CHICAGO - Scientists here this week have been cautiously optimistic about the future of the Great Lakes, the world's largest collection of fresh surface water.
But some, such as Dr. Joseph Koonce, are downright nervous.
“It is my impression that Lake Erie is structurally and functionally unhealthy,” said Dr. Koonce, a biology professor at Case Western Reserve University in Cleveland. He is viewed by his peers as an esteemed colleague.
Dr. Koonce is one of about 650 people from 30 countries attending a weeklong summit hosted by the International Association for Great Lakes Research and the International Lake Environment Committee.
The Great Lakes are not deteriorating from a new onslaught of poisonous chemicals. Although scientists believe the impact of some chemicals have been overlooked and misunderstood, they generally agree that in the last generation or so there has been gradual progress toward reducing them.
But during a 20-minute talk in which Dr. Koonce summarized numerous presentations, he said he's concerned about the level of stress being placed on Lake Erie in particular.
He fears the lake could be victimized not so much by the chemicals that threatened it in the 1960s and early 1970s, but by a lack of coordinated vision.
Shoreline development is rampant, large species of fish are being exploited, and invasive species continue to disrupt the equilibrium while the Earth's temperature is rising and water levels fluctuate.
At the same time, farm fertilizers and sewage - plus airborne chemicals from miles away - get into the water and do everything from growing algae, choking oxygen supplies, and contaminating fish.
Lake Erie's western basin between Monroe and Sandusky is one of the most vital pieces of the Great Lakes puzzle. It is the warmest and shallowest part of the Great Lakes; therefore, it is the most productive for spawning fish - and one of the most complex regions to study, officials said.
“It is certainly less robust than it once was,” Dr. Koonce said of the lake in general. “About the only thing we can say about the future is we should expect the unexpected.”
He said officials need to do a better job of defining which problems to address, because some - such as global warming - are beyond their grasp.
“It's not hopeless, but we're going to need a new set of management strategies,” Dr. Koonce said.
Lake Erie's western basin has been one of the most talked-about regions at the conference, which ends today.
Issues yesterday ranged from the ecological impact of dredging Toledo's shipping channel to the habitat destruction on Lake Erie islands caused by the return of cormorants, a large bird.
A recent U.S. Environmental Protection Agency report ranked western Lake Erie 19th out of 70 Great Lakes regions in terms of biological diversity.
The top two were along the northern shoreline of pristine Lake Superior in Ontario, followed by northern Wisconsin's Great Chequamagon region. The Keweenaw Peninsula and Grand Sable Dunes, both in Michigan's Upper Peninsula, rounded out the top five spots.
Officials learned that one of western Lake Erie's symbols of recovery, the mayfly, could be headed for trouble as the Earth's temperature continues to rise.
Mayfly reproduction can be curtailed when the oxygen supply is diminished. That can happen during extended heat waves and when warm water near the surface doesn't mix properly with cooler water near the lakebed. Such a situation can lead to “stratification” - a condition which has occurred in western Lake Erie three of the last six years, according to Thomas Bridgeman, a University of Toledo researcher.
“Stratification events are more important in western Lake Erie than previously thought,” he said, comparing it to putting a lid over a jar. “It would be a cruel irony if we cleaned up the lake enough to bring back the mayfly and they got wiped out by stratification.”