Biochemical and histochemical responses to environmental contaminants in clam, Tapes philippinarum, transplanted to different polluted areas of Venice Lagoon, Italy

In this study the clam, Tapes philippinarum, a filter-feeding bivalve livin g in soft bottoms, was used to investigate the water/sediment pollution in Venice Lagoon (Venice, Italy), a heavily urbanised and industrialised area. To this end, clams collected from indigenous populations in a clean farmin g area (Val Doga) were transplanted into a relatively low contaminated site (Palude della Rosa) and in a heavily polluted area (Porto Marghera), for 5 weeks. A range of possible induced stress indices were measured, on the ba sis of potential toxicity mechanisms, including specific enzymatic activiti es [Bap hydroxylase and NADPH cytochrome c reductase, superoxide dismutase, catalase, glutathione peroxidase and propionaldehyde dehydrogenase (PDH)] and general cellular responses (lysosomal latency). Moreover, chemical anal yses (polychlorinated biphenyls, polycyclic aromatic hydrocarbon, DDTs) wer e carried out on sediments and animal tissues at the beginning and end of t he transplantation experiments. The chemical results show an active bio-acc umulation activity from sediment in clams translocated to the most polluted area. Correspondingly, biological data indicate marked effects on PDH acti vity and latency in T. philippinarum from the same site. In contrast, no si milar pattern has been observed in the other considered indices, possibly d ue to antagonistic effects of the complex contaminant mixture present in th e environment. (C) 2000 Elsevier Science Ltd. All rights reserved.