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Sep 09, 2023

Zebra mussels found in aquarium moss balls sold in Montana

Invasive zebra mussels found another avenue for potential infestation of Montana waters. Montana Fish, Wildlife & Parks was notified Wednesday that zebra mussels were detected in aquarium moss balls

Invasive zebra mussels found another avenue for potential infestation of Montana waters. Montana Fish, Wildlife & Parks was notified Wednesday that zebra mussels were detected in aquarium moss balls sold at a pet store in Washington state. FWP immediately checked pet stores around Montana and found invasive mussels in moss balls at multiple locations.

"It appears these moss balls were imported from Ukraine to a distributor in California and were shipped to pet stores nationwide," an FWP news release states. "The facility that imports the moss balls has been quarantined and all shipments of moss balls have been stopped."

A moss ball is a species of green algae that is formed into a ball and is 2 to 5 inches in diameter. Moss balls are purchased for home aquariums to help absorb harmful nutrients in the water and limit the growth of undesirable algae.

FWP reports that all of the mussels detected in Montana so far have been dead shells. However, live mussels were found on moss balls in Oregon and Idaho.

Zebra mussels; and their larger cousins quagga mussels, originated in eastern Europe around the Caspian Sea. They were first detected in Lake Michigan in 1989, and were likely transported to the area within the bilge water of an ocean going vessel.

Though small (about the size of a fingernail) they reproduce rapidly and will adhere to almost any surface, even mud. Their hard shells growing in clusters can plug up intake systems at dams, water treatment plants and irrigation systems, causing millions of dollars in damage and additional maintenance costs.

Even more concerning is the ecologic devastation zebra/quagga mussels can effect. They are voracious filter feeders, rapidly stripping small organisms and nutrients from the water column. Invasive mussels are blamed for the collapse of the Great Lakes' salmon fishing industry, and could potentially wreak havoc on Montana's sport fisheries if allowed to colonize the area's lakes and streams.

"These things are permanent biological pollution," said Eric Hanson, Aquatic Invasive Species Coordinator for the Salish/Kootenai Tribes. "Once they're here they'll never go away and the impacts will always be there."

Until 2016, neither zebra nor quagga mussels had been detected in Montana. The first sign of a problem came on Oct.17, 2016 when the U.S. Bureau of Reclamation announced that multiple water samples taken from Tiber Reservoir in northcentral Montana contained larval invasive mussels. An additional suspect sample from Canyon Ferry Reservoir was announced by FWP 11 days later.

In 2019, Canyon Ferry Reservoir was delisted as a suspect waterbody after three years of monitoring with no detections of invasive mussels or larvae. Because of multiple confirmed water samples, Tiber Reservoir will continue to be listed as an invasive mussel contaminated water body until at least 2021. That designation triggers significant boating restrictions, including mandatory inspection and decontamination for all vessels and equipment leaving the reservoir.

FWP is requesting that anyone who has recently purchased moss balls to remove them from the water, place them in a plastic bag and put them in the freezer overnight. Additional guidance for addressing potential mussels in aquariums and how to treat tank water will be available soon.

FWP is also asking people to never dump aquarium tank water down a household drain, or to dump aquarium tank pets, plants, or water into Montana’s waterways as it could result in destructive invasive species entering Montana's lakes, rivers and streams.

"Aquarium water can harbor pathogens and diseases," the FWP news release states. "Dispose of tank water on the ground away from waterways. Let unwanted plants dry and then dispose of them in the garbage."

"It is illegal to release fish and other aquarium pets into natural waterways," the news release warns. "If you can’t keep your pet, find someone else who can adopt it, turn it in to a pet store or the humane society, or euthanize it."

For more information on responsible pet ownership visit Don’t Let It Loose at https://www.dontletitloose.com/

If you have any questions on how to protect Montana's waterways from invasive species call the Aquatic Invasive species hotline: 406-444-2440.

David Murray is Natural Resources/Agriculture reporter for the Great Falls Tribune. To contact him with comments or story ideas; email [email protected] or call (406) 403-3257. To preserve quality, in-depth journalism in northcentral Montana subscribe to the Great Falls Tribune.