The Biotic Index combines the aquatic grasses, Benthic Index of Biotic Integrity, and Phytoplankton Index of Biotic Integrity into a single overarching score.
Chesapeake Bay - Indicator Details:
This map shows the 2011 Biotic Index scores for each of the 15 reporting regions. Highest Biotic Index scores occurred in the Upper Bay and Lower Bay regions. The Upper Bay scored high for all three biotic indicators. The lowest Biotic Index scores occurred in the Elizabeth and Patuxent River regions. Biotic Index scores increased in six regions in 2011, decreased in seven, and remained steady in two. This was the first year a Biotic Index grade has been assigned for the Elizabeth River because Benthic IBI data was available for 2011.
This map shows Biotic Index values for each of the regions. Biotic Index for each reporting region is the average of the aquatic grasses, Benthic Index of Biotic Integrity, and Phytoplankton Index of Biotic Integrity scores.
Comparison of Bay Health Index scores for 2011 () compared to ()
|0 20 40 60 80 100|
|Upper Western Shore|
|Lower Western Shore (MD)|
|Lower Eastern Shore (Tangier)|
|Upper Eastern Shore|
|Patapsco and Back Rivers|
This figure ranks each region from best to worst for the Biotic Index. Highest ranked region in 2011 was the Lower Bay, with a score of 65% (moderately good). Second highest ranked region was the Upper Bay, at 61%. High Biotic Index Scores in these two regions are generally due to good benthic community scores. The Elizabeth and Patuxent River regions had the lowest Biotic Index scores in 2011, both scoring less than 20% (very poor). Biotic index scores increased in six regions in 2011 compared to 2010 and decreased in seven.
This graph is dynamic, you can: a) show and hide items by clicking them in the legend, b) select year range (click and drag), and c) export as an image.