METAL TRANSFER IN MARINE FOOD-CHAINS - BIOACCUMULATION AND TOXICITY

Metal transfer in marine food chains may be examined at different scal es from field studies to cellular level. Some years ago, the major que stion was to verify the existence of metal biomagnification, a phenome non which seems in fact to be limited to mercury and the radionuclide cesium-137. In numerous cases, metal incorporation is not determined c hiefly by the trophic level in the food chain. It is also controlled b y both the metabolic characteristics of species or populations and the biological role of each element. The most accurate assessment of trop hic transfer may be by determining the physico-chemical state of metal s in marine organisms, a methology which can be used for both field an d experimental samples. Some species exhibiting high detoxication abil ity may be interpreted as highly contamined links in food chains but a ccording to the nature of the detoxifying ligands - in outline, minera l granules or metalloproteins - the bioavailability to the next trophi c level may vary widely.