Chesapeake Bay Benthic Monitoring Program

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How's the Bay Doing?

Benthic community condition in Chesapeake Bay is assessed using a benthic index of biotic integrity (B-IBI), which evaluates the ecological condition of a sample by comparing values of key benthic community attributes to reference values expected under non-degraded conditions in similar habitat types. Probability-based sampling and the B-IBI are used to estimate the area of Chesapeake Bay with degraded bottom habitat condition.

Click here to see a map of the bottom habitat condition for each of the 2014 sampling sites.

The area with degraded benthic community condition (failing the Restoration Goals) in the Maryland portion of the Chesapeake Bay decreased in 2014, from 64% to 60%, and the area with degraded benthos in Virginia decreased from 41% to 19%. The Patuxent River, Potomac River, and Maryland mainstem were in worst condition. Baywide, the area with degraded benthos decreased from 53% to 41%, the lowest percent degraded area of the monitoring record.

The large improvement in benthic condition observed between 2013 and 2014 was associated with exceptionally low hypoxic volumes (waters with low oxygen content), especially in the Virginia portion of the Bay. Notwithstanding this improvement, benthic communities in Chesapeake Bay remain in poor condition, with species diversity and biomass-dominant species declining over the 1995-2014 time period.

See results at right for further detail.

Patterns of condition within each stratum can be explored from the interactive stratum map below. 

Click on the stratum name or area for detailed results


      Summary of Results

      Baywide Results Graph

      Sampling Strata


Strata Comparison for Wet and Dry Years

      Areas Failing Goals

      Fixed Station Trends

   Recent Research Results


Benthic Feeding Habitats of Seaducks


Low dissolved oxygen and benthic production



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Revised: Sept 25, 2015

Upper Bay Western Tribs Eastern Tribs Mainstem Patuxent Potomac Upper Bay Western Tribs Eastern Tribs Mainstem Patuxent Potomac