Imperiled waters, impoverished future, the decline of freshwater ecosystems.
The richest ecosystems on earth are rivers, lakes, and wetlands. 41% of all fish species live in fresh water, which makes up 1% of the earth's surface. At least 20% of all freshwater species are either extinct or at risk of extinction, which is a tragedy for biodiversity and for human society. A senior researcher with the Worldwatch Institute lists the increasing damage to the earth's circulatory system. The supposed benefits of disrupting freshwater ecosystems backfire on us. For example, dikes or levees separate most of the floodplain from the Mississippi River in order to protect farms and cities, yet the frequency, severity, and cost of floods have increased. This Worldwatch paper provides examples of the benefits that ecosystem provide. For example, in Nigeria, an intact floodplain supports many thousands of people and provides economic value a thousand times greater than diverting the water for other uses. US wetlands provide billions of dollars of benefits in flood and pollution control, water storage, and support of fisheries. Yet at least 50% of all wetlands in the lower 48 US states have been drained. Many planned projects jeopardize the character of freshwater systems and the livelihoods of millions of people who depend on them. Two such planned projects are an aquatic highway in South America and a staircase of dams on the Mekong River. The paper first addresses the biodiversity deficit, then the restructuring of rivers. It then moves on to examine what humans take out of rivers and what humans put in them. One chapter is dedicated to fisheries management. Alien invaders is discussed in the next chapter. Habitat degradation is addressed in another chapter. The last chapter, entitled Reconnecting the Fragments, lists the steps needed to reverse current trends.