Lost habitats include salt marshes, grass beds, coastal forested wetlands, shellfish beds and deltas. In the Bay, for example, more than 90 percent of the estimated 600,000 acres of grass beds that once filled the Chesapeake have been lost as a result of worsened water quality, though the grasses have made a slight comeback in the past decade. The grass beds help maintain water quality while providing food and habitat for a variety of waterfowl, fish and shellfish. As is the case around the Chesapeake, population growth is concentrating in estuarine regions around the nation, placing added stress on the ecosystems. Coastal lands in many areas, including the Bay, are sinking into the water.
Dams block fish from reaching spawning areas, and polluted runoff degrades water quality.