Taking To The Air In Fight Against Invasive Species

Locals are utilizing a new tool in the fight against invasive species.

The first step in dealing with the likes of Eurasian milfoil, oriental bittersweet, and purple loosestrife that are crowding out native species and impacting forests and waterways is simply finding them. And that task is especially difficult with aquatic invasives; boaters or swimmers can see those floating on the lakes, but determining how far they’ve spread is a difficult task – unless you’re looking down from above.

Now Dennis Wiand and Rob Dreer of Zero Gravity Aerial are using drones to seek out Eurasian milfoil on Traverse City's Long Lake.

“It’s a huge tool,” says Wiand of the overhead view. The drones can produce real-time video and photos of the lake to more effectively guide those treating the milfoil, offering advantages that ground- or water-based detection methods or even sonar can’t match.

Emily Cook, outreach specialist for the Northwest Michigan Invasive Species Network, notes that “submerged aquatics are really hard to see. When you’re in the air you can see the color differences,” she says.

It’s not foolproof. The sun shining on the surface of the lake can be reflective, necessitating the use of filters. And for lakes where clarity is an issue or when the wind whips up waves, the cameras are at a disadvantage. But as an additional means to help in detection and ultimately in treating problem plants, drones offer options and advantages over the naked eye.

Long Lake isn’t the only lake on the lookout for these pests. Garfield Township Supervisor Chuck Korn says Silver Lake has been treating milfoil for the past five and a half years. “The problem was getting out of hand,” he says.

Lakefront residents in both Garfield and Blair Townships were levied a special assessment tax to pay for treatment. “The eradication is ongoing,” says Korn. “It’s never really gone, but you can minimize it.”

Removing invasive species can take a number of different forms. Plants are routinely cut by hand or by machine, or pulled directly from the ground. But aquatic pests are often treated by chemicals, which experts say makes it even more important to precisely locate and target invasives from above.

Milfoil is just one of many plants on Cook’s list of “enemies.”

“Autumn olive was introduced by soil and water conservation districts in the ‘90s before we knew the side effects,” Cook says. "It was intended to help with erosion control and as habitat for birds. The problem is it spreads far more quickly than anyone realized, and creates a huge canopy, blocking out native plants.”

Phragmites is a grass found in wetlands, ditches, and stream and pond banks, which can grow to a height of 13 feet. Garlic mustard is an edible plant which was introduced in the late 1800s and soon escaped cultivation. It takes over the forest floor to the exclusion of almost all other herbaceous species, and destroys the fungi needed by woody plants for regeneration.

Cook calls Japanese knotweed “absolutely the worst,” so much so that it is now illegal to own. Not only does it crowd out species due to its density, it can also attack other plants by releasing chemicals that inhibit competitors. It takes just a fingernail-sized fragment to create a new population.