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Browse History: Benthic Index of Biotic Integrity (2010)
Indicator Icon Benthic Index of Biotic Integrity

The Benthic Index of Biotic Integrity (BIBI) measures the condition of the benthic community (e.g. clams and others) living in or on the soft bottom areas of the Bay. These organisms are a key food source for many species including perch, spot, and croaker.

Chesapeake Bay - Indicator Details:





  Indicator Selection Diagram


Threshold Map


This map shows the overall Benthic Index of Biotic Integrity (Benthic IBI) scores for each of the 15 reporting regions in 2010. Benthic IBI evaluates the health of the benthic, or bottom-dwelling community (in soft-bottomed areas only).

Overall, benthic condition within Chesapeake Bay during 2010 was moderate, which was not a significant change from 2009. The highest scoring region in 2010 was the Upper Bay region, where benthic condition was classified as moderately good. Second best Benthic IBI occurred in the Lower Bay region where conditions are classified as moderately good. Lowest scores occurred in the Rappahannock River, Mid Bay, and Lower Western Shore (MD) regions, where the Benthic IBI condition was classified as poor or very poor.

Creating this map
Samples for assessing benthic community (bottom habitat) were collected at approximately 250 sites in August and September by the Chesapeake Bay Benthic Monitoring Program. Data from each sampling station is used to calculate a Benthic Index of Biotic Integrity (BIBI) score. The proportion of the reporting regions area meeting the Benthic Index of Biological Integrity score is calculated and mapped.

Data Map


This map shows the Benthic Index of Biotic Integrity (Benthic IBI) values for the summer of 2010. This Benthic IBI evaluates the health of the benthic community, or bottom-dwelling community (in soft-bottomed areas only). Values between 1 and 3 are considered to be degraded relative to reference communities, while values between 3 and 5 are considered to be close to reference community condition (i.e., moderate to good condition).

Stations with relatively good benthic community health tended to be in the Upper Bay, Lower Bay, and James River regions. Areas with poor Benthic IBI scores can be seen in many regions including the Rappahannock River, Mid Bay, and the smaller tributaries within the Lower Western Shore (MD) region. The Upper Western Shore benthic community declined sharply this year.

Understanding this map
Samples for assessing the Benthic Index of Biotic Integrity (soft bottom community condition) were collected at approximately 250 sites in August and September. Data from each sampling station is used to calculate a Benthic IBI score which ranges from 1 (poor benthic condition) to 5 (good benthic condition).

Ranking


Comparison of Bay Health Index scores for 2010 () compared to
()


Score Legend
 Score (%)
 0               20               40               60               80              100
  
Upper Bay  
Lower Bay  
James River  
Lower Eastern Shore (Tangier)  
Overall Bay  
Patapsco and Back Rivers  
York River  
Potomac River  
Choptank River  
Upper Eastern Shore  
Upper Western Shore  
Patuxent River  
Mid Bay  
Rappahannock River  
Lower Western Shore (MD)  
 0
Elizabeth River  
 Insufficient Data

This figure ranks each region from best to worst for the indicator Benthic Index of Biotic Integrity (Benthic IBI). The Benthic IBI evaluates the health of the benthic community, or bottom-dwelling community (soft-bottomed areas only).

The highest scoring region in 2010 was the Upper Bay, where benthic condition was classified as moderately good. The second best Benthic IBI occurred in the Lower Bay region where conditions are classified as moderately good. Three regions had very poor Benthic IBI scores in 2010, these being the Rappahannock River, Mid Bay, and the Lower Western Shore regions. Overall, benthic community condition declined in 2010, compared to 2009. It is not possible to provide a score for the Elizabeth River Region until 2010 monitoring data becomes available later this year.


Excel Spreadsheet