Role of estuarine habitats for the feeding ecology of the European eel (Anguilla anguilla L.)

• Published in: PLOS ONE
• Main Authors: Denis, Jérémy, Rabhi, Khalef, Le Loc’h, François, Ben Rais Lasram, Frida, Boutin, Kévin, Kazour, Maria, Diop, Mamadou, Gruselle, Marie-Christine, Amara, Rachid
• Other Authors: Hsieh, Chih-hao, Parc Naturel Marin des estuaires Picards et de la Mer d'Opale, European Maritime and Fisheries Fund, Région Hauts-de-France
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2022
• Subjects: Anguilla anguilla
• Online Access: http://dx.doi.org/10.1371/journal.pone.0270348; https://dx.plos.org/10.1371/journal.pone.0270348

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. δ 15 N and δ 13 C 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 δ 13 C 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 δ 13 C values showed significant enrichment from upper to lower along the estuaries while the δ 15 N values showed an inverse effect, with the lowest values in the lower part and highest in the upper part. Higher variability in δ 13 C 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. δ 15 N 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.