A VIBRIO SP ASSOCIATED WITH MORTALITIES IN COCKLE LARVAE FULVIA-MUTICA (MOLLUSCA, CARDIIDAE)

In 1990, mass mortalities occurred frequently in reared larvae of cockle (Fulvia mutica) in the laboratory of Kyoto Institute of Oceanic and Fishery Science, and a bacterium (strain 90F-1) was predominantly isolated from water of a tank during mortality. Inoculation of the isolate into rearing water at levels of 10(4) to 10(5) CFU/ml, killed larvae (95-292 mum in shell length) and juveniles (0.7-1.6 mm) of cockles within 2 or 3 days, and inoculated bacterium was re-isolated from these experimentally infected larvae. Thus the isolate was proved to be pathogenic to larval and juvenile cockles. The phenotypic characteristics of the pathogen indicated that it belongs to the genus Yibrio, but it could not be identified as any known species.