moderate phytoplankton–bacterioplankton coupling of biomass and activity was only observed in the bloom and post-bloom phases, while relationships between both compartments were not significant under stratification. With all data pooled, bacteria were only weakly bottom-up controlled. Our analyses show that the biomass and production of planktonic algae and bacteria followed opposite paths in the transition from bloom to oligotrophic conditions.
Paraules clau: Bacteria, Phytoplankton, Bacterial production, Primary production, Phytoplankton–bacterioplankton coupling, Winter–spring bloom, Mediterranean
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Fernández-Castro B., B. Mouriño-Carballido, E. Marañón, P. Chouciño, J. Gago, T. Ramírez, M. Vidal, A. Bode, D. Blasco, S.-J. Royer, M. Estrada, R. Simó
Nature Communications, 6, 8002. DOI: 10.1038/ncomms9002 (BibTeX: fernandezcastro.etal.2015)
Resum: Veure
The input of new nitrogen into the euphotic zone constrains the export of organic carbon to the deep ocean and thereby the biologically mediated long-term CO2 exchange between the ocean and atmosphere. In low-latitude open-ocean regions, turbulence-driven nitrate diffusion from the ocean’s interior and biological fixation of atmospheric N2 are the main sources of new nitrogen for phytoplankton productivity. With measurements across the tropical and subtropical Atlantic, Pacific and Indian oceans, we show that nitrate diffusion (171±190 μmol m−2 d−1) dominates over N2 fixation (9.0±9.4 μmol m−2 d−1) at the time of sampling. Nitrate diffusion mediated by salt fingers is responsible for ca. 20% of the new nitrogen supply in several provinces of the Atlantic and Indian Oceans. Our results indicate that salt finger diffusion should be considered in present and future ocean nitrogen budgets, as it could supply globally 0.23–1.00 Tmol N yr−1 to the euphotic zone.
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Pinedo-González P., A.J. West, A. Tovar-Sánchez, C.M. Duarte, E. Marañón, P. Cermeño, N. González, C. Sobrino, M. Huete-Ortega, A. Fernández, D.C. López-Sandoval, M. Vidal, D. Blasco, M. Estrada, S.A. Sañudo-Wilhelmy
Global Biogeochemical Cycles, 29, 10, 1763-1781. DOI: 10.1002/2015GB005149 (BibTeX: pinedogonzalez.etal.2015)
Resum: Veure
The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.
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Agusti S., J.I. González-Gordillo, D. Vaqué, M. Estrada, M.I. Cerezo, G. Salazar, J.M. Gasol, C.M. Duarte
Nature Communications, 6, 7608. DOI: 10.1038/ncomms8608 (BibTeX: agusti.etal.2015)
Resum: Veure
The role of the ocean as a sink for CO2 is partially dependent on the downward transport of phytoplankton cells packaged within fast-sinking particles. However, whether such fast-sinking mechanisms deliver fresh organic carbon down to the deep bathypelagic sea and whether this mechanism is prevalent across the ocean requires confirmation. Here we report the ubiquitous presence of healthy photosynthetic cells, dominated by diatoms, down to 4,000 m in the deep dark ocean. Decay experiments with surface phytoplankton suggested that the large proportion (18%) of healthy photosynthetic cells observed, on average, in the dark ocean, requires transport times from a few days to a few weeks, corresponding to sinking rates (124–732 m d−1) comparable to those of fast-sinking aggregates and faecal pellets. These results confirm the expectation that fast-sinking mechanisms inject fresh organic carbon into the deep sea and that this is a prevalent process operating across the global oligotrophic ocean.
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Arin L., R. Almeida, N.Sampedro, A. Reñé, D. Blasco, A. Calbet, J. Camp, M. Estrada
Harmful Algae news, 48, 14-15. (BibTeX: arin.etal.2014a)
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Llebot C., F.J. Rueda, J. Solé, M.L. Artigas, M. Estrada
Journal of Sea Research, 85, 263-276. DOI: 10.1016/j.seares.2013.05.010 (BibTeX: llebot.etal.2014)
Resum: Veure
A conceptual model of the physical behavior of a shallow (6 m deep) micro-tidal estuary (Alfacs Bay) is proposed, based on the interpretation of a field data set, and subsequently tested against the results of three-dimensional hydrodynamic simulations. At seasonal timescales, the buoyancy associated with freshwater inflows dominates the tidal forcing, yielding a strongly stratified two-layered system, with the surface and the bottom layers flowing in opposite directions (classical estuarine circulation). Wind controls the physical behavior of the bay at shorter (days to weeks) timescales. Three scenarios or states have been defined, depending on the strength of stratification relative to the predominant direction and magnitude of the wind forcing, parameterized through the Wedderburn number, W. For weak winds (scenario 1), with W ≫ 1, mixing occurs as a consequence of stirring and convective cooling, and the mixed layer deepens slowly. For strong winds, with W ≪ 1/2, mixing is fast and is largely driven by shear at the pycnocline. Two scenarios are further identified for W ≪ 1/2 depending on the directionality of the winds: one for persistent NW winds (scenario 2) and another for diurnal SW winds (scenario 3). In scenario 2, the water is pushed laterally, overturning the stratification and generating transverse density gradients. In scenario 3, the estuarine circulation is weakened and even reversed, yielding strong longitudinal density gradients. The bay waters relax quickly (within 10–18 h) back to the original state, after the wind ceases, as a result of the horizontal density gradients developed under wind forcing. Bay-sea exchange rates are shown to decrease significantly in the low W scenarios, the magnitudes of these changes being largely dependent on wind direction. These scenarios have important implications for the ecology of the bay, including the occurrence of phenomena such as harmful algal blooms.
Paraules clau: NW Mediterranean; Hydrodynamic Modeling; Richardson Number; Wedderburn Number; Wind Mixing; Microtidal Estuary
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Estrada M., D. Vaqué
In: The Mediterranean Sea: Its History and Present Challenges, Ed. Stefano Goffredo, Zvy Dubinsky. Springer. 87-111. DOI: 10.1007/978-94-007-6704-1_6 ISBN: 978-94-007-6703-4 (BibTeX: estrada.vaque.2014a)
Resum: Veure
This chapter presents an overview of the diversity, distribution and ecology of major groups of microbial plankton in the Mediterranean Sea, including phytoplankton, viruses, heterotrophic prokaryotes and flagellates, and ciliates. Some protists with hard structures like diatoms, thecate dinoflagellates, coccolithophorids and tintinnids have been relatively well studied from a morphological point of view, but in general microbial diversity is poorly known, in particular with respect to prokaryotes and the smallest eukaryotes. This situation is rapidly changing, in a large part due to the incorporation of molecular techniques. The general oligotrophy of the Mediterranean, which increases from west to east, is reflected in a strong contribution of the picoplankton and the microbial food web. However, a variety of nutrient-enrichment mechanisms, including winter mixing, mesoscale hydrographic structures and land runoff, which operate at various spatio-temporal scales, may enhance primary production and result in the intermittent dominance of diatoms and the herbivorous food web. During the stratification period, a deep chlorophyll maximum is a general feature throughout the basin and plays a substantial role in the fertility of the Mediterranean
Paraules clau: “Phytoplankton mandala” Bacteriophages Blooming taxa Chemotaxonomic and molecular techniques Chlorophyll maximum, Colonial diatoms Cryptophytes Cyanobacterial genera
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Berdalet E., M.L. Artigas, C. Llebot, O.N. Ross, A.B. Hoyer, N.Z. Neszi, J. Piera, F. Rueda, M. Estrada
Harmful Algae 2012, Proceedings of the 15th International Conference on Harmful Algae, . Ed. H.G. Kim, B. Reguera, G.M. Hallegraeff, C.K. Lee, M.S. Han, J.K. Choi. International Society for the Study of Harmful Algae. 55-58. ISBN: 978-87-990827-4-2 (BibTeX: berdalet.etal.2014c)
Resum: Veure
Understanding the spatio-temporal variability of phytoplankton in aquaculture areas is necessary for the appropriate management of natural resources and the prevention of toxic outbreaks. With this objective, we combined synoptic cruises, time series of physical parameters, and modeling, to study the ecosystem of Alfacs Bay, an important shellfish and fish production area commonly affected by toxic outbreaks.Synoptic cruises performed during relevant harmful species proliferations, such as a Karlodinium spp. outbreak in 2007, showed the existence of a preferential phytoplankton accumulation area in the inner NE side of the Bay. We explored the role of nutrient supply (which takes place mainly through the irrigation channels discharging into the northern coast) and the hydrodynamic regime in explaining the observed phytoplankton distribution patterns. Based on a 3D hydrodynamic model combined with a particle-tracking module, we suggest that the phytoplankton confinement in that area could be fostered by the estuarine circulation dynamics taking place in the bay.
