Cytotoxic Effects of Vicicitus globosus (Class Dictyochophyceae) and Chattonella marina (Class Raphidophyceae) on Rotifers and Other Microalgae

Cultures of Vicicitus globosus (previously Chattonella globosa) and Chattonella marina, established during the 2010 fish kill event in Mahanga Bay, Wellington Harbour, are confirmed to be cytotoxic. The aggregate potency of lipophilic cell extracts of each species were evaluated using three species each of flagellates, dinoflagellates and diatoms, and a rotifer as test organisms. The cell extract of V. globosus destroyed cells of all nine microalgae in a matter of a few minutes to less than 15 min, while that of C. marina, destroyed all species over 10 to 30 min. The lipophilic extract of V. globosus caused partial disintegration of both theca wall and cytoplasm of cells of Alexandrium catenella in a matter of minutes. This effect, however, was not observed in cells of A. catenella exposed to that of C. marina. Tests conducted on rotifers showed similar fast-acting trends, with animals exposed to a cell extract of V. globosus died in a much shorter time (Lt50 = 80 min) than those exposed to that of C. marina (20 h).