Mayfly mayhem on shores of Lake Erie is a sign of good water quality

[Spiel]

Mayfly mayhem on shores of Lake Erie is a sign of good water quality

 

 

Thursday, June 24, 2010

 

Micheal Scott / cleveland.com

 

 

 

 

If you think this summer's mayfly madness is madder than most, you may be right -- depending on where you live along the Lake Erie shoreline.

 

And if it turns out that these funky-looking, nonbiting bugs are a big batch which have molted from the underwater sediment offshore from Cleveland, we might be witnessing the next stage in an ongoing ecological recovery of Lake Erie.

 

So holster your fly swatters, everyone: This is the kind of bad bug problem that's really a good thing for Northeast Ohio.

 

First of all, more mayflies means bigger fish, including prized Lake Erie yellow perch, which feast on the insects just as they are emerging from the water.

 

And an exploding insect population coming out of the lake each summer is also considered a sign of a healthier, oxygen-rich waters, lake scientists say.

 

"That's true: A thick emergence of mayflies might be a symbol that we've cleaned up our act on Lake Erie," said Don Schloesser, a veteran mayfly researcher who at the U.S. Geological Survey's Great Lakes Science Center in Ann Arbor, Mich. who said the insects returned in earnest to Lake Erie only in the last 20 years.

 

"But it will take a little longer to see whether this is a permanent comeback -- for the bugs and for the lake."

 

Bug bodies piling up on lakeshore

 

Temporary or not, the annual invasion of the bothersome insects often overwhelm some lakeside neighborhoods:

 

• Suburban observers from Rocky River to Bay Village to Euclid began noticing the long-legged pests gathering around street lights and screen doors over the last week or so.

 

• In Vermilion Lagoons, ducks and other shorebirds have been seen gobbling up piles of mayfly carcasses.

 

"That's fine for the birds, but the mayflies smell fishy when they die and I had a pile about two or three feet in diameter by my garage door," said longtime lagoons resident Tody Root, 82.

 

•Workers at Lakeside, a small resort community near Kelley's Island, pushed the bugs off streets with a front-end loader and then off sidewalks with leaf blowers.

 

"The worst day was probably last Wednesday -- every light in town had a cloud of mayflies around it at night," said Alex Kontos, marketing director for the Lakeside Association. "But we get it like this almost every year, so we're used to getting bugged."

 

Most everyone on the west end of Lake Erie would agree -- and has a big bug story to tell.

 

• The most notable was the brownout of June 1996, when mayflies actually briefly conducted electricity across insulators after they were drawn to the lights of Toledo area lakeshore electrical substation.

 

* In Port Clinton, one former mayor actually secured grant money in the 1990s to compost the rotting mayfly bodies.

 

• In 1999, a Pennsylvania researcher teamed up with meteorologists at a local TV station to capture Doppler radar images of the clouds of bugs coming ashore near Erie, Pa.

 

Bug biology tells a story

 

But the story of those big bugs also mirrors the history of changing water quality conditions of the lake, Schloesser said.

 

"The mayflies were abounding in the 1920s and '30s in the Western Basin, but then almost completely disappeared in the late 1950s" because of worsening pollution, he said.

 

They returned in the 1990s, researchers said, because the lake was generally cleaner following the pollution control measures of the 1970s. Scientists were also pleased to find mayfly nymphs in the sediment of the entire lake -- beyond just the biologically rich western side of the lake.

 

But something happened again in about 2001 to practically eliminate the nymphs everywhere but in that far west end.

 

"We suspected environmental factors, focusing in on the lack of oxygen," said Ken Krieger, acting director of the National Center for Water Quality Research at Heidelberg College. Krieger and others suspect the role of algae die offs, which create an oxygen-depleted "dead zone" in the lake.

 

Krieger had also written an Ohio Sea Grant publication (pdf) in the 1990s heralding the return of the mayfly.

 

But suspicion isn't proof. Since Krieger's lab and others haven't sampled the central basin of the lake for mayfly nymphs much since then, no one knows for certain if mayflies found near Cleveland are just the ultralight, wind-blown refugees from the west or a new emergence of a central basin population.

 

New theories on mayfly life

 

Schloesser has suggested another explanation for the up-and-down appearance of mayflies in recent years: A four-year cycle -- one year of abundance followed by three years of lesser populations, sometimes dramatically so.

 

He says that might be evidence of a cycling of oxygen availability -- either because of the rising tide of quagga mussels in the lake or because of the mayfly nymphs themselves who use vast amounts of oxygen in their peak year.

 

Or maybe the the mayflies are telling us something important about Lake Erie.

 

"It's good news that there are so many mayflies, but we know the cycling is not part of the their natural system," he said. "So maybe something else we're unaware of is teetering in the balance.

 

"That teetering could go backwards and they'll disappear again or it could be what we're all hoping for -- that Lake Erie is really recovering and on its way to being fully restored."