Rivers
Rivers are freshwater biomes characterized by moving water. Rivers and streams, like lakes, vary tremendously in size and chemistry. Because of currents, rivers are generally well oxygenated, although oxygen levels may be lower in slowly moving rivers on floodplains. As with lakes, plants and large algae grow along river margins, while phytoplankton photosynthesize throughout the water column. Insects are important consumers, but other invertebrates, fish, turtles, and birds can all be abundant and diverse. Salmon and some other fish spend much of their lives in the oceans but swim up rivers to reproduce.