Aquatic ecosystems are essential to life--and they're very fragile. When we alter these systems--from wetlands to rivers to coral reefs--we often transform them so much that they no longer function at all. But there's hope: Many aquatic systems tend to be resilient. Although we cannot completely recreate destroyed ecosystems, we can often help such systems heal themselves.
Projects are under way around the world to help aquatic systems mend themselves after years of damage. But these efforts, which include bringing water back to the systems to mimic natural water flow and reintroducing plants and animals, are costly and labor-intensive and outcomes are not always certain. It would be better--both ecologically and economically--to protect these ecosystems before they are disrupted.