Influence of food on the assimilation of essential elements (Co, Mn, and Zn) by turbot Scophthalmus maximus

Abstract

Food is an important route of metal uptake in marine organisms and assimilation efficiency (AE) is a key physiological parameter that can be used to systematically compare the bioavailability of different metals from food. This parameter may be influenced by various factors, including diet. The present study aimed at examining the influence of diet on AEs of three essential metals (Co, Mn and Zn) in the turbot, Scophthalmus maximus. The pulse-chase feeding method was used with three radiolabelled natural prey: fish, shrimp and ragworm. The results showed that AE was strongly influenced by the prey and the metal considered. However, the influence of these parameters on AE was variable and no general trend was observed. The AEs ranged between 5-43% for Co, 23-44% for Mn and 17-32% for Zn. Results suggest that relationships between metal distribution in the prey (at tissue and subcellular levels) and bioavailability to predator fish is not obvious as previously assumed based on marine organisms feeding on unicellular or simple pluricellular organisms. Finally, we modelled how S. maximus is accessing foodborne essential elements using experimentally-derived parameters, the concentration of these elements in prey, and different data on stomach contents from wild turbot. Results emphasize the importance of crustaceans in the nutrition of turbot showed that this taxa is generally the most important source of essential metals for turbot although in some cases polychaetes can make a high contribution to dietary Co and Mn uptake.