Paraules clau: Alfacs bay, NW Mediterranean, phytoplankton dynamics, estuarine circulation
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Estrada M., M. Latasa, M. Emelianov, A. Gutiérrez-Rodríguez, B. Fernández-Castro, J. Isern-Fontanet, B. Mouriño-Carballido, J. Salat, M. Vidal
Deep-Sea Research. Part I: Oceanographic Research Papers, 94, 45-61. DOI: 10.1016/j.dsr.2014.08.003 (BibTeX: estrada.etal.2014c)
Resum: Veure
The phytoplankton bloom in the Liguro-Provençal deep convection region represents one of the main fertilization mechanisms in the Mediterranean. This communication examines nano- and microphyto- plankton observations, and measurements of primary production and chlorophyll a concentration (Chl a) in the southwestern part of the deep convection region, where such information is scarce. Data were obtained from four cruises, carried out in 2005 (EFLUBIO project) and 2009 (FAMOSO project), covering the seasonality between mid-March and September in the region.Our aims were to constrain primary production estimates and to ascertain the importance of short-term variability on the photosynthetic response of phytoplankton assemblages during bloom, post-bloom and late-summer stratification periods in the area. Overall, the initial slope of the P–E relationship (αB) increased and the Chl a-normalized photosynthetic rate(PBm) decreased with increasing optical depth of sample origin,but there were exceptions. In general, there were marked seasonal trends , with stratification increasing and Chl a concentration, primary production and dissolved inorganic nitrogen and phosphate fluxes decreasing from winter to late summer. Chl a at 5 m depth reached a maximum of 7 mg m-3 on 25 March 2005, one of the highest values measured in the region. Average surface values (+-SD) ranged from respectively 2.4+-2.3 mg m-3 and 2+-0.7 mgm-3 in the March 2005 and March 2009 cruises to 0.12+-0.01mg m-3 in the September 2009 cruise. Vertically integrated (0–80 m) primary production (PP int) attained 1800mg Cm-2 d-1 in March 2009, with an average of 1024+-523 mg Cm-2 d-1, and decreased to a mean of 141+-0.43 mg Cm-2 d-1 in September 2009. Superimposed to the seasonal trends, there was a considerable within-cruise variability of biomass and primary production, especially during the spring-winter bloom and post-bloom periods, when PPint could change more than threefold within a few days. These differences were mainly associated with the intense hydrographic mesoscale and sub-mesoscale heterogeneity in the region and with the differences in the physiological and ecological history of the phytoplankton communities in habiting the different water bodies. In late summer, most PP int variability could be explained by fluctuations insurface incident irradiance
Paraules clau: Phytoplankton, Chlorophyll a, Primary production, NW Mediterranea, Seasonal bloom, Mesoscale
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Artigas M.L., C. Llebot, O.N. Ross, N.Z. Neszi, V. Rodellas, J. Garcia-Orellana, P. Masqué, J. Piera, M. Estrada, E. Berdalet
Deep-Sea Research Part II: Topical Studies in Oceanography, 101, 180-192. DOI: 10.1016/j.dsr2.2014.01.006 (BibTeX: artigas.etal.2014)
Resum: Veure
Understanding the spatio-temporal variability of phytoplankton in aquaculture zones is necessary for the prevention and/or prediction of harmful algal bloom events. Synoptic cruises, time series analyses of physical and biological parameters, and 3D modeling were combined to investigate the variability of phytoplankton biomass in Alfacs Bay at basin scale. This microtidal estuary located in the NW Mediterranean is an important area of shellfish and finfish exploitation, which is regularly affected by toxic outbreaks. Observations showed the existence of a preferential phytoplankton accumulation area on the NE interior of the bay. This pattern can be observed throughout the year, and we show that it is directly linked to the physical forcing in the bay, in particular, the interplay between freshwater input and wind-induced turbulence. Both drivers affect the strength of the estuarine circulation, explaining nearly 75% of the variability in phytoplankton biomass. More cells are retained when stratification is weakened and the estuarine circulation reduced, while flushing rates are higher during times of increased stratification and stronger estuarine flow. This has been confirmed by using a 3D hydrodynamic model with Eulerian tracers. Nutrients, while important to support phytoplankton populations, have been found to play only a secondary role in explaining this variability at basin scale.
Paraules clau: Microtidal estuary; Phytoplankton variability; Alfacs Bay; Physical–biological interactions; Estuarine circulation; Meteorological forcing
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Cros L., J.-M. Fortuño, M. Estrada
Scientia Marina, 77, ss1, 63-67. DOI: 10.3989/scimar.03727.27E (BibTeX: cros.etal.2013)
Resum: Veure
Coccolithophores produce calcium carbonate platelets, the coccoliths, and play a significant role in the C and Ca cycles. Coccoliths are important components of marine biogenic carbonate sediments and their chemical analysis can provide tools for paleoceanographic investigation. In particular, the Mg/Ca ratio of coccoliths has been proposed as a paleotemperature proxy. The present study uses X-ray microanalysis to evaluate the Ca and Mg composition of heterococcoliths and holococcoliths of different coccolithophore species. Our measurements indicate that the Mg values in heterococcoliths do not exceed a low threshold and do not show any consistent relationship with the Ca content, while the Mg content of holococcoliths spans a wider range, can reach much higher values and shows a linear relationship with the Ca content. Several heterococcolithophore species tend to form separate clusters according to their Mg and Ca values. Within each cluster, there were no consistent differences in the Mg/Ca ratios of specimens sampled at different temperatures or seasons, suggesting that using the Mg/Ca ratio as a paleothermometer may be problematic. Our findings could have implications for the interpretation of the fossil record because Mg-rich calcite dissolves more easily.
Paraules clau: coccolithophores, X-ray microanalysis, calcium, magnesium, holococcoliths, heterococcoliths
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Cros L., M. Estrada
Marine Ecology Progress Series, 492, 57-68. DOI: 10.3354/meps10473 (BibTeX: cros.estrada.2013)
Resum: Veure
Many coccolithophores have complex life cycles with haploid and diploid stages bearing structurally different coccolith types (holococcoliths and heterococcoliths, respectively). Laboratory studies suggest that holo- and heterococcolithophores may occupy distinct ecological niches, but the potential ecological implications of the existence of haploid and diploid stages are poorly known. We present here a study of holo- and heterococcolithophore distributions in the Catalano-Balearic Sea, during 2 cruises (MESO-96, from 18 June to 3 July, and FRONTS-96, from 16 to 21 September) that covered 2 intervals of the stratification period of 1996. We define a holococcolithophore prevalence index (HOLP index), calculated for each coccolithophore-containing sample, as the percent ratio between the number of holococcolithophores and the total number of holo- and heterococcolithophores belonging to families with alternation of holo- and heterococcolithophore life stages (coccolithophores having HOL-HET life cycles; Total_HHLC). In both cruises, the distribution of holo- and heterococcolithophores and the HOLP index indicated a preference of the holococcolithophores for shallower waters and of the heteroccolithophores for deeper layers. This segregation may be linked to a differentiation of ecological niches, with the haploid holococcolithophores occupying the more oligotrophic upper layers and the diploid heterococcolithophores inhabiting relatively rich deeper waters.
Paraules clau: Holococcolithophore prevalence index · Haploid-diploid life cycles · Coccolithophores · NW Mediterranean
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Arin L., J. Guillén, M. Segura-Noguera, M. Estrada
Estuarine, Coastal and Shelf Science, 133, 116-128. DOI: 10.1016/j.ecss.2013.08.018 (BibTeX: arin.etal.2013)
Resum: Veure
The dynamics of inorganic nutrients and phytoplankton was studied along two transects located in the coastal area of Barcelona (NW Mediterranean), from March 2002 to March 2006. Similar seasonal variability patterns were observed in the four annual cycles and in general, the nutrient concentrations were highest in winter and lowest in summer. Two phytoplankton peaks, composed mainly by diatoms and nanoflagellates, were generally detected during the year with the main peak during winter-early spring, linked to different fertilization mechanisms, and a secondary peak generally found in autumn, probably related both to the new availability of nutrients due to the disruption of the thermocline and to freshwater inputs. During the rest of the year, with a stratified water column and low nutrient concentrations, phytoplankton remained at a low abundance and comprised mainly small dinoflagellates, although there was smaller scale variability conditioned by rainfall events and subsequent freshwater discharges. Despite the similarity of the seasonal patterns, there were interannual changes in origin of new nutrient inputs into the coastal zone and in the taxonomic composition of the winter-early spring phytoplankton maxima. The main source of nutrients for the winter-early spring maxima of 2003 and 2004 was river runoff, while fertilization events in the two following winters were mainly due to the intrusion, onto the Barcelona shelf, of intermediate waters in 2005, and of surface offshore waters, which also carried a different phytoplankton community, in 2006. These changes were linked to unusually cold and dry weather in the winters of 2005 and 2006, which resulted in strong vertical mixing and deep water formation events in the NW Mediterranean basin. The overall amount of nutrients provided to the coastal zone by offshore water fertilization was higher (2005) or equal (2006) than that provided by freshwater inputs in 2003 and 2004. Our findings highlight the importance of identifying the different sources of nutrients in understanding the dynamics of phytoplankton and for devising management strategies of the coastal environment.
Paraules clau: inorganic nutrients; phytoplankton; coastal waters; hydrographic features; meteorology
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Alonso-Sáez L., A.S. Waller, D.R. Mende, K. Bakker, H. Farnelid, P.L. Yager, C. Lovejoy, J.-É. Tremblay, M. Potvin, F. Heinrich, M. Estrada, L. Riemann, P. Bork, C. Pedrós-Alió, S. Bertilsson
Proceedings of the National Academy of Sciences of the United States of America, 109, 44, 17989–17994. DOI: 10. 1073/pnas.1201914109 (BibTeX: alonsosaez.etal.2012)
Resum: Veure
Despite the high abundance of Archaea in the global ocean, their metabolism and biogeochemical roles remain largely unresolved. We investigated the population dynamics and metabolic activity of Thaumarchaeota in polar environments, where these microorganisms are particularly abundant and exhibit seasonal growth. Thaumarchaeota were more abundant in deep Arctic and Antarctic waters and grew throughout the winter at surface and deeper Arctic halocline waters. However, in situ single-cell activity measurements revealed a low activity of this group in the uptake of both leucine and bicarbonate (<5% Thaumarchaeota cells active), which is inconsistent with known heterotrophic and autotrophic thaumarchaeal lifestyles. These results suggested the existence of alternative sources of carbon and energy. Our analysis of an environmental metagenome from the Arctic winter revealed that Thaumarchaeota had pathways for ammonia oxidation and, unexpectedly, an abundance of genes involved in urea transport and degradation. Quantitative PCR analysis confirmed that most polar Thaumarchaeota had the potential to oxidize ammonia, and a large fraction of them had urease genes, enabling the use of urea to fuel nitrification. Thaumarchaeota from Arctic deep waters had a higher abundance of urease genes than those near the surface suggesting genetic differences between closely related archaeal populations. In situ measurements of urea uptake and concentration in Arctic waters showed that small-sized prokaryotes incorporated the carbon from urea, and the availability of urea was often higher than that of ammonium. Therefore, the degradation of urea may be a relevant pathway for Thaumarchaeota and other microorganisms exposed to the low-energy conditions of dark polar waters.
