Ecological Risk Screening Summary - Green Floater (Lasmigona subviridis) - 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.

Lasmigona subviridis, Green Floater, is freshwater mussel native to Atlantic Slope drainages including the Hudson, Susquehanna, Potomac, upper Savannah, Kanawha-New, and Cape Fear rivers. Several States within this species’ native range have listed populations of L. subviridis as threatened. This species lives 3 to 4 years and can grow to 65 mm in length. L. subviridis is found in small rivers, streams, and canals with fine gravel and sand substrate. They are intolerant to strong currents, flooding, erosion, and pollution. L. subviridis is one of few North American unionid mussels that do not require a host fish for larval dispersal, self-fertilizing when population densities are low. Although this species has been reported as introduced and established outside of its native range, there is no information on the impact of these populations. The History of Invasiveness is thus classified as Data Deficient. Possession of L. subviridis is currently regulated in South Carolina and Virginia where this species is listed as threatened. The climate matching analysis for the contiguous United States indicates establishment concern outside its native range. The highest matches were found within this species’ native range in the Northeast, Mid-Atlantic, Southeast, Appalachia, and expanding westward into the Midwest. The Certainty of Assessment for this ERSS is classified as Low due to the lack of information regarding introduced populations and uncertainty with this species’ distribution. The Overall Risk Assessment Category for L. subviridis in the contiguous United States is Uncertain.