Bioavailability of dietborne metals to a freshwater bivalve (Dreissena polymorpha)

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCAInternational audienceThis study concerns the bioavailability of dietborne metals to a feshwater bivalve: dreissena polymorpha. Bioavailability of dietborne metals is a critical component in the development of quality criteria. Indeed extensive research has been carried out on both aqueous and dietary exposure pathways of metals in bivalves. And it is now accepted that dietary accumulation of metals is at least as important as metal uptake from the aqueous phase and in many cases dominates metal accumulation in bivalves. The major fraction of the trace metals introduced into the aquatic environment is found associated with the particles or the sediments, distributed among a variety of physico-chemical forms. As these different metal forms will generally exhibit different chemical reactivities, the measurement of the total concentration of a particular metal provides little indication of potential interactions with the abiotic or biotic components present in the environment. One way to assess the bioavailability of dietborne metals is by calculating AE: the assimilation efficiency of metals by organisms. AE is the percentage of ingested element that crosses gut lining. It is also one parameter of the following toxico-kinetic model. In this biodynamic model, the metal is accumulated from both the dissolved and the particulate phase. There's also a elimination term due to growth and elimination of metal.AE reflects the bioavailability of a metal for a given animal and under a specified set of conditions. These conditions, include for example the digestive process occuring and the metal speciation, make the determination of AE difficult