A group of University of Wisconsin limnology students ran into quite the surprise Friday when a set of routine experiments led to the discovery of a new invasive animal species living in Lake Mendota.
Jake Vander Zanden, an associate professor of zoology and a researcher with the Center of Limnology, sends his students in Zoology 315 out in small groups to explore the waters of Lake Mendota every year, but he said they’ve never made a discovery like this.
“We tolled a zooplankton net into the lake as one of our tests,” Vander Zanden said.
The discovery was made after the group of students brought in the net for examination.
“I placed the jar beneath it to catch the water and any organisms that were in it,” said UW junior Joanna Klass. “Our professor came around to see what we had found, and as he was looking at the jar, he grew quiet.”
Vander Zanden said he was stunned when he looked at the sample because it didn’t look as it should have.
“It had a lot of material in it, so I diluted it and saw that the spiny flea was there,” Vander Zanden said. “I did a double take because they’re not supposed to be there.”
According to Jeff Bode, chief of the Lakes and Wetlands Section with the Wisconsin Department of Natural Resources, the spiny water flea is free floating and usually dwells in open water at the center of lakes.
He added this is the first time large zooplankton have been introduced into Lake Mendota or other Madison lakes.
Vander Zanden said the species feeds on other zooplankton, which are critical to the ecosystem.
He added zooplankton feed on algae and therefore keep algae levels down.
“The more spiny water fleas, the more algae and the lower the water quality,” Vander Zanden said.
An invasive species like this can have negative implications to the beneficial qualities of a lake, according to Bode, who said swimming, boating and fishing are some activities that could be diminished due to the presence of the spiny water flea.
Bode said this is not the first time the university has found invasive species.
Researchers from the Center of Limnology also found the spiny water flea in Stormy Lake, located in Vilas County in the summer of 2008.
“That lake provided us a chance to see how water quality changes because of this species, as will Lake Mendota,” Vander Zanden said.
Bode said the DNR is happy it was identified early on, and they plan to continue to work with the university to monitor other lakes to make sure the species doesn’t spread.
The university has plans to design a long-term study to see what the implications could be on this particular lake, according to Bode.
“It was definitely not the most positive of discoveries, but I’m glad we did find it so that measures can be taken to prevent its spreading,” Klass said.
