USGS Nonindigenous Aquatic Species (NAS) Database Releases 500+ Alert Risk Maps

These maps display lakes, river reaches, and other water bodies potentially at risk of invasion by a new non-native species. The ARM tool uses the current range of a non-native species to assess the risk of it possibly invading new water bodies within 6 months of its introduction and develop credible scenarios of its potential movement within a drainage based on the species mobility and drainage barriers (e.g., dams and waterfalls).

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The NAS database tracks the distribution of introduced aquatic organisms across the United States. The publicly accessible information repository monitors, records, and analyzes reported sightings for >1,300 species like lionfish, zebra mussels, and hydrilla. The database contains observations from as early as 1800, derived from many sources, including scientific literature; federal, state, and local natural resource monitoring programs; museum collections; news agencies; and direct submission through on-line reporting forms from citizen scientists.

Subscribers to NAS alerts emails can be informed when a new non-native species has been reported in their area as part of a national early detection and rapid response (EDRR) system. The NAS program also uses the data to help forecast where these species may go next, via tools like the ARMs.

Since the release of the ARM tool in June 2018, the NAS team has produced maps for 198 (39%) plants, 111 (22%) mollusks, 106 (21%) fishes, 44 (9%) crustaceans, and 22 (4%) reptiles and amphibians, with 25 (5%) other aquatic animals, including mammals. These introductions occurred primarily at the drainage level (68%), followed by counties (20%), and states (11%), with 4 (1%) species reported for the first time ever in the U.S.

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