Published October 13, 2010, 02:38 PM

Tracking an invader: Science class studies zebra mussels with DNR

Although Nathan Olson knows a lot about zebra mussels, they are still surprising to him.

By: Celeste Beam, Northland Outdoors

Although Nathan Olson knows a lot about zebra mussels, they are still surprising to him.

Olson, an invasive species specialist with the Department of Natural Resources (DNR), spent last Friday afternoon with students from Jefferson High School.

The group of environmental science students, along with their teacher, John Esbjornsson, and Olson, walked along the shore and in deeper water at L’Homme Dieu Beach on Highway 29, as well as at the channel between Lakes L’Homme Dieu and Carlos.

The number of newly settled zebra mussels found by the students was impressive, said Olson.

“We knew there were a lot of veligers [baby zebra mussels] this summer, but it was surprising how many have successfully settled on rocks and other things in L’Homme Dieu,” said Olson in an e-mail to the newspaper on Monday.

“Also, the amount of mussels that now exist in Carlos is amazing.”

Olson noted that this is only the second summer since zebra mussels were first confirmed in Douglas County’s chain of lakes.

Last year, some zebra mussels were found on rocks at the channel between Lakes L’Homme Dieu and Carlos, but this year, Olson said they were found in abundance on plants, rocks, sticks and native mussels all throughout the lakes.

“It appears we have gone from only a few zebra mussels spotted in July of 2009 to zebra mussels being virtually innumerable after the summer of 2010,” said Olson.

He talked about the size of the zebra mussels and that they are much smaller this year than last year. The reason, he said, could be due to the extensive colonization by the zebra mussels this year compared to last year.

Last summer, zebra mussels could be found in a ring around rocks, but this year, they are so numerous, that they may be limiting their own growth rate, surmised Olson.

He also noted that weather and the temperature of the water could have something to do with the over abundance of the zebra mussels.

Last September, Olson was still snorkeling in the chain of lakes and the water temperature was slightly more than 70 degrees. This year, the water temperature had already dropped to around 65 degrees at the end of September.

The higher water temperature later in the year could have given the mussels a chance to get bigger last year, noted Olson.

Despite the reasons, people have to be aware that the mussels’ small size makes them easier to unknowingly be transported.

“Everyone must be extra cautious that they are inspecting, cleaning, drying and draining water from all of their boats and equipment before anything is transported to another body of water,” he said.


Find out more about the zebra mussel problem in Friday’s Echo Press – including an infestation in Gull Lake and a promising new study that reveals a possible solution.