“Chessie BIBI” stream health indicator

Interstate Commission on the Potomac River Basin

Chessie BIBI

The Chesapeake basin-wide index of biotic integrity for stream macroinvertebrates, or “Chessie BIBI,” is a multi-metric index of stream health applicable to freshwater streams and small rivers across the Chesapeake Bay watershed. It is composed of family-level macroinvertebrate metrics (indicators) that are especially responsive to differences between high quality and degraded stream conditions. The index is calculated from stream macroinvertebrate samples collected and counted by state, federal, and local agencies and other groups. Data are integrated into a common database by the Chesapeake Bay Program (CBP) and the Interstate Commission on the Potomac River Basin (ICPRB).

The Chessie BIBI index was developed in 2011 and updated and refined in 2016-2017 with support from the CBP. The final report, appendices, related spreadsheets, and a basin map are available below.

Click here to view an annotated presentation on the Chessie BIBI.

Creating a Management Tool

CBP aims to use the Chessie BIBI as a management tool to track progress in restoring stream health across the Chesapeake Bay watershed. The following is Chesapeake Bay Program’s goal for Stream Health Outcome:

“Continually improve stream health and function throughout the watershed. Improve health and function of ten percent of stream miles above the 2008 baseline for the watershed.”

Turning the BIBI index into an effective management tool requires decisions on when and how to use it. Scientists and managers addressed these issues at an April 2018 workshop. They agreed to measure stream health basin-wide with the Chessie BIBI and selected the 6-year period between 2006 and 2011 as the most practical “2008 baseline.” They identified other needs such as building consensus on what qualifies as 10% improvement, developing indicators of stream function to complement the Chessie BIBI, and using the CBP data protocols and Chesapeake Environmental Data Repository to merge stream datasets in the future.

Click here to view the Stream Health Baseline Workshop Summary.

Quantifying the “2008 Baseline”

Roughly a third of the small watersheds in the Chesapeake region during the 2006 – 2011 baseline period have no macroinvertebrate data, so stream health in these places is estimated with a model that predicts the Chessie BIBI from various landscape and stream features. Data analysis of the combined monitoring and model data indicates about 60% of the Chesapeake basin area supported streams in Excellent, Good, or Fair condition during the baseline period.

Click here for the 2008 Stream Health Baseline Report.

Calculating the Index

In 2019, ICPRB produced a Chessie BIBI package containing the R-scripts, shape files, spreadsheets, and documentation needed to calculate a suite of metrics and the family-level, bioregion-specific Chessie BIBI from raw macroinvertebrate counts. The open source RStudio program will be needed to run the R-scripts.

The package is currently being updated. A new link will be added soon. In the meantime, please use the Contact Us form if you have specific questions.

Chessie BIBI Scores and Ratings v. 2.01

As demonstrated in the Chessie BIBI package, repeated runs of the program can produce slightly different index scores and ratings. This is due to the random selection of individuals in each program run as a sample is reduced to 100 individuals (rarefaction) for comparison purposes. Minor modifications made in 2019 to the habit assignments of a few macroinvertebrate taxa also changed the index scores and ratings at several stations. The scores and ratings used in the 2017 refinement version are called Version 2.0. Those calculated with the 2019 program from the same raw data are called Version 2.01. Both versions are included in the Chessie BIBI package (above).

Chessie BIBI Map

A map showing stream health within the Chesapeake Bay.

Chessie BIBI (family-level version of the bioregion index) ratings for streams and small rivers in the Chesapeake Bay watershed. When sufficient data (n > 3 catchments) are available, HUC12 watersheds are colored per the rating of their average index score. Otherwise, individual sampling locations are indicated and colored per their ratings.

Chessie BIBI Index Development



Full citation: Smith, Z., C. Buchanan, and A. Nagel. 2017. Refinement of the Basin-Wide Index of Biotic Integrity for Non-Tidal Streams and Wadeable Rivers in the Chesapeake Bay Watershed. ICPRB Report 17-02. Interstate Commission on the Potomac River Basin. Available online at www.potomacriver.org.

Baseline Workshop, 2018

A technical workshop at Cacapon State Park W.Va. was held April 5-6th 2018 to establish a “2008 baseline” for the Chessie BIBI. Links to the workshop summary, background materials, and some of the presentations are below: