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 2016 sampling sites.

The overall condition of Chesapeake Bay declined in 2016, with 55% of the Bay’s tidal bottom meeting the Benthic Community Restoration Goals (45% failing), down from 62% in 2015. The largest decline occurred in the Maryland portion of the Chesapeake Bay, with 34% of its tidal bottom meeting the Restoration Goals (66% failing) in 2016, down from 47% in 2015. There was no statiscally significant change in percent area degraded over the 1985-2016 time series.

The decline in benthic condition in 2016 was associated with high hypoxic volumes (waters with low oxygen content in mid summer). High hypoxic volumes were likely the result of prolonged warm temperatures and lack of significant winds in late July 2016. Benthic communities in Chesapeake Bay remain in poor condition, with species diversity and biomass-dominant species declining over the 1995-2016 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: November 29, 2017

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