MUSKEGON (AP) — A potent group of toxic compounds has been
discovered in a common algae found in Muskegon Lake and the
poisons, blamed on the invasive zebra mussels, may be present in
other Michigan lakes.

Imported to the Great Lakes by freighters, the mollusks have
increased water clarity in lakes by eating algae as they filter
huge volumes of water through their tiny bodies. A down side is
that zebra mussels eat only nutritious algae — they spit out
algae containing toxic compounds.

The result: Blue-green algal blooms, which can contain
microcystins, are proliferating in relatively clean lakes across
Michigan and other states, including Muskegon and White lakes, Lake
Leelanau in northern Michigan.

When exposed to humans, microcystins can cause skin irritations
and abdominal pain.

The blooms create a blue-green layer of scum on the
water’s surface that looks like floating paint. Scientists
who recently tested algae scum on Muskegon Lake found elevated
concentrations of microcystins.

“I don’t want to scare people, but the levels of
microcystins we found are significant.” said Gary
Fahnenstiel, director of the National Oceanic and Atmospheric
Administration’s Lake Michigan Field Station. “These
are very high concentrations and are on the same order of magnitude
as the highest concentrations of microcystins ever
reported.”

Fahnenstiel, a leading expert on algae, said people should avoid
swimming, wading, windsurfing, canoeing or water-skiing in areas of
lakes with blue-green algal blooms. Dogs also should avoid those
waters.

Blue-green algal blooms have long been common in lakes with high
levels of phosphorous, such as Spring Lake. Zebra mussels are now
causing the blooms in lakes with low phosphorous levels, according
to scientific studies.

Rick Rediske, a professor of water resources at Grand Valley
State University and chairman of the Muskegon Lake Public Advisory
Council, said he would limit activities in any lake with a
blue-green algal bloom.

“I would boat in it but I wouldn’t swim in
it,” he said.

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