BEMIDJI, Minn. — Bruce Anspach stood on the public-access dock of Big Turtle Lake on a recent Thursday afternoon and threw the head of a rake into the water. He dragged it back by the attached rope and knelt down to look at the tangled glob of the invasive species Starry Stonewort he just fished out from the bottom of the lake.
The algae strands were fairly small, and there were only a few of the telltale white, star shaped bulbils scattered in the mix. But, judging from what he’s seen in recent years, Anspach knows the strands of starry stonewort will undoubtedly grow before the summer’s over.
As the aquatic invasive species technician for Beltrami County, Anspach is tasked with monitoring and preventing the spread of the algae that is relatively new to northern Minnesota waters. If not addressed, it has the potential to overtake whole sections of a lake — and Beltrami County already has numerous infested lakes to worry about.
Starry stonewort wasn’t confirmed in Minnesota until 2015 when it was identified at Lake Koronis. Officials then began to identify it elsewhere, as well. However, they are still trying to understand the species.
“There’s a ton of unknowns,” Anspach said. “There’s a lot of different studies going on about it, trying to answer a lot of different questions we have.” For example, they don’t know how fast it spreads. Nicole Kovar with the Minnesota Department of Natural Resources is trying to figure that out by periodically tracking the algae in the lakes to see how much it grows over a given amount of time.
Anspach also works with researchers at the University of Minnesota who are looking into potential ways the species could be controlled.
While it’s technically a threat to any one of the state’s 10,000-plus lakes, it’s hit Beltrami County a little harder than most. There are 13 lakes in Minnesota that have confirmed infestations of Starry Stonewort, and five of those are in Beltrami County. They include Big Turtle, Moose, Wolf, Upper Red and Cass.
Hard to treat
Big Turtle Lake is the only one of the five they chemically treat to help combat the starry stonewort. It was one of the earlier lakes found with starry stonewort, and they’re unsure if they’ll continue to treat the problem in the same way in the future.
For now, though, Anspach chemically treats Big Turtle Lake twice a summer, which helps suppress the algae. It has not been able to eradicate the species from the lake, though, and it costs roughly $800 per treatment.
“There’s been a ton of chemical treatments on starry stonewort already, and none of them have worked,” Anspach said.
In one area, they also dredged a foot off of the bottom of the lake a few years ago, but that didn’t eradicate the problem, either.
Not all of the five lakes in Beltrami County are infested to the same degree. The infestation in Upper Red Lake is relatively contained since it’s located in a private harbor and the flow of water keeps it largely controlled. Moose Lake is the worst, Anspach said, as starry stonewort has consumed much of the lake’s north end.
“It’s widespread at Moose Lake,” Anspach said. “In August, it’s solid starry stonewort from just below the surface all the way down.”
He said he’s seen starry stonewort grow to 11½-foot tall in sections of Moose Lake that are only 12 feet deep.
In Big Turtle, the algae is located in about 0.7 acres of the lake. And even though he chemically treats Big Turtle every summer, starry stonewort always grows back. Starry stonewort isn’t the only invasive species in Beltrami County. However, Anspach says it is more troubling than the more commonly recognized zebra mussel.
“You’re not taking your boat in it; you’re not going to be fishing in it; you can’t swim in it,” Anspach said about waters infested with starry stonewort when it’s grown. “It takes away a lot of the area of the lake that you can use.”
While Starry stonewort may be something Anspach has to worry about on a regular basis, it’s something other lake enthusiasts can help control as well. In August, there’s a statewide search for the invasive species, organized by the Minnesota Aquatic Invasive Species Research Center and the University of Minnesota Extension in partnership with the DNR.
So far, that event, dubbed as “Starry Trek,” may have saved a sixth lake in Beltrami County from a starry stonewort infestation.
A volunteer and Anspach raked out a small amount of starry stonewort during the event. They continued to search but couldn’t find any more. The DNR later went out to see how much more was in that location, but they couldn’t find any more, either.
It’s possible they found the only presence of starry stonewort in the lake and were able to eliminate it before it spread.
“I’d be really, really surprised if that wasn’t the one (piece) that someone brought in and it got off their trailer,” Anspach said about the starry stonewort they found in Beltrami Lake. He’s gone back multiple times to make sure, but so far he hasn’t seen any remaining signs of the invasive species. “It’s high on our search list; I’ve already looked three times this year.”