W2 PM Chesapeake Bay Restoration (Part 2)
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in Ballroom 2

(BOY-1117-209225) Historical Patterns and Ecological Interactions Associated with Eutrophication in Chesapeake Bay.

Boynton, W¹, Kemp, W², ¹ Univ MD Chesapeake Biological Lab, Solomons, MD, USA² Univ MD Horn Point Laboratory, Cambridge, MD, USA

ABSTRACT- A synthesis of diverse Chesapeake Bay data sets provided insights regarding eutrophication patterns and ecological consequences. Various analyses indicated initial signs of organic enrichment 200 years ago, increased algal growth and declines in water clarity 100 years ago, and recurring deep-water hypoxia/anoxia and loss of submersed vascular plants since 1950. Degradation of benthic habitats appears to have contributed to declines in abundance and production of mesohaline macrofauna and polyhaline blue crab populations. In contrast, copepod communities, which are heavily grazed, appear relatively unaffected by nutrient-induced changes in food abundance and phytoplankton species composition. Intense fisheries harvest and disease have caused a dramatic decline in oyster reefs and associated filtration of estuarine water and also exacerbated eutrophication effects on phytoplankton and water clarity. There is little direct evidence that overall fisheries production has been affected by nutrient enrichment, but demersal fish catch and food web efficiency have both declined suggesting fundamental changes in ecosystem structure. Ecosystem responses to nutrient load changes tend to be non-linear involving important roles for benthic plants and oxygen effects on sediment biogeochemistry. Recent nutrient load reductions have elicited rapid responses for some ecosystem functions but lags in others.

Key words: eutrophication, chesapeake bay