A warning that the current El Nino event may unleash a plague of toxic algal blooms in Australia's rivers and drinking water reservoirs has been issued by the nation's senior land and water scientist.
Professor Graham Harris, Chief of CSIRO Land and Water, says there is clear evidence that El Nino events have a "quite disastrous" impact on Australia's water quality.
"For example, we have twenty-five years of data from North Pine Dam, near Brisbane, which shows a very clear relationship between El Nino events and increased blooms of toxic blue-green algae.
"What happens is, we get less rainfall and we're extracting a lot of water from the rivers and the dams anyway. Once the flow slows down, it has now been shown very clearly to favour the growth of these toxic blue-green algal blooms."
Blooms of a subtropical toxic algae, Cylindrospermopsis, in North Pine Dam had been found by Australian, Israeli and American scientists to coincide exactly with recent El Nino events over a 25-year period.
On a much larger scale, Professor Harris said that the 1992/3 drought provided clear evidence of the link between climatic phenomena and algal blooms.
"If you look at a map showing the outbreaks of those blooms in 1992/3, they extend right across the southeast corner of this continent, from a line stretching from Adelaide across to Brisbane.
"So if we do see much reduced summer rainfall, then we will start to see outbreaks of these toxic algal blooms through the summer."
Fortunately, scientific understanding of the causes of the blooms has advanced greatly in the past five years, due to a combined national research effort by CSIRO, the Murray-Darling Basin Commission, the Co-operative Research Centre for Freshwater Ecology and the Land and Water Research and Development Corporation.
This led to the recent release of a report, Managing Australia's Algal Blooms, which outlines a strategy for water and land managers to combat the menace.
Control strategies designed to minimise the risks to human health include:
Australia is also a world leader in the design and manufacture of scientific instruments for monitoring waterbodies for the chemical and biological changes which lead to blooms, Professor Harris says.
New catchment management software is also helping water managers to pinpoint the sources of nutrient pollution which trigger algal blooms, and a range of sediment remediation materials are being tested which are designed to "lock up" nutrients and deprive the algae of sustenance.
"There is no question that Australia is developing world-class expertise in the identification and control of algal blooms and that these skills are in growing demand right around the world, as more and more water systems come under acute stress from overuse.
"As we improve our techniques, we will not only enhance the quality
of Australia's water systems but also build a major new high-technology
export industry for the 21st century, when water will be, perhaps, the critical
issue for human development."
More information:
Professor Graham Harris, CSIRO Land & Water 02 6246 5621
mobile 0417 463 158
or
Margaret Bryant, CSIRO Land & Water 08 9387 0215