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Start Over Author "Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM)" Journal journal of experimental marine biology and ecology
12 results on '"Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM)"'

1. Benthic response to ammonium pulses in a tropical lagoon: implications for coastal environmental processes

Author

Jacques Clavier, Sandrine Chifflet, Laurent Chauvaud, Renaud Fichez, Guy Boucher, Laboratoire des Sciences de l'Environnement Marin (LEMAR) ( LEMAR ), Institut de Recherche pour le Développement ( IRD ) -Institut Français de Recherche pour l'Exploitation de la Mer ( IFREMER ) -Université de Brest ( UBO ) -Institut Universitaire Européen de la Mer ( IUEM ), Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut de Recherche pour le Développement ( IRD ) -Université de Brest ( UBO ) -Centre National de la Recherche Scientifique ( CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Biologie des organismes marins et écosystèmes ( BOME ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), PNEC, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Biologie des organismes marins et écosystèmes (BOME), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, microphytobenthos, tropic, Heterotroph, Aquatic Science, Biology, 010603 evolutionary biology, 01 natural sciences, chemistry.chemical_compound, Nutrient, Benthos, Nitrate, Ammonium, 14. Life underwater, Autotroph, Ecology, Evolution, Behavior and Systematics, Ecology, nutrient, [SDV.BID.EVO]Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE], 010604 marine biology & hydrobiology, benthos, tropical lagoon, 6. Clean water, flux, eutrophication, [ SDV.BID.EVO ] Life Sciences [q-bio]/Biodiversity/Populations and Evolution [q-bio.PE], chemistry, 13. Climate action, Benthic zone, Environmental chemistry, Eutrophication, metabolism
Abstract

In New Caledonia, the benthic communities living in the coral reef lagoon around Noumea city are subjected to regular shifts from oligotrophic conditions typical of lagoon waters to nutrient enrichment due to waste water inputs. The influence of ammonium pulses on microphytobenthos production was experimentally tested under varying light intensities in the vicinity of Noumea. Benthic oxygen, ammonium and silicon fluxes at the sediment-water interface were measured in situ using benthic enclosures. Three ammonium concentrations were tested. Gross primary production was doubled with a 13.8 mu mol 1(-1) ammonium concentration increase. Fitted PI curves showed that maximum production (F-max) was linearly related to ammonium concentration, but not the optimal irradiance (I-k). Silicon fluxes were characterized by dissolution in the absence of light, a process that declined with increasing illumination. These results were attributed to microphytobenthos activity, mainly diatoms that are nutrient-limited and strongly reactive to ammonium inputs. Production may result from a multiplication of cells, but migration up to the water sediment interface may also be involved. Oxygen consumption was also significantly influenced by ammonium concentration as a positive linear relationship with added ammonium concentration was established. Even during short-term experiments, ammonium enrichment stimulated photoautotrophic production, increasing the energy available to heterotrophs. Furthermore, microbenthic activities as well as nitrate production were increased by ammoniaoxidizing bacteria able to grow chemolithotrophically at the expense of oxygen. Therefore, in the study area, pulses of urban waste waters resulted in a decrease of plant-related autotrophy in benthic communities. (c) 2004 Elsevier B.V. All rights reserved.

Published
2005
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2. Estimation of physical and physiological performances of blacklip pearl oyster larvae in view of DEB modeling and recruitment assessment

Author

Benoit Beliaeff, Yoann Thomas, Serge Andréfouët, Nathanaël Sangare, Laure Pecquerie, Alain Lo-Yat, Gilles Le Moullac, Ecosystèmes Insulaires Océaniens (UMR 241) (EIO), Université de la Polynésie Française (UPF)-Institut Louis Malardé [Papeete] (ILM), Institut de Recherche pour le Développement (IRD)-Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Ecologie marine tropicale des océans Pacifique et Indien (ENTROPIE [Nouvelle-Calédonie]), Ifremer - Nouvelle-Calédonie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Université de la Nouvelle-Calédonie (UNC), ANR-16-CE32-0004,MANA,Gestion des Atolls(2016), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Polynésie Française (UPF)-Institut Louis Malardé [Papeete] (ILM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Ifremer - Nouvelle-Calédonie, and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Nouvelle-Calédonie (UNC)

