Warmer lakes, rivers and streams threaten aquatic species, by disrupting reproductive cycles, displacing cold-water species and creating dead zones in deep lakes.
For details on the dangerous effects of warmer water, see the page on Lakes and Rivers.
Scientists rely on automatic stream gauges to measure the temperature of rivers. Researchers can use techniques similar to those used to monitor ocean temperatures—ships, buoys, remote vehicles, airplanes, and satellites—to record the temperature of large lakes.
Scientists also know that freshwater temperatures are rising because warm-water species are moving into areas that were formerly too cold, while cool- and cold-water species are likewise on the move.