Paraules clau: amoA ureC Beaufort Sea Ross Sea Amundsen Sea
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Llebot C., J. Solé, M. Delgado, M. Fernández-Tejedor, J. Camp, M. Estrada
Journal of Marine Systems, 86, 3-4, 69-86. DOI: 10.1016/j.jmarsys.2011.01.004 (BibTeX: llebot.etal.2011b)
Resum: Veure
Alfacs and Fangar (North East of the Iberian Peninsula) are two embayments of the Ebre Delta complex with typical Mediterranean characteristics. Both are subject to the same meteorological forcing and receive similar freshwater inputs from irrigation drainage channels. However the basin volume in Alfacs is about ten times larger than in Fangar. We studied the temporal patterns of series of chlorophyll a and phytoplankton counts sampled between 1990 and 2003 from two depths of a fixed station in each bay, and related them to the variability of environmental variables (water, temperature, salinity and stratification). A principal component analysis performed on the correlation matrix among the (log-transformed) abundance data of the most frequent taxa revealed three main trends of variability. The first principal component (PC1) indicated a gradient of marine (more important in Alfacs) versus freshwater (particularly in Fangar) influence. PC2 reflected the seasonal cycle of phytoplankton in Alfacs, characterized by the dominance of a diatom assemblage typical of Mediterranean coastal waters in autumn and a group of dinoflagellates, including toxic taxa, in winter–early spring. PC3 expressed mainly the seasonal changes in Fangar and opposed a mixed phytoplankton group, including mostly dinoflagellates, with population maxima between May and October, to dinoflagellates of the winter group. Empirical Mode Decomposition was applied to the environmental variables and to the principal components in order to analyze the temporal structure of the data. All the series presented strong seasonal modes; an index based on phase shift between pairs of series revealed correlations between some of the principal components and environmental variables (temperature and salinity in Alfacs and temperature, salinity and stratification in Fangar). Water temperature showed a slight increasing trend along the sampling period. Between 1997 and 2003, some phytoplankton taxa also presented a weak increasing trend, particularly in the bottom samples of Fangar. This finding does not indicate a direct relationship between phytoplankton variability and the actual magnitudes of temperature or salinity. Rather, these environmental variables should be considered here as proxies of the seasonal behavior of a complex of environmental and biotic factors. Differences among the seasonal patterns of phytoplankton variability in Alfacs and Fangar could be attributed to the lower residence times of the water in Fangar, which resulted in a stronger hydrological control of phytoplankton abundance and composition. Research highlights
Paraules clau: Spain, Catalunya, Alfacs Bay; Fangar Bay; Mediterranean Sea; Phytoplankton; Community composition; Marine ecology; Physico-biological coupling
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Gutiérrez-Rodríguez A., M. Latasa, M. Estrada, M. Vidal, C. Marrasé
Deep-Sea Research. Part I: Oceanographic Research Papers, 57, 4, 486-500. DOI: 10.1016/j.dsr.2009.12.013 (BibTeX: gutierrezrodriguez.etal.2010)
Resum: Veure
The carbon flux through major phytoplankton groups, defined by their pigment markers, was estimated in two contrasting conditions of the Northwestern Mediterranean open ocean ecosystem: the spring bloom and post-bloom situations (hereafter Bloom and Post-bloom, respectively). During Bloom, surface chlorophyll a (Chl a) concentration was higher and dominated by diatoms (53% of Chl a), while during Post-bloom Synechococcus (42%) and Prymnesiophyceae (29%) became dominant. The seawater dilution technique, coupled to high pressure liquid chromatography (HPLC) analysis of pigments and flow cytometry (FCM), was used to estimate growth and grazing rates of major phytoplankton groups in surface waters. Estimated growth rates were corrected for photoacclimation based on FCM-detected changes in red fluorescence per cell. Given the 30% average decrease in the pigment content per cell between the beginning and the end of the incubations, overlooking photoacclimation would have resulted in a 0.40 d−1 underestimation of phytoplankton growth rates. Corrected average growth rates (μo) were 0.90±0.20 (SD) and 0.40±0.14 d−1 for Bloom and Post-bloom phytoplankton, respectively. Diatoms, Cryptophyceae and Synechococcus were identified as fast-growing groups and Prymnesiophyceae and Prasinophyceae as slow-growing groups across Bloom and Post-bloom conditions. The higher growth rate during Bloom was due to dominance of phytoplankton groups with higher growth rates than those dominating in Post-bloom. Average grazing rates (m) were 0.58±0.20 d−1 (SD) and 0.31±0.07 d−1. The proportion of phytoplankton growth consumed by microzooplankton grazing (m/μo) tended to be lower in Bloom (0.69±0.34) than in Post-bloom (0.80±0.08). The intensity of nutrient limitation experienced by phytoplankton indicated by μo/μn (where μn is the nutrient-amended growth rate), was similar during Bloom (0.78) and Post-bloom (0.73). Primary production from surface water (PP) was estimated with 14C incubations. A combination of PP and Chl a synthesis rate yielded C/Chl a ratios of 34±21 and 168±75 (g:g) for Bloom and Post-bloom, respectively. Transformation of group-specific Chl a fluxes into carbon equivalents confirmed the dominant role of diatoms during Bloom and Synechococcus and Prymnesiophyceae during Post-bloom.
Paraules clau: Community structure; Phytoplankton growth; Microzooplankton grazing; Carbon flux; NW Mediterranean
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Coll M., C. Piroddi, J. Steenbeek, K. Kaschner, F.B. Rais Lasram, J. Aguzzi, E. Ballesteros, C.N. Bianchi, J. Corbera, T. Dailianis, R. Danovaro, M. Estrada, C. Froglia, B.S. Galil, J.M. Gasol, R. Gertwagen, J. Gil, F. Guilhaumon, K. Kesner-Reyes, M.-S. Kitsos, A. Koukouras, N. Lampadariou, E. Laxamana, C.M. López-Fé de la Cuadra, H.K. Lotze, D. Martin, D. Mouillot, D. Oro, S. Raicevich, J. Rius-Barile, J.I. Saiz-Salinas, C. San Vicente, S. Somot, J. Templado, X. Turon, D. Vafidis, R. Villanueva, E. Voultsiadou
Plos One. Open acces, 5, 8, e11842. DOI: 10.1371/journal.pone.0011842 (BibTeX: coll.etal.2010a)
Resum: Veure
The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well.
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Llebot C., Y.H. Spitz, J. Solé, M. Estrada
Journal of Marine Systems, 83, 3-4, 192-209. DOI: 10.1016/j.jmarsys.2010.06.009 (BibTeX: llebot.etal.2010)
Resum: Veure
The effect of Dissolved Organic Phosphorus (DOP) availability and nutrient limitation of phytoplankton growth in an estuarine bay (Alfacs Bay, NW Mediterranean) have been studied by means of a zero-dimensional ecological model including nitrogen, phosphorus (organic and inorganic), two groups of phytoplankton (diatoms and flagellates), one group of zooplankton, and detritus. Simulations with and without DOP as an extra source of phosphorus for phytoplankton growth suggest that DOP plays an important role in the dynamics of the Alfacs Bay ecosystem. DOP is indeed necessary to simulate the observed draw-down of nitrate and build up of phytoplankton biomass. Two non-exclusive mechanisms allowing DOP availability for phytoplankton are possible: direct uptake, or remineralization to Dissolved Inorganic Phosphorus. Including both gives a better agreement with the observations. Inclusion of DOP in the model leads to predominance of phosphorus limitation of phytoplankton growth in fall and winter, and of nitrogen limitation in late spring and summer. Simulations with and without sediment resuspension suggest that this process does not significantly affect the nutrient budget in the bay.
Paraules clau: Spain; Catalunya; Alfacs Bay; Mediterranean Sea; Dissolved organic phosphorus; Resuspended sediments; Ecological modeling; Phytoplankton; Limiting factors
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Estrada M., J. Solé, S. Anglès, E. Garcés
Deep-Sea Research Part II: Topical Studies in Oceanography, 57, 3-4, 308-321. DOI: 10.1016/j.dsr2.2009.09.007 (BibTeX: estrada.etal.2010)
Resum: Veure
The role of resting cysts on the development of Alexandrium minutum blooms in a typical Mediterranean semi-enclosed water body (Arenys de Mar Harbor, NW Mediterranean) was studied by means of matrix and dynamic population models. We used a series of scenarios, constrained when possible by experimentally measured parameters to test whether excystment and encystment fluxes and changes in the dormancy period had a major effect on bloom intensity and duration. The results of the simulations highlighted the importance of knowing not only the magnitude and variability of growth and life-cycle transition rates, but also those of loss rates (both in the water column and in the sediment) due to physical or biological factors. Given the maximum encystment rates determined for A. minutum in the study area (0.01 d−1), this process contributed to reduce the peak concentrations of vegetative cells but did not have a dominant effect on bloom termination. Excystment fluxes could contribute to enhance population densities of vegetative cells during times or low or negative net growth rate and during the initial phases of a bloom, but once exponential growth had started, additional excystment had negligible effect on bloom magnitude. However, even if cysts did not contribute to larger blooms, they could represent a safety mechanism for reintroduction of the species when the vegetative cell population went extinct due to unfavorable environmental conditions. Increasing the dormancy time exposed newly formed cysts to a longer period of losses in the sediment that reduced the concentration of excystment-ready sediment cysts and decreased excystment fluxes. More complex models will be needed to explore the implications of different life-cycle strategies in a wider natural ecological context.
Paraules clau: Alexandrium minutum, Cysts, Dinophyceae, Harmful Algal Blooms, Mediterranean Sea, Models
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Solé J., A. Turiel, M. Estrada, C. Llebot, D. Blasco, J. Camp, M. Delgado, M. Fernández-Tejedor, J. Diogène
Continental Shelf Research, 29, 15, 1786-1800. DOI: 10.1016/j.csr.2009.04.012 (BibTeX: sole.etal.2009h)
Resum: Veure
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.
Paraules clau: Signal processing Empirical mode decomposition Intrinsic mode functions Alfacs Bay Mediterranean Sea Local phase
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Estrada M., M. Bayer-Giraldi, J. Felipe, C. Marrasé, M.M. Sala, M. Vidal
Aquatic Microbial Ecology, 54, 3, 217-231. DOI: 10.3354/ame01268 (BibTeX: estrada.etal.2009)
Resum: Veure
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.
Paraules clau: Phytoplankton · Protists · Nutrients · Stoichiometry · Light response · Sea ice · Beaufort Sea · Arctic
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Estrada M., M.M. Sala, K. Van Lenning, M. Alcaraz, J. Felipe, M.J.W. Veldhuis
Journal of Experimental Marine Biology and Ecology, 355, 1, 1-11. DOI: 10.1016/j.jembe.2007.10.017 (BibTeX: estrada.etal.2008)
Resum: Veure
A microcosm approach was used to test whether: a) growth under unbalanced nutrient conditions (varying N:P ratios) affected the susceptibility of a phytoplankton community including the dinoflagellate Alexandrium catenella (a paralytic shellfish toxin producer) to mesozooplankton grazing, and b) the potential effects of unbalanced nutrient conditions were mediated by changes in toxicity of A. catenella or by other mechanisms. The experimental setup consisted of fifteen 30 l microcosms, filled with water from the Barcelona Harbour and subjected to treatments combining nutrient inputs at three different N:P ratios (Redfield N:P ratio or nutrient-balanced, high N:P and low N:P), addition or omission of A. catenella (an estimated initial concentration of 38 A. catenella cells ml− 1, a value typical for blooms in harbours of the Catalan coast), and selective addition of a cultured population of Acartia grani. P sufficiency had a strong positive effect on the growth of A. grani, both with or without A. catenella addition, presumably due to enhanced food quality of the prey community. The presence of this copepod resulted in lower concentrations of ciliates, A. catenella, and other dinoflagellates, suggesting active grazing by the copepods. No noxious effects of A. catenella on the copepods were detected at the relatively low cell concentrations of that dinoflagellate used in the experiment.
