Invasive Algae Found In Second Lower Michigan River

GRAND TRAVERSE COUNTY, MI — An invasive alga, known as "rock snot" was found in a second northern Michigan river, state environmental officials announced Wednesday.

The Michigan Department of Environment, Great Lakes and Energy confirmed the presence of Didymosphenia geminata, or didymo (a nuisance algae known as "rock snot") in a stretch of the Boardman River in Blair Township, which is just south of Traverse City in Grand Traverse County.

The algae can destroy habitats for macroinvertebrates, including mayfly and caddisfly nymphs-which are important food for fish-by forming mats over streambeds.

It is also different from other harmful algal blooms in the Great Lakes, in that didymo blooms best in cold, low-nutrient steams utilized for sport fisheries that are often considered pristine.

"We don’t have a lot of historical samples to indicate whether didymo may be present but undetected in other Michigan waterways," EGLE Aquatic Invasive Species Program Coordinator Sarah LeSage said.

"It’s possible that environmental factors like changes in water chemistry or quality are causing it to ‘bloom’ or develop long stalks, making previously undetected alga cells now visible on hard surfaces in the streambed," she added.

State Officials visited Shumsky’s Canoe Launch and a bridge off East River Road in Blair Township on Tuesday to collect samples after a picture of the algae was submitted through its online forum. The Great Lakes Environmental Center verified the algae as didymo the next day.

There are currently no effective methods to get rid of didymo once it is found in a river or stream, according to the DNR. To prevent the algae from spreading the DNR urges recreational users to "thoroughly clean, drain and dry waders, equipment and boats upon leaving a waterway."

State Officials said remove mud and debris from all surfaces, drain water from all bilges, wells and tanks and dry equipment for at least five days or disinfect with hot water or a diluted bleach solution.

State officials first found didymo in the Upper Peninsula in 2015. It was detected again in the Upper Manistee River in Kalkaska County last December, making it the first time the invasive algae was found in lower Michigan.