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Auteur Potier, M.; Bach, P.; Ménard, F.; Marsac, F. url  doi
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  Titre (up) Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel Type Article scientifique
  Année 2014 Publication Revue Abrégée Deep-Sea Research Part II.Topical Studies in Oceanography  
  Volume 100 Numéro No spécial Pages 184-199  
  Mots-Clés Biodiversity; Mid-water trawl; Mozambique Channel; Oceanic eddies; Pelagic longline; Stomach contents  
  Résumé We investigated the diversity and distribution of two communities, micronekton organisms and large predatory fishes, sampled in mesoscale features of the Mozambique Channel from 2003 to 2009, by combining mid-water trawls, stomach contents of fish predators and instrumented longline fishing surveys. The highest species richness for assemblages was found in divergences and fronts rather than in the core of eddies. Despite an unbalanced scheme, diversity indices did not differ significantly between cyclonic and anticyclonic eddies, divergences and fronts. We found that eddies and associated physical cues did not substantially affect the distribution of micronektonic species which are mainly driven by the diel vertical migration pattern. Top predators exhibited a more complex response. Swordfish (Xiphias gladius) associated better with mesoscale features than tunas, with a clear preference for divergences which is consistent with the diel vertical migrations and occurrence of its main prey, the flying squids Sthenoteuthis oualaniensis (Ommastrephidae). On the other hand, the probability of presence of yellowfin tuna was not tied to any specific eddy structure. However, the highest values of positive yellowfin CPUEs were associated with low horizontal gradients of sea-level anomalies. We also showed a non-linear response of positive yellowfin CPUEs with respect to the depth of the minimal oxygen content. The larger the distance between the hooks and the minimal oxygen layer, towards the surface or at greater depths, the higher the CPUE, highlighting that yellowfin congregated in well-oxygenated waters. Micronekton sampled by mid-water trawls and stomach contents exhibited different species composition. The highly mobile organisms were not caught by trawling whereas they remain accessible to predators. The combination of stomach contents and mid-water trawls undoubtedly improved our understanding of the micronekton assemblage distribution. Our results provide some evidence that mesoscale features in the Mozambique Channel do not strongly affect the distribution of the mid-trophic level organisms such as micronekton and most of the large predatory fishes, and hypotheses are proposed to support this result.  
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  Editeur Lieu de Publication Éditeur Barlow, R.; Marsac, F.; Ternon, J.-F.; Roberts, M.  
  Langue Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 0967-0645 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 369  
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Auteur Walker, T.R.; Grant, J.; Weise, A.M.; McKindsey, C.W.; Callier, M.D.; Richard, M. url  doi
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  Titre (up) Influence of suspended mussel lines on sediment erosion and resuspension in Lagune de la Grande Entree, Iles-de-la-Madeleine, Quebec, Canada Type Article scientifique
  Année 2014 Publication Revue Abrégée Aquaculture  
  Volume 433 Numéro Pages 450-457  
  Mots-Clés Aquaculture; Biodeposits; biogeochemical fluxes; culture; dynamics; intertidal cohesive sediments; lagoon; Mytilus; Mytilus edulis; Particle; rates; Resuspension; Sediment erosion; Shear velocity; size; stability  
  Résumé Downward fluxes of organically rich biodeposits under suspended mussel lines can cause benthic impacts such as changes in benthic community structure or microbial mat production. Quantifying sediment erosion in these coastal ecosystems is important for understanding how fluxes of organic matter and mussel biodeposits contribute to benthic pelagic coupling. Critical shear velocity (u(crit)*(t)), erosion rates and particle size distributions of resuspended sediment were measured at four stations distributed along a transect perpendicular to a mussel farm in Lagune de la Grande Entree, Iles-de-la-Madeleine (Quebec, Canada). Stations were selected underneath the outer-most mussel line (0 m) and at distances of 15,30 m and at a reference station (500 m) further along the transect. Shear velocity was measured using a calibrated portable Particle Erosion Simulator, also referred to as the BEAST (Benthic Environmental Assessment Sediment Tool). Undisturbed sediment cores obtained by divers were exposed to shear stress to compare differences between stations. Erosion sequences indicated no significant differences in u(crit)* between stations, but there were significant differences in erosion rates beneath mussel lines compared to other stations. Erosion rates were the highest in cores from beneath mussel lines, but paradoxically had the lowest u(crit)* Mean erosion rates at u*crit varied between 25 and 47 g m(-2) min(-1) and critical erosion thresholds varied between 1.58 and 1.73 cm s(-1), which compare with intensive mussel culture sites elsewhere in eastern Canada. Significant differences existed in biotic and abiotic properties of sediments which could explain variation in maximum erosion rates within and between stations. Particle sizes measured by videography of resuspended sediment at different shear velocities ranged from 02 to 3.0 mm. Quantifying sediment erosion from intact marine sediments helps to improve our mechanistic understanding of these processes, and the BEAST further contributes to predictive capability in benthic pelagic coupling modeling. (C) 2014 Elsevier B.V. All rights reserved.  
