A 'red tide' of blooming algae stretched more than 20 miles along the coast near La Jolla, CA, in spring 1995. Blooms can be harmless, such as this one (the dinoflagellate Noctiluca scintillans), but blooms of some algae, including Alexandrium, can harm human health, coastal economies, and marine ecosystems. Peter Franks, Scripps Institution of Oceanography / oceanleadership.org

WASHINGTON (AFP) – Climate change could increase exposure to water-borne diseases originating in oceans, lakes and coastal ecosystems, and the impact could be felt within 10 years, US scientists told a conference in Washington on Saturday. Several studies have shown that shifts brought about by climate change make ocean and freshwater environments more susceptible to toxic algae blooms and allow harmful microbes and bacteria to proliferate, researchers from the National Oceanic and Atmospheric Administration said. In one study, NOAA scientists modeled future ocean and weather patterns to predict the effect on blooms of Alexandrium catenella, or the toxic “red tide,” which can accumulate in shellfish and cause symptoms, including paralysis, and can sometimes be deadly to humans who eat the contaminated seafood. “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,” said Stephanie Moore, one of the scientists who worked on the study. But the impact could be felt well before the end of this century — as early as 2040, she said at the annual meeting of the American Association for the Advancement of Science (AAAS). “Changes in the harmful algal bloom season appear to be imminent. We expect a significant increase in Puget Sound (off the coast of Washington state where the study was conducted) and similar at-risk environments within 30 years, possibly by the next decade,” said Moore. In another study, NOAA scientists found that desert dust that is deposited into the oceans from the atmosphere could also lead to increases of harmful bacteria in seawater and seafood. Researchers from the University of Georgia found that adding desert dust, which contains iron, to seawater significantly stimulated the growth of Vibrios, a group of ocean bacteria that can cause gastroenteritis and infectious diseases in humans. …

Global warming ‘may increase water-borne diseases’