Separation of Long-Term Variation in Benthic Organisms into Major Components

The benthic element of the Chesapeake Bay Monitoring Program, jointly sponsored by the Maryland Office of Environmental Programs (OEP) and the Maryland Power Plant Research Program (PPRP), is designed around the concept that benthic populations are likely to respond to changes in water and sediment quality resulting from specific management efforts. Both the OEP and PPRP monitoring programs have demonstrated that benthic organisms are sensitive indicators and integrators of cumulative environmental effects from a range of anthropogenic perturbations as long as major sources of natural variation are accounted for and partitioned. Results from the initial years of the benthic program element and from the PPRP long-term benthic monitoring program are being used to characterize major sources of variation in benthic communities. Annual salinity fluctuations are a major factor affecting long-term patterns in the benthos. Salinity is also the major factor controlling regional benthic distributions. Differences in sediment characteristics and dissolved oxygen concentrations that occur from nearshore to deepwater habitats control local benthic distributions. Spatial and temporal variations in sediment inputs of organics (detrital and phytoplankton) are reflected in patterns of benthic standing stocks. Benthic organisms respond sensitively and in an interpretable manner to changes in estuarine water and sediment quality.