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Auteur (up) Demarcq, H.; Reygondeau, G.; Alvain, S.; Vantrepotte, V.
Titre Monitoring marine phytoplankton seasonality from space Type Article scientifique
Année 2012 Publication Revue Abrégée Remote Sensing of Environment
Volume 117 Numéro Pages 211-222
Mots-Clés Biogeography; Phytoplankton; Phytoplankton Functional; remote sensing; seasonality; Seasonal parameters; Surface chlorophyll concentration; Types; Wavelet transform
Résumé Remote sensing techniques are used to study the large scale patterns related to the seasonal modes of variability of the marine phytoplankton. Ten years of monthly composite maps of sea surface chlorophyll-a concentration and the PHYSAT database of four Phytoplanktonic Functional Types (PFTs), both from SeaWiFS, are used to investigate characteristics of phytoplankton seasonality in the trades and westerlies wind oceanic biomes, where data density is adequate. We use a combination of wavelet transform and statistical techniques that allow us to quantify both intensity and duration of the seasonal oscillation of chlorophyll-a concentration and PFTs relative occurrence, and to map these relationships. Next, the seasonal oscillations detected are related to four PFTs revealing six major global phytoplanktonic associations. Our results elucidate the intensity and duration of the seasonal dynamic of the chlorophyll-a concentration and of the relative occurrence of four PFTs at a global scale. Thus, the typology of the different types of seasonality is investigated. Finally, an overall agreement between the results and the biogeochemical provinces partition proposed by Longhurst is found, revealing a strong environmental control on the seasonal oscillation of primary producers and a clear latitudinal organization in the succession of the phytoplankton types. Results provided in this study quantify the seasonal oscillation of key structural parameters of the global ocean, and their potential implications for our understanding of ecosystem dynamics.
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ISSN 0034-4257 ISBN Médium
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Numéro d'Appel LL @ pixluser @ collection 182
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Auteur (up) Denis, M.; Thyssen, M.; Martin, V.; Manca, B.; Vidussi, F.
Titre Ultraphytoplankton basin-scale distribution in the eastern Mediterranean Sea in winter: link to hydrodynamism and nutrients Type Article scientifique
Année 2010 Publication Revue Abrégée Biogeosciences
Volume 7 Numéro 7 Pages 2227-2244
Mots-Clés adriatic sea; community; cyanobacteria; general-circulation; nifh genes; phosphorus limitation; phytoplankton; pigment distribution; primary productivity; structure; unicellular; warm-core eddy
Résumé The basin-scale distribution of ultraphytoplankton (< 10 mu m) was determined in the upper 200 m of the eastern Mediterranean Sea during the winter season. Four clusters were resolved by flow cytometry on the basis of their optical properties and identified as Synechococcus, Prochlorococcus, pico- (< 3 mu m) and nanoeukaryotes (3-10 mu m). Synechococcus was the most abundant population (maximum abundance of about 37 000 cells cm(-3)) and contributed up to 67.7% to the overall ultraphytoplanktonic carbon biomass, whereas the contribution of Prochlorococcus never exceeded 6.5%. The maximum integrated carbon biomass was 1763, 453, 58 and 571 mg C m(-2) for nanoeukaryotes, picoeukaryotes, Prochlorococcus and Synechococcus respectively. Water mass properties were analyzed on the basis of temperature and salinity distributions in order to account for the general circulation and locate the main hydrodynamic structures (fronts, gyres, transition between western and eastern basins). The effect of the main hydrodynamic structures and nutrients on the ultraphytoplankton distribution was investigated. No positive correlation between nutrients and phytoplankton could be established when considering large scales. However, below 50 m depth, nutrient ratios between particular stations were correlated to corresponding density ratios. In contrast, significant relationships were found between Synechococcus abundance and density, resulting from the impact of a gyre in southern Adriatic basin and a thermohaline front in the Ionian basin. A significant relationship was also found between picoeukaryotes and salinity in the comparison of western and eastern Mediterranean Sea.
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Langue English Langue du Résumé Titre Original
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ISSN 1726-4170 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 914
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Auteur (up) Derolez, V.; Soudant, D.; Malet, N.; Chiantella, C.; Richard, M.; Abadie, E.; Aliaume, C.; Bec, B.
Titre Two decades of oligotrophication: Evidence for a phytoplankton community shift in the coastal lagoon of Thau (Mediterranean Sea, France) Type Article scientifique
Année 2020 Publication Revue Abrégée Estuarine, Coastal and Shelf Science
Volume Numéro Pages 106810
Mots-Clés Eutrophication; Mediterranean coastal lagoon; Nutrients; Oligotrophication; Phytoplankton community shift; Recovery
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ISSN 0272-7714 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2776
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Auteur (up) Dhurmeea, Z.; Pethybridge, H.; Langlais, C.; Somes, C.J.; Nikolic, N.; Bourjea, J.; Appadoo, C.; Bodin, N.
