Imperiled Aquatic Species (Southeast Blueprint Indicator)

Reason for Selection According to the Southeastern Freshwater Biodiversity Conservation Strategy, “the Southeastern United States is a global hotspot of freshwater biodiversity, supporting almost two-thirds of the country’s fish species, over 90% of the US total species of mussels and nearly half of the global total for crayfish species. More than a quarter of this region’s species are found nowhere else in the world. Unfortunately, this region is also a hotspot for imperilment. The number of imperiled freshwater fish species in the Southeast has risen 125% in the past 20 years” (RBC and TNACI 2023). This indicator identifies areas with abundant rare and endemic aquatic species that would benefit from conservation action. It captures patterns of rare and endemic species diversity not well-represented by other freshwater indicators. The Southeast Aquatic Resources Partnership (SARP) tracks the number of aquatic animal species in different conservation categories, including Species of Greatest Conservation Need (SGCN), Regional SGCN (RSGCN), and threatened or endangered. To depict the aquatic priorities of state fish and wildlife agencies, this indicator previously used SGCN, which are identified in each State Wildlife Action Plan (SWAP) as most in need of conservation action. In 2024, this indicator switched to using RSGCN. RSGCN are regional priority species derived from all Southeast SWAPs using a set of consistent criteria, such as level of conservation concern, regional stewardship responsibility, and biological or ecological significance (Terwilliger Consulting 2019). Using RSGCN provides more clarity and focus for regional conservation and enhanced opportunities for multi-state collaboration. It also accounts for differences in the ways aquatic species are identified as SGCN in each SWAP, which caused the indicator to overprioritize some states because they had a more comprehensive SGCN list, but not necessarily more aquatic biodiversity. Input Data * [Southeast Blueprint 2024 extent] * [Southeast Aquatic Resources Partnership] (SARP) RSGCN HUC12 summaries SARP provided these summaries on May 8, 2024 as a spreadsheet containing the ID number for each HUC12 watershed and an attribute for the number of aquatic animal RSGCN observed in that watershed. This dataset is based on state Natural Heritage Program occurrence records for fishes, mussels, snails, crayfish, and amphibians. It was last updated in April 2024. More information on this dataset is available in the appendix of [the Blueprint development process pdf]. * Estimated Floodplain Map of the Conterminous U.S. from the [Environmental Protection Agency’s (EPA) EnviroAtlas]; [see this factsheet] for more information; [download the data] The EPA Estimated Floodplain Map of the Conterminous U.S. displays “...areas estimated to be inundated by a 100-year flood (also known as the 1% annual chance flood). These data are based on the Federal Emergency Management Agency (FEMA) 100-year flood inundation maps with the goal of creating a seamless floodplain map at 30-m resolution for the conterminous United States. This map identifies a given pixel’s membership in the 100-year floodplain and completes areas that FEMA has not yet mapped” (EPA 2018). * [National Hydrography Dataset Plus (NHDPlus) Version 2.1 medium resolution catchments] (note: V2.1 is just the current sub-version of the dataset generally called NHDPlusV2); [view the user guide] Catchments A catchment is the local drainage area of a specific stream segment based on the surrounding elevation. Catchments are defined based on surface water features, watershed boundaries, and elevation data. It can be difficult to conceptualize the size of a catchment because they vary significantly in size based on the length of a particular stream segment and its surrounding topography—as well as the level of detail used to map those characteristics. To learn more about catchments and how they’re defined, check out these resources: * [An article from USGS explaining the differences between various NHD products] * The glossary at the bottom of [this tutorial for an EPA water resources viewer], which defines some key terms Mapping Steps * Join the RSGCN count table to the HUC12 spatial data. * Convert to a 30 m raster, where the values represent the number of RSGCN. * Reclassify the species count values to the 1-9 indicator values below. * Mask the resulting raster to the EPA estimated floodplain. Assign a value of 0 to all areas outside the EPA floodplain. Zero values are intended to help users better understand the extent of this indicator and make it perform better in online tools. * Mask the resulting floodplain-masked raster to the NHDPlus medium resolution catchments layer to remove values in the nearshore environment. * As a final step, clip to the spatial extent of Southeast Blueprint 2024. 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: 9 = 8+ aquatic animal Regional Species of Greatest Conservation Need (RSGCN) observed 8 = 7 aquatic animal RSGCN observed 7 = 6 aquatic animal RSGCN observed 6 = 5 aquatic animal RSGCN observed 5 = 4 aquatic animal RSGCN observed 4 = 3 aquatic animal RSGCN observed 3 = 2 aquatic animal RSGCN observed 2 = 1 aquatic animal RSGCN observed 1 = 0 aquatic animal RSGCN observed 0 = Not identified as a floodplain Known Issues * As this indicator is based on occurrence records, poorly surveyed areas may be scored too low. Therefore, this data does not imply absence of species. * While this indicator generally includes the open water area of reservoirs, some open water portions of reservoirs (e.g., Kerr Lake in NC/VA) are missing from the estimated floodplain dataset. * Small headwaters and creeks are not included in this indicator because the EPA estimated floodplain dataset does not include them. * This indicator may underprioritize areas important for aquatic plants. A list of [Southeastern plant Regional Species of Greatest Conservation Need] has recently been developed, but at this point SARP is only collecting information on aquatic animal species. We will explore ways to incorporate aquatic plant species in the future. * In the area just south of Guadalupe Mountains National Park in West Texas, this indicator depicts the floodplain as a series of straight lines that poorly match the actual floodplain. This is due to an error in the EPA floodplain map used in this indicator. * The catchment boundaries are inconsistent in how far they extend toward the ocean. As a result, this indicator does not consistently apply to estuaries, coastal areas, and barrier islands. 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 EPA EnviroAtlas. 2018. Estimated Floodplain Map of the Conterminous U.S. [[https://enviroatlas.epa.gov/enviroatlas/DataFactSheets/pdf/Supplemental/EstimatedFloodplains.pdf]]. Southeast Aquatic Resources Partnership. Species Summaries by HUC12. Accessed May 2024. Terwilliger Consulting, Inc. Regional Species of Greatest Conservation Need in the Southeastern United States. July 2019. [[https://secassoutheast.org/pdf/SEAFWA_RSGCN_Final_Report_20190715.pdf]]. The River Basin Center and The Tennessee Aquarium Conservation Institute. The Southeastern Freshwater Biodiversity Conservation Strategy. Accessed July 31, 2023. [[https://southeastfreshwater.org/]]. U.S. Environmental Protection Agency (USEPA) and the U.S. Geological Survey (USGS). 2012. National Hydrography Dataset Plus 2. [[https://www.horizon-systems.com/nhdplus/]].