News: Ohio Boaters Asked to Help Stop New Invasive Water Weed

Hydrilla infestation
Tangled up in green: Hydrilla forms dense mats of twisted-together stems. Infestations can foul beaches, marinas and boat propellers and choke out native plants and fish. (Photo: Leslie J. Mehrhoff, University of Connecticut,

COLUMBUS, Ohio – With the Labor Day weekend here, Ohio experts are reminding boaters to help stop the spread of “aquatic hitchhikers” -- invasive species that live in the water that can snarl boating, hurt fishing, wipe out native plants and animals, and cost people money.

And while Asian carp rightly get the headlines, there’s another new villain to watch out for: a fast-growing foreign water weed called hydrilla.

Native to Asia, Africa and Australia, hydrilla is choking parts of the Ohio River, is in five small water bodies in the Cleveland area and poses a threat should it reach Lake Erie, said a lake and fisheries expert with Ohio State University’s College of Food, Agricultural, and Environmental Sciences. Smaller lakes, ponds and wetlands are also at risk.

“Hydrilla can be spread from lake to lake by fragments attached to boat motors and trailers,” said Eugene Braig, aquatic ecosystems program director for Ohio State University Extension, the college’s statewide outreach arm. “It’s among the most invasive submersed aquatic weeds in the United States.”

The green, leafy water plant forms thick mats of twisted-together stems that can clog marinas and swimming beaches, foul boat propellers, overheat boat motors, and choke out local native plants. It roots on the bottom in sediment. It can grow up to 1 inch a day.

“It’s a serious nuisance,” Braig said. “It’s hard to move around in the stuff. And the places where it’s most likely to be a nuisance, like marinas and boat ramps, places where people are trying to get on and off the water, are the places where it’s most likely to grow -- in shallow, still water.”

Hydrilla’s secret weapons are small, tough, pea-sized reproductive structures called turions and tubers. The turions, which form on the plant’s stems, eventually break free from the parent plant, drift or get carried by boats or the current, settle to the bottom, and start more plants.

The tubers, like tiny potatoes, grow on root-like structures in the sediment. They can stay dormant a long time, then can sprout new plants when conditions are right. Similar native water plants, such as elodea, don’t make them.

“Hydrilla is really prolific, so a few turions or tubers can become a really large population in a short amount of time,” Braig said.

A square meter of hydrilla plants, about the size of the top of a desk, is said to be able to produce 5,000 tubers.

Braig recommends that boaters and anglers follow the four steps promoted by the national “Stop Aquatic Hitchhikers!” campaign. Each step should be done after every trip on the water:

  • Remove any visible mud, plants, fish or animals -- zebra mussels, for instance -- after taking a boat or trailer out of the water. Do this before towing or hauling the boat anywhere else.

“Hydrilla and other aquatic plants are very easy to get hung up on a trailer and get dragged from site to site,” Braig said. “So walk around, inspect your boat, and remove anything you see.”

  • Drain off any water that may have collected in the boat or trailer -- such as in the hull, motor or live well -- before going anywhere else.
  • Wash and dry any gear that comes in contact with the water, including not just the boat and trailer but boots, waders, bait buckets and other gear. Dogs, too, should be washed if they’ve gone in the water.
  • Don’t dump leftover bait in the water. And also don’t dump it in storm drains.

“If you go into a bait shop and buy a bunch of small fish to use as bait, you don’t necessarily know which body of water they came from. They might not even be all native minnows,” Braig said.

“Even if they’re all native species, they might be carrying disease that you wouldn’t want to introduce to native populations.”

Instead, dump leftover bait in the trash or on the ground far enough away so it can’t get into the lake or a storm drain.

The same goes for any unwanted, too-big aquarium fish, plants or animals: Don’t turn them loose. If a new owner can’t be found to adopt them, it’s best if the plants are thrown out and the animals are humanely euthanized, Braig said. While it might sound hard-hearted, he said, it’s to protect native wildlife and ecosystems.

