TRAVERSE CITY — Starry stonewort, an aquatic invasive species native to parts of Europe and Asia, was confirmed in Silver Lake on Aug. 7 by Benzie County Conservation District.
“This was big news for us,” said Kyla Robinson, aquatic invasive species coordinator for the conservation district. “Other than Portage Lake, this is the first detection of it in our four-county service area.”
The invasive macroalgae, often misidentified as an aquatic plant, is currently estimated to affect eight non-contiguous acres of the lake, often interspersed with native vegetation, according to Tim Brock, president of Silver Lake Improvement Association (SLIA).
“It is confined to the southern portions of the lake, in the same cove as Holiday RV Park & Campground,” Brock said. “There’s also a patch just north of Brakel Point.”
Originally discovered in Silver Lake in July by Restorative Lake Sciences (RLS) while surveying for eurasian water milfoil, another invasive species pestering Silver Lake, starry stonewort gets its name from its star-shaped reproductive structures, called bulbils.
“Those are smaller than a grain of rice,” Robinson said, noting that all of the known populations of starry stonewort across the entirety of the United States are male algae.
“It has been able to fragment and colonize without reproducing,” she said.
“It’s kind of alarming. Silver Lake is in the heart of Traverse City. It’s a major concern because we don’t want it to spread from Silver Lake into other lakes in our area like Long Lake, Crystal Lake, or Lake Leelanau.”
When the conservation district received news of the potential intrusion, Robinson said they were shocked.
Robinson and other conservation district members went out to Silver Lake, checked two different locations, and confirmed a positive identification.
This invasive’s ecological impacts in Michigan have not been well-studied, Robinson said, but in other areas where starry stonewort is present, it can grow quite tall, often getting tangled in boat propellers and making for uncomfortable swimming conditions.
“Given that this is our first detection of it in our service area, (SLIA and I) are learning together and trying to take the next best steps,” Robinson said. “Preventing the spread is the most important thing.”
Aquatic invasive species like starry stonewort colonize growing space from native plant communities, often affecting the food chain from the smallest trophic levels on up.
“As I’ve learned about this infestation, I’ve been doing a lot of research and really looking to the University of Minnesota, (which has) been managing starry stonewort for 11 years,” Robinson said, highlighting two primary methods of managing it.
One involves mechanical removal.
“If it’s a small enough area, divers can carefully hand-pull (starry stonewort) to prevent more fragmentation and spread. Diver-Assisted Suction Harvesting (DASH) is another manual option.
“There are also chemical treatments available,” Robinson said, “But since it’s not a true plant, that requires algaecide. A lot of folks are rightfully concerned about any kind of chemical that goes into the water for many different reasons.
“SLIA specifically are doing their own research to decide what steps they will take.”
According to Brock, the most common chemical treatment for starry stonewort is a chelated copper compound, which also kills off native vegetation.
To further complicate the matter, Brock said that when starry stonewort is chemically treated and the plant itself dies, its bulbils tend to embed themselves in the lake bottom, later creating a new organism.
Simply put, this method risks killing off native populations, thus removing the invasive’s competition.
“We have to be really careful about what we do,” Brock said. “We’re in conversation with RLS to get their recommendations insofar as what, if any, part of (the lake) should be treated, or if we should monitor populations for a while first.”
Preventing spread
Surveys throughout all different parts of the country show that lakes without public access sites tend not to have invasive aquatic species, Robinson said.
“More often than not,” she said, “when we find aquatic invasives in Michigan, we find them near a boat launch.”
While Robinson said she doesn’t want to place the blame on anyone, and believes that people are growing in their awareness of aquatic invasives prevention, “Some people still don’t realize how much of a positive impact the simple action of cleaning their boat can make.”
To prevent the spread of aquatic hitchhikers, “We always recommend the easy steps of ‘Clean, Drain, Dry,’” Robinson said.
According to Michigan Department of Environment, Great Lakes, and Energy (EGLE) Aquatic Biologist Kevin Walters, cleaning means removing all aquatic organisms, including plants, from watercraft and trailers before transportation or relaunch.
Draining means draining all water from live wells, bilges, drain plugs and ballast tanks before transportation.
Drying means allowing boats and equipment to air dry for up to five days after use, if possible, although Walters said boaters can also use a hand towel to dry off all equipment prior to transporting, if that length of time isn’t realistic for them.
In addition to cleaning, draining, and drying, all unused bait should be disposed of in the trash before launching from one water body into another.
“Aquatic invasive species are a big deal in our neck of the woods, especially this time of the year, when we have so many people enjoying our waterways,” Robinson said. “With everyone moving between water bodies, unfortunately it’s a really great time for invasive species to hitch a ride. That could be on a boat trailer, the boat itself, a paddle – or even you.”
Robinson said SLIA is in discussions with Garfield and Blair townships, as well as their community constituents, about fundraising a boat-wash station at Silver Lake’s main public access site.
She said they are also in conversation with the Holiday RV Park and Campground, on the other end of the lake, which has a water access site.
Brock said that, while SLIA is not against wake boats, which are intended to create controlled wakes and waves for towed water sports, they tend to “stir things up,” thus facilitating the spread of starry stonewort.
“It’s recommended that people operating wake boats stay 500 feet from shore, in 20 feet of water or deeper,” he said. “We have a nice area in the main body of the lake that we encourage wake boarders to utilize, (while avoiding) areas that have populations of starry stonewort.”
To view a map that shows “the best areas of our lake in which to enjoy this sport,” Brock said to visit silverlake.com and navigate under the environmental tab.
He said this will help prevent the invasive from getting “blasted all over the place.”
“There’s no right answer for a solution,” Robinson said. “You never get to a stage of eradication. It’s really just not possible when it comes to aquatic invasive species.
“Hopefully, by getting the word out early, folks will be more diligent as they travel between water bodies.”
Spot an invasive species? Report it through either the Michigan Department of Natural Resources’ Eyes on the Field app; or to the Michigan Invasive Species Information Network via their MISIN app; or by visiting misin.msu.edu. Take a photo to show its scale. If it’s a plant, try to separate out the leaves to show them as best you can. To learn more about Northwest Michigan’s invasive species, including how to properly identify them, go to michigan.gov/invasives. {related_content_uuid}e16657e5-70a7-4753-bc5c-525614238d14{/related_content_uuid}