University of Minnesota Rapid Response Project to Test Zebra Mussels Found in Pet Stores Across U.S. and Canada

April 19, 2021


The Minnesota Aquatic Invasive Species Research Center (MAISRC) has launched a rapid response project to conduct genetic testing on zebra mussels that were inadvertently distributed across the United States and Canada hiding within aquarium moss balls and sold at pet stores—including in Minnesota. MAISRC is partnering with the University of Minnesota Genomics Center (UMGC) to conduct the testing at the UMN’s Twin Cities campus. 

MAISRC Director and Research Fellow, Dr. Nicholas Phelps is managing the rapid response project. “We are sequencing the genetic markers from the moss ball zebra mussels to determine their origins and to build a database that can be used for future comparisons. That way, if any new lakes become infested with zebra mussels in Minnesota over the next few years, we may be able to genetically link those populations,” explained Phelps. “Was the new lake infested from a neighboring infested lake, or was it from the release of these moss ball zebra mussels? By conducting this genetic testing now, we’ll be able to know.” 

In March 2021, the United States Geological Survey was alerted that zebra mussels were being sold attached to and inside aquarium moss balls. Within the month, over 25 states, including Minnesota, reported moss balls containing zebra mussels. The United States Fish and Wildlife Service released guidance for aquarium owners to decontaminate their tanks, but the unknown amount spread of an incredibly destructive invasive species across the country continues to be a significant concern.

MAISRC and the UMGC have requested moss ball zebra mussel specimens for testing from invasive species collaboratives and government agencies across the U.S. and Canada. The specimens arrive preserved in alcohol or frozen to avoid any unintentional release and spread. The first shipment of moss balls arrived at the lab in mid-April 2021.

“We anticipate samples to continue arriving over the next few weeks. From there, the testing itself will be pretty straight forward,” explained Phelps. “MAISRC researchers have worked with the UMGC to conduct similar genetic analyses on many of the established populations of zebra mussels in Minnesota already. This research has helped us understand spread patterns—we can trace patterns of zebra mussel spread through lakes similar to how people can trace their own family trees.”

If you believe you purchased a moss ball containing zebra mussels, contact your local MnDNR office for instructions.




Dr. Nicholas Phelps, MAISRC Director and Research Fellow, [email protected]

Kristin Loobeek, MAISRC Communications Specialist, [email protected]