Genetic research fills out map of zebra mussels’ spread in Minnesota
New research findings from MAISRC are filling in the map of zebra mussel spread in Minnesota. These are helping us understand how many mussels it takes to establish a new population in a lake and have revealed that suspected “super-spreader” lakes have not spread mussels throughout the state—a major surprise.
By genotyping and analyzing thousands of zebra mussels in partnership with the University of Minnesota Genomics Center, researchers have found high genetic diversity in lakes. This means that lakes are being colonized by large numbers of mussels or larvae – either from several independent introductions, or through one or few introduction events of numerous mussels.
Researchers also found genetic clusters of zebra mussels that identified regional patterns of spread. The regions of Detroit Lakes, Alexandria, and Brainerd Lakes each have populations that are genetically unique, found nowhere else in the state. Lakes are closely linked, genetically, within each of these regions.
“These genetic clusters show us that lakes are most likely to be infested from other nearby lakes,” said Dr. Mike McCartney. “Therefore, identifying and blocking regional spread vectors should receive closer attention.”
Using these genetic data, researchers were also able to determine that lakes which had previously been considered “super-spreaders” – Mille Lacs and Prior Lake – have not infested other lakes. Their super-spreader status has been inferred due to high boater traffic. The discord between boater movements and genetics tells us that watercraft inspection and decontamination efforts have been effective on Mille Lacs and should be continued — on these and other high-traffic lakes.
“To explain our results regarding Mille Lacs, we’ve concluded that prevention efforts on boats leaving the lake must be working, so that’s satisfying” added Dr. McCartney. “But major questions remain, such as what are the sources for newly infested lakes in Minnesota? As we make more progress with genetic and genomics tools, we plan to answer this question, and directly pinpoint invasion sources and determine routes.”