A team of scientists at the University of Minnesota has uncovered the routes by which zebra mussels spread through Minnesota lakes, pointing to some surprising bodies of water that were the likely origins for the period of invasions that began over 15 years ago.
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR) as well as the United States Geological Survey (USGS) through the Minnesota Water Resources Center.
Zebra mussels are an invasive species that can alter aquatic food webs and threaten native species, leading to economic damage that impacts recreation, water treatment, hydroelectric and other industries. Since their introduction via transatlantic shipping to the Great Lakes in the 1980s, zebra mussels have infested over 1,000 lakes in North America. Their spread in Minnesota remains rapid, and recent detections in Canada as well as the western and southwestern United States underscore their growing reach.
In a study recently published in Scientific Reports, researchers at the University of Minnesota Genomics Center (UMGC) and the Minnesota Aquatic Invasive Species Research Center (MAISRC) analyzed genetic markers from thousands of zebra mussels collected throughout Minnesota and the surrounding region. Through a combination of DNA sequencing and invasion scenario modeling, the researchers were able to infer likely source populations for dozens of lakes. The study provides the first comprehensive map of zebra mussel invasions across North America to be generated using genomic analysis, and was made possible by the recent sequencing of the zebra mussel genome by the UMGC and MAISRC. Genomic signatures matched to specific lakes allowed researchers to reconstruct detailed invasion histories, demonstrating the value of genomic surveillance for future prevention efforts.
The researchers found:
- Populations in the Great Lakes and the Upper Mississippi and St Croix Rivers were the sources for 87% of the analyzed Minnesota inland lakes that were invaded prior to 2010.
- After 2010, spread increased rapidly in the state, and other Minnesota inland lakes appeared to be the sources for 64.1% of the lakes that were invaded later. Most of these were found within three lake-rich regions in which spread continues to be concentrated.
- By comparing genomic results and estimates of boater and angler traffic, several low-traffic lakes were surprisingly identified as likely sources for multiple infestations. Among reputed "super-spreader" lakes (Gull, Prior, Minnetonka and Mille Lacs) that ranked high in recreational traffic, only Mille Lacs was detected as a source population (for three infested lakes) despite extensive genomic testing in each case.
"Our results show that several earlier zebra mussel invasions trace back to the Great Lakes, the Mississippi River, and a few previously infested lakes that later became sources for nearby spread," said Michael McCartney of the UMGC Innovation Lab. "This genomic approach enables robust tracing of source populations, underscoring the value of expanding this work and sharing it with managers to help protect the many lakes that remain zebra mussel-free,"
Researchers plan to extend this analysis to the more than one hundred lakes in Minnesota that have been infested since 2018, as well as to other zebra mussel populations throughout the Upper Mississippi River Basin. The researchers will make this information available to the public through an interactive genomic database, enabling managers to track connections between lakes and adapt prevention strategies.
