Zebra mussels invade Thompsons Lake

HILLTOWNS — Zebra mussels, an invasive species that has caused economic and environmental harm in bodies of water across the country, have made their way to Thompsons Lake. A full-on infestation can drain a lake of the microorganisms on which its native species feed, and their sharp shells can cut people.

There is currently no solution to this problem, which for decades has plagued natural bodies of water and power plants alike, changing ecosystems and causing economic problems by limiting productivity.

But steps can be taken to make their presence less imposing on lakeside residents, and scientists at the New York State Museum have been working for almost 20 years to design a biological weapon against invasive mussels, which may soon be marketed.

Nancy Engel, director of the Emma Treadwell Thacher Nature Center next to Thompsons Lake, said the mussels likely came here in the stored water on the boats of lakeside residents. The New York State Department of Environmental Conservation encourages the thorough cleaning of all surfaces and compartments of a boat before traveling between bodies of water, to prevent the spread of invasive species.

“What we’ve found this year is that they’re widespread, from one end of the lake to the other,” said Engel. “I found little baby ones on plants at this end, and larger ones when I scooped stuff out for our turtles,” she said.

Engel and those she has consulted are unsure how long the mussels have been in the lake.

“I think we’re going to try to get some other samples, and try and get as large a sample as possible, to find out how long they’ve really been in there,” said Engel. “We think it’s at least a year, and I’m guessing it’s been more than that, because they’re everywhere.”

Paul Whitbeck, a Berne resident and owner of the Hilltown Locksmith Shop, helps maintain the homes of Thompsons Lake residents who move south in the winter. He first noticed the mussels last year, but did not recognize them as an invasive species.

“Just about every day, I snorkel in the lake,” Whitbeck said. He has noticed the mussels clinging to lake residents’ water intakes, a common problem in other lakes that have been infested.

“They’re more plentiful on certain days than others, and I haven’t figured out why that is,” he said. “I see them on a lot of old drums on the bottom of the lake…There’s a big snail population, and [the mussels] seem to be clinging to the snails.”

The largest mussel he has seen was about the size of a quarter, he said.

Problems and solutions

Zebra mussels, Engel said, can cause several problems.

“One thing that happens is they clog up water intakes very badly,” Engel said. This is also true in pipes that feed water into factories and power plants. “So people on the lake are concerned because you can suck them up into anything, and then they grow there,” she said.

Steve Sanford, director of the Office of Invasive Species Coordination at the DEC, does not anticipate that the mussels’ presence will be too problematic for lake residents.

“It may be that, if they have water intakes, that they could have problems, and I couch that term because, from my experience, the larger water intakes that are continually bringing in water are the ones that really have problems with zebra mussels,” said Sanford. “I’m not sure that residential intakes, with intermittent flow, are going to have a problem.”

Sanford and his family have a camp on Lake Champlain, he said, and the mussels have caused little interference in his family’s routine. He went on to say that copper repels zebra mussels.

“What I did with my water intake at Lake Champlain is, I have copper screening over my water intake, so they’re less likely to settle on the screen and block the screen, because it’s not a healthy place for them to live,” said Sanford. “Another thing is, if they come into my camp and sit in the pipe, they’re in an anoxic environment, so they can’t survive in there. Whereas, if they’re in a constantly used and oxygenated water pipe,” like in an industrial setting, he said, “that’s more of a problem.”

If the lake were to become fully infested, residents may be at risk of injury if they are not cautious, he went on.

“If you swim in the lake, and zebra mussels are on the bottom, you should have water shoes on, because they’re going to cut your feet, and that’s true if you have pets, too,” Sanford said. “They’re small, and they’re pretty sharp-edged, so that’s something people have had to contend with.”

Filter feeders

The other main issue, Engel explained, is an ecological one: Zebra mussels are filter feeders.

“They suck water in, and they filter out every little particle that’s edible,” she said of the zebra mussels. “Microscopic organisms are what they’re feeding on. So, they’re cleaning the water very well, and one thing that happens with this kind of infestation is the water becomes very clear, but it’s also taking food away from the other small organisms that would be eating it. So, the diversity goes down because they’re eating up all the really tiniest food, the food at the bottom of the food web.”

There are few fish in the lake that eat zebra mussels, Engel said, and the mussels reproduce too rapidly to be consumed by other fish at a rate that would control the population.

Asked if they could be eaten by people as an effective solution, she said, “I guess you could, but the shells are so hard and there’s very little in there. They don’t get to be the size of the mussels we harvest and eat. I don’t think it’s a viable alternative to getting rid of them.”

And, there is currently no method for cleansing a lake of the species without harming the rest of the ecosystem.

“You’d have to poison your lake with chemicals,” Engel said.

A natural enemy

Since 1992, Dr. Daniel Molloy from the New York State Museum has been working with a team of scientists on a biological weapon to fight this species that has become a growing problem in various parts of the country.