Paraules clau: Alexandrium catenella; Copepods; Harmful algal blooms; NW Mediterranean; Phosphorus; Toxins
Explorations on Phytoplankton Diversity. An Appreciation of Ramon Margalef’s Contributions (2008)
Estrada M.,
In: Unity in diversity: Reflections on ecology after the legacy of Ramon Margalef, Ed. Fernando Valladares, Antonio Camacho, Arturo Elosegi, Carlos Gracia, Marta Estrada, Joan Carles Senar y Josep-María Gili. Fundación BBVA. Chap. 8. 191-222. ISBN: 978-84-96515-53-6 (BibTeX: estrada.2008a)
Resum: Veure
Este libro se gestó en el congreso sobre Ecología celebrado en Barcelona entre el 16 y 18 de Noviembre de 2005 bajo el título “La unidad en la diversidad. Un congreso sobre ecología tras el legado de Ramón Margalef”. El lema del congreso intentaba resumir la contribución más importante del profesor a la vez que servir de estímulo para una reflexión del estado actual de la ecología y sus posibilidades de afrontar de manera conjunta los desafíos que impone el cambio global y la crisis ambiental. La Ecología, como ciencia de síntesis, trata de explicar el funcionamiento de los sistemas ecológicos mediante la integración de conocimientos procedentes, en buena medida, de otras ciencias. Además de con la biología, la ecología interacciona con ciencias como la física, y más concretamente la termodinámica, que ofrece un contexto para explicar el funcionamiento de los ecosistemas, así como con las matemáticas, que proporcionan herramientas para plasmar las teorías ecológicas en expresiones manejables, y con la química, que establece las bases para la comprensión de los ciclos biogeoquímicos y la transformación de la materia y la energía en los procesos ecosistémicos.
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Berdalet E., M. Estrada
In: Avances y tendencias en fitoplancton tóxico y biotoxinas : actas de la IX Reunión Ibérica sobre Fitoplancton Tóxico y Biotoxinas, Cartagena 7-10 de mayo de 2007., Ed. J. Gilabert. UPC. Universidad Politécnica de Cartagena. Chap. 1. 1-12. Cartagena. ISBN: 978-84-96997-06-6 (BibTeX: berdalet.estrada.2008)
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Nieves V., C. Llebot, A. Turiel, J. Solé, E. García-Ladona, D. Blasco, M. Estrada
Geophysical Research Letters, 34, L23602,. DOI: 10.1029/2007GL030823 (BibTeX: nieves.etal.2007)
Resum: Veure
Oceans and 2D turbulence present similar characteristics, as for instance the dominant role played by eddies in energy and matter transport. However, providing a complete justification of this analogy is difficult, as it requires knowledge of the ocean’s dynamic state at different instants and over large scales. Recently, new techniques coming from the Microcanonical Multifractal Formalism have made it possible to infer the streamlines from the analysis of satellite images of some scalar variables. In this paper, we will show that this information is enough to characterize the scaling properties of the energy cascade, which is manifested as a multifractal signature; further, the multifractal signature is obtained at each location in a local basis. Different scalars obtained from satellite measurements such as Sea Surface Temperature or Surface Chlorophyll Concentration present essentially the same multifractal structure, which is interpreted as a consequence of the pervading character of the turbulent advection at the scales of observation.
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Alcaraz M., A. Calbet, M. Estrada, C. Marrasé, E. Saiz, I. Trepat
Progress in Oceanography, 74, 2-3, 294-312. DOI: 10.1016/j.pocean.2007.04.003 (BibTeX: alcaraz.etal.2007a)
Resum: Veure
The study of the response of planktonic systems to environmental variability, and particularly to differences in the intensity and frequency of mechanical energy inputs, one of the leading objectives of GLOBEC, has been an important part of the research developed in the Spanish Mediterranean over the last decades. In this review we will discuss the research conducted at different space and time scales, intended to cope with the broad space and time variability scales of plankton. The time- and space scales considered range from small- (i.e., from seconds and mm, affecting zooplankton at individual level) to meso- (weeks and tens of km) and large scales (i.e., seasonal changes in the density structure of the water column). The discussion includes laboratory research using visual observation techniques at individual level, the use of experimental micro- and mesocosms, as well as data obtained by sampling natural systems during oceanographic cruises. At the smaller scales, mechanical energy inputs produce turbulent water movements that enhance the encounter probability between zooplankton and their prey, modify their swimming behaviour (higher frequency of fast-swimming events, escape responses), increase metabolic rates and affect energetic balances. Consequently, the development of organisms is accelerated, and the size of adults significantly reduced. The changes induced by turbulence on zooplankton at individual levels modify, by cumulative processes, the characteristics of zooplankton populations and of the whole planktonic ecosystems. Such changes can be observed by using micro- and mesocosm experiments. The physical control of zooplankton communities can also be observed, even at larger scales, in the highly hydrodynamic physical structures (i.e., fronts and ergoclines) of the Catalan Sea (NW Mediterranean). In these structures mechanical energy inputs are amplified, resulting in turbulence increases that contribute to modify, from individual rate processes, the structural and functional characteristics of plankton communities and of the whole ecosystem. Mesoscale hydrographic features, particularly the Catalan and Balearic permanent density fronts and the central divergence, are important fertilization sources for the relatively productive Catalan Sea. But during summer stratification, the nutrient depletion of surface waters and the higher penetration of light allow the development of a deep phytoplankton maximum. The consequence is the formation of a deep zooplankton maximum coinciding with that of phytoplankton. The vertical migration patterns of zooplankton during summer result in significant nocturnal inputs of recycled nutrients to the surface, thus counteracting the vertical downward flux of nutrients. The spatial distribution of zooplankton biomass and metabolic rates appear to be closely related to the physical characteristics of the different hydrographic features. Similarly, the intensity and the temporal and spatial scales of variability of the structural and functional properties of zooplankton are closely linked to those of the physical structures.
Paraules clau: Zooplankton; NW Mediterranean; Physical forcing; Community structure; Rate processes
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Berdalet E., F. Peters, V. Lila Koumandou, C. Roldan, O. Guadayol, M. Estrada
Journal of Phycology, 43, 965-977. DOI: 10.1111/j.1529-8817.2007.00392.x (BibTeX: berdalet.etal.2007)
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Solé J., M. Estrada, E. García-Ladona
Journal of Marine Systems, 61, 165-179. DOI: 10.1016/j.jmarsys.2005.06.004 (BibTeX: sole.etal.2006a)
Resum: Veure
A multispecies dynamic simulation model (ERSEM) was used to examine the influence of allelopathic and trophic interactions causing feeding avoidance by predators, on the formation of harmful algal blooms, under environmental scenarios typical of a Mediterranean harbour (Barcelona). The biological state variables of the model included four functional groups of phytoplankton (diatoms, toxic and non-toxic flagellates and picophytoplankton), heterotrophic flagellates, micro- and mesozooplankton and bacteria. The physical-chemical forcing (irradiance, temperature and major nutrient concentrations) was based on an actual series of measurements taken along a year cycle in the Barcelona harbour. In order to evaluate potential effects of advection, some runs were repeated after introducing a biomass loss term. Numerical simulations showed that allelopathic effects of a toxic alga on a non-toxic but otherwise similar competitor did not have appreciable influence on the dynamics of the system. However, induction of avoidance of the toxic alga by predators, which resulted on increased predation pressure on other algal groups had a significant effect on the development of algal and predator populations. The presence of advection overrided the effect of these interactions and only allowed organisms with sufficiently high potential growth rates to thrive.
Paraules clau: Marine algae; Algal blooms; Toxicity; Allelopathy; Feeding avoidance; Model studies
Effects of small-scale turbulence on the physiological functioning of marine microalgae (2006)
Berdalet E., M. Estrada
In: Algal, cultures, analogues of blooms and applications, Vol. 2. Ed. D.V.Subba Rao. Science Publishers. 459-500. Enfield (NH) USA. ISBN: 1-57808-394-X
Effects of Small-scale Turbulence on the Physiological Functioning of Marine Microalgae (2006)
Berdalet E., M. Estrada
In: Algal Cultures, Analogues of Blooms and Applications, Vol. 2. Ed. D.V. Subba Rao. Bedford Institute of Oceanography, Dartmouth, NS, Canada. Science Publishers. 1016. Enfield. ISBN: 978-1-57808-393-0
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Vaqué D., J. Felipe, M. M. Sala, A. Calbet, M. Estrada, M. Alcaraz
Scientia Marina, 70, 1, 59-65. DOI: 10.3989/scimar.2006.70n159 (BibTeX: vaque.etal.2006)
Resum: Veure
An experimental study was carried out to investigate whether two potential predators such as Oxyrrhis marina (phagotrophic dinoflagellate) and Acartia margalefi (Copepoda: Calanoida) had different responses when feeding on toxic (Karlodinium sp.-strain CSIC1-) or non-toxic (Gymnodinium sp1) dinoflagellates with a similar shape and size. Both prey were cultured at different N/P ratios (balanced N/P = 15, and P-limited N/P > 15) to test whether P-limitation conditions could lead to depressed grazing rates or have other effects on the predators. Both predators ingested the non-toxic Gymnodinium sp1, and low or non-ingestion rates were observed when incubated with Karlodinium sp. The dinoflagellate O. marina did not graze at all on Karlodinium sp. at N/P > 15 and very little at NP = 15, as its net growth rates were always negative when feeding on Karlodinium sp. cultured under P-limitation conditions. A. margalefi had lower ingestion rates when feeding on Karlodinium sp. grown at N/P = 15 than when feeding on Gymnodinium sp1, and did not graze on P-limited Karlodinium sp. Nevertheless, feeding on Karlodinium sp. grown under N/P =15 or N/P > 15 did not have any paralyzing or lethal effect on A. margalefi after 24 h. Finally, a direct effect on the viability of A. margalefi eggs was detected when healthy eggs were incubated for 5 days in the presence of Karlodinium sp. grown under N/P =15 or N/P > 15, producing a decrease in viability of 20% and 60% respectively.
Harmful algal bloom dynamics in relation to physical processes (2006)
Figueiras F.G., G.C. Pitcher, M. Estrada
In: Ecology of harmful algae, Ecological Studies. Ed. Edna Granéli and Jefferson T. Turner. Springer. 127-138. ISBN: 978-3-540-32209-2
Response of Southern Ocean phytoplankton and bacterioplankton production to short-term experimental warming (2006)
Morán X.A.G., M. Sebastián, C. Pedrós-Alió, M. Estrada
Limnology and Oceanography, 51, 4, 1791-1800.
