Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES PLoS One [23 p.] FRANCE MANCHE SLACK ESTUAIRE WIMEREUX ESTUAIRE LIANE ESTUAIRE CANCHE ESTUAIRE AUTHIE ESTUAIRE SOMME ESTUAIRE 2022 fdi:010085957 ENG PLoS One 1932-6203 ISI:000835338100026 7 10.1371/journal.pone.0270348 https://www.documentation.ird.fr/hor/fdi:010085957 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2022-09/010085957.pdf 17 Horizon (IRD) This study aims to characterize and compare the feeding ecology of the European eels (Anguilla anguilla L.) during the continental phase (i.e. yellow and silver) along a salinity gradient (i.e. lower, middle and upper) in six northern France estuaries (i.e. brackish water). The diet and stable isotopic (i.e. delta N-15 and delta C-13 values) compositions of eels collected with a fyke net in six estuaries (Slack, Wimereux, Liane, Canche, Authie and Somme estuaries) located along the French coast of the eastern English Channel per season over a year were described by combining gut content and stable isotope analyses. Eel guts were dominated by typical BW prey, Malacostraca and Actinopterygii (54% and 40%, respectively), with the gammare Gammarus zaddachi and the green crab Carcinus maenas (38% and 14%, respectively), and smaller yellow eels of A. anguilla and juvenile European flounder, Platichthys flesus (19% and 14%, respectively) being the most frequently found in their guts. The delta C-13 values of a majority of eels confirmed the sea- and brackish water-specific carbon resources. Dietary and isotopic niche revealed no clear change between total length, silvering stages and seasons, but a significant difference between salinity gradients and estuaries. Eels delta C-13 values showed significant enrichment from upper to lower along the estuaries while the delta N-15 values showed an inverse effect, with the lowest values in the lower part and highest in the upper part. Higher variability in delta C-13 values in larger estuaries suggested that eels feed on a wide range of food sources than in smaller estuaries. While eels in the smaller estuaries fed mainly on Actinopterygii prey, eels in the larger ones had a lower trophic level (i.e. delta N-15 values) and fed mainly on Malacostraca prey. This spatial difference in dietary and isotopic niche is discussed in relation to biological structure of eel and environmental variables. 034 ; 032 ; 040 UR195