Traverse City Record-Eagle

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June 17, 2010

Biologists suspect botulism outbreak

BY SHERI McWHIRTER smcwhirter@record-eagle.com

EMPIRE — Two dead birds found along the Sleeping Bear Dunes National Lakeshore beach could signal a toxic outbreak that's claimed thousands of lake-reliant birds in recent years.

Park biologists found one dead herring gull and a dead cormorant, along with hundreds of dead invasive goby fish. A cause hasn't been confirmed, but experts suspect it's another Type E botulism outbreak that plagued area beaches the past few years.

"It's really hard to predict this early in the game, but we're starting to gear up in anticipation. We expect to see more this summer," said Sue Jennings, park biologist.

Officials sent the two bird carcasses away for laboratory testing.

The first resurgence of avian botulism deaths in 25 years in northern Michigan came in 2006. But the following year brought the greatest impact, when thousands of dead birds washed ashore at the national park and other Lake Michigan beaches north to the Straits of Mackinac and across the Upper Peninsula's southern coast.

The last two summers saw minimal bird deaths, a trend that puzzled researchers.

"There's typically a summer die-off involving cormorants and the gulls. Then there's usually a gap before the fall die-off, when migrating birds like loons and long-tailed ducks are impacted," said Mark Breederland, of Michigan Sea Grant.

He said early summer bird deaths may be a result of an early spring and its warm temperatures, and potentially indicate more deaths come fall.

A local botulism network can be re-activated and volunteer "beach rangers" can hit the shorelines to make observations if an outbreak occurs, said Peg Comfort, network coordinator.

Experts believe bird deaths likely are a chain reaction from invasive species, including zebra and quagga mussels and round gobies.

The theory is that mussels filter the water, allowing more light to grow more cladophora algae, which hikes chances for botulism outbreaks as the plant matter decomposes. Birds can be poisoned and die by eating infected fish and mussels, and by scavenging carcasses and maggots on the beach.

National park biologists are studying the phenomenon to determine whether outbreaks can be controlled. Other research to better understand the toxin transmission mechanism also is under way, funded through the federal Great Lakes Restoration Initiative.

Jennings said park officials expect questions from visitors who are unfamiliar with such bird deaths. They also will reinforce how beaches remain safe for swimming, even during botulism outbreaks, she said.

Botulism is not an infectious disease, but a poison. Ingestion must occur before illness does.

Sleeping Bear is looking for volunteers to help with its beach monitoring program. Informational meetings for prospective volunteers will be on Friday and Wednesday from 2 to 4 p.m. at the park's visitor center, 9922 Front St. in Empire.

Call 334-7685 for more information.

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