A scourge of the '70s returns to Great Lakes
Algae blooms are back - perplexing researchers and grossing out beachgoers.
Spindly aquatic algae, once foul-smelling icons for Great Lakes pollution, are back. During the depths of the lakes' environmental troubles in the 1960s and '70s, the algae's population exploded. Vast clumps piled up on beaches, looking like untreated sewage and smelling like a pig farm.Skip to next paragraph
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Now, despite significantly cleaner lakes, the algae have staged a comeback in every lake but Lake Superior. In some areas, they appear to be more pervasive than before. Scientists are struggling to figure out why.
Some say Cladophora's resurgence is a nuisance algal bloom, not a harmful algal bloom, which can pose a direct danger to fisheries and public health. But the stakes are still high, specialists say.
The summertime appearance of dead clumps of odorous algae can close beaches and pinch property values. They also can trigger sudden shutdowns at nuclear power plants as algae clog pipes that suck cooling water from the lakes.
Even though it is often labeled a "nuisance," the algae's comeback raises public-health concerns, researchers add. As it decomposes, and as gulls stalk the mats looking for shellfish, levels of potentially harmful bacteria build.
"This is a huge issue for the entire region," says state Rep. Jonathan Richards (D) of Milwaukee, whose district includes a long stretch of shoreline. Public concern is not limited to lakefront property owners, he says, but reaches 10 to 20 miles inland.
The obvious suspect - nutrients from agricultural or urban runoff entering the lakes - may not tell the whole story.
"It's tempting to look at local sources - farms and industrial wastes," says Erica Young, an aquatic biologist at the University of Wisconsin at Milwaukee who is working on the problem. But although there are hot spots, "over the last couple of years, it's become clear that this is a lake-wide problem."
Cladophora's reemergence typifies a range of environmental challenges affecting lakes, rivers, and shorelines nationwide.
"I was a student on the first Earth Day, and I've been watching what's been going on around the globe ever since," says Marty Auer, an engineering professor at Michigan Technological University in Houghton, Mich. He's one of the sleuths credited with showing how Cladophora could be controlled in the 1980s. "It's amazing to me that as a society, we really do have the capability to engender massive changes in this ecosystem. This is another one of those cases."
Cladophora is an invasive species, notes Harvey Bootsma, a scientist at the University of Wisconsin at Milwaukee's Great Lakes Water Institute. It arrived in the 1800s. But it's not treated as invasive "because its genus is found all over the world," he explains.
Outbreaks during the last century were triggered when phosphates poured into the lakes, largely from household detergents and fertilizers. Dr. Auer and a colleague from the University of Michigan showed that when phosphate-laden water was properly treated, algae populations fell dramatically.
Phosphate levels fell after regulators put research results to work, and the US and Canada agreed to hold phosphate concentrations in the lakes to less-damaging levels.