In early September, The Lake Champlain Basin Program’s boat launch steward Matthew Gorton was conducting routine boat inspections at the South Hero John Guilmette. There to help prevent the introduction and spread of aquatic invasive species, Gorton noticed an unusual looking plant hanging off a trailer backing into the Lake.
While Lake Champlain is host to 51 known nonnative and invasive aquatic species, Hydrilla verticillata has not yet been found there. The watercraft carrying the plant was last in the Connecticut River, a system in which the highly invasive plant hydrilla is well established.
Hydrilla is an aquatic plant, common and often misnamed in aquarium trade, that grows aggressively while out-competing most native plants. Hydrilla causes significant economic and ecological impacts in Florida where it grows in dense beds.
There are efforts in Cayuga Lake and the Croton River in New York to treat hydrilla infestations to prevent spread into other water bodies. A large infestation in the Connecticut portion of the Connecticut River was confirmed in 2016, and New England states have joined together to survey the Connecticut River system and address that population. Smaller infestations are present and under management in smaller bodies of water in Maine, Connecticut, and Massachusetts.
Hydrilla looks very similar to a native aquatic plant, Elodea canadensis, which is common in many New England lakes and rivers. Hydrilla is different in that it has serrated or saw-toothed edges on the leaves and often has leaf in whorls (circles) around the stem with 4-8 leaves per whorl.
Stewards around Lake Champlain work mostly from Memorial to Labor Day weekends at launches on Lake Champlain in New York, Vermont, and Québec. The interception of this plant fragment after Labor Day suggests that there is a need for watercraft inspection and decontamination later in the season.
Boat Launch Stewards encourage boaters to clear their watercraft and equipment of aquatic invasive species in an effort to protect the Lake’s ecosystem, recreation opportunities, and local economies, but the numbers of invasives species continue to grow there.
The LCBP’s boat launch stewards say they have greeted nearly 250,000 boaters and intercepted 5,400 invasive species since the program started in 2007. The majority of these organisms have been found on boats leaving Lake Champlain, many no doubt headed for Adirondack waterways.
Photo of Hydrilla verticillata provided.