Temperature Sensitivity of a Ciliated Protozoa (Family Paranophryidae) from American Lobster, Homarus americanus

Abstract

Ciliated protozoan (family Paranophryidae) disease has been noted in American lobster, Homarus americanus, for twenty years. with annual outbreaks in impoundments since 1990. Mass mortalities and moribundity associated with this organism occur most frequently during periods when water temperatures are 2-3°C. Temperature sensitivity of this organism was evaluated in vitro. Results were compared to published data for lobsters to determine if interspecific differences in temperature tolerance could be exploited to control infections. Viability at human body temperature was also tested to determine if there was a health risk from eating infected (raw) lobster. Lethal temperature limit of this protozoan showed a time-temperature relationship: lowest temperature to show 100% mortality was 20°C; time to death was 150 minutes. The highest temperature tested was 37°C. At this temperature, mortality was 100% in one minute. The highest temperature tested which is tolerable to adult lobsters was 25°C. At that temperature, 100% mortality was achieved in 20 minutes.