We poled the flatboat through the shallow water of the Big Pond at Audubon. One volunteer, Bill, reached down and pulled gently on a small floating mass of leaves. The roots easily pulled out of the mud with a spiky seed still attached. Bill threw the plant on top of a mound of other plants in the boat. The water-loving plants were doomed to die a dry death in the woods, where the pile would be composted.
The job seemed endless, probably because it was endless. For every plant that was pulled, three more seemed to sprout. The summer wore on, and volunteers and time wore out. The effort to pull the plant stopped. The borrowed flatboat was returned. A sample was sent to the Brooklyn Botanical Gardens to confirm that it was in Chautauqua County. The plant continued to spread. That was seven years ago.
The plant is water chestnut, an invasive plant from Europe. It lives in shallow water, dropping spiky nutlets into the mud that grow into new water chestnuts. The nutlet is like an anchor with a long stem leading to a floating circle of leaves at the surface. The leaves crowd out native plants and can completely cover shallow water.
The water chestnut spreads through these sharp-lobed nutlets. Please be careful not to spread them.
Photos by Jeff Tome
Big Pond is the perfect place for water chestnut to grow. The bottom is only 2 to 5 feet down and covered with rich brown muck. Water chestnut likes water less than 12 feet deep.
Water chestnut has been in North America since the 1860s, when it was found in Massachusetts. Since then, it has spread to many areas of the Northeast. It has been a problem in the Hudson River for years and is found in some of the lakes of Central New York as well.
It probably came to Audubon and other local waterways by hitching a ride with birds. The leaves, with nutlet attached, tangle around the feathers and legs of birds and fall off somewhere else. The nutlet dies when it is air dried, so the birds would have to drop it in new water before it dried out.
I had the privilege of spending an educational hour with Bob Johnson last week. Bob was manager of Cornell University's research ponds for decades and has been researching lakes and invasive plants for years. He has received numerous awards for his work with aquatic plants and is known statewide and nationally as an expert in the control of aquatic weeds. In other words, this man was a powerhouse of knowledge and experience when dealing with aquatic invasive plants like the water chestnut growing in the Big Pond. An hour with an expert proved to be worth more than a day searching for information online.
Water Chestnut recently made the headlines when it was found in Chautauqua Lake. An all-out search for the plant was made by boaters to eradicate it before it got a foothold in the lake. Every one of those water chestnuts was found in the outlet of a creek. Bob Johnson's theory is that the plant was transported there last winter when ice froze the lake, but the running water in the creeks remained unfrozen. As birds flew in from other places to use the open water in the creeks, nutlets that were attached to them dropped off. Because the birds were only in the open water on the creeks, the water chestnut only grew there.
Audubon is lucky in that our shallow ponds are controlled by large water control boxes that act like tiny dams. We can make the dam higher and the water in the ponds go up or drain the ponds like a giant bathtub. OK, like a giant bathtub with the faucet running. Rain and freshwater springs will consistently add water, but giant mud flats can still be exposed.
According to Mr. Johnson, the pond can be drained in the winter to expose the seeds to freezing, which can kill them. Drying the pond in summer may dry seeds out and destroy them. Persistent wet areas may need volunteers to pull out remaining plants. It's the start of a plan to get rid of the water chestnut at Audubon, but it may take years of diligent work make it happen. We will be working closely with Jeff Diers, Chautauqua County's watershed specialist and others in the region to be an integral part of the management plan.
To our knowledge, the method we are trying has not been tried and researched elsewhere. Most lakes and rivers with water chestnut are not able to be drained. This sets Audubon up in the unique position of being able to work with students to research the effectiveness of the approach.
In the meantime, if you come to Audubon and notice there is no water in Big Pond, know that it is because of the effort to eliminate water chestnut. And, if you notice odd black seeds along the trails that have sharp points, please leave them there or throw them out. We don't want to spread the water chestnut any more than it has spread already.
Jeff Tome is senior naturalist at the Audubon Center and Sanctuary. Audubon is located at 1600 Riverside Road, just off Route 62 between Warren and Jamestown. The trails and bald eagle viewing are open from dawn to dusk daily. The center is open from 10 a.m. to 4:30 p.m. daily except, Sundays when it opens at 1 p.m. For more information visit jamestownaudubon.org or call 569-2345.