Long-Term Trends of Water Quality and Biotic Metrics in Chesapeake Bay: 1986 to 2008 |
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| Authors: | Michael R. Williams Solange Filoso Benjamin J. Longstaff William C. Dennison |
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| Affiliation: | (1) Annapolis Synthesis Center, University of Maryland Center for Environmental Science, Suite 301, Annapolis, MD 21401, USA;(2) Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, 1 Williams Street, P.O. Box 38, Solomons, MD 20688, USA;(3) NOAA-UMCES Partnership, Cooperative Oxford Laboratory, Oxford, MD 21654, USA;(4) Present address: Lake Simcoe Region Conservation Authority, 120 Bayview Parkway, P.O. Box 282, Newmarket, ON, L3Y 4X1, Canada |
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| Abstract: | We analyzed trends in a 23-year period of water quality and biotic data for Chesapeake Bay. Indicators were used to detect trends of improving and worsening environmental health in 15 regions and 70 segments of the bay and to assess the estuarine ecosystem’s responses to reduced nutrient loading from point (i.e., sewage treatment facilities) and non-point (e.g., agricultural and urban land use) sources. Despite extensive restoration efforts, ecological health-related water quality (chlorophyll-a, dissolved oxygen, Secchi depth) and biotic (phytoplankton and benthic indices) metrics evaluated herein have generally shown little improvement (submerged aquatic vegetation was an exception), and water clarity and chlorophyll-a have considerably worsened since 1986. Nutrient and sediment inputs from higher-than-average annual flows after 1992 combined with those from highly developed Coastal Plain areas and compromised ecosystem resiliency are important factors responsible for worsening chlorophyll-a and Secchi depth trends in mesohaline and polyhaline zones from 1986 to 2008. |
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