Parasites found in Pacific oysters, Crassostrea gigas from Korean waters

Pathological conditions of Pacific oysters were surveyed in some coastal areas of Korea. Samples of 30 to 45 oysters were collected in Kamakman, Masan and in Gosung Bay. Protozoan includes gregarine-like organism, Marteilioides chungmuensis, Haplosporidium; ciliates Ancitrocoma and Metazoa (termatode, nematode, copepod) were observed in samples from most of the sampling areas. Marteilioides chungmuensis was found in all sampling sites. Protozoan, Halosporidium sp. and Ancistrocoma sp. occurred in oysters from Gosung Bay (year 2000) with very low prevalence. Trematode Gymnophalloides was frequently found in oysters from all studied areas. Inflammation was frequently observed in oysters infected with M. chungmuensis and Pseudomyicola. The damaged structures were found in digestive tubes of oysters infected by Halosporidium sp. and Pseudomyicola sp. Some of the parasites and pathological status could associate with the conditions of oysters and the environment.