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Auteur Moreau, S.; Mostajir, B.; Almandoz, G.O.; Demers, S.; Hernando, M.; Lemarchand, K.; Lionard, M.; Mercier, B.; Roy, S.; Schloss, I.R.; Thyssen, M.; Ferreyra, G.A.
Titre Effects of enhanced temperature and ultraviolet B radiation on a natural plankton community of the Beagle Channel (southern Argentina): a mesocosm study Type Article scientifique
Année 2014 Publication Revue Abrégée Aquatic Microbial Ecology
Volume (down) 72 Numéro 2 Pages 155-173
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Résumé ABSTRACT: Marine planktonic communities can be affected by increased temperatures associated with global climate change, as well as by increased ultraviolet B radiation (UVBR, 280-320 nm) through stratospheric ozone layer thinning. We studied individual and combined effects of increased temperature and UVBR on the plankton community of the Beagle Channel, southern Patagonia, Argentina. Eight 2 m3 mesocosms were exposed to 4 treatments (with 2 replicates) during 10 d: (1) control (natural temperature and UVBR), (2) increased UVBR (simulating a 60% decrease in stratospheric ozone layer thickness), (3) increased temperature (+ 3°C), and (4) simultaneous increased temperature and UVBR (60% decrease in stratospheric ozone; + 3°C). Two distinct situations were observed with regard to phytoplankton biomass: bloom (Days 1-4) and post-bloom (Days 5-9). Significant decreases in micro-sized diatoms (>20 µm), bacteria, chlorophyll a, and particulate organic carbon concentrations were observed during the post-bloom in the enhanced temperature treatments relative to natural temperature, accompanied by significant increases in nanophytoplankton (10-20 µm, mainly prymnesiophytes). The decrease in micro-sized diatoms in the high temperature treatment may have been caused by a physiological effect of warming, although we do not have activity measurements to support this hypothesis. Prymnesiophytes benefited from micro-sized diatom reduction in their competition for resources. The bacterial decrease under warming may have been due to a change in the dissolved organic matter release caused by the observed change in phytoplankton composition. Overall, the rise in temperature affected the structure and total biomass of the communities, while no major effect of UVBR was observed on the plankton community.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 555
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Auteur BRIND'AMOUR, A.; LAFFARGUE, P.; MORIN, J.; VAZ, S.; FOVEAU, A.; LE BRIS, H.
Titre Morphospecies and taxonomic sufficiency of benthic megafauna in scientific bottom trawl surveys Type Article scientifique
Année 2014 Publication Revue Abrégée Continental Shelf Research
Volume (down) 72 Numéro Pages 1-9
Mots-Clés Bay of Biscay; Benthic descriptor; Bottom trawl surveys; English Channel; North sea; Taxonomic sufficiency
Résumé Scientific fisheries surveys routinely identify a large diversity of commercial and non-commercial benthic megainvertebrates that could provide useful information for Marine Strategy Framework Directive (MSFD) descriptors. Species is obviously the basic taxonomic level to which most ecological studies and theories refer. Identification at this level of organization is indeed always preferred over any other taxonomic level. Nevertheless, aggregation of species to higher taxonomic levels may be unavoidable sometimes, since errors of identification are known or suspected to occur in many surveys. Using analyses of taxonomic sufficiency (identification of organisms at various taxonomic resolutions) and groups of morphospecies (taxa identified easily by non-experts on the basis of evident morphological traits), this study aims to quantify the loss of ecological information incurred by partial identification of benthic megafauna in bottom trawl surveys in order to put such data to good use. The analyses were conducted on five scientific surveys representing a large range of geographical areas (from 150 km2 to 150 000 km2) and environmental conditions. Results show that genus, family and, particularly, morphospecies are good surrogates for species identification in community analyses. We suggest that bottom trawl surveys can provide reliable megafauna data that may usefully complete those obtained by grab surveys. The use of morphospecies could lead to new strategies, combining different datasets to provide indicators for MSFD descriptors (e.g. D6).
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ISSN 0278-4343 ISBN Médium
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1141
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Auteur Robert, M.; Dagorn, L.; Bodin, N.; Pernet, F.; Arsenault-Pernet, E.J.; Deneubourg, J.L.