Subjects
0106 biological sciences, Physiology, media_common.quotation_subject, Dynamic energy budget, Dynamic, Aquaculture, Aquatic Science, 010603 evolutionary biology, 01 natural sciences, Pinctada margaritifera, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Animal science, Energetics, Phytoplankton, Bivalve larvae, Metamorphosis, Ecology, Evolution, Behavior and Systematics, Margaritifera, media_common, Trophic level, Dynamic energy budget theory, Larva, biology, business.industry, ACL, 010604 marine biology & hydrobiology, fungi, Pearl farming, biology.organism_classification, energy budget theory, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, business
Abstract

International audience; In French Polynesia black pearl farming represents one of the dominant business sectors. However, it still entirely relies on unpredictable Pinctada margaritifera spat collection success, which is itself conditioned by larval development completion. To assess the relationship between larval development and recruitment success, we studied under controlled conditions the effect of food concentration on development, growth, ingestion rate, survival and metabolic rate at the larval stage. Larvae were exposed to four different phytoplankton densities (2,5; 7,5; 15 and 30 cell.mu L-1). Larvae survived equally all over the range of phytoplankton concentration with an average survival rate of 16% at the end of experiments. Food concentration significantly affected the larval physiology throughout its development from birth to metamorphosis. Growth and feeding were close to those reported by previous laboratory observations with young spat of 210 mu m long obtained in 18 days of rearing at 28 degrees C for the highest food concentration. Differences in length at metamorphosis and cumulated energy ingested until settlement occurred according to trophic levels with a saturation threshold close to 0.0086 J.ind(-1). This level was reached at the food concentration of 15 cell.mu L-1. Larval development stages could be divided on the basis of the energy balance between feeding and respiration rates. An initial mixotrophic period with a lower and constant ingestion/respiration ratio over the first three days (from birth to D-veliger larva) was followed by an exotrophic phase characterized by a sharp increase in energy balance highly dependent of food concentration. Finally two sharp decreases of feeding rates were recorded during metamorphosis before umbonate and eyed stages. This study provided numerous new clues to establish a quasi-deterministic relationship between food condition and larval development. It highlights the major effect of food concentration and how energy intake through feeding as well as behavioral and physiological transitions can optimize larval development duration and minimize "the risky phase" of their life cycle. By taking into account the observed metabolic switches, the results provide a strong foundation for Dynamic Energy Budget model development and better description of the complex interactions between P. margaritifera physiology and environmental conditions.

Published
2019
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3. Commensalism, antagonism or mutualism? Effects of epibiosis on the trophic relationships of mussels and epibiotic barnacles

Author

Eleonora Puccinelli, Christopher D. McQuaid, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Interdisciplinary Graduate School for the Blue planet, and ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017)

Subjects
0106 biological sciences, [SDV]Life Sciences [q-bio], Intertidal zone, Zoology, Aquatic Science, 010603 evolutionary biology, 01 natural sciences, South Africa, Barnacle, Rocky shore, 14. Life underwater, Intertidal rocky shore, Epibiont, Ecology, Evolution, Behavior and Systematics, Trophic level, Chthamalus dentatus, Mutualism (biology), biology, Perna perna, 010604 marine biology & hydrobiology, Mussel, Fatty acid, biology.organism_classification, Commensalism, Stable isotope, [SDE]Environmental Sciences
Abstract

International audience; he dynamics determining the establishment and maintenance of epibiotic relationships are fundamental to understand the role of biological interactions in the functioning of marine coastal ecosystems. Epibiosis of barnacles on mussels is a common feature of many intertidal rocky shores. There are several possible explanations for this relationship, but it is unclear whether the association is commensal, antagonistic, or mutualistic. We investigated the diets of barnacles and mussels in an epibiotic relationship (epibiont barnacle and basibiont mussel), and compared them to the diets of conspecifics living on the same rocky shore but independently (free barnacle and free mussel), using stable isotope (SI) and fatty acid (FA) techniques. The SI results indicated that the diet of mussels did not change as a function of epibiosis, while free barnacles were characterized by higher δ15N values than epibiotic conspecifics, indicating that they were feeding on more recycled food sources. This result was, however, supported by data from only one site. Results from FA were partially consistent with those of SI analysis, indicating that mussel FA profiles did not change between basibiont and free mussels, but that epibiotic barnacles were characterized by a lower amount of polyunsaturated FA than free barnacles. This suggests that the diet of epibiotic barnacles is of lower quality. This could be due to competition for food with mussels, driven by the different mechanisms of food assimilation between epibiotic barnacle and basibiont mussel; or by the different sizes of particles ingested by the two species under epibiosis vs free-living conditions. The discrepancy between the FA and SI results observed could reflect the different integration time of the analytical techniques, with FA reflecting shorter term variability than SI. We conclude that epibiosis represents an unfavourable relationship for barnacles due to the lower quality of food available when colonizing mussel shells, whereas mussels neither benefit nor were harmed by this association. Thus, this relationship is amensalistic: negative for barnacles but neutral for mussels.

