The Minnesota Zoo has been supporting the freshwater mussel conservation projects of the Minnesota Department of Natural Resources (MN DNR) for many years with the goal of establishing healthy mussel populations in our beloved Minnesota lakes. You may be wondering, “What’s the big deal?” Though mussels are small in size, they have a big impact on the health of our lakes, ponds, rivers, and streams. Mussels are filter-feeders, which means they’re great at cleaning the water. Since mussels live in groups called mussel beds, they also stabilize riverbeds to protect against erosion from water flow. Unfortunately, 25 of our 48 remaining native mussel species are listed as endangered, threatened, or of special concern.   

Divers search for zebra mussel colonies in Lake Minnetonka.

Multiple factors impact the population of freshwater mussels in Minnesota, including habitat change and loss, pollution, and water quality. However, one of the more recent threats to face Minnesota mussels is the introduction of the zebra mussel, an invasive species from another part of the world. The zebra mussel colonizes on the shells of native mussels, intercepting food, taking over their habitat, and eventually killing the native mussel. It has also been discovered that zebra mussels over-filter water bodies and take food from plankton. Plankton is the main food source for many species of young fish in freshwater lakes and without it, fish populations suffer.   

Zebra mussel breeding facilities at the University of Minnesota.

Conservationists at the Minnesota Zoo have begun work at the University of Minnesota and the Aquatic Invasive Species Research Center to breed zebra mussels in a controlled environment. This may seem counterintuitive since we know that zebra mussels are detrimental to native mussels and damage aquatic habitats. Why would we want more of them?! Well, the answer is quite astonishing. Ben Minerich, a conservationist from the Minnesota Zoo, explains that “We’re working to establish methods of breeding and propagating zebra mussels through multiple generations so that researchers have on-demand access to various life stages of zebra mussels to test eradication methods in the lab.”  

Zebra mussel viewed under a microscope.

The project began last October after the Minnesota Aquatic Invasive Species Research Center contacted Minerich about breeding zebra mussels. Minerich started his career at the Minnesota Zoo propagating corals and jellyfish and has used this experience to support the MN DNR’s efforts to grow and release native mussels for the past several years.  Spawning and growing this species to a reproductive age has not been done before and is a unique challenge. Support from researchers at Auburn University and the University of Florida has helped to develop holding systems that will maximize survivability during the free-swimming larval phase of early development.  

At the end of April, Minerich was visiting local lakes in Minnesota with a dive team from the Minnesota Zoo to collect adult zebra mussels  to hold in a  prolonged winter environment at the University of Minnesota.  These adults are ready to reproduce but are waiting for the right environmental cues. The next phase of this project will be to construct rearing tanks to keep

Ben and Josh from the Minnesota Zoo discuss their diving strategy.

the delicate larvae suspended in the water as they would be in the wild and to provide microscopic food for them to grow. Successful growth to the settlement phase will allow future researchers to explore additional novel approaches to controlling this invasive species.  

In the meantime, there are many things you can do to help protect our beautiful lakes, rivers, ponds, and streams from invasive species. Invasive species can attach themselves to boats and watercraft, hide in fish wells and bait buckets, or hitch a ride on attached vegetation. To ensure you don’t have any unwanted passengers:   

  • Drain all water from your watercraft before leaving the boat launch.
  • Remove all visible vegetation from the watercraft and trailer.
  • Allow your boat, trailer, and equipment to dry out for five days before visiting another body of water.
  • Never use equipment that still has water from another lake or river on it.
  • Empty your bait buckets in the trash, not in the lake or river.   

   

To learn more about the Minnesota Zoo’s freshwater mussel conservation program, and other conservation programs, visit our Conservation webpage.