Researchers find new methods to combat invasive zebra mussels

Zebra mussels, an invasive species to Minnesota lakes, can cause disrupted food chains and economic problems.

Small zebra mussels

Courtesy of Minnesota Aquatic Invasive Species Research Center

Small zebra mussels

Lew Blank

A University of Minnesota study released last week looks at ways to kill one of Minnesota’s most harmful invasive species.

Zebra mussels have encrusted boats, disrupted food chains and cut the feet of beach-goers across Minnesota for decades. In an effort to reduce their population, a paper released by the University in partnership with the U.S. Geological Survey demonstrates the most effective ways to eradicate the inch-long critters, even in the icy waters of the North Star State.

Most chemicals used to exterminate zebra mussels are developed and tested in warmer states located south of Minnesota, said James Luoma, a USGS researcher who was one of the leaders of the study. While these chemicals may work efficiently in warmer climates, they do not operate as well in the frigid waters of Minnesota lakes in the fall, he said.

“A lot of these infestations are found late in the year when people are removing equipment such as docks or boats,” Luoma said. “In the past, [those treating zebra mussels] did not have the information available to [determine if] a product would be effective in cold waters.”

Researchers have now discovered how to most efficiently kill the mussels in Minnesota lakes without overusing chemicals.

The results of the study indicate three zebra mussel treatments have the ability to exterminate more than 90 percent of invasive populations in water temperatures of 45 degrees Fahrenheit. One of the treatments, Niclosamide, required only 24 hours of exposure to achieve this high mortality rate. The others required more time.

By using the proper amounts of these products, the researchers hope to find the “sweet spot” that kills a substantial number of zebra mussels without affecting harmless non-invasive species, said Nicholas Phelps, the director of the University’s Minnesota Aquatic Invasive Species Research Center. MAISRC funded the study.

“This is the first time that we’ve really created a plan that people in Minnesota can actually put into action on their lakes to control zebra mussels,” said Christine Lee, communications specialist for MAISRC.

By reducing populations of zebra mussels, the researchers hope to mitigate the species‘ negative economic impact, which can total approximately $310 million per year nationwide, according to the U.S. Department of State.

Much of this economic damage occurs when zebra mussels latch onto boats and docks on lake shores, cementing them into place. The mollusks can also cause damage by consuming organisms like zooplankton, which can make it harder for species at higher levels of the food chain to find sufficient food, Luoma said.

“Zebra mussels are one of Minnesota’s most problematic aquatic invasive species,” Phelps said. “They re-engineer the ecosystem … [they] can take out the base of the food web.”

The mussels can also promote algae blooms through a process called filter feeding, in which mussels consume forms of algae that are beneficial to the ecosystem while refraining from eating detrimental varieties like blue-green algae, Luoma said.

“Lakes and the health of our … aquatic ecosystems … are core to Minnesota values,” Phelps said. “We want healthy, clean, sustainable lakes. And invasive species, in particular zebra mussels, threaten that.”