This indicator is a continuous index of water quality, sediment quality, and benthic community condition that reflects the overall abiotic status of open water estuaries.
Reason for Selection
This index measures the overall abiotic condition of the estuarine system and captures human impacts on the environment like nonpoint source pollution. It is well-monitored and is synthesized by the Environmental Protection Agency (EPA) every five years. It integrates measures of water quality, sediment quality, and benthic habitat quality.
– The EPA Coastal Condition Index (CCI) is a ranking derived from a water quality index, sediment quality index, benthic index, coastal habitat index, and fish tissue contaminants index (US EPA 2012). The coastal habitat index and fish tissue contaminants are region-wide measures and were not included in the indicator. For our objectives, we only used the indices derived from point sampling (water quality index, sediment quality index, benthic index), and the data were scored in the same way as EPA’s scoring: 1 = poor, 3 = fair, and 5 = good.
– Both the 2010 (sampling conducted in 2010) and 2006 (sampling conducted from 2003-2006) data were used in this indicator. In calculating the overall rank for each point, the mean of the three indices was taken for each sampling period.
– Blueprint 2.1 ecosystem map (see Appendix A)
1) The 2006 data and the 2010 point data were converted to separate rasters with 200 m pixel cell size using interpolation. Interpolation of point data from the CCI was conducted with the ArcGIS Spatial Analyst-Inverse Distance Weighted function. This function interpolates among points by weighting a specified number of nearby points as having a large influence if they are in close proximity and a declining influence as they are farther away. We used a power function of 5 to emphasize local samples (> 5 had little influence), the 3 nearest points were used in interpolation, and a maximum distance to points of 36 km was used. CCI scores ranged continuously from 1-5.
2) The 2006 and 2010 raster data were averaged together to create the final score.
3) We clipped the resulting raster to the “Estuaries - open water” class in the Blueprint 2.1 ecosystem map.
Final indicator values
The final indicator is continuous, with values ranging from:
High: 5 (good water quality, sediment quality, and benthic community condition)
Low: 1.13 (poor water quality, sediment quality, and benthic community condition)
– Estimates for areas not near monitoring points used in the Coastal Condition Index are highly uncertain. This is particularly true for most areas along the Gulf where there are few points within the South Atlantic region.
– This indicator uses only two snapshots in time in a highly dynamic system.
– Please note that this indicator is at a 200 m resolution, which is coarser than other indicators used in the 2020 Blueprint. This is an artifact of the approach used for the marine environment in Blueprint 2020.
Disclaimer: Comparing with Older Indicator Versions
There are numerous problems with using South Atlantic indicators for change analysis. Please consult Blueprint staff if you would like to do this (email email@example.com).
Literature CitedU.S. Environmental Protection Agency (EPA). 2012. National Coastal Condition Report IV. Office of Research and Development/Office of Water. Washington D.C. EPA-842-R-10-003. June 2014. http://water.epa.gov/type/oceb/assessmonitor/nccr/upload/0_NCCR_4_Report_508_bookmarks.pdf
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