PARENT SESSION

3D - Exposure and effects of environmental contaminants in marine organisms
Poster Hall
8:30 AM - Tuesday, 29 April 2003
Chair: Scholz, N.¹, ¹
Co-chair: Karbe, L.², ²

(TUP/192) Heavy metal polluted sediment, biota uptake and metallothionein induction: does it always exist linear relation?

Manente, Sabrina¹, Perin, Guido¹, ¹ Environmental Sciences Dept., Ca' Foscari University, Venice, Venice, Italy

ABSTRACT- Heavy metals concentrations in coastal sediments are typically much bigger than concentrations in the overlying waters, this happens in Venice Lagoon (Italy) too. Problems related to these high concentrations are due to the fact that polluted sediments are an important food source for many deposit- and suspension-feeding animals. In our research we have tried to address a relation between sediments, considered as an enriched pool of potentially bioavailable metals, and the bivalve mollusc Mytilus galloprovincialis. Then we have chosen six sites in central lagoon: three of them inside and very close to the extremely polluted industrial area of Porto Marghera and the others external to Venice city. All of them are located along different main channels where waters flow abundant and where an intensive maritime traffic is present. Furthermore we have collected a local bivalves pool in each site which has been analyzed for soft tissue, epatopancreas and shell cadmium content. We have also determined epatopancreas metallothionein concentration in order to verify a possible relation between bioavailable cadmium content in sediments and the occurred Cd uptake from M. galloprovincialis. The sediment samples from the three industrial sites have shown higher sand content values, as well as a bigger total cadmium concentration and higher levels of Cd in third, fourth and fifth geochemical phases. Thus we expected a similar trend for Cd in M. galloprovincialis. On the contrary, mollusc Cd content showed an unclear distribution among the three considered compartiments. From recent studies it seems, in fact, that the first storage compartment in Mytilus sp. is epatopancreas where primarily metallothionein are synthesized. Then cadmium is kept in soft tissues and finally in shells as substitutive metal. Moreover metallothionein content is not related neither to the epatopancreas cadmium value nor to the sediment (both total and bioavailable geochemical phases) Cd concentration.

Key words: mollusc, sediment, heavy metal, metallothionein