On a spring day one year ago, scientists in life vests and blue jeans invaded the bucolic slice of nature where Perche Creek empties into the Missouri River. The scientists, representing the U.S. Geological Survey and a lab from the University of Missouri-Columbia, suspended mesh cages in the river's current and filled them with fathead minnows — the white rat of the aquatic world, ideal for biological testing. Meanwhile, from... More >>>