Great Lakes Article:

Scientists keeping count of mayflies
Molly Kavanaugh  Plain Dealer Reporter
02/10/2002

Tiffin

- Think of mayflies as lost children who return home.

After the celebration, the tough questions get asked: How can we keep better track of them? What are the signs they might disappear again? How does this affect the lives of those around them?

About two dozen scientists from Ohio, Michigan, Pennsylvania and Windsor, Ontario, met Friday and yesterday to discuss this winged, nonbiting insect in which they share an interest. The two-day gathering took place at Heidelberg College, where mayfly studies funded by the Lake Erie Protection Fund are being conducted.

"We don't just have a passing interest in what this group is doing. It's going to be very critical in the way agencies manage the environment," said Roger Thoma, Lake Erie biologist with the Ohio Environmental Protection Agency.

Mayflies, prominent along the lake for years, disappeared from the polluted waters of Lake Erie in 1953 - scientists call it "the crash" - and did not return for 40 years. By 1996, the western basin was full of the flies, which have an unusual life cycle on water and an annoying one on land.

The flies spend about two years as nymphs in the lake sediment, then emerge, usually in June and July. For 24 hours, they molt, mate and die, leaving behind a fishy odor and bodies that litter streets and sidewalks.

In Port Clinton, truckloads of dead insects have to be hauled to the dump. The insects have shorted out power plants in Toledo and Monroe, Mich.

Counting mayflies is tricky business, and speakers Friday shared some of their techniques. Canadian scientists head to harbors, put down a white sheet, cover it with a Hula Hoop and wait for nightfall. Then they count how many mayflies end up inside the ring. Along the Ohio shoreline, lakefront residents volunteer to count mayflies on their property.

Tracking the nymphs requires different tactics.

In Pennsylvania, researchers scuba dive and scoop up sediment. Ohioans drop a clawlike container over the side of the boat, gather mud and haul it in.

The month, time of day and frequency of visits also vary among scientists.

"One of the goals is to reach consensus on methods," said Kenneth Krieger, a senior research scientist at Heidelberg College and director of the college's mayfly studies.

While mayflies are a tasty diet for fish and aren't considered harmful to the lake, some scientists are taking a closer look. Since the nymphs spend a couple of years squirming around in the sediment, there is concern that they might be releasing contaminants into the water.