This indicator measures the protected status or potential stress (i.e., shipping traffic, dredge disposal) of solid substrate and rocky outcroppings.
Reason for Selection
Hardbottom extent and condition is particularly important for a variety of marine species. Hardbottom provides an anchor for important seafloor habitat such as deepwater corals, plants, and sponges, supporting associated invertebrate and fish species. It is impacted by landscape scale stressors (e.g., water quality degradation, mining, dredging, and beach renourishment), can be monitored and modeled with existing information, and is widely used and understood by diverse partners.
Input Data
– The Nature Conservancy’s (TNC) South Atlantic Bight Marine Assessment. Chapter 3 of the final report provides more details on the seafloor habitats analysis.
– South Atlantic Fishery Management Council (SAFMC) Deepwater Coral Habitat Areas of Particular Concern (Coral HAPCs)
– Commercial Vessel Density (2009 - 2010)
– Ocean dredge disposal sites for FL, GA, SC, and NC
– Blueprint 2.1 ecosystem map (see Appendix A)
Mapping Steps
Indicators that have not changed since Blueprint 2.0 were initially computed, or in the case of existing data, resampled to 1 ha spatial resolution using the nearest neighbor method. For computational reasons, we then used the ArcGIS Spatial Analyst-Aggregate function to rescale the resolution to 200 m. The aggregate function avoided loss of detail by taking the maximum value of each cell in the conversion (e.g., species presence).
We combined hardbottom predictions, areas of high commercial shipping traffic, dredge disposal sites, and SAFMC Deepwater Coral HAPCs to classify three types of potential hardbottom condition: areas likely stressed by human activity (category 1, those overlapping with high shipping traffic or dredge disposal sites), areas less likely stressed by human activities (category 2, comprised of areas not part of category 1, but lacking the additional protections in the next category), and areas likely in best condition due to additional protections (category 3, those that are part of the Deepwater Coral HAPCs and have additional restrictions on fishing gear and coral harvest). We defined high commercial shipping traffic as 501 vessels and above (classification code 7 and above).
We clipped the resulting raster to the “Marine” class in the Blueprint 2.1 ecosystem map.
Final indicator values
Data were classified into the following rankings:
3 = Hardbottom likely in best condition due to additional protections
2 = Hardbottom less likely stressed by human activities
1 = Hardbottom likely stressed by human activities
0 = Hardbottom not predicted
Known Issues
– Underpredicts hardbottom in many areas.
– Hardbottom under protection can take a long time to recover. Protected status may not always indicate hardbottom currently in good condition and may also include areas likely to be in good condition in the future if current protections continue.
– This indicator only considers commercial shipping traffic and dredge disposal sites as threats. Other threats, such as fishing gear, energy exploration/production, and impacts to water quality are not included.
– While this layer has a 200 m resolution, some of the source data was coarser than that, and some was finer.
– 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.
– While this layer has a 200 m resolution, some of the source data was coarser than that, and some was finer.
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 hilary_morris@fws.gov).
Literature Cited
Anderson, M.G., A. Barnett, M, Conley, K. Goodin, J. Prince and K. Weaver. 2015. Seafloor Habitats of the South Atlantic Bight Marine Region. in Conley, M, M.G. Anderson, L. Geselbracht, eds. The South Atlantic Bight Marine Ecoregional Assessment. The Nature Conservancy, Eastern U.S. Division, Boston, MA. [].
Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), National Ocean Service, Coastal Services Center. 2012. 2010 United States Automatic Identification System Database, Commercial Vessel Density (2009 - 2010). NOAA’s Ocean Service, Coastal Services Center. Available: http://gsaaportal.org/explore/catalog#commercial-vessel-density-2009-2010-links.
Florida Fish and Wildlife Conservation Commission (FWC), Fish and Wildlife Research Institute (FWRI). 2008. Deepwater Coral HAPCs. South Atlantic Fishery Management Council (SAFMC). Available: http://www.safmc.net/ecosystem-management/mapping-and-gis-data.
U.S. Army Corps of Engineers. 2010-2013. Ocean dredged material disposal sites for the state of North Carolina, South Carolina, Georgia, Florida. Available: http://gsaaportal.org/explore/catalog#ocean-dredge-material-disposal-areas-links.
