Algal blooms are nothing new in Lake Erie. Like many others, the lake—the 13th largest in the world, with an area of 25,655 square kilometers—suffered regular bouts of sudden algal growth during the 1960s and 1970s from phosphorous in detergents and agricultural runoff. After sewage treatment plants were upgraded and phosphorus was banned in detergents, the lake stayed clear. But in the 1990s, so-called algal blooms started to come back. In July 2011, Erie was hit by a monster bloom, which eventually covered a fifth of the lake. It was 2.4 times larger than the previous worst bloom, in 2008. Researchers have now pinned the blame on greater amounts of fertilizer used in the fall of 2010, combined with large storms the next spring that washed more of it into the lake and still waters that allowed the bloom to persist. Given high crop prices, the researchers expect that even more fertilizer will be used and that climate change will bring more storms and lower average wind speeds. Unless there's a plan to deal with these threats, the researchers report online today in the Proceedings of the National Academy of Sciences, Lake Erie will again be choked with algae.
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