Therin Bradshaw, Jeremy Corbett and Kelsie Durscher use GPS to track their crayfish traps. 

Three Wartburg College students are wading through the Cedar River in search of a voracious crayfish with a diet detrimental to the entire aquatic ecosystem.

The summer research project, done in conjunction with the Iowa Department of Natural Resources, will help determine just how pervasive the non-native rusty crayfish is in the Cedar River and its tributaries. Dr. Eric Merten, an assistant professor of biology overseeing the students, calls the crayfish the “raccoons of the streams and rivers.” 

The rusty crayfish feeds on aquatic insects, fish eggs and other invertebrates. A reduction in aquatic plant beds can lead to fewer nesting areas and shelter for fish and other species.

“They are omnivores. They like to eat everything — aquatic plants, dead material, live things. They really have a major effect because of that,” he said.

Though the species have been reported in numerous Iowa locations, their pervasiveness is still unclear. Jeremy Corbett of Cedar Rapids, Kelsie Durscher of Waverly, and Therin Bradshaw of Port Byron, Ill., are trying to answer that question. They have set about 150 crayfish traps in 50 locations along the Cedar River, Little Cedar River and other smaller tributaries.

“The rusty crayfish are competing with the native species, so they are actually killing them off,” Bradshaw said. “A healthy environment usually has multiple species of anything, so diversity is very important.”

The group has found four different species of crayfish, including the problematic rusty. More in-depth results from their research won’t be available until the project is complete later this month.

“In some places we get 10, in others we had zero. We definitely know that crayfish are around the Cedar River,” Corbett said.

The students’ information will be compiled and forwarded on to the DNR for possible further action.

In addition to helping the DNR, the research project is also helping the students focus their future plans.

“This is my neck of the woods. I like outdoorsy stuff. I can see myself working for the DNR or a forestry service,” said Bradshaw, who is majoring in biology and environmental studies.

The students will spend much of August working in the Superior National Forest in Minnesota to determine the long-term impact of the 2011 Pagami Creek wildfire in the Boundary Waters Canoe Area Wilderness. The fire burned about 100,000 acres.

“All of this research is getting them practical sampling experience. The techniques they are using are being used in the field as well,” said Merten, who worked for the Minnesota Department of Natural Resources for seven years. “The plan is for them to be first author on whatever products come out of this, so to write completion reports to Iowa DNR and the Forest Service. Ideally we will also submit papers to journals and have them present their findings.”