Trapdoor snails - an invasive threat to our lake
Last year, it was brought to the LVA’s attention that there was an explosion of Trapdoor Snails, an invasive species, in certain areas of Lake Vernon. On August 1st, two LVA volunteers helped a permanent resident, who had been vigilantly trying to remove the snails in her waterfront area by herself, to hand pick the snails from the lake. Within 30 minutes in the water, three volunteers took out a 10 litre bucket of snails. What does this mean for our lake? These snails achieve very high densities and adversely affect aquatic food webs. They compete with native snails for food and habitat and contribute to their decline. This species also clogs screens on water intake pipes, making them an economic nuisance as well as an ecological threat. Trapdoor Snails feed on algae and plankton, leading to clearer water but also encouraging monocultures of aquatic plant growth, which can make recreating in an area of the lake difficult. They also carry parasites that can affect waterfowl. How did they end up in our lake? They could have arrived on a boat hull, trailer or propeller, a live well, an aquarium, or even a dock or toy from a lake with Trapdoor Snails. Lacking natural predators, they are prolific reproducers, producing up to 400 offspring in their lifetimes. So, what can we do? Prevent Invasive Species from spreading. It is now provincial law that you need to drain your boat (including kayaks, canoes and sailboats) and wash it with high pressure hot water or let it dry in the sun for 5 days before taking it to another body of water. Never dump aquarium fish or plants into the lake. If you do suspect an invasive species, please report it by phoning 1-800-563-7111 or via www.EDDMaps.org/Ontario. If you do have a population of Trapdoor snails on your waterfront (see description below and photo above), it is recommended that you remove them, place them in a freezer for 4-6 hours and then bury them away from the water and/or bury them immediately. Confirm that the snail you have found is, in fact, a Trapdoor Snail by sending a photo of it to the EDDMaps website. Please join us for two Snails in Pails events this summer: Monday, July 3rd and Monday, August 14th from 9:30 - 11:00 a.m. at 161 Lighthouse Point Road. We will be sharing more information about this invasive species and will be removing as many snails as possible from this area of shallow water. Please bring your own mask and snorkel and wetsuit, if you have one. Nets and buckets will be provided.
6.5 cm in length Brownish to olive-green in colour Shell has six to seven whorls Live ones have an operculum “trap door” that allows the snail to close itself within its shell Can survive out of water for days by closing their shells