The taxonomy and ecology of cylindrospermopsin producers in Australia

In the 1970s initial data came from Australia in relation to the presence of straight Cylindrospermopsis raciborskii in two dams, the Solomon Dam, Palm Island and North Pine Dam near Brisbane. However, following the loss of macrophytes, floods and fish releases into various riverine impoundments, this species was identified in both the Murray Darling and Fitzroy River systems by 1991. Various coiled and straight morphotypes were documented. The ecology of Cylindrospermopsis in riverine impoundments was analyzed in the 1990s with emphasis upon the prediction of bloom formation and delimitation of growth conditions. It germinated when the temperature of the sediment water interface was 23º C, dominated in conditions of low nutrient concentrations in the epilimnion 1 to 3 ugL-1 then formed akinetes and disappeared from the water column just prior to flood events. Cultures of Cylindrospermopsis from various tropical and temperate regions of Australia were used to investigate the genetics of various morphotypes, germination of akinetes and toxin breakdown, bacteria responsible for toxin breakdown, toxin production under various conditions, bioaccumulation of cylindrospermopsin in both plants and animals and grazing by ciliates. More recently, Aphanizomenon ovalisporum and Lyngbya wollei Plectonema wollei have been identified as cylindrospermopsin producers. Dams and pipelines with alternating dominance of Aphanizomenon ovalisporum and Cylindrospermopsis raciborskii have recently been found and are currently being studied in relation to the ecology, toxicity taxonomy and genetics of these species.