Just Say No—to New Zealand Mud Snails
By Melina Sempill Watts
Reprinted with permission of the Topanga Messenger
New Zealand Mudsnails can be as small as a grain of sand or up to 1/8 inch.
They are typically brown or black.
WARNING! New Zealand Mudsnails Threaten Native Wildlife
The water that runs through Topanga Creek is the lifeline which fuels the whole ecosystem of our home town, and we are incredibly lucky because it houses so many beautiful native creatures, such as the endangered Southern Steelhead Trout, Arroyo Chub, Western Pond Turtles, Pacific Tree Frog, California Newt, Arboreal Salamander, Western Toad and more. A large part of why this is possible is that we have fewer invasive species living here than have moved into adjacent watersheds throughout Southern California.
Unfortunately, last month Mark Abramson of Heal the Bay discovered that the Malibu Creek Watershed has a serious infestation of New Zealand Mud Snails. These miniscule snails, measuring about 1/8 of an inch, breed quickly, have no local predators and are capable of lasting 30 hours with no water and up to 60 days in damp conditions. The problem is that local creatures try to eat the snails and then digest them whole, having received no nutrition from the snails —apparently a significant percentage of the snails survive the experience—becoming the equivalent of junk food. Even worse, as Abramson states, New Zealand Mud snails “can out-compete and reduce the number of native aquatic invertebrates that the watershed’s fish and amphibians rely on for food. This reduction in aquatic invertebrate food supply can disrupt the entire food web with drastic consequences.”
These snails are so tiny that it is very difficult to see them on the soles of boots, on wetsuits or in the cracks in a bicycle tire tread. One snail can reproduce asexually, rapidly infecting a pristine watershed.
What does this mean for the community of Topanga?
We need to take care when we are hiking, swimming, riding, biking and working in the Santa Monica Mountains. When feasible, stay off creek banks and creeks. Do not go from one watershed to the next in one day.
After visiting creeks, go home and remove all your gear. Dry everything completely for 48 hours. Put clothes, bathing suits and wetsuits in the dryer. Ideally, gear needs to get cleaned carefully with a 50/50 solution of Commercial Solutions Formula 409 Cleaner Degreaser Disinfectant and water or a 50/50 solution of Formula 409 All Purpose Cleaner Antibacterial Kitchen Lemon Fresh and water.
Other methods of decontaminating are available online.
Keep Topanga beautiful, be sure you are clean of snails before you play in the creek.