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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI:

    Prevalence of the scuticociliate Orchitophyra stellarum in seastars from the Pacific and Atlantic oceans

    C. Louise Goggin*, Tommy L. F. Leung, Maria Byrne, Nicole E. Murphy, Terry Koen

    *Corresponding author:

    ABSTRACT: As part of a study to investigate the use of the scuticociliate Orchitophrya stellarum as a biological control for the invasive seastar Asterias amurensis in Australia, we collected prevalence data for O. stellarum from three seastar species (A. amurensis, Asterias rubens, Pisaster ochraceus) between 1996-99 from the Pacific (Australia, Japan, Korea, Canada) and Atlantic (France, Netherlands, Canada) oceans. In the Pacific Ocean, for the first time, we found O. stellarum in male A. amurensis in Korea and female A. amurensis in Japan. The parasite was not detected in the invasive A. amurensis from Australia. There was no significant difference between size of infected and uninfected male seastars, nor a correlation between biased sex ratio and parasite prevalence in populations in the Pacific or Atlantic oceans. Therefore, unlike other studies, we found size and sex ratio in seastar populations in the field are unreliable indicators of parasite impacts. Regular monitoring of infected seastar populations in the field would be useful to better understand how sex ratio varies with parasite prevalence. We recommend laboratory studies under controlled conditions to determine the effect of O. stellarum on seastar populations.