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Crayfish: the new canary in a coal mine

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August 04, 2016

Every summer, a small room on the second floor of the Ford  Life Sciences Building is overrun by crayfish.

Captured on Detroit’s Belle Isle, the tiny crustaceans are the subject of research with unsettling results that lead to bigger questions about the health of streams and rivers as well as drinking water quality.

Watched over by Beyonce, a crayfish who is not part of the experiment, students study the response to odorants and eating patterns of the lobster-like creatures. The research, which has been part of Associate Professor of Biology Rachelle Belanger’s work at the University since 2011, looks at the effects of a particular herbicide on the ability of crayfish to respond to odorants.

Sana Khan takes data on a crayfish.

Sana Khan takes data on a crayfish.

Crayfish live on the bottom of streams and rivers and are nocturnal, so without a lot of light, they must rely heavily on chemical signals, or odors, to find things like mates and food. Belanger studied crayfish prior to joining UDM and she currently examines an herbicide called Atrazine. Research has shown it leads male frogs to develop female gonads, effectively feminizing the males.

“Crayfish are a keystone species,” Belanger said. “They are pivotal in the food web because they eat smaller things and they are prey to bigger fish. Birds and other land animals also feed on the creature, which makes them important to the terrestrial food web, too.”

Atrazine is the most heavily used herbicide in the United States, though it has not been approved for use in the European Union since 2003; Italy and Germany have not allowed its use since 1991. When used on farms, it washes into streams and rivers and comes into contact with animals, including crayfish.

Belanger’s research has shown that environmentally relevant levels—meaning levels likely to be found in streams and rivers in the Midwest — of Atrazine can temporarily turn off the chemical receptor that helps crayfish locate food. This can contribute to a drop in the population of crayfish, which could create food shortages across the food web. This could also lead to ramifications in the commercial fishing industry.

There are potentially bigger issues: “This is our drinking water,” Belanger said. “If it’s not good for animals, it’s not good for us.

The research, funded by the University, continues as Belanger begins to look at new information that arises. Her work has shown that the effects of Atrazine take 12 to 15 days to wear off, and that’s with a 96-hour exposure. Other research has shown that in the spring, crayfish can be exposed to high Atrazine levels for weeks at a time.

Perhaps the most exciting part of the research, Belanger said, is that much of it is done by undergraduate students. In one case, contributions were made by a high school student.

Students learn a great deal by doing this research, Belanger said, including formulating hypotheses, problem solving and creating methods, and writing papers that are submitted to peer-reviewed scholarly toxicology research journals.

“I was a pre-veterinary medicine student before I was introduced to this kind of research and I found that I liked it,” Belanger said. “I wanted to be part of the medical profession, but I discovered there are other avenues that are not in the medical profession, but can help them. This is what I want the students to learn, too.”

Tyler Peters ’14 learned exactly that. As a biology major working under Belanger, he wrote large sections of two papers published about the effects of Atrazine on crayfish.

“I wanted to go into the medical profession,” he said. “But in doing the research at UDM I had that ‘ah-ha’ moment that contributing to the literature could be an important contribution, too.” He is now in graduate school working on his Ph.D. in biochemistry and molecular biology, inspired by Belanger and his work with her.

She is also now working with other professors in the Biology and Chemistry and Biochemistry departments to see why this chemical has this effect.

She wants to look at whether the crayfish are absorbing the chemical and how it may be affecting their DNA.

by Ron Bernas

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