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Sala M.M., M. Estrada, J.M. Gasol
Aquatic Microbial Ecology, 44, 1-9. DOI: 10.3354/ame044001 (BibTeX: sala.etal.2006)
Resum: Veure
To understand the seasonal and intersite variations in the functional diversity of coastal bacterioplankton assemblages, their utilization of 31 different carbon sources was analyzed with Biolog-Ecoplates™ in waters from 3 harbours and 2 oligotrophic coastal environments of the NW Mediterranean. Polymers (α-cyclodextrin and glycogen) and carbohydrates (d-cellobiose and N-acetyl-d-glucosamine) were most utilized in the harbours, while carboxylic acids were mainly used in the coastal areas. Seasonal differences in the patterns of carbon source utilization (the so-called ‘functional diversity’) were investigated in 2 spatially close, but contrasting, coastal stations: the oligotrophic coastal site of Blanes Bay, and the Barcelona inner harbour. The existence of a possible seasonal trend in functional diversity of bacterioplankton in the oligotrophic coastal station, but not in the harbour, suggests that the bacterial assemblage of oligotrophic environments can adapt to changing inputs of nutrients and DOC. In contrast, the low water exchange in the harbour provides a pool of DOC of relatively stable composition throughout the year which could allow few potential bacterial metabolisms to persist. We considered the quantity of substrates used (of all those provided in the Biolog plate) as an index of potential functional diversity. The index calculated for the harbour and the coastal station samples was negatively correlated with chlorophyll a concentration, suggesting that the bacterial assemblages of oligotrophic systems have a higher number of metabolic pathways in order to be able to exploit a wide variety of DOC molecules present at low concentrations.
Paraules clau: Bacterioplankton, Biolog, Coastal carbon, Functional diversity, Carboxylic acids
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Quintero-Torres R., J.L. Aragón, M. Torres, M. Estrada, L. Cros
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics, 74, 3, 032901-1/4. DOI: 10.1103/PhysRevE.74.032901 (BibTeX: quinterotorres.etal.2006)
Resum: Veure
By considering the structure of holococcoliths (calcite plates that cover holococcolithophores, a haploid phase of the coccolithophore life cycle) as a photonic structure, we apply a discrete dipolar approximation to study the light backscattering properties of these algae. We show that some holococcolith structures have the ability to scatter the ultraviolet radiation. This property may represent an advantage for holococcolithophores possessing it, by allowing them to live higher in the water column than other coccolithophores.
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Solé J., E. García-Ladona, M. Estrada
Journal of Marine Systems, 62, 46-54. DOI: 10.1016/jmarsys.2006.04.002 (BibTeX: sole.etal.2006d)
Resum: Veure
A feature of marine plankton communities is the occurrence of rapid population explosions.When the blooming species are directly or indirectly noxious for humans, these proliferations are denoted as harmful algal blooms (HAB). The importance of biological interactions for the appearance ofHABs, in particular when the proliferatingmicroalgae produce toxins that affect other organisms in the food web, remains still poorly understood.Herewe analyse the role of toxins produced by a microalgal species and affecting its predators, in determining the success of that species as a bloom former. A three-species predator-prey model is used to define a criterion that determines whether a toxic microalga will be able to initiate a bloom in competition against a non-toxic one with higher growth rate. Dominance of the toxic species depends on a critical parameter that defines the degree of feeding selectivity by grazers. The criterion is applied to a particular simplified model and to numerical simulations of a full marine ecosystem model. The results suggest that the release of toxic compounds affecting predators may be a plausible biological factor in allowing the development of HABs.
Paraules clau: Harmful algal blooms; Feeding avoidance; Toxicity; Plankton; Predation
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Latasa M., X.A.G. Morán, R. Scharek, M. Estrada
Limnology and Oceanography, 50, 5, 1447-1458. DOI: 10.4319/lo.2005.50.5.1447 (BibTeX: latasa.etal.2005a)
Resum: Veure
We performed dilution experiments and primary production measurements in surface waters during a cruise in the northwestern Mediterranean Sea in June 2000 to quantify the carbon (C) flux through phytoplankton groups that can be distinguished by their pigment markers. Pigments in the dilution experiments were measured by highpressure liquid chromatography (HPLC). Pigment per cell and synthesis rates of photoprotectant versus light-harvesting pigments indicated that cells did not undergo photoacclimation during the 24-h dilution experiments. Mean chlorophyll a (Chl a) concentration was 0.128 mg m-3, and mean primary production was 4.99 mg of C m23 d21. Prymnesiophyceae contributed 51% of the total Chl a, green algae 21%, diatoms 13%, cyanobacteria 6%, and Pelagophyceae and Dinophyceae 4% each. Size fractionation showed that 68% of total phytoplankton were <5 µm. A mean growth rate of 0.89 d-1 was completely offset by a mean grazing rate of 1.01 d-1. Growth and mortality were also balanced for the individual phytoplankton groups, with highest rates for diatoms and lowest for green algae. Despite the high growth rates measured, nutrient-amended incubations showed that these rates were nutrient limited, although to a different extent for each group. Green algae experienced the most severe limitation and cyanobacteria the least. The comparison of C incorporation rates and Chl a synthesis rates permitted the estimation of a C: Chl a ratio of 47 (g : g) for newly produced organic matter in the study area. This value, corrected for the different degree of nutrient limitation, was used to estimate the C flow through the different phytoplankton groups. Because of their high growth rates, diatoms played a disproportionate role in the C flux compared to their biomass contribution.
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Solé J., E. García-Ladona, P. Ruardij, M. Estrada
Ecological Modelling, 183, 373-384. DOI: 10.1016/j.ecolmodel.2004.08.021 (BibTeX: sole.etal.2005b)
Resum: Veure
Allelopathy among microalgae has been modelled in order to fit the dynamics of mixed cultures of Chrysocromulina polylepis and Heterocapsa triquetra, carried out with three different initial concentrations of the allelopathic species C. polylepis. The experimental data have been analysed with a simple Lotka-Volterra type model including an allelopathic term. Based on the population dynamics of the two species in unialgal and mixed cultures, the model has been simplified and solved analytically. The best fit of the allelopathy parameter (gamma ≈ 10-5 to 10-6) provides a good agreement between the theoretical curve and the experimental data for the two highest initial concentrations of C. polylepis but, interestingly, shows a less accurate fit for low initial concentrations of the toxic alga. Following the same procedures, a modified model, in which the allelopathic effect is dependent on the square of the concentration of the toxic alga, has been adjusted to the experimental data. This modified model presents a good fit for all the range of initial concentrations of the toxic alga. These results allow a quantification of the strength of the allelopathic interaction between two marine phytoplankton species. The growth curve of the non-toxic alga is significantly affected by the allelopathy term only after the toxic alga has reached relatively high concentrations. This supports field observations suggesting that, at least in the case of C. polylepis, allelopathy may be important once a bloom is well developed, but is not likely to be a key factor in initial phases of the proliferation.
Paraules clau: Marine algae; Toxicity; Allelopathy; Mixed cultures; Fitting
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Sala M.M., V. Balagué, C. Pedrós-Alió, R. Massana, J. Felipe, L. Arin, H. Illoul, M. Estrada
FEMS Microbiology, Ecology, 54, 2, 257-267. DOI: 10.1016/j.femsec.2005.04.005 (BibTeX: sala.etal.2005)
Resum: Veure
The phylogenetic and functional diversity of the bacterioplankton assemblage associated with blooms of toxic Alexandrium spp. was studied in three harbours of the NW Mediterranean. Denaturing gradient gel electrophoresis and DNA sequence analysis revealed the presence of a bacterium within the Roseobacter clade related to the presence of Alexandrium cells. Phylogenetic diversity was affected by the presence of Alexandrium spp., geographic situation and seasonality. In contrast, functional diversity, assessed with Biolog plates, was clearly affected by seasonality, but not by the presence of Alexandrium, indicating that the presence of the bacterium associated with the blooms was not enough to modify the metabolic pattern of the bacterioplankton assemblage.
Paraules clau: Alexandrium, Bacterioplankton, Phylogenetic diversity, Functional diversity, BIOLOG, DGGE
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Arin L., M. Estrada, J. Salat, A. Cruzado
Continental Shelf Research, 25, 9, 1081-1095. DOI: 10.1016/j.csr.2004.12.011 (BibTeX: arin.etal.2005d)
Resum: Veure
The mesoscale distribution and seasonal variation of the size structure of phytoplankton biomass, as measured by chlorophyll a (chl a), was studied in the Ebro shelf area (NW Mediterranean) during three different seasons: autumn, winter and summer. In autumn and summer, when the water column was, respectively, slightly or strongly stratified and nutrient concentrations were low at surface, average total chl a values were 0.31 and 0.29 mg m-3, respectively. In winter, the intrusion of nutrients into the photic zone by intense vertical mixing and strong riverine inputs, produced an increase of the total autotrophic biomass (0.76 mg m-3). In the three seasons, the main contributor to total chl a was the picoplanktonic (<2 mi m) size fraction (42% in winter and around 60% in autumn and summer). The nanophytoplankton (2–20 mi m) contribution to total chl a showed the lowest variability amongst seasons (between 29% and 39%). The microplanktonic (>20 mi m) chl a size fraction was higher in winter (27%) than in the other seasons (less than 13%). The maximum total chl a concentrations were found at surface in winter, at depths of 40 m in autumn and between 50 and 80 m in summer. The relative contribution of the <2 mi m size fraction at these levels of the water column tended to be higher than at other depths in autumn and winter and lower in summer. In autumn and winter, nutrient inputs from Ebro river discharge and mixing processes resulted in an increase on the >2 mi m contribution to total chl a in the coastal zone near the Ebro Delta area. In summer, the contribution of the <2 and >2 mi m chl a size fractions was homogeneously distributed through the sampling area. In autumn and summer, when deep chl a maxima were observed, the total amount of the autotrophic biomass in the superficial waters (down to 10 m) of most offshore stations was less than 10% of the whole integrated chl a (down to 100 m or to the bottom). In winter, this percentage increased until 20% or 40%. The >2 mi m chl a increased linearly with total chl a values. However, the <2 mi m chl a showed a similar linear relationship only at total chl a values lower than 1mg m-3 (in autumn and summer) or 2 mg m-3 (winter). At higher values of total chl a, the contribution of the <2 mi m size fraction remained below an upper limit of roughly 0.5 mg m-3. Our results indicate that the picoplankton fraction of phytoplankton may show higher seasonal and mesoscale variability than is usually acknowledged.
