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NEW ZEALAND MUD SNAILS FOUND IN MALIBU CREEK WATERSHED

Harmful Invasive Species Threatens Stability of Ecosystem

The New Zealand Mud Snail was positively identified this month in the Malibu Creek Watershed by Kim Kratz of Aquatic Bioassay and Consulting Laboratories in Ventura.  The California Department of Fish and Game verified the finding on Tuesday, May 30^th.

The snails are an extremely harmful invasive species that consume algae resulting in population crashes of native bottom-dwelling invertebrates like dragonfly larva.  The destruction caused by these small aquatic organisms cause a reduction in forage and thus a reduction in fish and amphibian populations.  This is especially troublesome for the Malibu Creek Watershed because it is home to two already endangered fish species, the Steelhead Trout and the Tidewater Goby.

The New Zealand Mud Snails were introduced to North America’s Snake and Madison Rivers in the 1980s, and very quickly colonized Yellowstone National Park.  Since then populations have spread to California, probably by attaching to waders, fishing gear and boats. 

Averaging an 1/8 inch in length, the snail appears as a grain of sand during development.  Ranging in color from gray to brown to black, the snails can survive in most types of water and can live for days attached to moist gear.  Densities of over 750,000 per square meter have been found in Yellowstone National Park waters.

Aquatic Bioassay and Consulting Laboratories discovered the snails in samples for the Malibu Creek Watershed Monitoring Program.  The snails are already out-competing native invertebrates at Medea Creek in Agoura Hills.  Individuals have also been identified in samples from lower Malibu Creek, just north of the lagoon.  No known method exists to eradicate the snail invasion.  Recommended procedures for decontamination of exposed equipment and clothing include freezing for eight hours, saturating in a diluted bleach solution, brushing with industrial strength 409 or cleaning with powdered copper sulfate.

An emergency summit was held by the Santa Monica Bay Commission on Tuesday, June 20^th at the Los Angeles Regional Water Quality Control Board.  About forty people attended the meeting including representatives from the California Department of Fish and Game and Heal the Bay.  Mark Abramson of Heal the Bay referred to the finding as “an ecological disaster in the making.”