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Auteur 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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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 1726-4170 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 914
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Auteur Gowen, R.J.; Collos, Y.; Tett, P.; Scherer, C.; Bec, B.; Abadie, E.; Allen, M.; O'Brien, T.
Titre Response of diatom and dinoflagellate lifeforms to reduced phosphorus loading: A case study in the Thau lagoon, France Type Article scientifique
Année 2015 Publication Estuarine, Coastal and Shelf Science Revue Abrégée Estuarine, Coastal and Shelf Science
Volume Numéro Pages 45-52
Mots-Clés Euclidean distance; eutrophication; lifeform; phosphorus; state-space; Thau lagoon
Résumé The basin of Thau in southern France is a shallow, weakly flushed lagoon which is an important location for oyster cultivation. Phytoplankton analyses were carried out in 1975–1976 and then (almost) continuously since 1987. We report an investigation of ‘the balance of organisms’ in phytoplankton in relation to reductions in phosphorus loading, using two new tools based on phytoplankton lifeforms: the Plankton Index for Phytoplankton (PIp); Euclidean distance in state-space. Our results show the utility of the tools for analysing changes in the ‘balance of organisms’ at the level of functional groups (in our study diatoms and dinoflagellates), but also illustrate the difficulties in demonstrating the reversal of human impacts resulting from eutrophication. The comparison between 1987–89 and 1976 showed the expected ‘de-eutrophication’ due to the reduction in dissolved inorganic phosphate (DIP), with a decrease in dinoflagellate abundance. Since 1989, year-to-year variation in annual mean concentrations of DIP may have contributed to inter-annual variability in the balance of the two lifeforms, but the data suggest that the system has remained in a dynamically stable regime because: (1) there was no long-term trend in Euclidean distance from the reference; and (2) there was no increase in inter-annual variability about the time-series mean Euclidean distance suggesting there has been no decrease in resilience which might signal a regime change. Integrated management of human activities will be required to manage (and reduce) total P in the system. Monitoring phytoplankton and nutrients concentrations to determine how primary production and the balance of species respond to further changes in the nutrient status of the lagoon should be an integral part of any management programme.
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Editeur Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Special Issue: Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems Titre de collection Abrégé
Volume de collection 162 Numéro de collection Edition
ISSN 0272-7714 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ alain.herve @ collection 1620
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Auteur Pagès, R.; Baklouti, M.; Barrier, N.; Richon, C.; Dutay, J.-C.; Moutin, T.
Titre Changes in rivers inputs during the last decades significantly impacted the biogeochemistry of the eastern Mediterranean basin: A modelling study Type Article scientifique
Année 2020 Publication Revue Abrégée Prog. Oceanogr.
Volume 181 Numéro Pages 102242
Mots-Clés Biogeochemistry; Coupled physical-biogeochemical model; ecosystem changes; Flexible stoichiometry model; Mediterranean Sea; nitrogen; Nutrient; nutrients; organic-carbon; phosphate; phosphorus limitation; phytoplankton; primary productivity; River inputs; sea; western
Résumé The Mediterranean Sea (MS) is a semi-enclosed sea characterized by a zonal west-east gradient of oligotrophy, where microbial growth is controlled by phosphate availability in most situations. External inputs of nutrients including Gibraltar inputs, river inputs and atmospheric deposition are therefore of major importance for the biogeochemistry of the MS. The latter has long been considered to be driven mainly by nutrient exchanges at Gibraltar. However, recent studies indicate that river inputs significantly affect nutrients concentrations in the Mediterranean Sea, although their resulting impact on its biogeochemistry remains poorly understood. In this study, our aim was to help fill this knowledge gap by addressing the large-scale and long-term impact of variations in river inputs on the biogeochemistry of the Mediterranean Sea over the last decades, using a coupled physical-biogeochemical 3D model (NEMO-MED12/Eco3M-Med). As a first result, it has been shown by the model that the strong diminution (60%) of phosphate (PO4) in river inputs into the Mediterranean Sea since the end of the 1980s induced a significant lowering of PO4 availability in the sub-surface layer of the Eastern Mediterranean Basin (EMB). One of the main consequences of PO4 diminution is the rise, never previously documented, of dissolved organic carbon (DOC) concentrations in the surface layer (by 20% on average over the EMB). Another main result concerns the gradual deepening of the top of the phosphacline during the period studied, thus generating a shift between the top of the nitracline and the top of the phosphacline in the EMB. This shift has already been observed in situ and documented in literature, but we propose here a new explanation for its occurrence in the EMB. The last main result is the evidence of the decline in abundance and the reduction of size of copepods calculated by the model over the years 1985-2010, that could partially explain the reduction in size of anchovy and sardine recently recorded in the MS. In this study, it is shown for the first time that the variations in river inputs that occurred in the last decades may have significantly altered the biogeochemical cycles of two key elements (P and C), in particular in the EMB. To conclude, the magnitude of the biogeochemical changes induced by river inputs and runoff alone over the last thirty years clearly calls for the use of realistic scenarios of river inputs along with climate scenarios for coupled physical-biogeochemical forecasts in the MS.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue English Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0079-6611 ISBN Médium
Région Expédition Conférence
Notes WOS:000512481200014 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2757
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Auteur Pete, R.; Guyondet, T.; Bec, B.; Derolez, V.; Cesmat, L.; Lagarde, F.; Pouvreau, S.; Fiandrino, A.; Richard, M.
