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Auteur (down) van der Geest, M.; van der Lely, J.A.C.; van Gils, J.A.; Piersma, T.; Lok, T. url  doi
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  Titre Density-dependent growth of bivalves dominating the intertidal zone of Banc d’Arguin, Mauritania: importance of feeding mode, habitat and season Type Article scientifique
  Année 2019 Publication Revue Abrégée Marine Ecology Progress Series  
  Volume 610 Numéro Pages 51-63  
  Mots-Clés Carrying capacity; Chemosymbiosis; Density dependence; Environmental heterogeneity; Feeding guild; Seagrass; Soft-sediment habitat  
  Résumé Accurate predictions of population dynamics require an understanding of the ways by which environmental conditions and species-specific traits affect the magnitude of density dependence. Here, we evaluated the potential impact of season and habitat (characterized by sediment grain size and seagrass biomass) on the magnitude of density dependence in shell growth of 3 infaunal bivalve species dominating the tropical intertidal benthic communities of Banc d’Arguin, Mauritania. Two of our focal species were filter feeders (Senilia senilis and Pelecyora isocardia) and one was a facultative mixotroph (Loripes orbiculatus), mainly relying on organic carbon provided by sulphide-oxidizing endosymbiotic gill-bacteria (i.e. chemosymbiotic). Distinguishing 2 seasons, winter and summer, we manipulated local bivalve densities across habitats (from bare sandy sediments to seagrass-covered mud). In situ growth of individually tagged and relocated clams was measured and compared with those of tagged clams that were allocated to adjacent sites where local bivalve densities were doubled. Growth was negatively density-dependent in both winter and summer in P. isocardia and L. orbiculatus, the 2 species that mainly inhabit seagrass sediments, but not in S. senilis, usually found in bare sediments. As reproduction and survival rates are generally size-dependent in bivalves, our results suggest that in our tropical study system, the bivalve community of seagrass-covered sediments is more strongly regulated than that of adjacent bare sediments, regardless of species-specific feeding mode or season. We suggest that ecosystem engineering by seagrasses enhances environmental stability, which allows bivalve populations within tropical seagrass beds to stay close to carrying capacity.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0171-8630, 1616-1599 ISBN Médium  
  Région Expédition Conférence  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2488  
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Auteur (down) Van Beveren, E.; Keck, N.; Fromentin, J.-M.; Laurence, S.; Boulet, H.; Labrut, S.; Baud, M.; Bigarre, L.; Brosset, P.; Saraux, C. doi  openurl
  Titre Can pathogens alter the population dynamics of sardine in the NW Mediterranean? Type Article scientifique
  Année 2016 Publication Revue Abrégée Mar. Biol.  
  Volume 163 Numéro 12 Pages Unsp-240  
  Mots-Clés age; gulf; herpesvirus; lions; melano-macrophage centers; pilchard; sea; small pelagic fish; systems; vibrio-alginolyticus  
  Résumé Sardine populations worldwide can fluctuate drastically over short time periods, in terms of both biomass and biological characteristics. Fluctuations might be amplified by pathogens, but such hypotheses have never been considered in the absence of clear macroscopic symptoms. In the Gulf of Lions (NW Mediterranean), an enduring severe decrease in sardine (Sardina pilchardus) size, condition and age has been observed since 2008, resulting in a strong decline in landings. This situation might have been caused or aggravated by diseases, especially as other drivers such as fisheries are not expected to be important. Therefore, we developed and performed a general veterinary study, aimed at detecting a wide range of potential pathogens, including parasites, viruses and bacteria. We explored which infectious agents are most likely to produce a causal relationship with sardine health, important information for future infection experiments. Among about 1300 sardines sampled during June 2014-July 2015, microscopic parasites (often trematodes and coccidians) and bacteria Tenacibaculum and Vibrio spp. were found. However, no clear damage to tissue was observed and there was generally no link between the agents' presence and host size or condition, so that no strong indications of pathogenicity were present. Nonetheless, 54 % of the sardines analysed in 2015 had elevated quantities of melano-macrophage centres (macrophage aggregates), indicating stress on the fish that might potentially be related to starvation and/or pollution.  
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  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0025-3162 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 1698  
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Auteur (down) Van Beveren, E.; Fromentin, J.-M.; Bonhommeau, S.; Nieblas, A.-E.; Metral, L.; Brisset, B.; Jusup, M.; Bauer, R.K.; Brosset, P.; Saraux, C. doi  openurl
  Titre Predator-prey interactions in the face of management regulations: changes in Mediterranean small pelagic species are not due to increased tuna predation Type Article scientifique
  Année 2017 Publication Revue Abrégée Can. J. Fish. Aquat. Sci.  
