Parasitic infections of Chamelea gallina (Mollusca, Bivalvia) from commercially exploited banks of the Adriatic Sea

A parasitological survey of the bivalve Chamelea gallina was carried out from natural beds of the Adriatic Sea, where anomalous mortalities were observed during the last years (1997-1999). The occurrence of protozoans belonging to the families Porosporidae, Hemispeiridae and Trichodinidae was recorded. Porosporidae of the genus Nematopsis, present with 4 species, showed a prevalence of 100%, irrespective of sampling localities, season or bivalve size, but differences were found when percentage of infection was calculated per organ. As for the genus Porospora this is the first record in C. gallina. Among Hemispeiridae, the genera Ancistrum and Boveria were found in the gills. The results suggest that severe infections of protozoans of the genus Nematopsis could cause a not negligible respiratory sufferance, with a possible role in the decline of the natural banks.