|Propelled by their large webbed feet, diving ducks like the canvasback
illustrated here fold their wings close to the body while foraging underwater.
For the millions of waterfowl that make the Chesapeake their full or part-time home, the Bay is a veritable smorgasbord. Its mix of salt and fresh water and its vast acres of shallow water and tidal marshes support sixteen species of underwater grasses, also called SAV (submerged aquatic vegetation). Among them are eelgrass, redhead grass and wild celery. Sheltering in the grass beds is a waterfowl feast of small marine animals like clams, worms and crustaceans.
The Chesapeake watershed's human population now measures more than 15 million, with an expected increase to 18 million by 2020. The resulting development has an impact on water quality in the Bay—and hence on the underwater grasses so vital to the food supply of Bay waterfowl.
Scientists believe the Bay probably once supported several hundred thousand acres of SAV, but for decades the grasses have been declining along with the Bay's overall water quality. Many factors have contributed to the decline. One is an excess of nutrients (such as nitrogen) washing into the Bay when fertilizers are applied to lawns and agricultural fields. Another is development that leads to soil erosion, adding silt that clouds Bay waters and reduces the amount of light available to aquatic plants.
Waterfowl that depend heavily on SAV for food have been most seriously affected. Current restoration efforts are aimed at achieving an average of 185,000 acres of SAV by 2010.
- More about Bay grasses and their restoration.