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Auteur Tremblay, Y.; Thiebault, A.; Mullers, R.; Pistorius, P.
Titre Bird-borne video-cameras show that seabird movement patterns relate to previously unrevealed proximate environment, not prey Type Article scientifique
Année 2014 Publication (up) Revue Abrégée Plos One
Volume 9 Numéro 2 Pages
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Résumé The study of ecological and behavioral processes has been revolutionized in the last two decades with the rapid development of biologging-science. Recently, using image-capturing devices, some pilot studies demonstrated the potential of understanding marine vertebrate movement patterns in relation to their proximate, as opposed to remote sensed environmental contexts. Here, using miniaturized video cameras and GPS tracking recorders simultaneously, we show for the first time that information on the immediate visual surroundings of a foraging seabird, the Cape gannet, is fundamental in understanding the origins of its movement patterns. We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats. Contrary to a widely accepted idea, our data suggest that foraging seabirds are not directly looking for prey. Instead, they search for indicators of the presence of prey, the latter being targeted at the very last moment and at a very small scale. We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology. Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.
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Numéro d'Appel LL @ pixluser @ collection 337
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Auteur Ba, K.; Thiaw, M.; Lazar, N.; Sarr, A.; Brochier, T.; Ndiaye, I.; Faye, A.; Sadio, O.; Panfili, J.; Thiaw, O.T.; Brehmer, P.
Titre Resilience of Key Biological Parameters of the Senegalese Flat Sardinella to Overfishing and Climate Change Type Article scientifique
Année 2016 Publication (up) Revue Abrégée PLoS One
Volume 11 Numéro 6 Pages e0156143
Mots-Clés age; aurita; eba val; growth; length; maderensis lowe; maturity; pointe-noire region; recruitment; west-africa
Résumé The stock of the Senegalese flat sardinella, Sardinella maderensis, is highly exploited in Senegal, West Africa. Its growth and reproduction parameters are key biological indicators for improving fisheries management. This study reviewed these parameters using landing data from small-scale fisheries in Senegal and literature information dated back more than 25 years. Age was estimated using length-frequency data to calculate growth parameters and assess the growth performance index. With global climate change there has been an increase in the average sea surface temperature along the Senegalese coast but the length-weight parameters, sex ratio, size at first sexual maturity, period of reproduction and condition factor of S. maderensis have not changed significantly. The above parameters of S. maderensis have hardly changed, despite high exploitation and fluctuations in environmental conditions that affect the early development phases of small pelagic fish in West Africa. This lack of plasticity of the species regarding of the biological parameters studied should be considered when planning relevant fishery management plans.
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Langue English Langue du Résumé Titre Original
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Numéro d'Appel MARBEC @ alain.herve @ collection 1630
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Auteur BORDIER, C.; SARAUX, C.; VIBLANC, V.A.; GACHOT-NEVEU, H.; BEAUGEY, M.; LE MAHO, Y.; LE BOHEC, C.
Titre Inter-Annual Variability of Fledgling Sex Ratio in King Penguins Type Article scientifique
Année 2014 Publication (up) Revue Abrégée Plos One
Volume 9 Numéro 12 Pages 1-17
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Résumé As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (20002009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1:1 equilibrium upon first breeding attempts, as would be expected from Fisher's classic theory of offspring sex-ratio variation.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1126
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Auteur Rocklin, D.; Tomasini, J.A.; Culioli, J.M.; Pelletier, D.; Mouillot, D.
Titre Spearfishing Regulation Benefits Artisanal Fisheries: The ReGS Indicator and Its Application to a Multiple-Use Mediterranean Marine Protected Area Type Article scientifique
Année 2011 Publication (up) Revue Abrégée PLoS One
Volume 6 Numéro 9 Pages
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 872
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Auteur NIEBLAS, A.-E.; DRUSHKA, K.; REYGONDEAU, G.; ROSSI, V.; DEMARCQ, H.; DUBROCA, L.; BONHOMMEAU, S.
Titre Defining Mediterranean and Black Sea Biogeochemical Subprovinces and Synthetic Ocean Indicators Using Mesoscale Oceanographic Features Type Article scientifique
Année 2014 Publication (up) Revue Abrégée Plos One
Volume 9 Numéro 10 Pages 1-13
Mots-Clés
Résumé The Mediterranean and Black Seas are semi-enclosed basins characterized by high environmental variability and growing anthropogenic pressure. This has led to an increasing need for a bioregionalization of the oceanic environment at local and regional scales that can be used for managerial applications as a geographical reference. We aim to identify biogeochemical subprovinces within this domain, and develop synthetic indices of the key oceanographic dynamics of each subprovince to quantify baselines from which to assess variability and change. To do this, we compile a data set of 101 months (2002-2010) of a variety of both “classical'' (i.e., sea surface temperature, surface chlorophyll-a, and bathymetry) and ”mesoscale'' (i.e., eddy kinetic energy, finite-size Lyapunov exponents, and surface frontal gradients) ocean features that we use to characterize the surface ocean variability. We employ a k-means clustering algorithm to objectively define biogeochemical subprovinces based on classical features, and, for the first time, on mesoscale features, and on a combination of both classical and mesoscale features. Principal components analysis is then performed on the oceanographic variables to define integrative indices to monitor the environmental changes within each resultant subprovince at monthly resolutions. Using both the classical and mesoscale features, we find five biogeochemical subprovinces for the Mediterranean and Black Seas. Interestingly, the use of mesoscale variables contributes highly in the delineation of the open ocean. The first axis of the principal component analysis is explained primarily by classical ocean features and the second axis is explained by mesoscale features. Biogeochemical subprovinces identified by the present study can be useful within the European management framework as an objective geographical framework of the Mediterranean and Black Seas, and the synthetic ocean indicators developed here can be used to monitor variability and long-term change.
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Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1130
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