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

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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).

Map of the United States with red dots indicating the geographic position of all USGS Alert Risk Maps created

USGS Alert Risk Maps (ARMs) display lakes, river reaches, and other water bodies potentially at risk of invasion by a new non-native species. The ARMs span the conterminous U.S.

(Public domain.)

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.

An Alert Risk Map (ARM) indicates where the non-native Northern snakehead could potentially invade

Northern snakehead (Channa argus), native to China, Russia, and Korea, was found in a river in King William County, Virginia, on March 20, 2020. The non-native species can survive in poorly oxygenated water and can adapt to a wide range of aquatic environments. USGS Alert Risk Maps (ARMs) display lakes, river reaches, and other water bodies potentially at risk of invasion by a new non-native species, like the northern snakehead.

(Public domain.)