Aquatic Snails Infest Santa Monica Mountain Watersheds

By Jeff Klinger
New Zealand mudsnails have taken over four watersheds in the Santa Monica Mountains and are spreading fast, expanding from the first confirmed sample in Medea Creek in Agoura Hills to nearly 30 other stream sites in four years, according to a recent LA Times article on mudsnail infestation.

New Zealand mudsnails around a dime

Mudsnails now infest the Malibu Creek, Trancas Creek, Ramirez Creek and Solstice Creek watersheds. They’ve claimed Malibou Lake, Malibu Lagoon and Cold Creek. “Mudsnails don’t look like much: An adult is about the size of a grain of rice. But one can produce 40-million clones and they quickly drive out insects and tiny animals that provide food for frogs, birds and fish,” said Danuta Bennett, a researcher at UC Santa Barbara. 

“With their hard shells, mudsnails make a poor food substitute. Trout fed a diet of mudsnails get thinner. Tadpoles in mudsnail havens starve,” Bennett said. 

Ironically, the local infestation may be the result of efforts to improve stream-water quality in the Santa Monica Mountains. Equipment used by contractors and volunteers to help test water may have spread the mudsnails from stream to stream. The mollusks cling to gear quite easily. Mudsnail infestations have cropped up where monitoring was completed. 

Hikers, bikers and horseback riders in the Santa Monica Mountains are being asked not to travel from one stream to another without taking steps to shed the tiny hitchhikers. 

What can you do to help? “Don’t go from stream to stream. Bring a separate set of gear. Clean your bicycle tires. Clean your horses’ hooves. Clean your boots, and if your shoes get wet, throw them in a dryer for a couple hours” said Mark Abramson, a stream restoration expert for the Santa Monica Bay Restoration Commission. 

As for cyclists, in addition to the above measures, walking your bike across a creek crossing could make a difference if you can find dry rocks to walk along.

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