Weather changes mean more dead zones for Lake Erie: expert
ERIE, Pa |
ERIE, Pa (Reuters) - After a celebrated comeback from abysmal water conditions and high pollution levels in the 1970s, Lake Erie is regressing to the highest levels of phosphorous contamination in 40 years, a Great Lakes expert said on Thursday.
"Levels are back-up to when it was considered a dead lake," said Jeff Reutter, director of the Ohio Sea Grant and Stone Laboratory at Ohio State University, speaking at the State of the Lakes Ecosystem Conference in Erie, Pennsylvania.
He said the lake is experiencing phosphorous levels equal to those of the 1970s, after levels had been reduced by two-thirds in the mid-1990s.
Reutter believes storms and heavy rains contribute to the high levels of phosphorous, a nutrient found in many commercial detergents, water treatments and agricultural fertilizers. The phosphorous gets into the lake through run-off.
When mixed with warm waters, phosphorous creates an ideal condition for the huge algae blooms seen in a number of the Great Lakes.
Algae blooms, in addition to fouling the water in general, contribute to low oxygen levels that kill off fish populations and create conditions favorable to avian botulism and other bacteria dangerous to animals and humans.
Blue-green algae cannot be removed from the water by boiling and has caused huge areas of Lake Erie to be deemed a "dead zone" where nothing can live for lack of oxygen and light, Reutter said.
He believes there is a correlation between record-setting high rainfall in the areas around Lake Erie and record-setting levels of phosphorous.
"The problem is an increased frequency of severe storms," Reutter said. "We don't have much phosphorous going into the water normally. I would say 90 percent of the phosphorous goes into the water 10 percent of the time."
The large algae blooms began as a problem at the eastern shoreline of the lake but have spread quicker than expected to the areas of the shoreline around Canada and Cleveland.
"Hopefully this year is an anomaly," said Reutter, though he worries it isn't. "Climate change, warming trends call it what you want. Storms are getting worse and more frequent and nutrients are flowing into the water."
Some climate scientists say warming temperatures may be making extreme weather events more common.
Reutter's says 2011 had all the conditions for big algae blooms -- early spring storms filled the shallow basin of the lake with a huge load of phosphorous only to be followed by a long drought, meaning less run-off into rivers and tributaries that drain the polluted waters.
But the algae problems seem not to be relegated to the warmer summer and spring months. Ice which once covered the lake in the fall is forming later and thawing earlier due to temperature changes and lower water levels.
"There are a number of things about the warmer winters that are important," says Reutter. A recent investigation of Lake Erie found what appeared to be blue-green algae blooms under the ice in the winter months when usually the cold months kill off most algae and bacteria.
"We are seeing blooms as early as April and as late as October," says Reutter.
Lake Erie is the most susceptible to algae blooms and dead zones because it is the southern-most and shallowest and therefore warmest of the Great Lakes but warming average temperatures are affecting other areas, Reutter said.
Even with recent bans of phosphorous in detergents around the Great Lakes area, a number of the Great Lakes and St. Lawrence River are reporting an increase in algae blooms.
"After decades of studying and reporting … we largely know what the solutions are," said Cameron Davis, senior advisor with the Environmental Protection Agency. "One of the big issues is the increase of algae blooms. We need to double down on the efforts to reduce phosphorous."
(Editing by Mary Wisniewski and Jerry Norton)
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