  Volume 74 Numéro 9 Pages 1422-1430  
  Mots-Clés anchovy engraulis-encrasicolus; atlantic bluefin tuna; Energy density; fish condition; fisheries; food-consumption; Proximate composition; sea; thunnus-thynnus; Yellowfin tuna  
  Résumé Recently, the abundance of young Atlantic bluefin tuna (Thunnus thynnus) tripled in the northwestern Mediterranean following effective management measures. We investigated whether its predation on sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) could explain their concurrent size and biomass decline, which caused a fishery crisis. Combining the observed diet composition of bluefin tuna, their modelled daily energy requirements, their population size, and the abundance of prey species in the area, we calculated the proportion of the prey populations that were consumed by bluefin tuna annually over 2011-2013. To assess whether tuna could alter the size structure of the three small pelagic fish populations (anchovy, sardine, and sprat (Sprattus sprattus)), the size distributions of the consumed prey species were compared with those of the wild populations. We estimated that the annual consumption of small pelagic fish by bluefin tuna is less than 2% of the abundance of these populations. Furthermore, size selectivity patterns were not observed. We thus concluded that tuna predation is unlikely to be the main cause of major changes in the small pelagic fish populations from this area.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0706-652x ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2195  
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Auteur (down) Tserpes, G.; Massuti, E.; Fiorentino, F.; Facchini, M.T.; Viva, C.; Jadaud, A.; Joksimovic, A.; Pesci, P.; Piccinetti, C.; Sion, L.; Thasitis, I.; Vrgoc, N. doi  openurl
  Titre Distribution and spatio-temporal biomass trends of red mullets across the Mediterranean Type Article scientifique
  Année 2019 Publication Revue Abrégée Sci. Mar.  
  Volume 83 Numéro Pages 43-55  
  Mots-Clés distribution; egg size; fishery; gamma; history; management; Mediterranean; mullus-barbatus l.; perciformes; red mullet; sea; stock structure; striped red mullet; surmuletus; trends  
  Résumé The present work examines the spatio-temporal biomass trends of Mullus barbatus and Mullus sunnuletus in the Mediterranean Sea through the analysis of a time series of data coming from the Mediterranean International Trawl Surveys (MEDITS), accomplished annually from 1994 to 2015. The biomass of both species showed clear declining trends below 150 to 200 m depth, which were steeper in the case of M. barbatus. Increases in temporal biomass trends were observed for M. barbatus from 2008 onward in most geographic sub-areas (GSAs), while stability was mostly observed for M. stumuletus. For both species, dynamic factor analysis revealed similarities among neighbouring GSAs and the subsequent cluster analysis identified two major GSA groups corresponding to the eastern and western basins of the Mediterranean. Overall, the results suggested that the combined effects of fishing and environmental conditions determine species abundance variations, but the relative importance of each component may vary among areas.  
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  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 0214-8358 ISBN Médium  
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  Notes WOS:000504829900004 Approuvé pas de  
  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2714  
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Auteur (down) Triki, H.Z.; Laabir, M.; Moeller, P.; Chomérat, N.; Kéfi Daly-Yahia, O. url  doi
openurl 
  Titre First report of goniodomin A production by the dinoflagellate Alexandrium pseudogonyaulax developing in southern Mediterranean (Bizerte Lagoon, Tunisia) Type Article scientifique
  Année 2016 Publication Revue Abrégée Toxicon  
  Volume 111 Numéro Pages 91-99  
  Mots-Clés Alexandrium pseudogonyaulax; goniodomin A; Mediterranean sea; morphology; Phylogeny  
  Résumé The dinoflagellate Alexandrium pseudogonyaulax is widely distributed around the world including the Mediterranean waters. The objectives of this study were to determine the morphology and phylogenic affiliation of A. pseudogonyaulax strain isolated from Bizerte Lagoon (Mediterranean waters, Tunisia) and investigate its toxicity. Molecular analyses confirmed the morphological identification of the isolated strain (APBZ12) as A. pseudogonyaulax. Moreover, it showed that it is 100% identical with strains of this species found in New Zealand, Japan, China and North Sea (Norway and Denmark) suggesting that this species is cosmopolitan. Until now, no toxin studies have been conducted on fully characterized (morphologically and molecularly) A. pseudogonyaulax. Cellular toxin production was determined using high pressure liquid chromatography coupled to mass spectrometry (HPLC/MS). Results showed for the first time that A. pseudogonyaulax contains goniodomin A (GDA), a highly toxic macrolide polyether previously shown to be produced by two other dinoflagellate species Alexandrium monilatum (Hsia et al., 2006) and Alexandrium hiranoi (erroneously identified as A. pseudogonyaulax in Murakami et al., 1988) in American and Japanese waters, respectively. This biologically active toxin has been associated over decades with fish mortality. Our study showed that the cell extracts of APBZ12 showed an important bioactivity using GH4C1 rat pituitary cytotoxicity bioassay.  
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  ISSN 0041-0101 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1524  
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