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Potier Michel, Bach Pascal, Ménard Frédéric, Marsac Francis. (2014). Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel. In : Barlow R. (ed.), Marsac Francis (ed.), Ternon Jean-Francois (ed.), Roberts M. (ed.) The Mozambique channel : mesoscale dynamics and ecosystem responses. Deep-Sea Research Part II.Topical Studies in Oceanography, 100 (No spécial), 184-199. ISSN 0967-0645

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Lien direct chez l'éditeur doi:10.1016/j.dsr2.2013.10.026

Titre
Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel
Année de publication2014
Type de documentArticle référencé dans le Web of Science WOS:000333721400015
AuteursPotier Michel, Bach Pascal, Ménard Frédéric, Marsac Francis.
InBarlow R. (ed.), Marsac Francis (ed.), Ternon Jean-Francois (ed.), Roberts M. (ed.) The Mozambique channel : mesoscale dynamics and ecosystem responses
SourceDeep-Sea Research Part II.Topical Studies in Oceanography, 2014, 100 (No spécial), p. 184-199. ISSN 0967-0645
RésuméWe 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.
Plan de classementEcologie, systèmes aquatiques [036]
Descr. géo.MOZAMBIQUE CANAL ; OCEAN INDIEN
LocalisationFonds IRD [F B010061902]
Identifiant IRDfdi:010061902
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010061902

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