Associated Press
In this photo taken Wednesday, Feb. 11, 2015, Kit Paulson, watershed planning manager for the city, cleans gear after she and a colleague waded through urban streams while researching whether a tiny destructive New Zealand mudsnail is present in the salmon-bearing stream in Bellevue, Wash. Scientists are turning to environmental DNA, or eDNA, an emerging surveillance tool that detects the presence of an organism by analyzing cellular material such as urine, hair, feathers or skin cells that are left behind in the environment. From Asian carp in the Great Lakes basin to salamanders in Kentucky to great crested newts in the United Kingdom, the tool is helping biologists look for reclusive or rare imperiled species, monitor unwanted creatures or gauge the overall biodiversity of a lake or stream. (AP Photo/Elaine Thompson)

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