Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures
Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures
Sturbois A., Cozic A., Schaal G., Desroy N., Riera P., Le Pape O., Le Mao O., Ponséro A., Carpentier A. (2022). Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures. Marine Environmental Research, 182, 105770. https://doi.org/10.1016/j.marenvres.2022.105770
Assessing organic matter fluxes and species interactions in food webs is of main interest to understand the ecological functioning in bays and estuaries characterised by a wide diversity of primary producers and consumers. Demersal fish and cephalopod assemblages were studied across a network of 24 shallow subtidal stations in the bay of Saint-Brieuc for their diversity, stable isotope compositions and stomach contents. The community was composed of 21 taxa, eight species accounting for 94.4% of the total abundance. Three different assemblages were identified along bathymetric gradient and spatial patterns in fish dredging. Marine POM and SOM were the most likely bases of food webs regarding δ13C range displayed by fish and cephalopod without differences among assemblages. Amphipoda was the main prey item in stomachs leading to significant diet overlaps among fish species, with some variations in additional items. Sepia officinalis was characterised by a singular diet and very low dietary overlap with other species. Contrasted stable isotope values and niche overlaps among species were evidenced in the δ13C / δ15N space. Callionymus lyra and Buglossidium luteum, characterised by the widest isotopic niches, encompassed those of other species, except the singular 13C-depleted Spondyliosoma cantharus. Coupling taxonomic assemblages, stomach contents and stable isotope analyses help disentangling the resources uses and evidencing trophic pathways. Contrasts in fish and cephalopod demersal assemblages occurring at different depths not necessarily imply differences in the trophic resources uses in such complex shallow coastal ecosystems under anthropogenic influences.
BOREA contact: Alexandre Carpentier, alexandre.carpentier@univ-rennes1.fr
Picture titles:
Fig. 4. Chevauchement des niches alimentaires des poissons et des céphalopodes calculées à partir des contenus stomacaux et des analyses isotopiques en zone subtidale de la baie de Saint Brieuc (France) / Overlap in fish and cephalopod’s feeding strategies assessed from stomach content (nicheSCA) and stable isotope (niche SIA) analyses in St Brieuc bay (France) in the subtidal zone of the bay of Saint-Brieuc (France). © Anthony Sturbois
Fig. 5. Représentation radar de l'indice alimentaire principal (Main Food Index) calculé pour chaque espèce de poisson et de céphalopode et pour chaque proie en zone subtidale de la baie de Saint Brieuc (France) / Radar plots of the main food index calculated for each fish and cephalopod species and for each prey item in the subtidal zone of the bay of Saint-Brieuc (France). © Anthony Sturbois
