Seasonal differences of stable isotope composition and lipid content in four bivalve species from the Adriatic Sea

Abstract

The feeding ecology of four bivalve species co-occurring in the Mali Ston Bay, the most important bivalve aquaculture area of the Eastern Adriatic, were investigated by analysing the stable isotope composition and lipid content in two tissue types. Analyses included two cultured species: Mytilus galloprovincialis and Ostrea edulis, and two naturally occurring species: Modiolus barbatus and Arca noae. Total lipid concentrations were higher in the digestive gland than in the adductor muscle in all species studied. The study confirmed seasonal variability of stable isotope signatures. Observed seasonal changes were more pronounced in the digestive gland than in the adductor muscle, suggesting that the former better reflects seasonal trophic patterns. The results obtained indicate isotopic niche overlap in the investigated species with the highest degree of overlap (~60%) among two cultured species during the spring–summer period, and between two naturally occurring species during the autumn–winter period (~60%). A lower degree of overlap between other species might suggest utilization of different additional food sources during certain times of the year. This study contributes to our understanding of trophic interactions between different bivalve species and is important for future modelling of food webs and sustainable management of wild and cultured populations.