Biochemical and histochemical responses to environmental contaminants in clam, Tapes philippinarum, transplanted to dierent polluted areas of Venice Lagoon, Italy C. Nasci a, *, L. Da Ros a , N. Nesto a , L. Sperni b , F. Passarini b , B. Pavoni b a Istituto di Biologia del Mare C.N.R., Castello 1264/a, 30122 Venice, Italy b Dipartimento di Scienze Ambientali, Universita Á di Venezia, Calle Larga Santa Marta, 30123 Venice, Italy Received 29 April 1999; received in revised form 26 November 1999; accepted 20 January 2000 Abstract In this study the clam, Tapes philippinarum, a ®lter-feeding bivalve living 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 farming area (Val DogaÁ) were transplanted into a relatively low con- taminated 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 basis of potential toxicity mechanisms, including speci®c enzymatic activities [Bap hydroxylase and NADPH cytochrome c reductase, superoxide dismutase, catalase, glutathione peroxidase and propio- naldehyde dehydrogenase (PDH)] and general cellular responses (lysosomal latency). More- over, chemical analyses (polychlorinated biphenyls, polycyclic aromatic hydrocarbon, DDTs) were carried out on sediments and animal tissues at the beginning and end of the transplan- tation experiments. The chemical results show an active bio-accumulation activity from sedi- ment in clams translocated to the most polluted area. Correspondingly, biological data indicate marked eects on PDH activity and latency in T. philippinarum from the same site. In contrast, no similar pattern has been observed in the other considered indices, possibly due to antagonistic eects of the complex contaminant mixture present in the environment. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Biomarkers; Biomonitoring; Pollution; Environmental toxicology; Clam; Venice Lagoon Marine Environmental Research 50 (2000) 425±430 www.elsevier.com/locate/marenvrev 0141-1136/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0141-1136(00)00037-4 * Corresponding author. Tel.: +39-0-41-5207-622; fax: +39-0-41-5204-126. E-mail address: nasci@ibm.ve.cnr.it (C. Nasci).