Denise Mayer, one of Molloy’s lead scientists, has been on the team since 1995, and now works out of Cambridge, N.Y. on the project.

“Dan and his team started looking for a natural control for zebra mussels, and they started screening for a bacterial product that would kill zebra mussels,” Mayer told The Enterprise. After screening 700 different bacterial strains over three years, they found one in 1995 that offered some hope.

“It’s a strain of a species of pseudomonas fluorescens,” Mayer said, “a soil microbe that lives in association with plant roots, and it’s a plant-growth promoting bacteria, so it tends to protect plants from fungal and bacterial diseases. And there’re billions of them in nature, in each cubic centimeter of soil.”

This particular strain, CL145A, naturally produces a compound that kills both zebra and quagga mussels, the latter of which has also become a problematic species.

“So far, we’ve found that it doesn’t kill anything else — any other aquatic life,” said Mayer. This characteristic of the compound is what makes it particularly valuable. “So, after culturing the bacteria, we can kill it and feed the compound to the mussels, and it still kills the mussels. That’s the reason the product was so attractive, because it’s a replacement for other compounds that are used to kill them in other systems, like power plants, where mussels clog their pipes for cooling, and transporting water and stuff.”

Many power plants use broad-spectrum chemical compounds to kill mussels and other invasive species, but these chemicals kill everything with which they interact, Mayer said.

“Plus, when it exits the facility into the natural waterway, the chlorinated compounds interact with the organic compounds and produce carcinogens,” she said. “So, our goal was to produce something for these industrial systems that would reduce the need for some of those more harmful chemicals.”

The costs, both financial and environmental, are what motivate the scientists in developing this new product, Mayer said. The team is licensing this bacterially produced compound to Marrone Bio Innovations, based in Davis, Calif., which will then market the compound as a product called Zequanox.

But, while the compound has yielded promising results for industrial uses, it cannot simply be applied to any body of water that has been infested.

“First of all, there’s [Environmental Protection Agency] registration; it’s not registered yet to be applied to open waters,” Mayer explained. “Second, it would just cost a lot. The amount you’d have to apply to treat entire water bodies like that would be just a lot of material. Depending on the size of the lake, it could be a long time before application would be practical, if ever.”

History and regulation

In 2008, a bill was passed that created the New York Invasive Species Council, Sanford said. The council is composed of individuals from nine state agencies: the DEC’s assistant commissioner for natural resources; the state agriculture commissioner; the commissioner of transportation; the commissioners of parks, recreation, and historic preservation; the commissioners of education; the secretary of state; the chairperson of New York State Thruway Authority; the director of the New York State Canal Corporation; and the chairperson of the Adirondack Park Agency.

The bill also created an advisory council made up of 25 representatives of different organizations, industry, academia, landowners, and people in the conservation world.

On June 10, the council released a report, “A Regulatory System for Non-Native Species,” asking for authority to implement a new system for developing regulations that will prevent the entry of invasive species into the state’s waterways, forests, and farms.

“This is a specific charge that describes a specific kind of regulatory framework, and this goes back to the bill that was passed in 2008,” Sanford said. “It talks about listing prohibited, regulated, and unregulated species. What we want is specific statutory authority to do this, rather than applying broader statutory mandates.”

This system would have four components:

— A list of prohibited species, illegal to possess, import, purchase, transport, or introduce into the environment, unless done so with a permit for disposal, control, research, or education;

— A list of regulated species that would be legal to possess, sell, buy, and transport, but not introduced into a free-living state;

— A list of unregulated, non-native species that should not be regulated; and

— A procedure for the review of non-native species that are not on the prohibited, regulated, or unregulated lists before their use, distribution, or release.

In the report, zebra mussels are listed as a priority species for initial assessment, among roughly 230 species.

“The way we approach our jobs here is what we call pathway by pathway,” Sanford said. “Pathways are the mechanisms organisms use to make their way around the world with human help. For instance, it could be ballast water in international shipping, and New York is very involved in trying to close that door.”

Zebra mussels, he said, most likely made their way to the United States as an unintended result of international trade.

“They’re from the Caspian Sea area over in Eurasia, as are a lot of the invasive aquatic species that have come into the Great Lakes,” Sanford said of zebra mussels. “The Great Lakes are fresh-water, low-salinity lakes. So, you might have fresh-water organisms that would never be able to get across the oceans. But, if a ship’s ballast water is fresh-water, they get a free ride. So, we’re working on regulatory stuff to also shut that door.”

However, Sanford expects the council may not be able to develop these new regulations until next year.

“A key thing is, even though we’ve identified zebra mussels as a higher-priority organism that needs to go through this process, it really looks at trying to regulate commerce in certain species, plants and animals that are purposely bought and sold for food, nursery stock, pets; things like that,” Sanford said. “The report was released just last month, and the legislature has other things on its mind right now with the budget issues. So, we think the next session, next year, is when they will act on that.”