Environmental factors and chemical agents affecting the growth of the pathogenic marine ciliate Uronema nigricans
[摘要] ABSTRACT: The scuticociliate
Uronema nigricans is an opportunistically parasitic marine ciliate known to cause disease in some aquacultural environments with epizootics documented from marine larval rearing systems, marine aquaria and insouthern bluefin tuna
Thunnus macoyii growout enclosures. This study examined growth responses of laboratory cultures of the ciliate and prey bacteria to variations in temperature and salinity, and the efficacy of potentialchemotherapeutants for control of
U. nigricans infections. Differences in ciliate growth responses were marginal at temperatures of 10 to 25°C and at salinities between 15 and 35 ppt, though 3.5 ppt or less was lethal. Ciliates were found to besensitive to fluctuations in bacterial densities, which may be a factor in the seasonal occurrence of the ciliate-related disease in tuna. Commonly used chemotherapeutants such as formalin, malachite green and hydrogen peroxide were all effective againstthe ciliate during
in vitro trials.