Titre Comparison of condition factors of skipjack tuna (Katsuwonus pelamis) associated or not with floating objects in an area known to be naturally enriched with logs Type Article scientifique
Année 2014 Publication Revue Abrégée Canadian Journal of Fisheries and Aquatic Sciences = Journal Canadien des Sciences Halieutiques et A
Volume (down) 71 Numéro 3 Pages 472-478
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Résumé Dans une région très peu modifiée par des dispositifs de concentration de poissons (DCP), le canal du Mozambique (naturellement riche en billes de bois, mais comptant peu de DCP), nous avons observé que l&8217;embonpoint de listao (Katsuwonus pelamis) associées à des objets flottants était plus faible que celui de leurs congénères nageant en bancs libres. Puisque ce résultat porte sur une zone analogue au milieu naturel avant l&8217;utilisation de DCP, il remet en question l&8217;interprétation d&8217;études antérieures voulant que cette différence reflète l&8217;incidence d&8217;un vaste déploiement de DCP sur les thonidés. Il est possible que, avant l&8217;utilisation de DCP, les thons associées aux billes de bois présentaient également un moins bon embonpoint que les thons nageant en bancs libres. Nos résultats semblent indiquer que la raison évolutive pour laquelle les thonidés sont associées à des objets flottants ne serait peut-être pas être reliée à des avantages trophiques à court terme, et d&8217;autres hypothèses (p. ex. l&8217;hypothèse du point de rencontre) sont invoquées pour expliquer ces résultats.
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Numéro d'Appel LL @ pixluser @ collection 338
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Auteur FROMENTIN, J.-M.; LOPUSZANSKI, D.
Titre Migration, residency, and homing of bluefin tuna in the western Mediterranean Sea Type Article scientifique
Année 2014 Publication Revue Abrégée ICES Journal of Marine Science
Volume (down) 71 Numéro 3 Pages 510-518
Mots-Clés feeding area; front; marine protected area; pop-up archival tag; Spatial distribution; Thunnus thynnus
Résumé This study presents the results of an electronic tagging programme on mature Atlantic bluefin tuna (ABFT) that has been conducted since 2007 offshore of the French Mediterranean Coast. The spatial distributions of ABFT showed little year-to-year variation and the fish concentrated in a small area of the central northwestern Mediterranean, where they may stay for several months. The individual tracks display sinuous trajectories in this area, indicating the possibility of feeding behaviour. No fish went out to the North Atlantic, but several fish displayed some migration to the southern western Mediterranean Sea during winter and the central Mediterranean during the spawning season. The homing behaviour of one fish after a full year as well as the back and forth of several fish further indicates that this restricted feeding area is probably persistent from year to year. We hypothesize that this area could result from local enrichment due to permanent mesoscale oceanographic features related to the North Mediterranean Current and the North Balearic front. The option of a spatial management, through marine protected areas, for a highly migratory species, such as ABFT, thus deserves more careful consideration because those species displayed complex spatial dynamics (e.g. homing), and population structure (e.g. several subpopulations of different sizes).
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ISSN 1054-3139 ISBN Médium
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Notes The following values have no corresponding Zotero field:<br/>Author Address: IFREMER, UMR 212 EME, Avenue Jean Monnet, BP 171, 34203 Se`te, France<br/>Author Address: BGFCF, (Big Game Fishing Club France), Carry le Rouet 13620, France<br/>PB – Oxford university press<br/> Approuvé pas de
Numéro d'Appel LL @ pixluser @ collection 339
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Auteur Bez, N.; Braham, C.B.
Titre Indicator variables for a robust estimation of an acoustic index of abundance Type Article scientifique
Année 2014 Publication Revue Abrégée Canadian Journal of Fisheries and Aquatic Sciences
Volume (down) 71 Numéro 5 Pages 709-718
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Résumé In North West Africa, pelagic fisheries are an essential economic sector. However, the scientific community fails to perform satisfactory assessments of key pelagic species like sardinella, owing to a lack of relevant indices of abundance to tune the model. This paper provides an alternative acoustic index based on a semiquantitative modelisation of acoustic densities. Acoustic energy is split into binomial variables coding for null, low, medium, large, and very large densities. A multivariate geostatistical approach allows (i) mapping the spatial distribution of classes of densities and (ii) computing a new acoustic index of abundance for Sardinella aurita and Sardinella maderensis. We used the surveys of RV Fridtjof Nansen (1995-2006) and RV Al-Awam (2007-2010). Our results indicated that empirical spatial structures were highly stable over time for both between areas and surveys. Co-kriging maps also showed that sardinella had stable hot spots of distribution. The indices of abundance developed in the present study were tested in an assessment procedure and outperformed all the indices used routinely by the FAO-CECAF (Fishery Committee for the Eastern Central Atlantic) assessment working group.
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Numéro d'Appel LL @ pixluser @ collection 352
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