Titre A box-model of carrying capacity of the Thau lagoon in the context of ecological status regulations and sustainable shellfish cultures Type Article scientifique
Année 2020 Publication Revue Abrégée Ecological Modelling
Volume 426 Numéro Pages 109049
Mots-Clés Carrying capacity; Coupled biogeochemical-deb model; Ecological indicators; Nitrogen and phosphorus inputs; Phytoplankton depletion; Shellfish farming; Stakeholder implication; Water frame directive
Résumé The decrease of microbial and nutrient inputs from the watershed has long dominated lagoon ecosystem management objectives. Phytoplankton biomass and abundance have drastically decreased for more than a decade and Zostera meadow have gradually recovered, expressing lagoon ecosystem restoration such as Thau lagoon. Do the progressive achievement of the good ecological status of the Thau lagoon possibly threatens the shellfish industry in terms of production and oyster quality, by reducing the carrying capacity? To provide answers about the right balance to be achieved between conservation and exploitation, a new numerical tool was developed to help in decision-making. We hereby propose to incorporate a Dynamic Energy Budget type shellfish production model to an existing lagoon ecosystem box-model. The influence of different scenarios of nutrient inputs (related to projections of population growth or improvement of treatment plants) and shellfish stocks were tested on oyster performances (production, oyster condition index), carrying capacity of the lagoon and ecological status indices used within the EU Water Framework Directive. Model outputs demonstrated that shellfish production was mainly controlled by nutrient inputs, which depend on hydro-meteorological variability, and specifically by phosphorus and N:P ratios of nutrient inputs. Scenarios tested, however, demonstrated smaller differences of oyster production in comparison to inter-annual variability. The overall ecological status of the lagoon remained in a “good” status with acceptable lagoon-scale phytoplankton depletion, regardless of scenarios, setting the carrying capacity of this ecosystem to be sustainable.
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Auteur institutionnel Thèse
Editeur Lieu de Publication Éditeur
Langue en Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0304-3800 ISBN Médium
Région Expédition Conférence
Notes WOS:000529795300004 Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2762
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Auteur ROQUE D'ORBCASTEL, E.; BLANCHETON, J.-P.; BOUJARD, T.; AUBIN, J.; MOUTOUNET, Y.; PRZYBYLA, C.; BELAUD, A.
Titre Comparison of two methods for evaluating waste of a flow through trout farm Type Article scientifique
Année 2008 Publication Aquaculture Revue Abrégée
Volume 274 Numéro 1 Pages 72-79
Mots-Clés Phosphorus; Nitrogen; Suspended solids; Trout farm; Waste
Résumé European water legislation enforces increasingly restrictive measures with regards to reduction of water consumption and waste emission in order to minimise the potential environmental impact of the agro industry sector. Fish farms are particularly concerned, but legislation covering effluent discharge varies significantly from country to country. However, recommendations and directives from institutional, national or regional bodies suggest the enforcement of increasingly strict waste reduction measures and the development of waste treatment. Before treatment, it is necessary to evaluate waste production in terms of composition and quantity. The waste quantification methods used today for fish culture systems are either based on direct measurements of nutrient and suspended solid fluxes or on indirect evaluation based on the digestibility coefficients of the feed constituents. The objective of the present study is to evaluate the waste of a freshwater flow through farm using both approaches and to discuss their applicability, drawbacks and advantages from the viewpoints of fish farmers and control authorities. Waste production on the farm was monitored during several 24 hour cycles in order to characterise the effluents of the system. The predictions and measurements for the total nitrogen (TN) parameter were well correlated, but measured and predicted suspended solids (SS) and total phosphorus (TP) values presented a weaker correlation coefficient. The hydrobiological method gives details on the N and P forms of waste but this method is heavy and it is difficult to obtain representative samples and flow rate measurements. The nutritional method is the simplest to use, provided that feed data are available. (C) 2007 Elsevier B.V. All rights reserved..
Adresse ENSAT, Ecole Natl Super Agron Toulouse, F-31326 Castanet Tolosan, France.
Auteur institutionnel Thèse
Editeur Elsevier Lieu de Publication Éditeur
Langue Langue du Résumé Titre Original
Éditeur de collection Titre de collection Titre de collection Abrégé
Volume de collection Numéro de collection Edition
ISSN 0044-8486 ISBN Médium
Région Expédition Conférence
Notes Approuvé pas de
Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ 6822 collection 1222
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