Cyanobacteria in Australia : management of blooms and toxins
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NO FULL TEXT AVAILABLE. Access is restricted indefinitely. ----- Cyanobacteria are believed to be one of the earliest life forms on this planet. Some cyanobacteria are toxic and some toxic species form blooms. Research into cyanobacterial toxicology in Australia has been carried out since 1970, but it was our inability to effectively manage a bloom of Anabaena circinalis in the Darling River, western NSW, in November 1991 that exposed gaps in our knowledge about causes and consequences of cyanobacterial blooms in Australia. CSIRO responded by building a team of scientists to compliment these studies and undertake additional research into cyanobacteria and their management. The program was called the CSIRO Multidivisional Program on Blue-green Algae. The 10 papers presented in this Thesis describe a component of the program that studied the genetics and physiology of toxin production by, and management of, toxic estuarine and freshwater cyanobacteria. The first four papers describe experiments that investigated the cellular and environmental basis for control of peptide hepatotoxin production by cyanobacteria. The first two papers examine the genetic basis for production of microcystin and nodularin by Microcystis aeruginosa and Nodularia spumigena respectively. The third and fourth papers examine the complex physiological relationship between nutrient limited growth and microcystin production by M. aeruginosa. These papers unified more than 40 years of disparate research results and enabled us to understand and better explain toxicity changes in natural blooms. The final six papers investigate aspects of toxin management to help minimise or prevent human and animal intoxication. Two papers deal directly with water treatment options for microcystins and saxitoxins, and quantify the changes in toxicity following treatment of human drinking water supplies. Two papers examine the fate of microcystin fed to cattle that produce milk and meat products for human consumption, and show that there is little risk to cattle health from the drinking water, or to human health from consumption of milk or meat products derived from those animals where cell concentrations don't exceed 1 x 10⁵ cells (M. aeruginosa) mL⁻¹. The remaining two papers examine toxicity changes in field derived bloom material. The first examines toxin persistence in a recreational lake and compares toxicity measured using protein phosphatase inhibition assay and high performance liquid chromatography. The second paper, examines the changes in toxicity of bloom material obtained from the Swan River Estuary when exposed to a range of salinities, and demonstrated different salinity tolerances for toxic and non-toxic strains.
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