Trophic links between microbenthic invertebrates and demersal fish communities in the Mont Saint-Michel macrotidal estuary prior to dams removal on the Sélune river - Archive ouverte HAL Accéder directement au contenu
Poster De Conférence Année : 2018

Trophic links between microbenthic invertebrates and demersal fish communities in the Mont Saint-Michel macrotidal estuary prior to dams removal on the Sélune river

Résumé

The restoration of the ecological continuity of rivers has today become a strong ecological issue. In some cases, it can lead to the dismantling of dams which ecological consequences must be known on dowstrea. In this context, we conducted a study to assess the initial state of the trophic functioning of a macrotidal estuarine ecosystem before the removal of two dams on a coastal river, Sélune, main contributor of this ecosystem. Fish (predator) and macroinvertebrate (prey) communities were sampled and characterized at two periods (late winter / late summer). A coupling analysis of stable isotopes (nitrogen and carbon) and analysis of digestive contents was conducted to understand the trophic functioning through the links between prey and preda- tors. The results showed that the invertebrate and fish communities were typical of European estuaries and had low species richness due to the physical constraints (variable salinity, strong currents) prevailing in the area. The abundance of fish was much higher in late summer where the abundance of invertebrates was paradoxically rather lower. Two species of sand gobies (Pomatoschistus microps and P. minutus), juvenile sea bass (Dicentrarchus labrax ) and juvenile flounder (Platichthys flesus) dominated the fish community, with each species showing particular feeding strategies. Harpacticoid copepods and amphipods (Corophium arenarium and Bathy- poreia pilosa) were the main prey of fish. The overlap analysis between digestive contents of fish and benthic invertebrate communities indicated the existence of preferential feeding zones that evolved according to the period. The results of the mixing model showed that microphytobenthos constituted a major primary source of the food chain of this ecosystem, whatever the period considered.
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hal-03403683 , version 1 (26-10-2021)

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Marie-Caroline Husset, Ludovic Goyot, Nicolas Desroy, Patrick Le Mao, Hervé Le Bris. Trophic links between microbenthic invertebrates and demersal fish communities in the Mont Saint-Michel macrotidal estuary prior to dams removal on the Sélune river. International Conference on Ecological Sciences. SFEcologie 2018, Oct 2018, Rennes, France. , pp.647, Abstract booklet. ⟨hal-03403683⟩
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