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Comparative ecophysiology, chemotaxonomy and ichthyotoxicity of Chattonella marina (Raphidophyceae) from Australia and Japan
thesisposted on 2023-05-26, 18:43 authored by Marshall, JA
The raphidophyte flagellate Chattonella Marina from South Australia that was associated with the mortality of farmed tuna in April 1996 was successfully cultured. This study investigates ecophenotypic variation in physiology, chemotaxonomy and ichthyotoxicity of Australian and Japanese C. marina. Australian C. marina had similar temperature and salinity requirements to the Japanese strain but was adapted to higher light intensities than the Japanese strain. This differentiation was reflected in high concentrations of mycosporinelike amino acids (MAA's), especially the antioxidant MAA mycosporine-glycine, in the Australian cultures. Mycosporine-glycine was absent in the Japanese strain which instead used a violaxanthin:zeaxanthin cycle to moderate inhibition by high PAR irradiance. Ecophenotypic variations in lipid profiles were also observed between Chattonella strains from different geographic locations. Fatty acid and sterol profiles allowed for a clear discrimination between the raphidophyte genera Chattonella, Heterosigma, Fibrocapsa and Olisthodiscus, but exhibited little differentiation between C. marina, C. antiqua and C. subsalsa. Sterol and fatty acid profiles do not support the separation of C. antiqua and C. marina as distinct species. Sterol signatures, which may be useful as chemotaxonomic markers, were identified. Lipid composition correlated more closely to recent molecular classification of raphidophytes than classification based upon carotenoid pigments. Previous research on ichthyotoxic principles of C. marina has focused on production of high levels of reactive oxygen species (ROS), a brevetoxin-like compound and free fatty acids. This study found that Chattonella marina produces levels of the ROS superoxide 100 times higher than most algae, which is partially controlled by electrons donated through photosynthetic electron transfer. Differing superoxide production and toxic effects on zooplankton and fish are documented between different geographic strains of C. marina and light treatments. These results suggest a synergistic effect between ROS and an ichthyotoxin, and cannot be explained on the basis of these mechanisms of toxicity on their own. Our investigations into Australian C. marina demonstrate an absence or only very low concentrations of brevetoxin-like compounds by LC-MS techniques and negative mouse bioassays. All raphidophyte species were found to have high levels of eicosapentaenoic acid (EPA), which tested positive as a potential ichthyotoxin using damselfish as a model organism. EPA produced a similar mortality and fish behavioural response to that of intact C. marina cells while superoxide alone was not sufficient to cause fish mortality. However, superoxide in combination with low concentrations of EPA accelerated fish mortality. Implications of this work for mitigating the impact of Chattonella algal blooms on finfish aquaculture are discussed.
Rights statementCopyright 2002 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Chapter 3 appears to be the equivalent of a post-print version of an article published as: Marshall, J. A., Nichols, P. D., Hallegraeff, G. M., 2002. Journal of applied phycology, 14(4), 255-265. The final publication is available at Springer via http://dx.doi.org/10.1023/A:1021101203543 Chapter 5 appears to be the equivalent of a pre-copyedited, author-produced version of an article accepted for publication in Journal of plankton research, following peer review. The version of record, Marshall, J. A., Hallegraeff, G. M., 1999. Comparative ecophysiology of the harmful alga Chattonella marina (Raphidophyceae) from South Australian and Japanese waters, Journal of plankton research, 21(10), 1809-1822, is available online at: https://doi.org/10.1093/plankt/21.10.1809 Chapter 6 appears to be the equivalent of a post-print version of an article published as: Marshall, J. A., Newman, S., 2002. Differences in photoprotective pigment production between Japanese and Australian strains of Chattonella marina (Raphidophyceae). Journal of experimental marine biology and ecology, 272(1), 13-17 Chapter 7 appears to be the equivalent of a post-print version of an article published as: Marshall, J. A., Munday, B., Yoshizawa, Y. Hallegraeff, G. M. (2001) Effect of irradiance on superoxide production by Chattonella marina (Raphidophyceae) from South Australia and Japan, in Hallegraeff, G. M., Blackburn, S. I., Bolch, C. J., Lewis, R. J. (eds). Harmful algal blooms 2000. Intergovernmental Oceanographic Commission of UNESCO, Paris, 316-319. It is available online at: http://unesdoc.unesco.org/images/0012/001266/126659eo.pdf Chapter 8 appears to be the equivalent of a pre-copyedited, author-produced version of an article accepted for publication in Journal of plankton research, following peer review. The version of record, Marshall, J. A., Hovenden, M., Oda, T., Hallegraeff, G. M., 2002. Photosynthesis does influence superoxide production in the ichthyotoxic alga Chattonella marina (Raphidophyceae), Journal of plankton research, 24(11), 1231-1236, is available online at: https://doi.org/10.1093/plankt/24.11.1231 Chapter 9 appears to be the equivalent of a post-print version of an article published as: Marshall, J. A., Nichols, P. D., Hamilton, B., Lewis, R. J., Hallegraeff, G. M., 2003. Ichthyotoxicity of Chattonella marina (Raphidophyceae) to damselfish (Acanthochromis polycanthus): the synergistic role of reactive oxygen species and free fatty acids, Harmful algae, 2(4), 273-281