New Zealand Mudsnail
Potamopyrgus antipodarum, commonly known as the New Zealand Mudsnail (NZMS) pronounced enzymes, are tiny, invasive snails that were introduced to the Western United States from New Zealand in the 1980’s. New Zealand Mudsnails have already invaded many Western rivers in California, Idaho, Montana and Wyoming including Yellowstone National Park. NZMS were first documented in the Santa Monica Mountains in Spring of 2005. In July of 2006 when NZMS were first reported in the Malibu Creek watershed, a survey was conducted to determine the severity of the infestation. 44 locations were surveyed on 19 streams in the Santa Monica Mountains of these 44 sites 16 tested positive for mudsnails.
NZMS range in size from a grain of sand to 1/8 of an inch, these tiny snails are capable of wreaking havoc on native organisms and watershed ecosystems. NZMS are transported from stream-to-stream by hitchhiking, they attach to shoes (especially waders), equipment (fishing gear, bicycle tires), animals (native and non-native), and even boats. Anything that contacts a stream infested by NZMS will likely become contaminated. It is believed that the mudsnail was spread by anglers to most of the western rivers in the United States, likely on their waders and equipment. In the Malibu Creek watershed we believe the Infestation was brought by groups and agencies who monitor our streams for water quality.
NZMS are asexual it only takes one mudsnail to reproduce. These creatures multiply at alarming rates, in one year a single snail can result in a colony of more than 40 million snails! The mudsnails overwhelm streams by growing to densities of up to 500,00 organisms per square yard. These massive colonies simply out compete native aquatic invertebrates that the watershed’s fish and amphibians rely on for food, disrupting the entire food web.
New Zealand Mudsnails have been found in at least three streams in the Malibu Creek Watershed during the July 2006 surveys: Medea Creek, Malibu Creek, and Las Virgenes Creek. These surveys were repeated by the Santa Monica Baykeeper and the Santa Monica Bay Restoration Commission in July 2007. The preliminary evaluation of the 2007 survey shows that the density of NZMS has dramatically increased and that NZMS have expanded their territory within streams and to new streams throughout the Santa Monica Mountains. More studies will help determine the snail’s long-term impact on the aquatic life in the mountains.
We need your help to prevent the spread of this insidious invader.
The easiest way to prevent mudsnails from spreading is to avoid water contact when possible. However, if your activities include water contact, you can follow these simple steps to reduce the chances of spreading this invader to another stream:
1: Don't be a carrier!
Avoid transferring anything wet (especially, waders, boots, and gear) from stream to stream.
2: Keep it DRY!
After every trip to a stream or lake, remove all mud and debris, visually inspect, and completely dry your belongings. If you can, put your wet things in the dryer on high heat for a minimum of 2 hours. Air drying your belongings at temperatures of at least 85°F for 24 -48 hours will also kill mudsnails.
If you frequently visit lakes and streams, (e.g., you are a stream researcher, monitoring crew, watershed survey group, and others who access streams and lakes regularly), you should refer to "How to Prevent the Spread of New Zealand Mudsnails through Field Gear" produced by Oregon Sea Grant.
This guide provides more detailed information on currently accepted methods for treating gear and preventing the spread of mudsnails.
It only takes one snail to infest a waterbody! Please help protect our creeks and streams!
For more information please see www.watersnails.com