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There is something new on the menu at the Chicago Zoological Society’s Brookfield Zoo, and it is part of a national study to help track Asian carp. Cormorants and white pelicans at Brookfield Zoo are feasting on a tasty treat of Asian carp, an invasive species that threatens the Great Lakes. The goal of the study—led by the U.S. Geological Survey’s Upper Midwest Environmental Sciences Center (UMESC) as part of the U.S. Army Corps of Engineers ECALS project ( and in collaboration with Brookfield Zoo and the National Eagle Center (Wabasha, Minn.)—is to identify and understand potential vectors of environmental DNA (eDNA), a monitoring tool used to track these fish throughout waterways. The eDNA Calibration Study (ECALS) is a collaborative project between several federal agencies (U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service, and U.S. Geological Survey) designed to better interpret detections of eDNA and increase the efficiency with which samples can be processed.

Managers and scientists use eDNA to monitor for the presence of Asian carp throughout the Chicago Area Waterway System, the Des Plaines River, and the Upper Mississippi River. They sample river or lake water and then test for the presence of genetic material from that species of fish. Typically, this genetic material has been thought to come from sloughed skin cells, fecal material, and slime from the fish. Wild birds, however, have been observed eating Asian carp, which has caused some scientists to question whether fish-eating birds, or more specifically, their droppings, may be a source of eDNA in waters containing no carp.

To help answer this question and to better callibrate eDNA as a tool for monitoring Asian carp, Brookfield Zoo’s cormorants and white pelicans feasted on Asian carp, and this week biologists gathered their fecal samples. In the wild, these bird species may feed on Asian carp in areas with high populations of these fish and then fly to and defecate in areas where no carp are present, thus transferring Asian carp DNA directly through their feces. The samples from the birds at Brookfield Zoo will be tested to determine whether DNA from Asian carp can be detected in their feces and, if so, how long it persists within their bodies and in their excreted feces in the environment.

The study is important since eDNA is being used to aid federal agencies to keep Asian carp out of the Great Lakes. Information garnered from this study will be used to help select sampling sites and infer the significance of some positive detections.

“Conservation research is an important contribution the Chicago Zoological Society makes to studies that, like this one, involve wildlife,” said Jason Watters, Ph.D., director of animal behavior research for the Society. “We are happy to collaborate with the U.S. Geological Survey in this study because it can have a profound impact on the waterways in our region. Our birds can help researchers determine if environmental DNA is the most effective and accurate way to track Asian carp.”

“We want our research to shed light on the use of environmental DNA to track Asian carp. Everything we can learn about this invasive species could help us find more solutions to controlling it,” said U.S. Geological Survey research fish biologist Jon Amberg, Ph.D., the principal investigator of the studies at Brookfield Zoo and the National Eagle Center.

Five American white pelicans and two cormorants from Brookfield Zoo and four bald eagles from the National Eagle Center were fed silver carp as part of this study. Results from this study are expected to be released late in 2012 or early 2013.
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