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Abstract

This investigation aimed to elucidate the relative roles of putative brevetoxins, reactive oxygen species and free fatty acids as
the toxic principle of the raphidophyte Chattonella marina, using damselfish as the bioassay. Our investigations on Australian
C. marina demonstrated an absence or only very low concentrations of brevetoxin-like compounds by radio-receptor binding
assay and liquid chromatography–mass spectroscopy techniques. Chattonella is unique in its ability to produce levels of
reactive oxygen species 100 times higher than most other algal species. However, high levels of superoxide on their own
were found not to cause fish mortalities. Lipid analysis revealed this raphidophyte to contain high concentrations of the
polyunsaturated fatty acid eicosapentaenoic acid (EPA; 18–23% of fatty acids), which has demonstrated toxic properties
to marine organisms. Using damselfish as a model organism, we demonstrated that the free fatty acid (FFA) form of EPA
produced a mortality and fish behavioural response similar to fish exposed to C. marina cells. This effect was not apparent
when fish were exposed to other lipid fractions including a triglyceride containing fish oil, docosahexaenoate-enriched ethyl
ester, or pure brevetoxin standards. The presence of superoxide together with low concentrations of EPA accelerated fish
mortality rate threefold. We conclude that the enhancement of ichthyotoxicity of EPA in the presence of superoxide can
account for the high C. marina fish killing potential.

Item Type:	Article
Authors/Creators:	Marshall, JA and Nichols, PD and Hamilton, B and Lewis, RJ and Hallegraeff, GM
Keywords:	Ichthyotoxicity; Reactive oxygen species; Free fatty acids; Chattonella marina; Superoxide; Eicosapentaenoic acid
Journal or Publication Title:	Harmful Algae
ISSN:	1568-9883
DOI / ID Number:	10.1016/S1568-9883(03)00046-5
Additional Information:	The definitive version is available at http://www.sciencedirect.com
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