Abstract
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).
Highlights
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)
A very small number of Chattonella marina was recorded after the multispecies blooms. Both V. globosus and C. marina were successfully cultured from the harbour during this period and provided an opportunity to evaluate the harmful effects of lipophilic cell extracts of these two species on a range of algal species and on rotifers
In this study lipophilic extracts of Vicicitus globosus and Chattonella marina were found to cause destruction and death of both algal cells and rotifers in a relatively short time, confirming that lipophilic extracts of both species are cytotoxic to all test organisms
Summary
Recent studies of Marshall et al [19] and McNabb et al [22] failed to detect the presence of significant quantities of this toxin in both the Australian and New Zealand strains. This fat-soluble toxin has been suggested to be mainly responsible for the toxic effects of this species (e.g., [20,21,23]). During the fish kill event of May 2010 in Wellington Harbour, New Zealand, Heterosigma akashiwo (Hada) Hada was found to dominate a multispecies bloom, with Karenia concordia Chang, Vicicitus globosus and Pseudochattonella cf verruculosa as subdominant [2,27]. Both V. globosus and C. marina were successfully cultured from the harbour during this period and provided an opportunity to evaluate the harmful effects of lipophilic cell extracts of these two species on a range of algal species and on rotifers
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