A citizen’s report of an invasive zebra mussel found in an aquarium moss package found in a pet store prompted a U.S. Geological Survey expert on invasive aquatic species to trigger nationwide alerts that have led to the discovery of the destructive shellfish in pet stores in at least 21 states from Alaska to Florida.
Amid concerns that the ornamental aquarium moss balls containing zebra mussels may have accidentally spread the pest to areas where it has not been seen before, federal agencies, states, and the pet store industry are working together to remove the moss balls from pet store shelves nationwide. They have also drawn up instructions for people who bought the moss balls or have them in aquariums to carefully decontaminate them, destroying any zebra mussels and larvae they contain using one of these methods: freezing them for at least 24 hours, placing them in boiling water for at least one minute, placing them in diluted chlorine bleach, or submerging them in undiluted white vinegar for at least 20 minutes. The decontamination instructions were developed by the U.S. Fish and Wildlife Service, the USGS and representatives of the pet industry.
Zebra mussels are an invasive, fingernail-sized mollusk native to freshwaters in Eurasia. They clog water intakes for power and water plants, block water control structures, and damage fishing and boating equipment, at great cost. The federal government, state agencies, fishing and boating groups and others have worked extensively to control their spread.
In 1990, in response to the first wave of zebra mussel invasions, the USGS set up its Nonindigenous Aquatic Species Database, which tracks sightings of about 1,270 non-native aquatic plants and animals nationwide, including zebra mussels. State and local wildlife managers use the database to find and eliminate or control potentially harmful species.
The coordinator of the Nonindigenous Aquatic Species Database, USGS fisheries biologist Wesley Daniel, learned about the presence of zebra mussels in moss balls on March 2 and alerted others nationwide about the issue. Moss balls are ornamental plants imported from Ukraine that are often added to aquariums.
“The issue is that somebody who purchased the moss ball and then disposed of them could end up introducing zebra mussels into an environment where they weren’t present before,” Daniel said. “We’ve been working with many agencies on boat inspections and gear inspections, but this was not a pathway we’d been aware of until now.”
On February 25, an employee of a pet store in Seattle, Washington, filed a report to the database that the employee had recently recognized a zebra mussel in a moss ball. Daniel requested confirming information and a photograph and received it a few days later.
Daniel immediately notified the aquatic invasive species coordinator for Washington State and contacted invasive species managers at the USGS and USFWS. He visited a pet store in Gainesville, Florida, and found a zebra mussel in a moss ball there. At that point federal non-indigenous species experts realized the issue was extensive.
The USFWS is coordinating the response along with the USGS. The U.S. Department of Agriculture, several state wildlife agencies and an industry group, the Pet Industry Joint Advisory Council, are also taking steps to mitigate the problem. National alerts have gone out from the USFWS, the federal Aquatic Nuisance Task and regional aquatic invasive species management groups. Reports of zebra mussels in moss balls have come from Alaska, California, Colorado, Florida, Georgia, Iowa, Massachusetts, Michigan, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, Tennessee, Vermont, Virginia, Wisconsin, Washington and Wyoming.
“I think this was a great test of the rapid-response network that we have been building,” Daniel said. “In two days, we had a coordinated state, federal and industry response.”
The USGS is also studying potential methods to help control zebra mussels that are already established in the environment, such as low-dose copper applications, carbon dioxide and microparticle delivery of toxicants.
To report a suspected sighting of a zebra mussel or another non-indigenous aquatic plant or animal, go to https://nas.er.usgs.gov/SightingReport.aspx.