The non-native invasive species that were introduced to the Lake Champlain Basin include 50 species of plants, animals and pathogens. Some were planted because they had flowers; others got here through ballast or bilge water from boats. Since 2009, the Lewis Creek Association has worked closely with the Vermont Department of Environmental Conservation and the Lake Champlain Basin Program to monitor and remove European frogbit, water chestnut, yellow iris and flowering rush in Charlotte’s Town Farm Bay and Shelburne’s LaPlatte Natural Area.
Non-native species can, in some cases, spread and take over because they have no natural predators. They cause problems for ecologically rich natural areas, not only for native plants and animals that get choked out by these intruders, but also for people who recreate on the water. Plants like water chestnut, European frogbit and Eurasian watermilfoil can grow so thick it becomes difficult or even impossible to boat, swim or fish.
Some aquatic invasive species, like zebra mussels, can be difficult to control. Others, like European frogbit, are more easily removed in order to limit their spread.
When frogbit was first discovered in Town Farm Bay, there was over 50 percent cover throughout the wetlands. The LaPlatte Natural Area had lower frogbit levels, due to earlier detection.
Funded by the towns of Charlotte and Shelburne, the Lewis Creek Association organized groups of volunteers, such as the Charlotte Land Trust, Lake Champlain Lake Stewards, and other interested community groups, to rake frogbit off the surface of the water in these areas. Through this work, the coverage has been reduced to five percent or less annually.
The frogbit season was delayed this spring due to high water and cool weather. Some frogbit was present in early July when the association led their annual check on each wetland, but percent cover was very low.
Since then, Lewis Creek has led several expeditions to remove frogbit. In Charlotte, volunteers have removed approximately 475 pounds, and in Shelburne, approximately 250 pounds. In addition, volunteers pulled two water chestnut plants and found some interesting large colonial bryozoans.
The Lewis Creek Association will host several more field days before the end of the season. All the equipment is provided. Volunteers must be able to paddle in a canoe or kayak, rake plants off the water surface, depositing them into a bucket or basket in the boat. While paddling, leaders help identify as many animals and plants as possible. To join the effort and make a difference in the health of local wetlands, contact Lewis Creek Association Program Coordinator Kate Kelly at email@example.com, or visit lewiscreek.org to sign up.
By Kate Kelly for Lewis Creek Association. Kelly is a is a conservation biologist and herpetologist living in Hinesburg. She also works for the Vermont Reptile and Amphibian Atlas and is a member of the Hinesburg Conservation Commission.