Overview of the U.S. Geological Survey Chesapeake Bay Ecosystem Program
By Scott Phillips and Bill Caughron
Excerpt from Introduction
The ecosystem of the Chesapeake Bay (fig. 1) has been adversely affected by a combination of nutrient enrichment, toxic substances, sediment, and overharvesting of shellfish and finfish. Excessive nutrient inputs have caused eutrophication and periods of hypoxia (dissolved-oxygen concentrations lower than 1.0 milligram per liter), which in turn have killed and stressed living resources in many areas of the bay. The algal blooms from high nutrient inputs and sediment loads also decrease water clarity, which is largely responsible for the decline of submerged aquatic vegetation (SAV). Submerged aquatic vegetation, one of the most important components of the ecosystem, provides critical habitat for shellfish and finfish and food for waterfowl. Finally, fish health is threatened by toxic dinoflagullates which may be related to adjacent land-use practices.
In 1987, the Chesapeake Bay Program (CBP), a multiagency restoration effort, established a goal to reduce controllable nutrient loads into the estuary 40 percent by the year 2000. The goal was based on the results of a computer model, that indicated a 40-percent reduction in nutrient loads would eliminate hypoxia in the mainstem of the bay. The nutrient-load reduction is expected to decrease the severity of algal blooms in the tributaries and encourage the regrowth of SAV. However, resource managers are concerned that the bay and watershed will respond more slowly to the nutrient-reduction measures than was previously anticipated. Therefore, scientific information on lag times between nutrient inputs and water-quality and living-resource response, is needed to assess the effectiveness of nutrient-reduction strategies. Analysis of long-term biological, chemical, and hydrogeologic records integrated with new collected information can help managers gain a perspective on the bounds of inherent variability of the ecosystem and its effect on restoration goals. The U.S. Geological Survey (USGS), through its Ecosystem Program, collects and interprets scientific information to help resource managers determine the success of management strategies and the response of the ecosystem to nutrient reduction.
