Temperature-dependent development rate of Amyloodinium ocellatum, parasite of marine finfish, and a theoretical approach to its life-stage prediction.

The development rate of the economically important finfish parasite, Amyloodinium ocellatum, is crucial for determining effective treatment strategies in aquaculture. The relationship between temperature and development is linear for this species. However, environmental temperatures are rarely constant, influencing the time to emergence of infective dinospores. This results in treatment strategies that are largely informed by symptoms of disease, rather than timed to coincide with predicted emergence. We determined the development time of the tomont (environmental stage) and first release and cessation of release of dinospores at six temperatures for a cold-water tolerant isolate from South Africa. We then used those data to determine development rate and theoretical thermal constant for each developmental stage of the tomont and period of infectivity, using physiological time, and heat-units in growing degree hours. These preliminary results can be used to model larger studies where the theoretical thermal constant can be tested against aquaculture conditions.