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Call it the Snailpocalypse or Snailzilla, but the New Zealand mud snail is an invasive species that is no laughing matter. It has the potential to rapidly reproduce through cloning and then displace native macroinvertebrates. This can have upstream affects in the food chain, by pushing out native aquatic insect larva and snail populations which feed fish and insect-eating terrestrial species like bats, dragonflies, and birds. Just this month, its presence was recorded in the Musconetcong River and the Little Lehigh River - the first 2 sightings in the Delaware River Watershed.

Nancy Lawler taking benthic sample

MWA sent routine macroinvertebrate samples for taxonomic identification and analysis to Cole Ecological, Inc. 5 sampling locations had the New Zealand mud snail. Because New Zealand mud snails were found at sites upstream and downstream of the 37.5 foot high Warren Glen Dam, it's not clear how it came into the Musconetcong River. They originally came into the United States in contaminated trout stocking shipments in 1987. The snails cling to anything and are remarkably tough; they can survive out of water for as many as 50 days by closing their operculum, the tiny trap door that seals their shell. When eaten, they have been known to pass through the digestive systems of predatory fish and birds whole and unharmed. But, it is likely that the snail spread from waterway to waterway by hitchhiking on waders and fishing gear.

The New Zealand mud snail is bad news for any stream. In North America, colonies of these tiny invasives - adults are less than a quarter of an inch long - can carpet the bottom of waterways. In Yellowstone National Park's Madison River, these snails were observed at densities of as much as 80,000 per square meter. Until recently, mud snails were unknown in the eastern part of the United States. Now, the tiny invasive as been documented in Gunpowder Creek in Maryland, Spring Creek in Pennsylvania, and the Musconetcong. Just days ago, MWA was told it has shown up in the Little Lehigh River and a stream in New York State.

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MWA has a strong education mission, including running a citizen science program for more than 10 years. Getting information about a threatening invasive species like the New Zealand mud snail is part of that effort. The NJDEP recently issued guidance, as has the PA Fish and Boat Commission. It's in its early stages still, and the research has yet to catch up on the best practices for containing the snail.

MWA works with citizens, municipalities, and state and federal agencies to protect and improve water quality in the Musconetcong River which flows 42 miles from its headwaters in Lake Hopatcong, through small scenic towns, downstream to where it finally joins the Delaware River in the town of Riegelsville. The river was designated as part of the Federal Wild & Scenic River system in 2006, and it is noted for its critically threatened brook floater mussel habitat.

Intern Levi Morris reviewing macroinvertrebrate sample with a volunteer.

MWA reached out to state and federal agencies to spread the word and shared information with project partners on the snail and how it might be controlled. There is no consensus on how to adequately clean gear without introducing harmful chemicals to the waterway, but experts agree that if fisherman, boaters, and scientists that work in the river clean their clothing and gear of debris or mud before leaving the river bank, it will slow or prevent the snail from moving between streams. MWA is already looking for funding to help the public learn how to identify this invasive critter, and prevent it from entering other local streams.

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