Estuarine Coastal Condition (Southeast Blueprint Indicator)

Reason for Selection This index measures the condition of the nation’s estuaries following standard national methodologies and is synthesized by the U.S. Environmental Protection Agency (EPA) roughly every five years. Estuaries serve as important nursery habitat for wildlife, including many species of fish and shellfish eaten as seafood. They also improve water quality by filtering out sediments and pollutants, provide recreational opportunities, and support coastal economies (NOAA 2019). The estuaries and surrounding coastal habitats of the Southeast coast “serve as important stopovers for migratory birds along the Atlantic Flyway as well as nurseries for fish and other animals. The highly productive ecosystems of Southeast estuarine waters contribute to commercial and recreational fishing. The Southeast Coast provides a wealth of economic and ecosystem services that sustain local economies and quality of life. These services include storm-surge and sea-level protection, maritime transportation and trade, commercial and recreational fisheries, and tourism.” Input Data * Environmental Protection Agency (EPA) [National Coastal Condition Assessment] (NCCA): [2010 data] and [2015 data]; [download NCCA data] The NCCA surveys the estuaries and nearshore waters of the Great Lakes using various indicators of ecological condition and human health risk. We use four ecological indicators (USEPA 2015, 2021): 1. The water quality/eutrophication index - includes measures of phosphorus, nitrogen, water clarity, chlorophyll a, and dissolved oxygen 2. The sediment quality index - includes sediment contaminant levels and sediment toxicity to live organisms 3. The benthic/biological condition index – measures the condition of the community of macroinvertebrates (worms, mollusks and crustaceans) living in the sediment, based on diversity, abundance and sensitivity to pollution 4. The fish tissue contaminants/ecological fish tissue quality index - measures the concentrations of metals and organic contaminants in fish and estimates potential harm to the wildlife that eat them This indicator is scored in the same way as EPA’s scoring: 1 = poor, 3 = fair, and 5 = good. The 2015 assessment reported no strong regional trends in coastal condition between 2010 and 2015, so we combined both assessments to increase the density of the point data used to create the interpolation. * [NOAA coastal relief model]: Shallow water bathymetry derived by extracting the area with depths from 0-10 m; we converted this spatial extent to a shapefile and used it to constrain the interpolation of the mean estuarine condition index * [Southeast Blueprint 2023 extent] Mapping Steps * The 2010 and 2015 point data contain separate fields for the water quality index, the sediment quality index, the fish tissue index, and the benthic index. Assign numeric values based on EPA’s scoring system. If a point scores poor in these fields, assign it a value of 1. If a point scores fair in these fields, assign it a value of 3. If a point scores good in these fields, assign it a value of 5. * Add and calculate a field to contain the average of the four indices for all sites sampled in either 2010 or 2015. Note: Sites are drawn randomly so are not usually sampled in both timesteps. * Import the tabular data into ArcPro and join to the table of EPA sampling locations. * Interpolate the mean EPA coastal condition index value using Spline with Barriers. To avoid interpolating estuarine scores over land areas, use as the barriers input the shallow water extent from the NOAA coastal relief model. If a shallow water bathymetry polygon does not contain an EPA sampling location, that polygon is classified as 0 in a later step because we don’t know anything about its condition. Note: This operation had to be accomplished in two steps (Gulf and Atlantic regions) because of file size limitations. * Merge the Gulf and Atlantic outputs and clip the resulting raster to the 0-10 m shallow water layer from the NOAA coastal relief model. * Reclassify the above raster into the 5 classes seen in the final indicator values below: * 0.3087-2 = 1 (Note: 0.3087 is the minimum value over the entire raster) * 2-2.4 = 2 * 2.4-3.7 = 3 * 3.7-4 = 4 * 4-5 = 5 * Intersect the shallow water bathymetry polygon with the EPA sampling locations. If a shallow water extent polygon does not contain an EPA sampling location, use the Calculate Field function to classify that polygon as 0 because we don’t know anything about its condition. Assign a value of 1 to all other polygons that do contain EPA sampling locations. * Convert the resulting vector layer to raster. * Multiply this new raster by the mean coastal condition index raster to produce a result that shows the mean coastal condition index where that value is known, and 0 for shallow estuaries lacking an EPA condition score. Zero values are intended to help users better understand the extent of this indicator and make it perform better in online tools. * As a final step, clip to the spatial extent of Southeast Blueprint 2023. Note: For more details on the mapping steps, code used to create this layer is available in the [Southeast Blueprint Data Download] under > 6_Code. Final indicator values Indicator values are assigned as follows: 5 = Good 4 = Good to fair 3 = Fair 2 = Fair to poor 1 = Poor 0 = Shallow estuary not assessed for condition Known Issues * The CCA was designed to support regional interpretations of coastal condition, not site-level interpolation as used in this indicator. As a result, estimates for areas far from NCCA sampling sites are highly uncertain. * This indicator uses only two snapshots in time in a highly dynamic system. * There is typically a significant time lag between the year the data is collected, and the year the data is published (allowing time for analysis, quality assurance, compiling the report, etc.). As a result, even the most recent available NCCA data (collected in 2015) is somewhat outdated. * There is an error in the interpolation off the coast of Pensacola, FL that creates an unusual spatial pattern in the indicator. However, this pattern is not reflected in the final Blueprint as the entire area scores highest priority. Disclaimer: Comparing with Older Indicator Versions There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email [hilary_morris@fws.gov]). Literature Cited National Oceanic and Atmospheric Administration (NOAA). Last updated February 1, 2019. Life in an estuary. [[https://www.noaa.gov/education/resource-collections/marine-life/life-in-estuary]]. U.S. Environmental Protection Agency (EPA). August 2021. National Coastal Condition Assessment: A Collaborative Survey of the Nation’s Estuaries and Great Lakes Nearshore Waters (National Coastal Condition Assessment 2015). EPA 841-R-21-001. [[https://www.epa.gov/system/files/documents/2021-09/nccareport_final_2021-09-01.pdf]]. U.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. [[https://www.epa.gov/national-aquatic-resource-surveys/national-coastal-condition-reports]]. U.S. Environmental Protection Agency. Office of Water and Office of Research and Development. (2015). National Coastal Condition Assessment 2010 (EPA 841-R-15-006). Washington, DC. December 2015. U.S. Environmental Protection Agency (EPA). Last updated June 3, 2022. Southeast Coast Estuaries: National Coastal Condition Assessment 2015 (Setting). [[https://www.epa.gov/national-aquatic-resource-surveys/southeast-coast-estuaries-national-coastal-condition-assessment]].