AWRI Newsletter #42: June 2005

AWRI has been in the news in June due to the discovery of a toxic, invasive alga in Mona Lake. Cyanobacteria (more popularly known as blue-green algae) are a class of algae that are found throughout the world, and are the most numerous organisms in the oceans. In freshwater environments, they frequently dominate lakes and ponds that are rich in nutrients, especially phosphorus. Some species of cyanobacteria also contain toxins, which if ingested in sufficient amounts, can pose a risk to human health. The species that we found in Mona Lake, which is called Cylindrospermopsis (Cylindro for short), was implicated as the source of a toxin that resulted in a major outbreak of human illness in Australia, so there was considerable concern when it was reported that it was present in Mona Lake. However, there were two very important differences between the event in Australia and our observations in Mona Lake. First, the numbers of "Cylindro" in Australia were orders of magnitude greater than "Cylindro" in Mona Lake. Second, the toxin in Australia entered the drinking water supply, so unsuspecting people were drinking water containing the toxin; Mona Lake does not serve as a source of potable water. In summary, although the presence of Cylindrospermopsis in Mona Lake is clearly a cause for concern, it is not a cause for panic. We need to monitor Mona Lake, and other susceptible water bodies in the region for both this toxic alga and other potentially toxic algae. However, at present, the numbers of Cylindrospermopsis do not present a human health risk.

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