Effets combinés des facteurs naturels et anthropiques sur la diversité fonctionnellle des vasières à langoustines (Nephrops norvegicus) du golfe de Gascogne

Abstract : This PhD thesis aims at increasing the knowledge on factors influencing the benthic community structures of the « Grande Vasière » (GV) of the Bay of Biscay. Particular attention has been paid to the role of bottom trawling whose intensity has been estimated using VMS data. At the scale of the GV, our results suggest that bottom-trawling is the main driver of the megabenthic community structure (> 10mm). However, this hypothesis has not been formally demonstrated due to the co-variations between the trawling intensity and certain environmental characteristics. Hence, works continued on a restricted part of the GV that displayed minimal variations of environmental characteristics while exhibiting a wide gradient of trawling intensityResults suggest that bottom-trawling induces seasonnal and transient modifications on the mega and macrobenthic (> 1mm) communities. These changes could be due to an increase of food availability for the megabenthic predator-scavengers and to changes of sedimentary characteristics for macrofauna. However, investigation about functional diversity showed that these changes did not have major consequences on ecosystem functioning. We concluded that decades of bottom trawling may have shaped the benthic ecosystem of the GV and that it is currently adapted to frequent disruptions.
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Alexandre Robert. Effets combinés des facteurs naturels et anthropiques sur la diversité fonctionnellle des vasières à langoustines (Nephrops norvegicus) du golfe de Gascogne. Biodiversité et Ecologie. Agrocampus Ouest, 2017. Français. ⟨NNT : 2017NSARH101⟩. ⟨tel-02170685⟩

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