Published
2021
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4. Simulation of an artificial upwelling using immersed in situ phytoplankton microcosms

Author

Marie Boye, Denis de la Broise, Anne Donval, Mélanie Giraud, Véronique Garçon, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and France Energies Marines [Brest]

Subjects
0106 biological sciences, Ocean Thermal Energy Conversion, Chlorophyll a, Microcosms, 010504 meteorology & atmospheric sciences, growth, Population, coastal waters, prochlorococcus, Aquatic Science, 01 natural sciences, surface waters, chemistry.chemical_compound, pacific, Phytoplankton, Incubation experiment, north-atlantic, 14. Life underwater, Artificial upwelling, diatom blooms, education, Ecology, Evolution, Behavior and Systematics, atlantic-ocean, 0105 earth and related environmental sciences, education.field_of_study, biology, Ecology, ACL, nutrient, 010604 marine biology & hydrobiology, Food web, biology.organism_classification, Oceanography, chemistry, Intertropical area, Upwelling, Seawater, Prochlorococcus, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Microcosm, Martinique
Abstract

00000 ăWOS:000369212600010; International audience; The inflow of deep seawater in the surface layer by an Ocean Thermal Energy Conversion (OTEC) plant will generate artificial upwelling. In order to study the potential impact on biogeochemical processes that could result, in situ microcosms were designed to simulate seawater plant discharge and these were deployed off the Caribbean coast of Martinique. Seawater was collected in ultra-clean conditions at maximum chlorophyll a concentrations (45 m depth). The water was then mixed with either 2% or 10% deep seawater (1100 m depth) and put in 2.3 L polycarbonate bottles. These microcosms were immersed for 6 days at 45 m depth on a 220 m mooring. Samples from the surrounding environment and from the microcosms were analyzed by pigment quantification, counting of picophytoplankton groups and macronutrient analyses. Similar trends in the evolutions of the phytoplankton populations were observed over time between the control microcosms (without addition of deep seawater) and the surrounding environment, suggesting that these microcosms can be used as a realistic representation of the natural surrounding waters over a 6-day incubation period. Microcosm enrichment with 10% deep seawater induced a shift in the phytoplankton assemblage towards the development of diatoms, haptophytes, and Prochlorococcus, whereas 2% enrichment only led to an increase in the Prochlorococcus population.

Published
2016
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5. Impact of fishing gears and fishing intensities on maerl beds: An experimental approach

Author

Julien Dubreuil, Benjamin Guyonnet, Jacques Grall, Adeline Tauran, Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Inconnu, TBM environnement, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
ecosystem, 0106 biological sciences, ACL, 010604 marine biology & hydrobiology, Fishing, Aquatic Science, Biology, 010603 evolutionary biology, 01 natural sciences, Fishery, shelf, bay, DISCOVERY, habitats, 14. Life underwater, Maerl, community structure, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, rhodoliths, UBO, trawl disturbance, Ecology, Evolution, Behavior and Systematics
Abstract

WOS:000588286500005

Published
2020
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6. Measurement and analysis of small pelagic fish condition: A suitable method for rapid evaluation in the field

Author

Sandrine Choy, Pablo Brosset, Fabrice Pernet, Frédéric Ménard, Elisabeth Van Beveren, Jean-Marc Fromentin, Maria A. Pérez Roda, Jean-Hervé Bourdeix, Jean-Louis Bigot, Claire Saraux, MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), and Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)

