![]() ![]() It's unclear whether that happened in Toledo. Strong winds can drive blooms at the water's surface down into the depths of the lake, where water intake pipes can draw contaminated water into systems serving municipalities, he said. Toxins from algal blooms are of particular concern to water managers around Lake Erie, said Anderson. " Average surface water temperature in the lake has rebounded to within 1.68 degrees of the average of the last ten years," he said. But because Lake Erie is so shallow, water temperatures were able to recover quickly. The Great Lakes ice extent last winter was the second largest on record, Anderson said, with ice covering Lake Erie well into April. ![]() The western basin, the location of the current algae bloom, is even shallower, with an average depth of less than 26 feet (8 meters). Lake Erie's shallow depths-it's the shallowest of the Great Lakes, with an average depth of 62 feet (19 meters)-also contributed to this year's algae blooms, said Eric Anderson, a physical oceanographer with NOAA's Great Lakes Environmental Research Laboratory. The nitrogen and phosphorous in the runoff come from leaky septic tanks and from fertilizers used on farms and lawns. (Read about our "fertilized world" in National Geographic magazine.) Global warming is also boosting storm intensities in some parts of the world, which can increase the terrestrial runoff that supplies the nutrients that feed algae blooms. Microcystis is a kind of cyanobacteria, often mistakenly referred to as blue-green algae.Ĭlimate change is creating warming waters in many parts of the world, including the Great Lakes. The algae and bacteria responsible for blooms, including the one that created Toledo's tap water mess-a type of bacteria known as Microcystis-need warm temperatures and the nutrients phosphorus and nitrogen to grow. (See "Pictures: Extreme Algae Blooms Expanding Worldwide.") "Some of can be attributed to global climate change," said Timothy Davis, a research ecologist specializing in harmful algal blooms with the National Oceanic and Atmospheric Administration's (NOAA) Great Lakes Environmental Research Laboratory in Ann Arbor, Michigan. The blooms produce toxins that can cause neurological problems like paralysis and seizures in people, though such effects have been best documented in marine mammals and birds. (See "Record Number of Seals and Sea Lions Rescued in California.") They can also result in massive fish kills. Another bloom put a record number of marine mammals into California rehabilitation centers earlier this year. Northwest Ohio's water ban was lifted Monday morning, but experts say harmful algal blooms that can turn tap water toxic and kill wildlife are becoming more common in coastal oceans and in freshwater across the United States and around the globe.Ī toxic algae bloom killed record numbers of manatees in Florida early last year. The toxic algae bloom in Lake Erie that provoked last weekend's tap water ban in Toledo, Ohio-where nearly half a million people were told not to use water for drinking, cooking, or bathing-is a preview of similar problems to come around the world, scientists say, thanks in part to climate change. ![]()
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