Predicting the location of aquatic species - a tool for helping conserve and protect
160 Zillicoa St.
Asheville, NC 28801
828/258-3939, ext. 231
To better understand the geographic distributions of aquatic species in North Carolina, we created predictive habitat maps for 226 aquatic species using geographic information systems and maximum entropy (Maxent) modeling (Maxent is a machine learning technique that can be used to predict the geographic distribution of any spatial phenomena, including plants or animals). These maps were derived by comparing known species occurrences with a suite of stream or landcover derived environmental variables. They provide a coarse-scale look at the potential stream suitability of many aquatic animals present and hope our mapping efforts help efforts to prioritize stream systems and help educate people on the spatial distributions and conservation needs of North Carolina aquatic species and habitats.
NOTE: These predictive habitat maps are the product of a modeling exercise. They may or may not reflect actual species distribution. For more information about the modeling effort and how the maps were created, please read the detailed analysis description available below.
Complete data is available as a geodatabase, a limited data set is available as shapefiles-both usable with ArcMap:
The species included in the analysis are listed below, alphabetical by scientific name. Species names link to a summary report (.pdf, approx 150 kb/each) of the analysis that generated each species's predicted distribution and includes a low-resolution map of predicted distribution.
- G1= Critically Imperiled. At very high risk of extinction due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors.
- G2= Imperiled. At high risk of extinction or elimination due to very restricted range, very few populations, steep declines, or other factors.
- G3= Vulnerable. At moderate risk of extinction or elimination due to a restricted range, relatively few populations, recent and widespread declines, or other factors.
- G4= Apparently Secure. Uncommon but not rare; some cause for long-term concern due to declines or other factors.
- G5= Secure. Common; widespread and abundant.
- G#G#= Range Rank.A numeric range rank (e.g., G2G3, G1G3) is used to indicate the range of uncertainty about the exact status of a taxon or ecosystem type.
- Q= Questionable taxonomy that may reduce conservation priority. Distinctiveness of this entity as a taxon or ecosystem type at the current level is questionable; resolution of this uncertainty may result in change from a species to a subspecies or hybrid, or inclusion of this taxon or type in another taxon or type, with the resulting taxon having a lower-priority (numerically higher) conservation status rank.
- T# = Infraspecific Taxon (trinomial). The status of infraspecific taxa (subspecies or varieties) are indicated by a “T-rank” following the species' global rank. Rules for assigning T-ranks follow the same principles outlined above. For example, the global rank of a critically imperiled subspecies of an otherwise widespread and common species would be G5T1.
- E = endangered. A species on the list of threatened and endangered species in danger of extinction throughout all or a significant portion of its range.
- T = threatened. A species on the list of threatened and endangered species likely to become endangered within the foreseeable future throughout all or a significant portion of its range.
- C = candidate. A species for which the Service has sufficient information on their biological status and threats to add them to the threatened and endangered species list, but whose addition is precluded by higher priority species.
- FSC = federal species of concern. A species under consideration for listing, for which there is insufficient information to support listing at this time.
December 7, 2011