Subjects
Sprattus sprattus, [SDE.MCG]Environmental Sciences/Global Changes, Population, EUROPEAN PILCHARD, Aquatic Science, Condition index, [SDV.EE.ECO]Life Sciences [q-bio]/Ecology, environment/Ecosystems, Anchovy, Mediterranean Sea, medicine, Fatmeter, European anchovy, 14. Life underwater, education, Ecology, Evolution, Behavior and Systematics, education.field_of_study, biology, ACL, Sardine, Sprat, biology.organism_classification, Lipids, Fishery, medicine.drug_formulation_ingredient, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; As condition is a key variable in population dynamics (especially for survival, growth and reproduction), the use of well-defined and accurate fish condition indices is capital. In particular, condition indices (morphometric, bioenergetic and biochemical) have never been compared and validated for the European anchovy Engraulis encrasicolus, the European pilchard Sardina pilchardus and the European sprat Sprattus sprattus. The accuracy of two indirect methods, the morphometric relative condition index Kn and the bioenergetics index determined with the Distell Fish Fatmeter was investigated by comparing with a direct measure of relative lipid content carried out with a thin layer chromatography-flame ionization detector. Estimations from the fatmeter correlated quite well with the relative lipid contents of all species, regardless of the reproductive period (R2 = 0.69 for anchovy, R2 = 0.75 for sprat and R2 = 0.48 for sardine). Kn correlated more poorly with relative lipid content (R2 = 0.22 for anchovy and R2 = 0.41 for sardine, ns for sprat), especially during the reproductive period, pointing out the difficulty for such an index to precisely reflect changes in fat allocation. During the reproductive period, changes in Kn could reflect other processes, such as changes in protein content. Therefore, these different types of commonly used indices do not reflect exactly the same type of energy stores. The high repeatability of the fatmeter was brought to light, so that only one measurement on each fish side may be necessary to evaluate the relative lipid content of a small pelagic fish. Finally, fatmeter measurements were not affected by freezing storage up to one month for anchovy (R2 = 0.66) and sardine (R2 = 0.90), making it possible to use frozen samples of both commercial and scientific survey. In contrast, the freezing storage for sprat should be avoided. Based on this study, the Fatmeter appears to be a suitable indirect method to assess condition and fat content of sardine and anchovy on a large number of individuals.

Published
2015
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7. Tissue-diet discrimination factors of isotopic ratios (∆δ13C and ∆δ15N) in two brittle star species: Effect of reproductive state, diet and tissue composition

Author

Stanislas F. Dubois, Fabrice Pernet, Jean-Dominique Gaffet, Aline Blanchet-Aurigny, Monique Guillou, Laboratoire d'Ecologie Benthique, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Environnement Ressources (LER-LR), and PNEC

Subjects
0106 biological sciences, δ13C, Physiological state, 010604 marine biology & hydrobiology, Ophiocomina nigra, Fractionation, δ15N, Mussel, Aquatic Science, Biology, Enrichment factors, biology.organism_classification, 010603 evolutionary biology, 01 natural sciences, Isotopic signature, Animal science, Brittle star, [SDE]Environmental Sciences, Botany, Ophiothrix fragilis, Ecology, Evolution, Behavior and Systematics, Echinoderms, Stable isotopes
Abstract

International audience; Tissue-diet discrimination factors (TDDFs) for carbon (∆δ13C) and nitrogen (∆δ15N) were estimated for two brittle star species (Ophiocomina nigra and Ophiothrix fragilis) in tissues of two body compartments (disk and arms) according to different diets (fish muscle, mussel and macroalgae). Variations in TDDFs are studied in the light of physiological changes, as two phases were revealed over the course of the experiment, i.e. a gonadal rest and a gonadal maturation. Overall, the average ∆δ13C and ∆δ15N values ranged from − 4.1 ± 0.2 to 1.5 ± 0.2‰ and from − 1.8 ± 0.2 to 4.0 ± 0.3‰, respectively. Variability in TDDFs revealed little differences between species but appeared to be mainly driven by the diet and the physiological state of the organisms to a lesser extent. ∆δ13C in gonadal resting organisms were systematically ca. 0.8‰ lower than in gonadal maturing species. TDDF values for organisms fell within the range of expected values, except for ∆δ13C with macroalgae diet and ∆δ15N with fish muscle diet. As revealed by %N and CN ratios, high dietary-protein seemed to play a key role in explaining ∆δ15N values, while ∆δ13C seemed to be affected by differential assimilation efficiency in dietary components. We also suggested a possible effect of isotopic signature of the diet on TDDFs showing that the more enriched the diet in δ15N and δ13C, the lower the TDDF.

