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Auteur Zilius, M.; Bartoli, M.; Bresciani, M.; Katarzyte, M.; Ruginis, T.; Petkuviene, J.; Lubiene, I.; Giardino, C.; Bukaveckas, P.A.; De Wit, R.; Razinkovas-Baziukas, A. url  doi
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  Titre Feedback Mechanisms Between Cyanobacterial Blooms, Transient Hypoxia, and Benthic Phosphorus Regeneration in Shallow Coastal Environments Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée Estuaries and Coasts  
  Volume 37 Numéro 3 Pages 680-694  
  Mots-Clés baltic sea; chesapeake bay; curonian lagoon; Cyanobacterial blooms; ecosystem metabolism; Estuary; gulf; Hypoxia; Net; nutrient limitation; Oxygen; Phosphorus release; respiration; satellite data; temporal variability  
  Résumé We investigated the dissolved oxygen metabolism of the Curonian Lagoon (Baltic Sea) to assess the relative contributions of pelagic and benthic processes to the development of transient hypoxic conditions in shallow water habitats. Metabolism measurements along with the remote sensing-derived estimates of spatial variability in chlorophyll a were used to evaluate the risk of hypoxia at the whole lagoon level. Our data demonstrate that cyanobacterial blooms strongly inhibit light penetration, resulting in net heterotrophic conditions in which pelagic oxygen demand exceeds benthic oxygen demand by an order of magnitude. The combination of bloom conditions and reduced vertical mixing during calm periods resulted in oxygen depletion of bottom waters and greater sediment nutrient release. The peak of reactive P regeneration (nearly 30 mu mol m(-2) h(-1)) coincided with oxygen depletion in the water column, and resulted in a marked drop of the inorganic N:P ratio (from > 40 to < 5, as molar). Our results suggest a strong link between cyanobacterial blooms, pelagic respiration, hypoxia, and P regeneration, which acts as a feedback in sustaining algal blooms through internal nutrient cycling. Meteorological data and satellite-derived maps of chlorophyll a were used to show that nearly 70 % of the lagoon surface (approximately 1,000 km(2)) is prone to transient hypoxia development when blooms coincide with low wind speed conditions.  
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  ISSN 1559-2723 ISBN Médium  
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  Notes <p>ISI Document Delivery No.: AF0SM<br/>Times Cited: 1<br/>Cited Reference Count: 66<br/>Zilius, Mindaugas Bartoli, Marco Bresciani, Mariano Katarzyte, Marija Ruginis, Tomas Petkuviene, Jolita Lubiene, Irma Giardino, Claudia Bukaveckas, Paul A. de Wit, Rutger Razinkovas-Baziukas, Arturas<br/>European Union Structural Funds project “Postdoctoral Fellowship Implementation in Lithuania”; Fulbright Fellowship; ESA project [AO-553]; CYAN-IS-WAS (Ministero dell'Istruzione dell'Universita e della Ricerca, Science and technological of Sweden); CLAM-PHYM (Italian Space Agency) [ASI I/015/11/0]<br/>Mindaugas Zilius was supported by a postdoctoral fellowship funded by the European Union Structural Funds project “Postdoctoral Fellowship Implementation in Lithuania.” Paul Bukaveckas was supported by a Fulbright Fellowship during his residence at Klaipeda University. MERIS data were made available through the ESA project AO-553 (MELINOS). This study was co-funded by CYAN-IS-WAS (Ministero dell'Istruzione dell'Universita e della Ricerca, Science and technological cooperation between Italy and the Kingdom of Sweden) and CLAM-PHYM (Italian Space Agency, contract ASI I/015/11/0) projects. We gratefully thank the Lithuanian Hydrometeorological Service of the Ministry of Environment for providing meteorological data. We also gratefully thank three anonymous reviewers for valuable comments which improved the quality of the manuscript.<br/>Springer<br/>New york</p> Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 1184  
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Auteur Benazzouz, A.; Pelegri, J.L.; Demarcq, H.; Machin, F.; Mason, E.; Orbi, A.; Pena-Izquierdo, J.; Soumia, M. url  doi
openurl 
  Titre On the temporal memory of coastal upwelling off NW Africa Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée J. Geophys. Res.-Oceans  
  Volume 119 Numéro 9 Pages 6356-6380  
  Mots-Clés atlantic; Canary Current; cape blanc region; circulation; Coastal upwelling; eastern boundary; Ekman transport; interannual variability; northwest africa; NW Africa; sea-surface temperature; SST difference; system; temporal memory; water  
  Résumé We use a combination of satellite, in situ, and numerical data to provide a comprehensive view of the seasonal coastal upwelling cycle off NW Africa in terms of both wind forcing and sea surface temperature (SST) response. Wind forcing is expressed in terms of both instantaneous (local) and time-integrated (nonlocal) indices, and the ocean response is expressed as the SST difference between coastal and offshore waters. The classical local index, the cross-shore Ekman transport, reproduces reasonably well the time-latitude distribution of SST differences but with significant time lags at latitudes higher than Cape Blanc. Two nonlocal indices are examined. One of them, a cumulative index calculated as the backward averaged Ekman transport that provides the highest correlation with SST differences, reproduces well the timing of the SST differences at all latitudes (except near Cape Blanc). The corresponding time lags are close to zero south of Cape Blanc and range between 2 and 4 months at latitudes between Cape Blanc and the southern Gulf of Cadiz. The results are interpreted based on calculations of spatial and temporal auto and cross correlations for wind forcing and SST differences. At temporal scales of 2-3 weeks, the alongshore advection of alongshore momentum compensates for interfacial friction, allowing the upwelling jet and associated frontal system to remain active. We conclude that the coastal jet plays a key role in maintaining the structure of coastal upwelling, even at times of relaxed winds, by introducing a seasonal memory to the system in accordance with the atmospheric-forcing annual cycle.  
