The fight for a plant-free Chautauqua Lake

Photo courtesy of Bob Johnson
Caddisflies feed on Eurasian watermilfoil.

Products and lifestyles that claim to be all-natural or organic have exploded in popularity, stretching from the healthiest foods to the softest clothing and the most earthy way to build a house. The claim that living “au naturel” is all-around healthier and less destructive than using manufactured goods and practices has been applied to virtually every facet of American modern life.

Even something as obscure as invasive plant management in Chautauqua Lake has gone the organic route.

Bob Johnson worked for 45 years in Cornell University’s aquatic research laboratory as the research ponds manager until his retirement in 2008. During his tenure, he became an expert on how freshwater ecosystems interact and what the best methods of managing these habitats are. Much of his work was centered on an invasive species of plant called Eurasian watermilfoil that has become an established nuisance in many ponds and lakes in New York state. By 2002, milfoil had all but taken over parts of Chautauqua’s South Basin, especially in the Burtis Bay area.

“In 2002, I began my yearly work with the Chautauqua Lake Association because the aquatic plant growth was so bad down at Burtis,” Johnson said. “I began doing intensive studies at Burtis until last year, mainly looking at population densities with insects, focusing on three: a weevil, a moth and the caddisfly.”

Johnson thought these tiny insects could make a huge difference toward halting the growth of the lake’s excessive vegetation problem. The hope was that, through monitoring and active management of these three herbivores, the Eurasian milfoil problem could essentially be eaten into nonexistence each year.

Photo courtesy of Bob Johnson
A sample of healthy Eurasian watermilfoil (left), and a plant eaten clean by caddisflies (right).

The aquatic weevil, E. lecontei, mines through the center of the milfoil during its larval stage, halting its growth for good. The caterpillar of the aquatic moth, A. ephemerella, eats away at the tips of the plant, pruning away its access to the sun. The caddisfly will shred the plant down to the bare stems, Johnson said, and was responsible for the destruction of the Burtis Bay watermilfoil population in 2007.

While the majority of Johnson’s work with the CLA over the past 12 years has been spent monitoring the populations of the lake’s insects and plants to draw conclusive relationships, he has also facilitated the introduction of biological controllers into the Chautauqua ecosystem.

“We know the moths were here at Prendergast in 1993,” Johnson said. “But since 2002 we’ve continued to add additional populations in. We added 100,000 larvae into the water through the ice in December that year, and then did it again in the North Basin in ’06.”

According to Johnson, one of the best tools to fight invasive plant growth in the lake is to increase the amount of natural vegetation along Chautauqua’s shoreline, which enlarges the habitat for the bugs.

“We can see when our milfoil populations go down directly correlated to high numbers of insects in the year before, so anything that is good for the insects is generally good for controlling the vegetation,” he siad. “But it’s very variable from year to year. … We’re pushing very hard for increased shrubbery around the lake.”

After his retirement from Cornell, Johnson created the consulting firm Racine-Johnson Aquatic Ecologists to continue his contracted work with the CLA and the Chautauqua County Department of Economic Planning and Development, which has provided him with much of his funding over the past 12 years.

Johnson said his firm also produces yearly data reports that he gives to the CLA and Department of Economic Planning, and that these reports are available to the general public as well.

“There will always be plants in the lake. That’s not going to change,” Johnson said. “But rooted plant growth does affect recreation and that’s a big problem for Chautauqua tourism, which is why we have to try and manage it.”