Published
2012
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8. Experimental growth pattern calibration of Antarctic scallop shells (Adamussium colbecki, Smith 1902) to provide a biogenic archive of high-resolution records of environmental and climatic changes

Author

Laurent Testut, Claire Bollinger, Aurore Toulot, Joëlle Richard, Yves-Marie Paulet, Franck Lartaud, Laurent Chauvaud, Laboratoire d'Ecogéochimie des environnements benthiques (LECOB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Domaines Océaniques (LDO), Centre National de la Recherche Scientifique (CNRS)-Institut d'écologie et environnement-Observatoire des Sciences de l'Univers-Université de Brest (UBO)-Institut national des sciences de l'Univers (INSU - CNRS), Océan du Large et Variabilité Climatique (OLVAC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Observatoire des Sciences de l'Univers-Institut d'écologie et environnement-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Aquatic Science, 01 natural sciences, Paleontology, 14. Life underwater, LA-ICP-MS, Mollusca, Ecology, Evolution, Behavior and Systematics, Sea level, 0105 earth and related environmental sciences, Adamussium colbecki, biology, 010604 marine biology & hydrobiology, Calcein marking, Bivalvia, biology.organism_classification, Annual cycle, Antarctic scallop, Oceanography, 13. Climate action, Benthic zone, Indicator species, Growth pattern, [SDE]Environmental Sciences, Scallop, Seawater
Abstract

International audience; To determine the potential of Antarctic bivalve shells as biomonitors for environmental and climatic variations in polar marine areas, we developed a growth model for juvenile Adamussium colbecki Smith, 1902 based on the use of in situ temporal calcein markings to calibrate growth patterns in the external striae formation. To minimize scallop stress caused by excessive handling, in situ benthic chambers were used for the marking experiment, during an exposure time of 6 h. Once marked, scallops remained on site in a benthic cage and were collected 18, 26, and 41 days later. Apart from a few specimens affected by possible calcein toxicity effects, the detectable mark in all shells revealed a higher austral summer growth rate for A. colbecki compared to other Antarctic bivalves. Using calcein labeling, we identified a near 14-day periodicity in the striae formation associated with the fortnightly seawater level regime. Striae counting and increment width measurements showed an annual cycle, with no clear cessation of growth in juvenile specimens, allowing age determination. Because of the relatively high growth rate for a polar species and easily recognizable sclerochronological calendar in the shell striae formation, A. colbecki is an appropriate species for high-resolution (infra-monthly) geochemical sampling. Comparison between LA-ICP-MS analyses (Li, B, Mg, Mn, Co, Sr, Ba, Pb) from one shell and hydrological parameters (sea level, temperature, salinity) measured in seawater suggests, however, that more work is needed to calibrate the trace element proxies. Nevertheless, the shell of the Antarctic scallop A. colbecki has tremendous potential for recording environmental conditions from time periods covering months to a few years in polar waters, notably the ice melting date.

Published
2010
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9. Variability of the hemocyte parameters of Ruditapes philippinarum in the field during an annual cycle

Author

Jonathan Flye-Sainte-Marie, Madeleine Goncalvez, Marie-Agnès Travers, Nelly Le Goïc, Christine Paillard, Christophe Lambert, Philippe Soudant, Fred Jean, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Veterinary medicine, Hemocyte parameters, Manila clam, Ruditapes, Aquatic Science, medicine.disease_cause, 01 natural sciences, Perkinsus, 03 medical and health sciences, Condition index, Dry weight, Environmental factors, medicine, Variability, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics, Shellfish, 030304 developmental biology, Abiotic component, 0303 health sciences, biology, Ecology, 010604 marine biology & hydrobiology, Environmental factor, Bivalvia, biology.organism_classification, Brown Ring Disease
Abstract

International audience; A field monitoring of hemocyte parameters of the Manila clam Ruditapes philippinarum was conducted from July 2004 to September 2005 in Gulf of Morbihan (France), in order to assess (1) the factors controlling the hemocyte parameters of the Manila clam and (2) their relative contribution to the overall variability of these parameters. Monthly, sixty clams were sampled and total hemocyte count (THC), granulocyte and hyalinocyte counts, phagocytosis, phenoloxidase specific activity, length, flesh dry weight, and condition index were measured individually. Perkinsus sp. infection and Brown Ring Disease symptoms were also monitored. Temperature and trophic resource were also monitored. Results indicate that temperature controls granulocyte counts and subsequently THC. Other environmental factors had no direct influence on the measured hemocyte parameters. Almost all measured parameters were significantly affected by size/age and condition index. There were poor relationships between both pathologies and hemocyte parameters presumably because of low infection intensities. Nevertheless, high Perkinsus sp. infection intensity significantly increased total and granulocyte counts and decreased phagocytosis. An interesting result of this study is that the measured biotic and abiotic factors poorly contribute to the explanation of the total variability of hemocyte parameters. Granulocyte concentration was the best explained parameter. However, only 16.4% of its variance was explained by cumulating temperature, length, condition index and Perkinsus sp. infection effects. This study emphasizes the need for a better understanding of hemocyte functions and the factors modulating these functions.