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  ISSN 2169-9275 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1194  
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Auteur Darnaude, A.M.; Sturrock, A.; Trueman, C.N.; Mouillot, D.; Eimf; Campana, S.E.; Hunter, E. url  doi
openurl 
  Titre Listening In on the Past: What Can Otolith δ18O Values Really Tell Us about the Environmental History of Fishes? Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée PLoS ONE  
  Volume 9 Numéro 10 Pages  
  Mots-Clés  
  Résumé Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L.) in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values of did not fully match. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are clarified.  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1195  
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Auteur Christensen, V.; Coll, M.; Steenbeek, J.; Buszowski, J.; Chagaris, D.; Walters, C.J. url  doi
openurl 
  Titre Representing Variable Habitat Quality in a Spatial Food Web Model Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée Ecosystems  
  Volume 17 Numéro 8 Pages 1397-1412  
  Mots-Clés Ecology; Ecopath; ecospace; Environmental Management; food web model; foraging capacity model; Geoecology/Natural Processes; habitat modeling; Hydrology/Water Resources; Plant Sciences; sampling; simulation model; species distribution model; Zoology  
  Résumé Why are marine species where they are? The scientific community is faced with an urgent need to understand aquatic ecosystem dynamics in the context of global change. This requires development of scientific tools with the capability to predict how biodiversity, natural resources, and ecosystem services will change in response to stressors such as climate change and further expansion of fishing. Species distribution models and ecosystem models are two methodologies that are being developed to further this understanding. To date, these methodologies offer limited capabilities to work jointly to produce integrated assessments that take both food web dynamics and spatial-temporal environmental variability into account. We here present a new habitat capacity model as an implementation of the spatial-temporal model Ecospace of the Ecopath with Ecosim approach. The new model offers the ability to drive foraging capacity of species from the cumulative impacts of multiple physical, oceanographic, and environmental factors such as depth, bottom type, temperature, salinity, oxygen concentrations, and so on. We use a simulation modeling procedure to evaluate sampling characteristics of the new habitat capacity model. This development bridges the gap between envelope environmental models and classic ecosystem food web models, progressing toward the ability to predict changes in marine ecosystems under scenarios of global change and explicitly taking food web direct and indirect interactions into account.  
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  ISSN 1432-9840, 1435-0629 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1196  
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Auteur Colléter, M.; Gascuel, D.; Albouy, C.; Francour, P.; Tito de Morais, L.; Valls, A.; Le Loc'h, F. url  doi
openurl 
  Titre Fishing inside or outside? A case studies analysis of potential spillover effect from marine protected areas, using food web models Type Article scientifique
  Année 2014 Publication (down) Revue Abrégée Journal of Marine Systems  
  Volume 139 Numéro Pages 383-395  
  Mots-Clés Biomass exports; Ecopath; EcoTroph; Fishing impact; food web model; Marine protected area (MPA)  
  Résumé Marine protected areas (MPAs) are implemented worldwide as an efficient tool to preserve biodiversity and protect ecosystems. We used food web models (Ecopath and EcoTroph) to assess the ability of MPAs to reduce fishing impacts on targeted resources and to provide biomass exports for adjacent fisheries. Three coastal MPAs: Bonifacio and Port-Cros (Mediterranean Sea), and Bamboung (Senegalese coast), were used as case studies. Pre-existing related Ecopath models were homogenized and ecosystem characteristics were compared based on network indices and trophic spectra analyses. Using the EcoTroph model, we simulated different fishing mortality scenarios and assessed fishing impacts on the three ecosystems. Lastly, the potential biomass that could be exported from each MPA was estimated. Despite structural and functional trophic differences, the three MPAs showed similar patterns of resistance to simulated fishing mortalities, with the Bonifacio case study exhibiting the highest potential catches and a slightly inferior resistance to fishing. We also show that the potential exports from our small size MPAs are limited and thus may only benefit local fishing activities. Based on simulations, their potential exports were estimated to be at the same order of magnitude as the amount of catch that could have been obtained inside the reserve. In Port Cros, the ban of fishing inside MPA could actually allow for improved catch yields outside the MPA due to biomass exports. This was not the case for the Bonifacio site, as its potential exports were too low to offset catch losses. This insight suggests the need for MPA networks and/or sufficiently large MPAs to effectively protect juveniles and adults and provide important exports. Finally, we discuss the effects of MPAs on fisheries that were not considered in food web models, and conclude by suggesting possible improvements in the analysis of MPA efficiency.  
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  ISSN 0924-7963 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1197  
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