Chesapeake Bay Ecosystem Program

WRD PROJECT #: MD130
PROJECT CHIEF: Phillips, Scott W.
BEGIN DATE: 01-May-1996
END DATE: 30-September-2002

Customers currently supporting the project:

U.S. Geological Survey

Chesapeake Bay Ecosystem Program Homepage

Problem

The ecosystem of the Chesapeake Bay, the Nation's largest estuary, has been negatively affected by a combination of population growth and natural processes during the past several centuries. Water quality is degraded as a result of nutrient enrichment, toxic substances, and sediment. Eutrophication, brought on by excessive nutrients entering the Bay, was identified as the primary cause of periods of hypoxia in the estuary, which in turn has killed and stressed living-resources in many areas of the Bay. The high nutrient and associated sediment loads have also decreased water clarity, which is largely responsible for the decline in submerged aquatic vegetation (SAV). Submerged aquatic vegetation is considered one of the most important components of the ecosystem because it provides critical habitat for shellfish and finfish and food for waterfowl. The Chesapeake Bay Program, a coordinated Federal and State restoration effort, has signed a new Chesapeake Bay Restoration agreement that includes goals to reduce nutrients and sediment entering the Bay to improve water-quality conditions for living resources.

Objectives

One of the most critical needs for the restoration effort in the Bay is to improve the current understanding of the response of the Chesapeake Bay watershed and estuary to changes in the sources and transport of nutrients and sediment. Water quality and the ecological balance of the Bay should respond positively to the Bay Program restoration efforts, but the effects will take time to be transmitted through the entire watershed and into the estuary. Therefore, data on water quality and living resource response must be understood in relation to changes in management practices have and climate variability and integrated with data at different spatial scales including the river basins and the estuary. The principal temporal scales that need to be considered are (a) recent past (1-15 years); (b) past 40 years; and (c) past 4 centuries. By understanding the response time of the ecosystem to nutrient and sediment changes and transport at several spatial scales over recent time, the USGS can provide information needed by the Bay Program and resource managers to help meet the nutrient and sediment reduction goals. Understanding the response time of the ecosystem to longer periods can provide an assessment of the effect of population growth and natural long-term variations in the ecosystem, such as variation in flow (floods and droughts) and sea level and climate change, on sedimentation rates and their effect on critical habitat of benthic organisms, SAV, and biodiversity.

Approach

Participate in the effort to expand the cartographic data base and associated data sets for the Bay Program. Further define the factors that affect the sources, sinks, transport, and residence time of nutrients and sediments in major areas that drain into the Bay and their relation to the estuary. Quantify the nutrient load entering the Bay from Groundwater and identify the effect of residence time of nutrients in the Groundwater system on water-quality response in the rivers and the Bay. Develop a better understanding of the hydrologic, geologic, and water-quality factors affecting living resources and their associated habitat in the rivers, tidal tributaries, and the estuary. Study the history and evolution of the Chesapeake Bay ecosystem and its response to changes in sedimentation, salinity, and nutrient load during historic and geologic time scales. Results are provided to the Chesapeake Bay Program through USGS participation on technical subcommittee and publication of reports and journal articles.