Paraules clau: Spatio-temporal variation; Chlorophyll a fractionation; Picoplankton; Nanoplankton; Microplankton; Ebro river shelf; Northwestern Mediterranean.
Winter pelagic photosynthesis in the NW Mediterranean (2005)
Morán X.A.G., M. Estrada
Deep-Sea Research. Part I: Oceanographic Research Papers, 52, 1806-1822.
Distribution of eukaryotic picoplankton assemblages across hydrographic fronts in the Southern Ocean, studies by denaturing gradient gel electrophoresis (2004)
Díez B., R. Massana, M. Estrada, C. Pedrós-Alió
Limnology and Oceanography, 49, 4, 1022-1034.
Diversity of planktonic photoautotrophic microorganisms along a salinity gradient as depicted by microscopy, flow cytometry, pigment analysis and DNA-based methods (2004)
Estrada M., P. Henriksen, J.M. Gasol, E.O. Casamayor, C. Pedrós-Alió
FEMS Microbiology, Ecology, 49, 281-293.
Evidence for enhanced primary production resulting from relative vorticity induced upwelling in the Catalan Current (2004)
Granata T.C., M. Estrada, U. Zika, C. Merry
Scientia Marina, 68, Suppl.1, 113-119. (BibTeX: granata.etal.2004)
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Estrada M., J. Salat, M. Emelianov, L. Arín, D. Blasco, A. Morales
, Rapports et Proces-verbaux des Réunions. Com. Int. Explor. Sci. Mer Mediterranée, CIESM.. Ed. CIESM. 37, 96. Montecarlo (Monaco). ISSN: 0373-434X (BibTeX: estrada.etal.2004c)
Resum: Veure
The reduction of deep mixing extent and changes in phytoplankton distributions due to an anomaly in the circulation during winter are presented and compared with a typical winter
Paraules clau: Deep mixing, phytoplankton, NW Mediterranean, marine circulation
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Vázquez-Domínguez E., J.M. Gasol, D. Vaqué, M. Estrada
Rapports et Proces-verbaux des Réunions. Com. Int. Explor. Sci. Mer Mediterranée, CIESM., 37, 296. (BibTeX: vazquezdominguez.etal.2004)
Modeling physiological processes in plankton on enzyme kinetic principles (2004)
Packard T., D. Blasco, M. Estrada
Scientia Marina, 68, Suppl. 1, 49-56. (BibTeX: packard.etal.2004)
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Berdalet E., C. Roldán, M. Latasa, C. Marrasé, M. Vidal, M. Estrada, A. Malits, J. Salat, M. Emelianov, A. Sabatés
, Rapports et Proces-verbaux des Réunions. Com. Int. Explor. Sci. Mer Mediterranée, CIESM.. Ed. CIESM. CIESM. 37, 313. Montecarlo (Monaco). ISSN: 0373-434X (BibTeX: berdalet.etal.2004d)
Resum: Veure
We studied physico-chemical (temperature, salinity, inorganic nutrients) and biological (phytoplankton pigment composition, bacterial numbers, protein, DNA, RNA, and POM) characteristics of a hydrographically diverse area of the northern Catalan sea during the stratification period (June 2000). The sampled stations were affected by a) continental shelf (coastal waters), and b) low salinity surface waters from the Gulf of Lions influenced by the Rhone runoff (called Plume), carried by the shelf-slope Catalan current. We compared these areas with oceanic waters. The relative fertilising effect of the Plume for the plankton communities is discussed
Paraules clau: nutrients, pigments, plankton, Rhone plume
Picarola margalefii, gen. Et sp. Nov., a new planktonic coccolithophore from NW Mediterrranean waters (2004)
Cros L., M. Estrada
Scientia Marina, 68, Suppl. 1, 243-248.
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Estrada M., E. Berdalet, M. Vila, C. Marrasé
Aquatic Microbial Ecology, 32, 1, 61-71. DOI: 10.3354/ame032061 (BibTeX: estrada.etal.2003)
Resum: Veure
A microcosm experiment was carried out during early spring 1994 in order to investigate the effect of Si-sufficient but low N:P ratio or high N:P ratio nutrient inputs, added at different frequencies, on phytoplankton succession patterns. Eight Perspex cylinders were filled with 30 l of coastal water from Masnou (20 km north of Barcelona) and placed in a chamber at 17°C under a 12:12 h light:dark photoperiod. Four experimental conditions were randomly assigned to duplicate containers: low N:P ratio (N-deficient) or high N:P ratio (P-deficient) nutrient inputs (including sufficient Si in all cases), in combination with addition intervals of 2 or 6 d. Integrated chlorophyll a (chl a) concentrations in the P-deficient containers were significantly higher than in the N-deficient ones, presumably due to the faster recycling of P with respect to N, but differences between addition intervals were non-significant. All microcosms presented an initial bloom dominated by diatoms. In the post-bloom phase, after depletion of the nutrient in short supply, dinoflagellate abundances were higher and diatom abundances lower in the N-deficient than in the P-deficient microcosms. Within nutrient treatments, the qualitative composition of the phytoplankton assemblages was similar across frequencies and replicates. In contrast, characteristics, such as total phytoplankton biovolume or the abundance of dominant taxa, presented significant variability, presumably due to non-linear interactions, even within replicates. This finding suggests the importance of focussing on assemblages rather than on individual taxa when attempting to derive regularities concerning the response of phytoplankton to environmental factors.
Paraules clau: NW Mediterranean · Nitrogen · Phosphorus · Nutrient ratios · Chlorophyll a concentration · Phytoplankton biomass · Phytoplankton succession · Phytoplankton assemblages
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Calbet A., D. Vaqué, J. Felipe, M. Vila, M.M. Sala, M. Alcaraz, M. Estrada
Marine Ecology Progress Series, 259, 303-309. DOI: 10.3354/meps259303 (BibTeX: calbet.etal.2003a)
Resum: Veure
Grazing can be a substantial loss factor for harmful algal blooms (HABs) and a possible cause of their termination. There is, however, a considerable gap in our knowledge of the relative grazing impact of the different components of the planktonic community on a red tide. In this study, we examine the importance of grazing control on a naturally occurring bloom of the toxic dinoflagellate Alexandrium minutum. We estimated the grazing impact of microzooplankton (by the dilution method) and copepods (by 24 h incubations with cultured populations of Acartia grani and Oithona davisae) on a bloom of A. minutum. Grazing by microzooplankton (0.84 d-1) was equal to and even exceeded A. minutum growth rates (0.79 d-1). On the other hand, copepod impact on the A. minutum population was not significant, although they were actively feeding on the dinoflagellate, which accounted for 78 and 86% of the daily carbon intake of A. grani and O. davisae, respectively. Even if these results were extended to the highest realistic copepod abundance attainable in the area, the grazing impact on highly concentrated HABs would not be sufficient to significantly reduce the algal concentrations. In summary, grazing by microzooplankton can represent an important factor for the regulation of HABs.
Paraules clau: Harmful algal bloom, Alexandrium minutum, Microzooplankton, Mesozooplankton, Acartia grani, Oithona davisae, Grazing
Dissolved Primary Production and the Strength of Phytoplankton-Bacterioplankton Coupling in Contrasting Marine Regions (2002)
Morán X.A.G., M. Estrada, J.M. Gasol, C. Pedrós-Alió
Microbial Ecology, 44, 3, 217-223.
Microcosms: applications in marine phytoplankton studies (2002)
Estrada M., F. Peters
In: Pelagic ecology methodology, Ed. D.V. Subba Rao. Balkema Publishers. 359-370. Rotterdam.
Partitioning of phytoplanktonic organic carbon production and bacterial production along a coastal-offshore gradient in the NE Atlantic during different hydrographic regimes (2002)
Morán X.A.G., J.M. Gasol, C. Pedrós-Alió, M. Estrada
Aquatic Microbial Ecology, 29, 3, 239-252.
Phytoplanktonic DOC and POC production in the Bransfield and Gerlache Straits as derived from kinetic experiments of 14C incorporation (2002)
Morán X., M. Estrada
Deep-Sea Research Part II: Topical Studies in Oceanography, 49, 4-5, 769-786.
Phytoplankton size distribution and growth rates in the Alboran Sea (SW Mediterranean): short term variability (2002)
Arin L., X.A. G. Morán, M. Estrada
Journal of Plankton Research, 24, 1019-1033.
The FRUELA cruises. A carbon flux study in productive areas of the Antarctic Peninsula (December 1995-February 1996) (2002)
Anadón R., M. Estrada
Deep-Sea Research Part II: Topical Studies in Oceanography, 49, 4-5, 567-583.
Dissolved and particulate primary production and bacterial production in offshore Antarctic waters during austral summer: coupled or uncoupled? (2001)
Morán X.A.G., J. M. Gasol, Carlos Pedrós-Alió, Marta Estrada
Marine Ecology Progress Series, 222, 25-39.
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Morán X.A.G., I. Taupier-Letage, E. Vázquez-Dominguez, S. Ruíz, L. Arin, P. Raimbault, M. Estrada
Deep-Sea Research. Part I: Oceanographic Research Papers, 48, 2, 405-437. DOI: 10.1016/S0967-0637(00)00042-X (BibTeX: moran.etal.2001b)
Resum: Veure
The biomass and production of phytoplankton and bacterioplankton was investigated in relation to the mesoscale structures found in the Algerian Current during the ALGERS'96 cruise (October 1996). Biological determinations were carried out in three transects between 0o and 2oE aimed at crossing a so-called event, formed by a coastal anticyclonic eddy associated with an offshore cyclonic eddy to the west. The concentration of chlorophyll a (Chl) was maximum (>1.2mgm-3) within the cyclonic eddy and at the frontal zones between the Modified Atlantic Water (MAW) of the Algerian Current and the Mediterranean waters further north. Chl (total and >2 m) was significantly correlated with proxies of nutrient flux into the upper layers. Autotrophic picoplankton and heterotrophic bacterial abundance and production presented clear differences between MAW and Mediterranean water, with higher values at those stations under the influence of the Algerian Current. In general, greater differences were observed in production than in biomass variables. The photosynthetic parameters (derived from P-E relationships) and integrated primary production (range 189-645mgm-2d-1) responded greatly to the different hydrological conditions. The mesoscale phenomena inducing fertilization caused a 2 to 3-fold increase in primary production rates. The relatively high values found within the cyclonic eddy suggest that, although short-lived in comparison with anticyclonic eddies, these eddies may produce episodic increases of biological production not accounted for in previous surveys in the region.