Titre Spatial variation in stable isotopes and fatty acid trophic markers in albacore tuna (Thunnus alalunga) from the western Indian Ocean Type Article scientifique
Année 2020 Publication Revue Abrégée Deep Sea Research Part I: Oceanographic Research Papers
Volume Numéro Pages 103286
Mots-Clés Climate change; Environmental parameters; Phytoplankton; Trophodynamics
Résumé Albacore tuna (Thunnus alalunga) is a highly economically important species in the western Indian Ocean. However, knowledge of its ecological and nutritional characteristics, essential for proper management of the species, is lacking in the region. The trophodynamics of the Indian Ocean albacore was thus examined using known fatty acid trophic markers (FATMs) of primary producers, nutritional condition indices (NCIs) (omega-3/omega-6 ratio and total fatty acid content (TFA)), and baseline and lipid corrected stable isotope of carbon (δ13Ccorr) and nitrogen (δ15Ncorr), measured in the muscle tissue. We applied generalized additive mixed models to understand the spatiotemporal patterns and drivers of these tracers, taking into consideration several intrinsic and extrinsic variables: fish size, fishing position, month, chlorophyll-a and sea surface temperature (SST). Both chlorophyll-a and SST were significant as single explanatory variables for all tracers with SST being the best predictor for docosahexaenoic acid/eicosapentaenoic acid ratio, the omega-6 protists FATM, omega-3/omega-6 ratio, δ13Ccorr and δ15Ncorr. TFA was best predicted by fish size only. Higher primary productivity, as inferred by high δ13Ccorr values and diatom contribution, nutritional condition and trophic position, as inferred by high δ15Ncorr values, were observed in albacore from the temperate southern waters than in the northern tropical regions. Relationships between environmental variables and corrected stable isotopes, FATMs confirm that ocean warming and changes in primary productivity will impact nutrient flow and energy transfer in the marine food web which may have negative nutritional outcomes for albacore. This knowledge is particularly crucial in areas where oceanographic conditions and seawater temperatures are changing at a fast rate and should also be taken into consideration by fisheries managers.
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Volume de collection Numéro de collection Edition
ISSN 0967-0637 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2783
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Auteur (up) Diaz, F.; Bănaru, D.; Verley, P.; Shin, Y.-J.
Titre Implementation of an end-to-end model of the Gulf of Lions ecosystem (NW Mediterranean Sea). II. Investigating the effects of high trophic levels on nutrients and plankton dynamics and associated feedbacks Type Article scientifique
Année 2019 Publication Revue Abrégée Ecological Modelling
Volume 405 Numéro Pages 51-68
Mots-Clés End-to-end model; Fisheries; Food web functioning; Plankton; Two-ways coupling
Résumé The end-to-end OSMOSE-GoL model parameterized, calibrated and evaluated for the Gulf of Lions ecosystem (Northwestern Mediterranean Sea) has been used to investigate the effects of introducing two-ways coupling between the dynamics of Low and High Trophic Level groups. The use of a fully dynamic two-ways coupling between the models of Low and High Trophic Levels organisms provided some insights in the functioning of the food web in the Gulf of Lions. On the whole microphytoplankton and mesozooplankton were found to be preyed upon by High Trophic Levels planktivorous groups at rates lower than 20% and 30% of their respective natural mortality rates, but these relatively low rates involved some important alterations in the infra-seasonal and annual cycles of both High and Low Trophic Levels groups. They induced significant changes in biomass, fisheries landings and food web interactions by cascading effects. Spatial differential impacts of High Trophic Levels predation on plankton are less clear except in areas in which primary productivity is high. Higher predation rates on plankton groups were encountered within the area of the Rhone river’s influence and in areas associated to the presence of mesoscale eddies in the Northwestern part of the Gulf of Lions, especially. Generally, the pressure of the High Trophic Levels predation was the highest in areas of highest biomass whatever the plankton group considered. The two-ways coupling between Low and High Trophic Levels models revealed both bottom-up and top-down controls in the ecosystem with effects on planktivorous species similar to those observed in the field. The use of the end-to-end model enabled to propose a set of potential mechanisms that may explain the observed decrease in small pelagic catches by the French Mediterranean artisanal fisheries over the last decade.
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ISSN 0304-3800 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2577
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