Community Metabolism of Chesapeake Bay:
Importance of Shallow-water Regions
Nutrient overenrichment can lead to massive growth of single-celled algae and subsequent depletion of oxygen, especially in the Chesapeake Bay's deeper waters. To help monitor the effect of nutrient reduction strategies designed to improve water quality, resource managers need reliable indicators of the Bay's ecological condition. The net community metabolism of the ecosystem — the sum of photosynthesis and daily respiration for all organisms — could serve as such an indicator.
In 1992, Michael Kemp began a project to develop an index that would serve as a measure of trophic condition and oxygen depletion potential. Measuring integrated metabolic process as changes in oxygen concentrations along the Bay's axis, his results to date show significant differences between the upper, mid and lower portions of the Bay.
In the next two years, Kemp, Christopher Madden and Water Boynton are extending this study to cover the Bay's shallow regions, which represent over 50 percent of the Chesapeake's total area. Preliminary results indicate that these regions have metabolic characteristics quite different from the deep areas. For example, the shallow waters can Support considerable algal production; and recycle of nutrients and organic material in bottom waters, thus contributing significantly to net community metabolism. They can also be a source of organic matter to deeper waters which can lead to oxygen depeletion.
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W. Michael Kemp
Christopher J. Madden
Horn Point Laboratory
University of Maryland Center for Environmental Science
Walter R. Boynton
Chesapeake Biological Laboratory
University of Maryland Center for Environmental Science
University System of Maryland
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