U.S. study predicts prolonged toxic algal outbreaks due to climate change

Xinhua, February 20, 2011

Climate change could prolong toxic algal outbreaks by 2040 or sooner, posing a health threat to humans, a new study suggests.

Using cutting-edge technologies to model future ocean and weather patterns, a team of U.S. researchers from the National Oceanic and Atmospheric Administration (NOAA) the University of Washington looked at blooms of Alexandrium catenella, more commonly known as "red tide," which produces saxitoxin, a poison that can accumulate in shellfish.

If consumed by humans, saxitoxin can cause gastrointestinal and neurological symptoms including vomiting and muscle paralysis or even death in extreme cases, the researchers said in the study published Saturday by the American Association for the Advancement of Science (AAAS).

Longer harmful algal bloom seasons could translate to more days the shellfish fishery is closed, threatening the vitality of the 108-million-dollar shellfish industry in Washington state, according to the study.

The team predicted that places like Washington State's Puget Sound would experience longer seasons of harmful algal bloom outbreaks in the "imminent" future.

"Changes in the harmful algal bloom season appear to be imminent and we expect a significant increase in Puget Sound and similar at- risk environments within 30 years, possibly by the next decade," said Stephanie Moore, Ph.D., with NOAA's West Coast Center for Oceans and Human Health.

"Our projections indicate that by the end of the 21st century, blooms may begin up to two months earlier in the year and persist for one month later compared to the present-day time period of July to October."

Natural climate variability also plays a role in the length of the bloom season from one year to the next. Thus, in any single year, the change in bloom season could be more or less severe than implied by the long-term warming trend from climate change, said the study.

The research team indicated that the extended lead time offered by these projections would allow managers to put mitigation measures in place and sharpen their targets for monitoring to more quickly and effectively open and close shellfish beds instead of issuing a blanket closure for a larger swath of coast or be caught off guard by an unexpected bloom.

The same model can be applied to other coastal areas around the world increasingly affected by harmful algal blooms and improve protection of human health against toxic outbreaks, the researchers said.