Ecosystem Processes
How Do Nutrients Affect The Deep
Waters In The Chesapeake Bay?

Nutrients and organic matter enter the bay from a variety of sources, including:  sewage treatment plant effluents, stream inputs, local non-point drainage and direct rainfall on bay waters. A portion of organic matter sinks to the bottom, decomposes and contributes to the development of hypoxic (low oxygen) and anoxic (no oxygen) conditions. Estuarine sediments have the ability to store nutrients that can later allow a "flux" of nutrients from sediments to the water. These fluxes can fuel high rates of phytoplankton growth and biomass accumulation. Once phytoplankton die, they fall to the bottom where they are decomposed by bacteria. The process of decomposition requires the use oxygen.  Therefore, large amounts of organic matter created by dead phytoplankton blooms can deplete oxygen in benthic sediments which can lead to hypoxia or anoxia. Hypoxia and anoxia are common in eutrophic estuarine systems and threaten our living resources, including: SAV, shellfish, fishes and other fauna. The figure below illustrates the various components in the Chesapeake Bay that produce and consume oxygen.

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Illustration of the trajectories for both a degraded eutrophic system and a restored eutrophic system. Colored boxes in the illustration indicate components of the EPC program in the Patuxent River

For more information, please contact Renee Karrh at (410) 260-8628.

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