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Green Glop Returns to Great Lakes06-15-06 | News

Green Glop Returns to Great Lakes

Cameron Man, FASLA, FCSLA (left) with Don Vaughan, FASLA, during the ASLA 2005 Fellows induction ceremony. Man, who sponsored Vaughan, was inducted as an ASLA Fellow in 1985. He is also a Fellow of the Canadian Society of Landscape Architects. photo by Stephen Kelly

The algae that clogged the Great lakes in the 1960s is mounting a comeback and controlling it may be tougher this time, according to the Michigan Environmental Council, an umbrella organization for a host of environmental and public interest organizations in the state.

Algae blooms have been on the rise since the mid-1990s in parts of all of the Great Lakes except Lake Superior, whose icy waters are not as hospitable to the slimy aquatic plants. Algae blooms can reduce oxygen levels in the waters, causing fish kills. Some clumps are thick enough to block water intake pipes.The surge four decades ago was blamed on excessive phosphorus, an essential plant nutrient. A single pound of phosphorus can stimulate growth of up to 500 pounds of algae, the report said. Legislatures in Michigan and some neighboring states imposed limits on phosphate laundry detergents in the 1970s that were credited with significantly reducing the algae buildup.

But phosphorus continues flowing into the lakes from fertilizer runoff from farms and residential lawns, pet and livestock waste and leaky residential sewage systems, the report said. However, a more likely cause—and the reason the problem may be harder to solve this time—is the arrival in the 1980s of two exotic species of mussels, the zebra mussel and its cousin, the quagga mussel. The mussels filter water, making it clearer, allowing sunlight to penetrate deep into the lakes, possibly enabling algae to thrive at greater depths than before. The mussels also eat microscopic algae and excrete nutrient-rich wastes. Source: Associated Press