Around the Circle This Week: September 25, 2015

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"Rock snot" found in St. Marys River

A nuisance algae species – Didymosphenia geminata, or didymo – was found this summer in the St. Marys River, the waterway that connects Lake Superior at its eastern tip to the lower Great Lakes.

It's the first time that didymo has been confirmed in Michigan waters, reported the state's Department of Environmental Quality this week. The DEQ says "extensive mats" are growing on the river bottom. Michigan's Department of Fisheries and Oceans Canada have also found didymo on lamprey traps in the river's main rapids.

Known as "rock snot" for its mucus-like appearance, didymo is an ultra-oligotrophic algae that thrives in cold, nutrient-poor waters, unlike most algae. When it blooms, it can take over a waterway or shoreline with thick mats on the bottom.

Though it's thought to be native to Lake Superior, or has at least been here for a long time, didymo acts like an invasive species when it blooms. Its sprawling mats, which feel like wet wool to the touch, deprive native fish of food resources. That's especially worrisome to anglers on the St. Marys River, which supports a valuable fishery and a hatchery run by Lake Superior State University.

On western Lake Superior, didymo isn't new. Researchers have collected didymo cells from the Lester River all the way to Grand Portage. "It seemed to be doing quite well in Burlington Bay, last time I looked," says Doug Jensen, aquatic invasive species program coordinator for Minnesota Sea Grant. But, he adds, "we're not seeing huge mats of it."

So what triggers the blooms? New research led by Max L. Bothwell of Environment Canada suggests that low phosphorus levels are the cause. Climate change and agricultural fertilization that retains phosphorus on land are a few of the factors that may have contributed to a reduction in phosphorus concentration, down to a level at which didymo thrives. (Science geeks should read the full paper for much more detail.)

Lake Superior State's Aquatic Research Laboratory hopes to secure research funding to "better understand the dynamics of didymo blooms and provide recommendations to prevent future blooms and protect Great Lakes resources,” according to co-director Ashley Moerke.

To prevent the spread of didymo and other aquatic hitchhikers to new waters, Sea Grant offers these recommendations:

Update on fall color

The autumn foliage continues to develop on Lake Superior's shores.

Michigan color is still minimal, with the peak expected in early October.

Grand Portage, at Minnesota's northeastern tip, has 25 to 50 percent color change. There's much less farther down the shore.

On the Ontario shores, the color ranges from 40 percent on the Sleeping Giant to just 10 percent north of Sault Ste. Marie.

Wisconsin color hasn't progressed much. Superior-Douglas County reports 20 percent, the city of Ashland 30 percent and Bayfield just 5 percent.

+ CBC News: Adventurer Markus Pukonen travels across the top of Lake Superior during his five-year, non-motorized trip around the world. He's posting photos on Instagram.

+ Ironwood Daily Globe: "The Michigan Natural Resources Commission last week approved the purchase of seven permanent trail easements from private property owners in the Wakefield area."

+ Video from Fox 21: University of Wisconsin-Superior student researchers collect plastic debris on Wisconsin Point.

+ David Helwig, SooToday: “A new archives building, offering public access to local historical treasures for the first time, is being proposed by staff at the Sault Ste. Marie Public Library.”

+ ABC10, with video: Michigan Tech researchers use parasitic wasps to battle the invasive emerald ash borer.

+ Two Harbors Community Radio went live this week, reports the News Chronicle. KTWH is on 99.5 FM.

+ "Great Lakes iron ore shipments take hit: The cascading impact of foreign steel's play on the international markets has reached the Great Lakes shipping industry," reports the Duluth News Tribune.