Vehicle exhaust and farm fertilizer are helping to warm the alpine lakes of Rocky Mountain National Park, creating unwanted algae that’s no more than “junk food for fish,” according to a study that will be released in the journal Science (via The Associated Press). Moreover, the problem—nitrogen—is worse than previously believed, says Arizona State University professor James Elser, the study’s lead author. The lakes can lose biodiversity, a threat to fish like the rare greenback cutthroat trout, because the algae is less nutritious for the microscopic organisms that are at the basis of the food chain. “It’s like eating marshmallows all day and expecting to grow. You can’t do it,” Elser says. Colorado State University researchers are listed as co-authors on the reports, including U.S. Geological Survey research ecologist and Colorado State senior research scientist Jill Baron and Koren Nydick, a graduate of the CSU Graduate Degree Program in Ecology (via CSU). Meanwhile, The Colorado Independent notes that the upper Colorado River and Front Range water resources are threatened by population growth and the energy industry.