Environmental Science

Chesapeake Bay Watch

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Science  31 Jan 2003:
Vol. 299, Issue 5607, pp. 629
DOI: 10.1126/science.299.5607.629c

Eutrophication of lakes, bays, and estuaries caused by the addition of nutrients derived from human activities is a serious environmental problem. The Chesapeake Bay, one of the most productive and important ecosystems in the continental United States, has been seriously affected by nutrient excess and remains at great risk for the foreseeable future.

In order to establish a history of the anthropogenic contribution to primary productivity there, Colman and Bratton have measured the biogenic silica content of well-dated Chesapeake Bay sediments from the past 1500 years. Because diatoms are the major primary producers in the bay, biogenic silica is a good proxy for productivity in the overlying water column. Comparison of sedimentation and productivity before and after European settlement shows that both sediment and biogenic silica fluxes in Chesapeake Bay waters have increased by factors of 4 to 5 since settlement. These results quantify the range of changes that have occurred in response to human activity and should be useful in the design of nutrient and suspended-sediment targets for restoration of the bay. — HJS

Geology31, 71 (2003).

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