Paraules clau: Phytoplankton; Bacteria; P-E relationships; Primary production; Bacterial production; Mesoscale; Mediterranean; Algerian basin
Short-term variability of photosynthetic parameters and particulate and dissolved primary production in the Alboran Sea (SW Mediterranean) (2001)
Morán X.A.G., Marta Estrada
Marine Ecology Progress Series, 212, 53-67.
A comparison between glass fiber and membrane filters for the estimation of phytoplankton POC and DOC production (1999)
Morán X.A.G., J.M. Gasol, L. Arin, M. Estrada
Marine Ecology Progress Series, 187, 31-41.
Bacterioplankton and phytoplankton biomass and production during summer stratification in the northwestern Mediterranean Sea (1999)
Pedrós-Alio C., J.-I. Calderón-Paz, N. Guixa-Boixereu, M. Estrada, J.-M. Gasol
Deep-Sea Research. Part I: Oceanographic Research Papers, 46, 985-1019.
Effect of upwelling pulses on excess carbohydrate synthesis as deduced from nutrient, carbon dioxide and oxygen profiles (1999)
Fraga F., A.F. Ríos, F.F. Pérez, M. Estrada, C. Marrasé
Marine Ecology Progress Series, 189, 65-75.
Hidrodinàmica i fotoplàncton en el mar català (1999)
Estrada M.,
In: Memorias de la Real Academia de Ciencias y Artes de Barcelona, Vol. LVIII. Chap. 6. 189-241.
Implications of bio-optical modeling of phytoplankton photosynthesis in Antarctic waters: Further evidence of no light limitation in the Bransfield Strait (1999)
Figueiras F.G., B. Arbones, M. Estrada
Limnology and Oceanography, 44, 7, 1599-1608.
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Arin L., E.E. Berdalet, C. Marrasé, M. Estrada, N. Guixa-Boixereu, J. Dolan
Journal of Plankton Research, 21, 7, 1299-1316. DOI: 10.1093/plankt/21.7.1299 (BibTeX: arin.etal.1999)
Resum: Veure
Using microscopic and biochemical approaches, the relative contribution of the main groups of pelagic microorganisms (bacteria, heterotrophic nanoflagellates, phytoplankton and ciliates) and detritus (<150m) to total particulate protein and DNA was investigated at two stations of the Catalano-Balearic Sea (NW Mediterranean) during the stratified period. The two stations, one located in the shelf break front (S) and the other in the open sea, above the central divergence zone (D), were sampled twice in early summer 1993. Both of them showed a well-developed deep chlorophyll maximum (DCM). Maximum DNA concentrations were observed close to the DCM, while protein concentrations were fairly homogeneous from the surface to 60 m depth in all samplings. In general, the microorganism distribution showed maximum concentrations at or near the DCM depths. At both stations, bacteria were the most important contributors to living particulate DNA (22.5-32.6%), while phytoplankton and heterotrophic nanoflagellates were the main contributors to living particulate protein (3.8-24.4 and 2.9-29.1%, respectively). In addition, an important amount of detrital DNA and protein was estimated to occur at both stations. Detrital DNA accounted for 23.9-42.9% of the particulate DNA, while detrital protein represented from 63.5 to 84.7% of the particulate protein. Because both protein and DNA contain nitrogen and DNA is also a phosphorus source, these results indicate that heterotrophic organisms and detrital particles play an important role in the nitrogen and phosphorus cycles in the open sea waters of the NW Mediterranean.
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Estrada M., R.A. Varela, J. Salat, A. Cruzado, E. Arias
Journal of Plankton Research, 21, 1, 1-20. (BibTeX: estrada.etal.1999a)
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Estrada M., E. Berdalet
In: Physiological ecology of harmful algal blooms, Series G: Ecological Series. Vol. 41. Ed. D. M. Anderson, A.D. Cembella & G. M. Halleagraaf (eds.). 601-618. ISBN: 978-3540641179 (BibTeX: estrada.berdalet.1998)
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Berdalet E., D. Vaqué, L. Arín, M. Estrada, M. Alcaraz, J.A. Fernández
Polar Biology, 17, 1, 31-38. DOI: 10.1007/s003000050102 (BibTeX: berdalet.etal.1997)
Resum: Veure
 The relationships between hydrography and spatial distribution of several biochemical indicators of microplankton biomass (chlorophyll, protein and ATP) were studied in an area covering the eastern part of the Bransfield Strait and the northern part of the Weddell Sea, during Antarctic summer (January 1994). Four hydrographic zones were identified: (a) the northern part of the Bransfield Strait, covered by waters of Bellings- hausen Sea origin; (b) a Weddell Sea water mass that affected most of the study area; (c) the Weddell-Scotia Confluence waters, observed north of Elephant Island; and (d) waters influenced by ice melting, found towards the southeastern part of the sampled area. The highest values of biomass indicators (chlorophyll a, ATP and protein) were found in the zones affected by ice-melting processes and in waters from the Bellingshausen Sea. The lowest values of all biochemical parameters were found in the Weddell Sea and in the Weddell-Scotia Confluence waters. A high variability in the hydrographic structure and the distribution of biochemical indicators was observed. The degree of stabilization of the water column, the depth of the upper mixed layer and the grazing pressure of herbivorous zooplankton played a major role in the development, accumulation and spatial variability of microplankton biomass.
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Estrada M., E. Berdalet
Scientia Marina, 61, suppl.1, 125-140. (BibTeX: estrada.berdalet.1997)
Resum: Veure
This contribution reviews relationships between turbulence and marine phytoplankton ecology, ranging from the mesoscale to the smallest scales. Phytoplankton life-forms, considered to be survival strategies in a turbulent environment, are briefly presented. The importance of mesoscale hydrodynamics on phytoplankton distributions and organisms physiology and behaviour, are examined. Finally, direct effects of small scale turbulence on phytoplankton are considered.
Effect of different nutrient combinations on phytoplankton development in microcosms (1996)
Estrada M., E. Berdalet, C. Marrasé, L. Arin, M.L. Mclean
In: Harmful and Toxic Algal Blooms, Intergovernamental Oceanographic Commission of UNESCO. Ed. T. Yasumoto, Y. Oshima and Y. Fukuyo (eds). 297-300.
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Estrada M., C. Marrasé, J. Salat
Scientia Marina, 60, suppl. 1, 317-325. (BibTeX: estrada.etal.1996)
Resum: Veure
This article reviews the main factors affecting the in vivo fluorescence versus chlorophyll relationships of phytoplankton and presents a case study based on data from three oceanographic cruises carried out, at different times of the year, in the Catalan-Balearic Sea. In all three surveys, the in vivo fluorescence/chlorophyll ratio of the upper euphotic layer samples presented a diel variability with a minimum at or before noontime. The relationships between the spatio-temporal distribution of this variability and characteristics of photosynthesis versus irradiance curves obtained during each cruise are discussed
Paraules clau: Phytoplankton, fluorescence to chlorophyll ratios, quenching, diel variability
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Berdalet ., E., C. Marrasé, M. Estrada, L. Arin, M.Maclean
Journal of Plankton Research, 18, 9, 1627-1641. DOI: 10.1093/plankt/18.9.1627 (BibTeX: .etal.1996a)
Resum: Veure
Natural plankton communities from Masnou, a locality 20 km north of Barcelona (NW Mediterranean coast), were enclosed in 30 l microcosms to test the effect of different availability of nitrogen (N) and phosphorus (P) on the biomass of the main microplankton groups, and the biochemical composition (DNA, protein and chlorophyll concentration) of microbial communities. Immediately after enclosure in microcosms, three different nutrient enrichments were performed: N-deficient, P-deficient and nutrient-balanced. N and P deficiencies affected the structure and the biochemical composition of the microbial communities. Phytoplankton assemblages showed similar temporal patterns under the three nutrient treatments, although the relative contribution of the different groups was notably affected. The lowest DNA concentration was measured in the P-deficient treatment, suggesting that P availability imposes the limits on the DNA levels in the ecosystem. The availability of N in the P-deficient microcosms allowed relatively high synthesis of chlorophyll and protein until the end of the experiment. Significantly high chlorophyll: DNA and protein: DNA ratios characterized the P-deficient treatment (where N was available) compared to the N-deficient microcosms. From the results obtained, we suggest that the protein: DNA ratios may constitute a biochemical indicator of the P versus N availability in natural ecosystems.
Phytoplankton assemblages across a NW Mediterranean front: persistence and variability (1996)
Estrada M., J. Salat
AGU Ocean Sciences Meeting 1996, . San Diego , California,USA. (BibTeX: estrada.salat.1996a)
Planktonic herbivorous food webs in the catalan Sea (NW Mediterranean): temporal variability and comparison of indices of phyto-zooplankton coupling based on state variables and rate processes (1996)
Calbet A., M. Alcaraz, E. Saiz, M. Estrada, I. Trepat
Journal of Plankton Research, 18, 12, 2329-2347.
Dinoflagellate assemblages in the Iberian upwelling area. (1995)
Estrada M.,
In: Harmful Marine Algal Blooms, Ed. P. Lassus et al. (eds.):. Lavoisier. 157-162.
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Granata T.C., T.D. Dickey, M. Estrada, A. Castellón
In: Mixing in Geophysical Flows, Ed. J.M. Redondo, O. Metais. CIMNE. 367-378. ISBN: 84-87867-68-5 (BibTeX: granata.etal.1995a)
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Granata T., T.D. Dickey, M. Estrada, A. Castellón
In: Mixing in Geophysical Flows, Ed. J.M. Redondo, O. Metais. CIMNE. 367-378. ISBN: 84-87867-68-5 (BibTeX: granata.etal.1995b)
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Granata T.C., T.D. Dickey, M. Estrada, A. Castellón
In: Mixing in Geophysical Flows, Ed. J.M. Redondo, O. Metais. 413. ISBN: 84-87867-68-5 (BibTeX: granata.etal.1995)
CO2 system in a Mediterranean frontal zone (1994)
Delgado O., M. Estrada
Scientia Marina, 58, 3, 237-250.
Berdalet E., M. Latasa, M. Estrada
Journal of Plankton Research, 16, 4, 303-316. DOI: 10.1093/plankt/16.4.303 (BibTeX: berdalet.etal.1994)
Resum: Veure
Changes in the protein, RNA and DNA content related to nitrogen (N) and phosphorus (P) starvation were studied in the marine dinoflagellate Heterocapsa sp. grown in batch cultures. In both cases of nutrient starvation, metabolic adaptations affected protein and RNA pools, while the DNA content per cell remained approximately constant. N starvation led to a parallel decrease in protein and RNA concentration which caused the protein/RNA ratios to remain constant. A dramatic decrease in the RNA content characterized the P-starved cultures, although protein synthesis continued. The ribosomal RNA content was lower than expected given the continuation of protein synthesis. It is suggested that protein/RNA ratios could be used as an indicator of P starvation, while protein/chlorophyll ratios would characterize N starvation
Excretion of ammonia by zooplankton and its potential contribution to nitrogen requirements for primary production in the Catalan Sea (NW Mediterranean). (1994)
Alcaraz M., E. Saiz, M. Estrada
Marine Biology, 119, 69-76.