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  Langue English Langue du Résumé Titre Original  
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  ISSN 0044-8486 ISBN Médium  
  Région Expédition Conférence  
  Notes <p>ISI Document Delivery No.: AQ1GH<br/>Times Cited: 0<br/>Cited Reference Count: 39<br/>Walker, Tony R. Grant, Jon Weise, Andrea M. McKindsey, Christopher W. Callier, Myriam D. Richard, Marion<br/>Natural Sciences and Engineering Research Council of Canada (NSERC); Aquaculture Collaborative Research and Development Program (ACRDP); Societe de Development de l'Industrie Maricole (SODIM); Fisheries and Oceans Canada<br/>We thank MAPAQ and B. Hargrave for the collaboration and C. Eloquin and associates for the permission to use their site. Funding was provided by the Aquaculture Collaborative Research and Development Program (ACRDP), the Societe de Development de l'Industrie Maricole (SODIM) and the Fisheries and Oceans Canada. We thank B. Schofield and M. Merrimen for the fabrication of the BEAST which formed part of the equipment necessary for the Canadian Arctic Shelves Exchange Study (CASES), a Research Network funded by the Natural Sciences and Engineering Research Council of Canada (NSERC).<br/>Elsevier science bv<br/>Amsterdam</p> Approuvé pas de  
  Numéro d'Appel MARBEC @ alain.herve @ collection 1180  
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Auteur Travis, J.; Coleman, F.C.; Auster, P.J.; Cury, P.; Estes, J.A.; Orensanz, J.; Peterson, C.H.; Power, M.E.; Steneck, R.S.; Wootton, J.T. url  doi
openurl 
  Titre (up) Integrating the invisible fabric of nature into fisheries management Type Article scientifique
  Année 2014 Publication Revue Abrégée Proceedings of the National Academy of Sciences of the United States of America  
  Volume 111 Numéro 2 Pages 581-584  
  Mots-Clés alternative states; ecosystem flips; fisheries collapse; ocean fisheries  
  Résumé Overfishing and environmental change have triggered many severe and unexpected consequences. As existing communities have collapsed, new ones have become established, fundamentally transforming ecosystems to those that are often less productive for fisheries, more prone to cycles of booms and busts, and thus less manageable. We contend that the failure of fisheries science and management to anticipate these transformations results from a lack of appreciation for the nature, strength, complexity, and outcome of species interactions. Ecologists have come to understand that networks of interacting species exhibit nonlinear dynamics and feedback loops that can produce sudden and unexpected shifts. We argue that fisheries science and management must follow this lead by developing a sharper focus on species interactions and how disrupting these interactions can push ecosystems in which fisheries are embedded past their tipping points.  
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  ISSN 0027-8424 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 336  
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Auteur BORDIER, C.; SARAUX, C.; VIBLANC, V.A.; GACHOT-NEVEU, H.; BEAUGEY, M.; LE MAHO, Y.; LE BOHEC, C. url  openurl
  Titre (up) Inter-Annual Variability of Fledgling Sex Ratio in King Penguins Type Article scientifique
  Année 2014 Publication Revue Abrégée Plos One  
  Volume 9 Numéro 12 Pages 1-17  
  Mots-Clés  
  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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  ISSN 1932-6203 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 1126  
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Auteur Sequeira, A.M.M.; Mellin, C.; Floch, L.; Williams, P.G.; Bradshaw, C.J.A. url  doi
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  Titre (up) Inter-ocean asynchrony in whale shark occurrence patterns Type Article scientifique
  Année 2014 Publication Revue Abrégée Journal of Experimental Marine Biology and Ecology  
  Volume 450 Numéro Pages 21-29  
  Mots-Clés <!–; –><keyword; Handled; id=; Not; Tag  
  Résumé Abstract The whale shark (Rhincodon typus, Smith, 1828) is a migratory species (classed as Vulnerable by the IUCN) with genetic and circumstantial evidence for inter-ocean connectivity. Given this migratory behaviour, population-wide occurrence trends can only be contextualized by examining the synchrony in occurrence patterns among locations where they occur. We present a two-step modelling approach of whale shark spatial and temporal probability of occurrence in the Atlantic and Pacific Oceans using generalized linear mixed-effects models. To test the hypothesis that the probability of whale shark occurrence is asynchronous across oceans, as expected if inter-ocean migration occurs, we used long-term datasets of whale shark sightings derived from tuna purse-seine logbooks covering most of the central-east Atlantic (1980–2010) and western Pacific (2000–2010). We predicted seasonal habitat suitability to produce maps in each area, and then evaluated the relative effect of time (year) on the probability of occurrence to test whether it changed over the study period. We also applied fast Fourier transforms to determine if any periodicity was apparent in whale shark occurrences in each ocean. After partialling out the effects of seasonal patterns in spatial distribution and sampling effort, we found no evidence for a temporal trend in whale shark occurrence in the Atlantic, but there was a weak trend of increasing probability of occurrence in the Pacific. The highest-ranked model for the latter included a spatial predictor of occurrence along with fishing effort, a linear term for time, and a random temporal effect (year), explaining 15% of deviance in whale shark probability of occurrence. Fast Fourier transforms revealed a prominent 15.5-year cycle in the Atlantic. The increase in the probability of occurrence in the Pacific is concurrent with a decrease previously detected in the Indian Ocean. Cyclic patterns driven by migratory behaviour would better explain temporal trends in whale shark occurrence at the oceanic scale. However, despite cycles partially explaining observations of fewer sharks in some years, overall reported sighting rate has been decreasing. As a result, we suggest that the current {IUCN} status of the species should be re-assessed, but more data are needed to examine the flow of individuals across oceans and to identify possible reasons for asynchronous occurrences.  
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  Volume de collection Numéro de collection Edition  
  ISSN 0022-0981 ISBN Médium  
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  Numéro d'Appel LL @ pixluser @ collection 314  
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