Monitoring of infections by Protozoa of the genera Nematopsis, Perkinsus and Porospora in the smooth venus clam Callista chione from the North-Western Adriatic Sea (Italy)

Abstract

Marketable smooth venus clams Callista chione from natural banks of Chioggia (Venice) and Goro (Ferrara), North-Western Adriatic Sea (Italy), were examined for protozoan parasites from November 1996 to November 1998. Out of the 375 bivalves examined, 149 (39.7%) were infected by Nematopsis sp. and 325 (86.7%) by Porospora sp. Oocysts of Nematopsis sp. were present with a prevalence that varied from 100% in November 1996 to 5% in June 1998; cystic and naked sporozoites of Porospora sp. were very common, with a prevalence of 100%. Out of the 229 bivalves examined between January and November 1998, 63 (27.5%) were also infected by Perkinsus sp.; the prevalence of Perkinsus sp. varied from 9.1% in January to 50% in February. To our knowledge this is the first report of Porospora sp. and Perkinsus sp. in C. chione.