This year’s Living Planet Report shows that populations of animals—including mammals, birds, fish, reptiles, and amphibians—plummeted by 60% between 1970 and 2014. But those living in freshwater are experiencing a far more drastic decline: 83% since 1970. It’s a sobering statistic and one tied directly to the ever-increasing pressures that people are putting on natural habitats.
We can learn a lot about the health of freshwater habitats overall by studying the animals that live in them. If freshwater animals are on the decline, that’s a sign that the entire ecosystem is in trouble. Freshwater habitats face a host of threats, including increases in the amount of water we take from them; drainage of wetlands; pollution from industry, sewage and farms; invasive plant and animal species; climate change; and infrastructure development in and along waterways. Perhaps the most urgent threat to freshwater animals and their homes is the dams, bridges, roads, and other infrastructure that interfere with the natural flow and connectivity of rivers. Many freshwater fish, for example, rely on free-flowing rivers to eat, reproduce, and access nutrients necessary for their survival.
Connected rivers help people, too. Free-flowing rivers move sediment to floodplains and deltas downstream, providing nutrients and soil for