Infectious diseases affecting mass production of the marine rotifer Brachionus plicatilis

During recent years, investigations on decrease ofrotifer density in culture tanks from severalhatcheries have shown that infectious diseases mightbe associated with abnormal mortality. The firstreported infection was caused by an unusual birnavirusreferred as rotifer birnavirus (RBV). Viral lesionsappeared in cells of gastric glands and spread toother epithelia. Virus particles were also foundwithin ovarian cells. Highly infected rotifersexhibited abnormal behavior and died. The secondimportant pathogen found in Brachionusplicatilis has been provisionally related to theLagenidiaceae. The fungus developed in up to 85% ofrotifers and caused sudden, precipitous decrease inanimal density. The occurrence of these diseases showsthat in the future infectious agents will have to beconsidered as important factors capable of reducingthe productivity of rotifer mass cultures.