July 20, 2006

Lake Erie's health pulse stressed with winter runoffs

Case geologist reports at International Association of Great Lakes Research

Cleveland Skyline from Lake Erie

Case Western Reserve University geologist Gerald Matisoff speculates the heavy winter snow melts contribute to the growing "dead zone" problem of low oxygen concentrations in Lake Erie's basin.

He reported on findings during the International Association of Great Lakes Research meeting at the University of Windsor in Ontario.

Matisoff provided an overview of 22 studies that will appear in an upcoming Journal of Great Lakes Research.

The 320 pages of research findings came from data collected on two research expeditions on Lake Erie in 2002 and 2003 and funded by the U.S. Environmental Protection Agency.

During the lake trips, Matisoff led a research team that took water and sediments samples to understand carbon and nutrient cycling, food dynamics and oxygen depletion in the basin.

The U.S.-Canadian and multi-institutional study sought answers to why the central basin has become a "dead zone."

According to Matisoff, the research yielded several other key findings:

  • The biological community of the lake is changing with a fewer number of species living in the lake. Exotic marine algae have adapted to living in the lake's fresh water.
  • A global climate model for Lake Erie predicts that by the middle of the century the lake's temperature will increase by 1.5° C., and the water level will be dropped by a half meter, with the amount of water spilling over Niagara Fall dropping by 10 to 20 percent.

Researchers for years believed that spring water flushed phosphorus into the lake, but Matisoff said the data revealed a new phenomenon that the year following some heavy winter melts raised phosphorous levels to those of the 1970s—before measures were taken to clean up the lake.

Matisoff said at this point it still is speculation that the problem results from human behavior such as spreading liquid manure on snow to no-till conservation efforts that keep fertilizers in the top soil and easily removed in quick melts or heavy rains and melts.

"We may have to rethink some of the environmental practices," he said.

Much of the phosphorus input is coming from the Detroit River from the flow from the upper lakes and as thought as from waste treatment plants that treat industrial wastes from the greater Detroit area. Another source of phosphorus is the Maumee River from farmland erosion and chemical leaching into the waterways.

While Matisoff speculates the winter runoff is the problem instead of the spring rains, he backs up his reasoning from other research.

In studies on Rock and Old Woman Creeks that feed water to Lake Erie, Matisoff found that particles from winter melts can "travel tens of kilometers from the field to the lake in one fell swoop."

"Once you get a good runoff event, all these particles wash right into the lake," he added.

In recent years, Matisoff has focused research on the waterways feeding into the lake.

"The watershed drives what is happening in the lake. Until we understand what takes place in the watershed, we will not be able understand what is happening in the lake," stated Matisoff.

Posted by: Heidi Cool, July 20, 2006 11:29 AM | News Topics: HeadlinesMain, Research

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