More details are at the Stop Aquatic Hitchhikers! website,, and the website for Habitattitude, The latter is a national campaign that aims to prevent the release of fish and aquatic plants from aquariums, water gardens and ornamental ponds into the wild.

Hydrilla is found today on every continent except Antarctica.

In the U.S., it first showed up in Florida, possibly entangled in aquarium plants. Since then it has spread up the East Coast, throughout the Southeast, and at last report was also in Texas, Arizona, California, Indiana, Iowa and Washington. The U.S. Department of Agriculture lists it as a federal noxious weed.

In Ohio, Eric Boyda, coordinator of the Appalachian Ohio Weed Control Partnership, is part of a multi-group, multi-state effort to control hydrilla in the Ohio River. Called the Central Hardwoods Invasive Plant Network, or CHIP-N, the network did plant surveys at boat ramps in 2010 that found hydrilla growing in the river from the Ohio-Pennsylvania border downstream to Adams County, Ohio.

Among other efforts, the network looked into using herbicides to kill hydrilla at popular boat ramps on the river but found it couldn’t be done: The herbicides weren’t labeled for use in a “high-flow” system like the river and also could kill endangered mussels.

“We’re also leading a basin-wide effort that includes publishing outreach materials to be distributed throughout the basin, installing signage in Ohio and Indiana along the river, and installing a hydrilla awareness billboard,” Boyda said. 

Details on the network are at

Also in Ohio, biologists have found hydrilla in five spots in Greater Cleveland. All five are water bodies located on Cleveland Metroparks land.

“Hydrilla was discovered in a constructed wetland in Cleveland Metroparks in 2011,” said Jennifer Hillmer, the parks’ invasive plant coordinator. “We don’t know how it got into the wetland, although the most likely sources were contaminated nursery stock or aquarium dumping.

“The plant went unrecognized for several years. This brings to light an overlooked problem: too few botanists and biologists are familiar with submersed aquatic plants, and most land managers focus on terrestrial issues.

“Hydrilla is now found within three major watersheds within Cleveland Metroparks, all of which drain into Lake Erie, because we transplanted emergent wetland plants between water bodies -- carrying tubers in the soil -- or didn’t adequately clean equipment or vehicles between water bodies.”

The specific water bodies infested by hydrilla are within Cleveland Metroparks’ Mill Stream Run Reservation in Berea, West Creek Reservation in Parma, Ohio and Erie Canal Reservation in Cuyahoga Heights and Valley View, and North Chagrin Reservation in Mayfield Village, Willoughby Hills and Gates Mills.

In April, the park district held a workshop on hydrilla called “Early Detection and Rapid Response in the Lake Erie Watershed.”

“There’s no substitute for awareness of the problem, watchfulness, and the adoption of best management practices by the public and land managers,” said Hillmer, who organized the workshop.

“This plant can have a huge impact on boating, swimming, fishing and biological diversity. The costs of treatment will be astronomical unless we catch it early and stay after it.”

The park district has a website on hydrilla at

Last year, Braig helped develop and release a new smart phone app that lets people report their sightings of invasive species -- whether hydrilla, Asian carp, emerald ash borer or otherwise. Called the Great Lakes Early Detection Network app, it’s available for Android, iPhone and iPad devices and may be downloaded free at

“Invasive species are expensive,” Braig said. “They cost us a tremendous amount of money either for control or in damage to resources that we value -- say, in the case of hydrilla, to spawning habitat for yellow perch, which is a valuable fish, or to boat ramps and marinas.

“If it spreads in Ohio, hydrilla will impede your ability to use your boat. It will slow you down. It will reduce the efficiency of your engine if your propeller gets tangled up in it, and that will cost you a lot in fuel. At worst, it clogs water pumps and causes boat engines to overheat, and rebuilding an engine isn’t cheap.

“Whether you’re boating for fun or boating to catch fish, hydrilla is a nuisance, and it’s a nuisance because it can cost you money. It’s better and cheaper to keep it out in the first place.”

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Kurt Knebusch


Eugene Braig, OSU Extension

Eric Boyda, Appalachian Ohio Weed Control Partnership

Jennifer Hillmer, Cleveland Metroparks