Published
2009
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10. Perkinsosis in the Manila clam Ruditapes philippinarum affects responses to the harmful-alga, Prorocentrum minimum

Author

Patricia Mirella da Silva, Gary H. Wikfors, Philippe Soudant, Sandra E. Shumway, Jennifer H. Alix, Inke Sunila, Hélène Hégaret, Mark S. Dixon, Department of Marine Sciences, University of Connecticut (UCONN), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratorio de Imunologia Aplicada à Aquicultura, Universidade Federal de Santa Catarina = Federal University of Santa Catarina [Florianópolis] (UFSC), Bureau of Aquaculture, Department of Agriculture [Connecticut], Northeast Fisheries Science Center, Northeast Fisheries Science Center (NEFSC), NOAA National Marine Fisheries Service (NMFS), and National Oceanic and Atmospheric Administration (NOAA)-National Oceanic and Atmospheric Administration (NOAA)

Subjects
0106 biological sciences, animal structures, Zoology, Hemocyte, Ruditapes, Aquatic Science, 01 natural sciences, 03 medical and health sciences, Condition index, Ruditapes philippinarum, Parasite hosting, Mollusca, Ecology, Evolution, Behavior and Systematics, Shellfish, 030304 developmental biology, 0303 health sciences, Harmful algal bloom, biology, Ecology, 010604 marine biology & hydrobiology, Bivalve, Dinoflagellate, Aquatic animal, Bivalvia, biology.organism_classification, Prorocentrum minimum, [SDE]Environmental Sciences, Perkinsus olseni
Abstract

The dinoflagellate Prorocentrum minimum is increasingly recognized as a harmful algal bloom (HAB) species that affects filter-feeding shellfish. An experiment was done to investigate possible interactions between parasitic diseases and exposure to P. minimum in Manila clams, Ruditapes philippinarum . Manila clams, with variable levels of infection with Perkinsus olseni , were exposed for three or six days to the benign phytoplankton species Chaetoceros neogracile or a mixed diet of C. neogracile and P. minimum . After three or six days of exposure, clams were assessed individually for condition index, parasite status, and plasma and hemocyte parameters (morphological and functional) using flow-cytometry. Histological evaluation was also performed on individual clams to assess prevalence and intensity of parasitic infection, as well as other pathological conditions. Prorocentrum minimum caused several changes in Manila clams, especially after six days of exposure, such as decreased hemocyte phagocytosis and size and clam condition index. Pathological conditions observed in Manila clams exposed to P. minimum were hemocyte infiltration in the intestine and gonad follicles, myopathy, and necrosis of the intestine epithelial cells. The parasite P. olseni alone had no significant effect on Manila clams, nor did it modulate the hemocyte variables in clams exposed to P. minimum ; however, the parasite did affect the pathological status of Manila clams exposed to the P. minimum culture, by causing atrophy and degeneration of residual ova in the gonadal follicles and hyaline degeneration of the muscle fibers, indicating synergistic effects of both stressors on the host over a short period of time. Additionally, an in vitro experiment also demonstrated detrimental effects of P. minimum and exudates upon P. olseni cells, thus suggesting HAB antagonistic suppression of transmission and proliferation of the parasite in the natural environment over a longer period of time. The results of this experiment demonstrate the complexity of interactions between host, parasite, and HAB.

