FOCUS: Large, invasive snails found at Lake Lanier

(Editor’s note: The following information is from the Georgia Department of Natural Resources, sent by the Lake Lanier Association.)

LAKE LANIER ISLANDS, Ga.  |  A new species of snails has been found in Lake Lanier that could be detrimental to the lake’s environment. Be on the lookout for them, and report any you find to the Department of Natural Resources.

The new species of mystery snails are fairly easy to distinguish from most native snails. Adults [mystery snails] are typically 2-3 inches long. None of the native species get much larger than one inch. There are a few native snails that look similar to these non-native mystery snails, however, so some care should be taken. The new species are olive green as adults and, like other members of their family, have an operculum or “trap door” that they can close when they pull in their foot.

Juveniles look quite different in that their spire is much lower and they appear clear or light green, sometimes with a dark band. At that stage they are very fragile and can appear transparent. They grow quickly and usually occur in large numbers where found.

Mystery snails are great invaders partially because their habitat requirements are not very specific. They can thrive in muddy or sandy bottoms as well as on hard surfaces like rip rap and bedrock. Typically they seem to prefer a mix of silty sand with cobble/boulder areas, similar to the abundant habitats in Lake Lanier. The only aspect limiting their ability to colonize the lake is depths that lack oxygen. 

In regards to removal, there is little that can be done once they are established. Methods that would eliminate them would also eliminate native mollusks and other native aquatic invertebrates. Adults and juveniles are capable of burrowing and are very effective at hiding in hard to reach places. They are also capable of surviving out of water for up to two weeks in a cool humid environment and “clamming up” and waiting out unfavorable conditions or chemical treatments so they are quite resilient.

The current primary concern over this species is the potential for parasites that could be detrimental to other wildlife and in some cases humans. The Department is currently collaborating with Dr. Tyler Achatz at Middle Georgia State College to assess the parasites present in the various new populations of invasive mystery snails in Georgia.

As to guidance on what to do as a landowner, there isn’t a whole lot that can or should be done. Reporting new sightings to DNR would be the most useful action so that the Department can monitor the impact of the invasion as it progresses. Certainly, don’t collect, transport, or eat the snails as they could potentially carry some unpleasant parasites that can transfer to humans. Additionally, they were added to the prohibited animals list last year in Georgia, so it is currently unlawful to possess them. This was done in an effort to prevent their continued spread around the state and avoid this scenario from occurring in other places.

Note the size of these photos. Report sighting of this invasive species to the Department’s regional supervisor, Anthony Rabern, at Anthony.Rabern@dnr.ga.gov. Give him your name, address, phone and email, and if possible, send a photo of the snail, and the GPS coordinates or some landmark or reference point. 

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