Conserving the Chesapeake Bay

An intimate relationship between ducks and water quality restoring habitat in an historic waterfowling region

By Tina Yerkes, Ph.D.

In Sommer no place affordeth more plenty of sturgeon, nor in winter more abundance of foule.”—John Smith 1607-08

Once a mecca for wintering waterfowl, Chesapeake Bay has had its fair share of abuses. When John Smith arrived in the early 1600s, he found a remarkable place with abundant natural resources, most notably wintering waterfowl. Although it is still an amazing place, the bay has undergone dramatic changes since that time.

Forests were cleared for settlement, wetlands were drained for agriculture, and land was converted to make way for the more than 15 million people who now live in this watershed. All of these human-induced changes have resulted in a major underlying problem: poor water quality. The byproducts of runoff from 64,000 square miles of the watershed accumulate in the bay. The most noted culprits are sediments, and nutrients like nitrogen and phosphorus. Sedimentation from erosion, construction, forestry, and agricultural practices causes murky water, which prevents light from reaching submerged aquatic vegetation (SAV). Increased nutrients such as nitrogen and phosphorus come from fertilizers, runoff from livestock operations, and outflow from sewage-treatment plants. These nutrients act as fertilizers in the water, too, causing algae growth that blocks out light and deprives SAV of oxygen.

Because light and oxygen cannot reach the SAV, it dies. SAV such as wild celery is the cornerstone of the food chain in the bay. Historically, there were more than 200,000 acres of SAV. By 1984, only 38,000 acres remained. SAV is not only important to waterfowl, it also provides habitat for spawning and nursery fishes, shellfish, and crabs. Unfortunately, the bay has suffered decreased fish populations, decreased commercial crab and oyster harvests, and significantly fewer waterfowl as the result of SAV loss.

Chesapeake Bay lies in the middle of the Atlantic Flyway where seasonal flights of millions of birds are common. The bay was once a favored wintering ground, especially for diving ducks. Dramatic decreases in wintering populations have been observed in redheads (-97 percent), canvasbacks (-63 percent), and scaup (-49 percent). Although each species will feed on the 16 different species of SAV, each has its preferences. The decline in redhead numbers was so dramatic because the birds overwhelmingly preferred ‘redhead grass' and were not successful in switching their diets to other sources. Canvasbacks numbers did not decrease as much because these ducks switched from their preferred wild celery to clams. Oddly enough, at the same time, wintering Canada and snow goose numbers have increased significantly because these species are very adaptable and adjusted their diets to agricultural-based products.

Chesapeake Bay was the first in the nation to be targeted for restoration as an integrated watershed. Coordinated efforts began in the 1980s, although the problem was recognized much earlier. Waters are cleaner now than they were 10 to 15 years ago and, in 1993, more than 73,000 acres of SAV were mapped.

What happened to clean up the bay? Coordinated restoration efforts of multiple conservation-minded partners representing all possible agencies and nonprofits began to restore wetlands and riparian zones around bay area waterways.

One of the most important functions of wetlands is to restore and maintain water quality. Wetlands upstream from the bay can filter sediments and remove pollutants from water before it reaches the bay itself. Wetlands are capable of removing up to 90 percent of nitrogen and 80 percent of phosphorus from water, as well as capturing particulate matter suspended in runoff.

The challenge becomes where to work within the 64,000-square-mile watershed to most effectively improve water quality through wetland restoration activity. In order to do our best with limited resources, DU developed the Chesapeake Bay Planning Network, which targets and ranks subwatersheds for restoration (see sidebar). Restoration activities in these subwatersheds will improve the quantity and quality of SAV for redheads and canvasbacks.

Focusing within these priority watersheds, biologists work with private and public landowners to restore and enhance wetlands, plant upland grass buffers, reforest riparian corridors, and improve coastal salt-marsh habitats, all of which improve water quality in the bay. DU restores previously converted wetlands to improve water quality and provide much-needed waterfowl and wildlife habitat. Riparian forests provide stream bank stabilization and act as buffers, filtering excess nutrients from runoff before it enters adjacent streams. Warm-season grass plantings perform a similar function. They filter sediment from surface runoff and uptake excess nutrients from groundwater. Grassland buffers are also effective in preventing topsoil erosion. Additionally, grass plantings provide habitat for waterfowl, upland game birds, and a variety of nongame species.