Toxic Algal Blooms in All the Genes
Beckmann, Roger, Ecos
Microscopic blue-green algae, or cyanobacteria, are a recurrent nuisance in our waterways, particularly during summer. They produce unsightly scums and deplete the water of oxygen, thereby killing aquatic life. More importantly, they produce potent toxins. On farms, this contaminated water can harm animals, and in waterbodies used to supply cities cyanobacterial toxins pose a health risk.
In Australia, four cyanobacteria species are known to produce toxins. The effect of the substances on us can range from skin irritation to serious liver damage or even paralysis. (The latter is caused by the paralytic shellfish poisons or PSPs which, although first observed in shellfish for human consumption, actually derive from dinoflagellates and cyanobacteria eaten by the shellfish.)
Keeping tabs on the toxicity of a bluegreen bloom is an expensive task for managers of river systems or domestic water supplies. It's not simply a matter of identifying the species involved. Some blooms are toxic while others -- seemingly identical -- are not. Does something in the environment influence toxicity, or act as a switch to turn on a latent ability to make a toxin? And once released into the water, how long does a toxin last in a natural setting?
Dr Sue Blackburn and her colleagues at CSIRO Marine Research, and Dr Gary Jones and his team from CSIRO Land and Water, wanted to know the answer to these and several other questions. For years, Blackburn's team has been studying the genetics of marine toxic algal populations. Her latest research formed part of CSIRO's Blue-Green Algal Research Program, which also involved many other research projects.
Blooms of blue-green algae are not unique to Australia. In many parts of the world, where human activities cause an unnaturally high and concentrated nutrient load in waterways, cyanobacteria (along with normal green algae) will proliferate, especially when the water flows slowly and there is plenty of sunlight. Until now, it was assumed that our cyanobacteria and the blooms they formed were much the same as those observed elsewhere.
To see if this was really the case, the CSIRO team established a unique collection of 160 Australian strains of toxic cyanobacteria, kept with the CSIRO Collection of Living Microalgae. They then used these strains in a series of genetic studies, from which they concluded that most types of Australian cyanobacteria are genetically different from populations in other parts of the world, even though they may be of the same species or have an identical appearance. As a result, knowledge of toxic cyanobacterial blooms outside Australia may not be transferable to Australian populations.
The team found no evidence for an environmental trigger for toxin production in our blooms. …