Phytoplankton composition in the Weddell-Scotia confluence area during austral spring in relation to hydrography (1994)
Schloss I., M. Estrada
Polar Biology, 14, 77-90.
Effects of turbulence on several dinoflagellate species. (1993)
Berdalet E., M. Estrada
In: In Toxic Phytoplankton Blooms in the Sea edited by T. J. Smayda and Y. Shimizu, Ed. T. J. Smayda and Y. Shimizu. 734-737.
Hydrographic structure and primary production in oligotrophic marine environments (1993)
Estrada M.,
In: In: Trends in Microbial Ecology edited by R. Guerrero and C. Pedrós-Alió, Ed. R. Guerrero and C. Pedrós-Alió. 453-458.
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Berdalet E., M. Estrada
Marine Biology, 117, 1, 163-170.. DOI: 10.1007/BF00346439 (BibTeX: berdalet.estrada.1993)
Resum: Veure
We explored the relationships between classical estimators of autotrophic biomass and primary production, such as chlorophyll a concentration and 14C-fixation rates, and biochemical indices based on DNA and RNA determinations, which have been proposed as indicators of physiological state in natural plankton populations. The measurements were made during two cruises across the Catalan Front, carried out in May 1989 and February 1990, corresponding respectively, to periods of stratification and moderate mixing. DNA and RNA concentrations (measured by a double-staining fluorimetric technique) were significantly correlated with chlorophyll a in February 1990, but not in May 1989, when a marked deep chlorophyll maximum was present. Significant positive correlations between RNA concentration and primary production and between RNA: DNA and primary production were found during both surveys, probably reflecting both higher RNA concentrations per cell and enhanced bacterial and microheterotrophic growth in high primary production situations. The results support the potential usefulness, in biological oceanography, of biochemical indicators based on DNA and RNA concentrations.
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Estrada M., C. Marrasé, M. Latasa, E. Berdalet, M. Delgado, T. Riera
Marine Ecology Progress Series, 92, 289-300. (BibTeX: estrada.etal.1993)
Zooplankton excretion and primary production: contribution of regenerated ammonia to nitrogen requirements of phytoplankton in the Catalan Sea (NW Mediterranean (1993)
Alcaraz M., E. Saiz, M. Estrada
In: In: Trends in microbial ecology edited by R. Guerrero & C. Pedrós, Ed. R. Guerrero & C. Pedrós. 465-470.
El fitoplancton antártico (1992)
Estrada M.,
Informes Técnicos de Scientia Marina, 167, 1-16.
Plankton-pigment relationships in the Northwestern Mediterranean during stratification (1992)
Latasa M., M. Estrada, M. Delgado
Marine Ecology Progress Series, 88, 61-73.
Respiratory electron transport activity in plankton of the Weddell and Scotia Seas during late spring-early summer: relationships with other biological parameters (1992)
Estrada M., R. Martínez, S. Mathot
Polar Biology, 12, 35-42.
Respiratory electron transport activity of microplankton in the Weddell Sea during early spring: influence of the ice cover and the ice edge (1992)
Martínez R., M. Estrada
Polar Biology, 12, 275-282. (BibTeX: martinez.estrada.1992)
Variability in size-fractionated distribution of the phytoplankton across the Catalan front of the north-west Mediterranean. (1992)
Delgado M., M. Latasa, M. Estrada
Journal of Plankton Research, 14, 5, 753-771.
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Berdalet E., M. Latasa, M. Estrada
Hydrobiologia, 238, 1, 139-147. DOI: 10.1007/BF00048782 (BibTeX: berdalet.etal.1992)
Resum: Veure
The division cycle of two phytoplankton species, Olisthodiscus luteus and Heterocapsa sp. was studied in relation to a 12:12 light:dark cycle. Batch cultures in exponential phase were sampled every three hours during 48 hours. Cell number, cellular volume and DNA and RNA concentrations were measured. Microscopic observations of the nuclei of Heterocapsa sp. were also performed. In both species, cell division took place in the dark. In Heterocapsa sp., DNA and RNA showed a similar diel variability pattern, with synthesis starting at the end of the light period, previously to mitosis and cytokinesis. In O. luteus. Major RNA synthesis occurred during darkness, and DNA was produced almost continuously. Both species presented different values and diel rhythmicity on the RNA/DNA ratios.
Paraules clau: Heterocapsa - Olisthodiscus - RNA/DNA - cell cycle
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Latasa M., E. Berdalet, M. Estrada
Hydrobiologia, 238, 1, 149-157. DOI: 10.1007/BF00048783 (BibTeX: latasa.etal.1992)
Resum: Veure
Photosynthetic pigment composition was studied in batch cultures of Heterocapsa sp. and Olisthodiscus luteus growing exponentially in a 12:12 light:dark cycle. Both species divided in the dark. The synthesis of pigments was continuous for both species. However for chlorophyll c and peridinin, in Heterocapsa sp., and chlorophyll c and fucoxanthin, in O. luteus, (pigments belonging to light harvesting complexes) the synthesis was significantly higher during the light period. Concentrations per total cell volume (TCV) of chlorophyll a, chlorophyll c, peridinin and diadinoxanthin in Heterocapsa sp., and chlorophyll a, chlorophyll c, fucoxanthin and violaxanthin in O. luteus, showed a maximum at the onset of light and decreased during the light period. The values of the chlorophyll a:chlorophyll c, chlorophyll a:peridinin and chlorophyll a:fucoxanthin ratios are compared with data reported in the literature.
Paraules clau: Heterocapsa sp.; Olisthodiscus luteus - cycles - pigments - HPLC
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Varela R., Grupo FRONTS (S. Agustí, P. Andreu, M. Alcaraz, J. Arístegui, E. Berdalet, J. Calderón, C. Castellón, A. Cruzado, M. Delgado, M. Estrada, X. Fusté, J. Gabarrou, M. Latasa, M. Manriquez, C. Marrasé, N. Martínez, R. Martínez, M. Masó, R. Massana, M. Palau, I. Palomera, T. Riera, V. Rodríguez, J. Ruíz, E. Saiz, J. Salat, J. Sanchez-Pardo
ISSN: 0210-0827 (BibTeX: varela.etal.1991h)
Resum: Veure
Las campañas FRONTS 1989,1990,1991 se desarrollaron dentro del marco del Proyecto FRONTS. Estudio de los efectos hidrodinámicos sobre la distribución y fisiología de las comunidades planctónicas en los frentes del Mar Catalán, subvencionado por la CYCYT (No.MAR88-0252). En particular, se trataba de analizar los efectos de inestabilidades intermitentes de mesoescala sobre la distribución del fitoplancton en un sistema frontal, y la influencia del frente costero catalán sobre la distribución espacio-temporal de las comunidades del zooplancton.
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Estrada M., J. Salat
Scientia Marina, 53, 2-3 SP, 203-214. (BibTeX: estrada.salat.1989)
Resum: Veure
A consistent hydrographical feature of the Catalan Balearic Sea is the presence of a doming of the isopycnals, approximately mid-way between the Catalan coast and the Balearic Islands. The Catalan and Balearic boundaries of this feature are marked by two fronts. In July 1983, high chlorophyll concentrations were found near the coast and in a deep chlorophyll maximum which extended across the frontal zones. The phytoplankton distribution was basically determined by the vertical stratification patterns of the water column. The distribution of oxygen and nutrients across the Catalan front, and the presence of relatively high diatom concentrations in the deep chlorophyll maximum of the frontal zone suggested the existence of intermittent fertilization events.
Paraules clau: fronts, phytoplankton, Catalan Sea, NW Mediterranean hydrography
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Masó M., Grup PEPS (M. Alcaráz, P. Algarra, E. Berdalet, G. Ganzani, E. Carr, A. Castellón, A. Cruz, A. Cruzado, M. Delgado, O. Delgado, M. Estrada, S. Ferrer, J. Flos, J.M. Fortuño, X. Fusté, S. Mallo, M. Manríquez, R. Margalef, X. Modamio, T.T. Packard, M. Pagespetit, R. Ras, T. Riera, E. Saiz, J. Salat, F. Vallespinós, D. Vaqué, M. Zabala)
ISSN: 0210-0827 (BibTeX: maso.etal.1988e)
Resum: Veure
Todas las campañas se realizaron a bordo del B/O "García del Cid". Las tres campañas FRONTS (3-85, 6-85,11 -86) formaban parte del proyecto "Contribución de frentes hidrográficos costeros a la producción estival en el mar Catalán-Balear" (financiado por el CSIC y la ayuda nº PR84-0067 de la Comisión Asesora de Investigación Científica y Técnica). Las campañas PEP-86 y PEP-87 eran parte del proyecto "El máximo profundo de clorofila" (financiado por el CSIC y el Comité Conjunto Hispano-Norteamericano de cooperación Científica y Técnica, ayuda nº CCA8411054). Las fechas de las campañas se dan en la tabla 1 y las estaciones visitadas se muestran en las figuras 1 a 6. El presente volumen de Datos Informativos recoge los datos básicos obtenidos.
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Alcaráz Grup PEPS (M., A. Castellón, A. Cruz, M. Delgado, M. Estrada, F. Fernández, J. Flos, X. Fusté, E. Gutiérrez, A. Lobo, M. Manríquez, R. Margalef, C. Marrasé, M. Masó, R. Ras, J. Romero, J. Salat, L. J. Tellería, F. Vallespinós, J. Zavatti)
Resum: Veure
Las campañas PEP (Producció Estival Profunda) se realizaron a bordo del B/O García del Cid, del 11 al 30 de julio de 1982, del 30 de junio al 17 de julio de 1983 y del 15 al 30 de mayo de 1948, como parte del Proyecto "Transferéncia vertical del nitrógeno y carbono en el mar Catalán durante el periodo de estratificación". Las estaciones visitadas durante cada una de las campañas se muestran en las fig. 1 a 3. El presente volúmen de Datos Informativos recoge los datos básicos obtenidos.
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Pérez F. F., M. Estrada , J. Salat
Investigación Pesquera, 50, 3, 333-351. (BibTeX: f.perez.etal.1986a)
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Estrada M.,
PhD thesis. Director/es: R. Margalef. Barcelona. (BibTeX: estrada.1976a)