EcoWatch: Declines of the food resources that feed lake organisms are likely causing dramatic changes in the Great Lakes, according to a new U.S. Geological Survey (USGS) study. USGS scientists and partners found that since 1998, water clarity has been increasing in a majority of the Great Lakes, while phytoplankton (the microscopic water organisms that feed all other animals), native invertebrates and prey fish have been declining. These food web changes fundamentally affect the ecosystems valuable resources...