Published
2009
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11. Response of a phytoplankton community to increased nutrient inputs: A mesocosm experiment in the Bay of Brest (France)

Author

Pascal Claquin, Stéphane L'Helguen, Philippe Pondaven, Aude Leynaert, Annick Masson, Pierre Fouillaron, Véronique Martin-Jézéquel, Gérard Thouzeau, Pierre Huonnic, Sorcha Ní Longphuirt, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO), Physiologie et Ecophysiologie des Mollusques Marins (PE2M), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Mer, molécules et santé EA 2160 (MMS), Université de Nantes - UFR des Sciences Pharmaceutiques et Biologiques, Université de Nantes (UN)-Université de Nantes (UN)-Le Mans Université (UM)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN), Région Bretagne and is part of an INVABIO 2 project that was funded by the Ministère de l'Ecologie et du Développement Durable, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Le Mans Université (UM)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Université de Nantes - UFR des Sciences Pharmaceutiques et Biologiques, and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, biology, Ecology, 010604 marine biology & hydrobiology, Chaetoceros, Aquatic Science, biology.organism_classification, 01 natural sciences, Algal bloom, Mesocosm, Diatom, Benthic zone, Phytoplankton, Dominance (ecology), 14. Life underwater, Bay, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Abstract

International audience; In the Bay of Brest (France), benthic fluxes of silicic acid (DSi) are thought to be strongly involved in diatom dominance and their intensity depends on the density of an invasive gastropod, Crepidula fornicata. While the proliferation of this gastropod is likely to support diatom dominance, local fishermen have proposed its removal as it perturbs the development of the native Great Scallop, Pecten maximus. However, such a removal may be associated with potentially harmful algal blooms. The response of the phytoplankton community to modifications of the benthic fluxes of DSi, resulting from a further proliferation or the removal of C fornicata, was examined in a mesocosm nutrient enrichment experiment over a period of 16 days in the spring of 2004. Six mesocosms (5.4 m(3)) were filled using a natural planktonic assemblage from the Bay and received N, P and Si additions at the stoichiometric ratio of the in situ benthic fluxes (Si:N:P=16:16:1), with a gradient of enrichment ranging from 0 to almost 4 times the maximal benthic flux measured in the Bay. The diatom Chaetoceros (mainly C. debilis) rapidly outgrew non-siliceous species of microphytoplankton in all enclosures although kinetic experiments provided direct evidence of Si limitation. This dominance of diatoms at DSi concentrations

Published
2007
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12. Copepod grazing during an iron-induced diatom bloom in the Antarctic Circumpolar Current (EisenEx): I. Feeding patterns and grazing impact on prey populations

Author

S. Schultes, Peter G. Verity, Ulrich Bathmann, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Skidaway Institute of Oceanography (SIO), Skidaway Institute of Oceanography, and Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI)

Subjects
Southern Ocean RHINCALANUS-GIGAS COPEPODA, CALANOID COPEPODS, 0106 biological sciences, copepods, 010504 meteorology & atmospheric sciences, Population, Iron fertilization, BELLINGSHAUSEN-SEA, Aquatic Science, Biology, 01 natural sciences, Algal bloom, AUSTRAL SUMMER, Grazing, POLAR FRONTAL ZONE, SPRING BLOOM, 14. Life underwater, education, SOUTHERN-OCEAN, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, education.field_of_study, Ecology, 010604 marine biology & hydrobiology, PHYTOPLANKTON BLOOM, ATLANTIC SECTOR, diatom mortality, iron fertilization, biology.organism_classification, MESOZOOPLANKTON COMMUNITY, Diatom, grazing selectivity, Bloom, Clearance rate, Copepod
Abstract

International audience; Feeding activity, selective grazing and the potential grazing impact of two dominant grazers of the Polar Frontal Zone, Calanus simillimus and Rhincalanus gigas, and of copepods < 2 mm were investigated with incubation experiments in the course of an iron fertilized diatom bloom in November 2000. All grazers were already actively feeding in the low chlorophyll waters prior to the onset of the bloom. C. simillimus maintained constant clearance rates and fed predominantly on diatoms. R. gigas and the small copepods strongly increased clearance and ingestion of diatoms in response to their enhanced availability. All grazers preyed on microzooplankton, most steadily on ciliates, confirming the view that pure herbivory appears to be the exception rather than the rule in copepod feeding. The grazers exhibited differences in feeding behavior based on selectivity indices. C simillimus and R. gigas showed prey switching from dinoflagellates to diatoms in response to the phytoplankton bloom. All grazers most efficiently grazed on large diatoms leading to differences in daily losses for large and small species, e.g. Corethron sp. or Thalassionema nitzschioides. Species-specific diatom mortality rates due to grazing suggest that the high feeding activity of C simillimus prior to and during the bloom played a role in shaping diatom population dynamics.

Published
2006
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