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Vulnérabilité de populations de poissons (Platichthys flesus) face aux multi-stress en estuaires : une approche intégrative

Abstract : The vulnerability level of natural flounder populations was assessed, integrating responses at the molecular, individual and population levels. A multi-estuary approach was carried out on the fish responses in contrasted environments (thermal stress: Mondego estuary; chemical stress: Seine estuary; moderately stressed systems: Bay of Douarnenez, Vilaine and Canche estuaries).A demo-genetic approach, considering the variability of microsatellites, underlined a reduced effective size for the southern peripheral population of the Mondego estuary, thus characterized by a high ecological risk.In the Seine population, a reduced interindividual variability was observed considering the expression levels of genes involved in bioenergetics (COII, 12S); this pattern could explain the reduced ability of this population to cope with another stress (ie thermal stress).Signatures of adaptation to pollutants (high level of energetic metabolism, management of oxidative stress, modification of membrane phopholipids) were observed in the Seine, but could be very costly (reduced muscle energetic reserve). Thus, we consider that the Seine population is displaying a high ecological risk.A one month fish caging experiment was conducted in the Seine estuary. Fish responses were analyzed by proteomic; they underlined a decreasing pollution gradient from upstream to downstream, and thus allowed to characterize the ecological status of the estuary atmicroscale.This study highlighted pertinent tools for the assessment of flounder population vulnerability and for the exploration of the ecological status of estuarine systems.
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Elodie Borcier. Vulnérabilité de populations de poissons (Platichthys flesus) face aux multi-stress en estuaires : une approche intégrative. Autre [q-bio.OT]. Université de Bretagne occidentale - Brest, 2019. Français. ⟨NNT : 2019BRES0020⟩. ⟨tel-02928183⟩

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