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EUTROPHICATION OF CHESAPEAKE BAY: HISTORICAL TRENDS AND ECOLOGICAL INTERACTIONS
Citation:
Kemp, Boynton, J. Adolf, D. F. Boesch, W. Boicourt, G. Brush, J. Cornwell, T. R. Fisher, P. Glibert, J. Hagy, J.D., III, L. W. Harding, E. Houde, D. Kimmel, W. Miller, R. Newell, M. Roman, E. Smith, AND J. Stevenson. EUTROPHICATION OF CHESAPEAKE BAY: HISTORICAL TRENDS AND ECOLOGICAL INTERACTIONS. LIMNOLOGY AND OCEANOGRAPHY 303:1-29, (2005).
Impact/Purpose:
To provide a synthesis of ecological responses to eutrophication in the Chesapeake Bay
Description:
This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in approximately 200 y-old strata, while signs of increased phytoplankton and decreased water clarity first appeared approximately 100 y ago. Severe, recurring deep-water hypoxia and loss of submersed vascular plants were first evident only since 1950s and 1960s respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food-chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in oyster stocks and associated Bay water filtrations, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea-level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and the efficiency with which primary production is transferred into harvest, suggest fundmental shifts in ecological structure. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others.