Ecological Risk Screening Summary - Dikerogammarus fluviatilis (an amphipod, no common name) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.

Dikerogammarus fluviatilis is an amphipod from riverine environments in the Ponto-Caspian region of Eurasia. There is little detailed information on the native range of this species, and no reports of introduced populations. Therefore, the history of invasiveness for D. fluviatilis is classified as No Known Nonnative Population. D. fluviatilis has a high climate match with the contiguous United States. Much of the contiguous United States has a high or medium match, including the Great Lakes basin, the Great Plains, and portions of the Southwest, Appalachia and the Interior West. However, this match is based on a single reported occurrence. There is significant taxonomic uncertainty, with some sources identifying this taxon as a full species, others as a subspecies (D. haemobaphes fluviatilis), and other sources rejecting the taxon entirely. This ERSS is specific to information available for Dikerogammarus fluviatilis and D. h. fluviatilis. The certainty of assessment is Low based on taxonomic uncertainty and scarcity of georeferenced locations. Further information is needed to adequately assess the risk this species poses to the contiguous United States. The overall risk assessment category is Uncertain.