Metal transfer in marine food chains: bioaccumulation and toxicity

Metal transfer in marine food chains may be examined at different scales from field studies to cellular level. Some years ago, the major question was to verify the existence of metal biomagnification, a phenomenon which seems in fact to be limited to mercury and the radionuclide cesium-137. In numerous cases, metal incorporation is not determined chiefly by the trophic level in the food chain. It is also controlled by both the metabolic characteristics of species or populations and the biological role of each element. The most accurate assessment of trophic transfer may be by determining the physico-chemical state of metals in marine organisms, a methology which can be used for both field and experimental samples. Some species exhibiting high detoxication ability may be interpreted as highly contamined links in food chains but according to the nature of the detoxifying ligands--in outline, mineral granules or metalloproteins--the bioavailability to the next trophic level may vary widely.