Ecological Risk Screening Summary - Red Algae (Bangia atropurpurea) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.

Red algae, Bangia atropurpurea¸ is native to freshwater environments in the amphi-Atlantic range, possibly including Atlantic coastal areas of the United States. This species can produce both asexual and sexual plants and can be found on a variety of substrates but prefers to grow on rougher mediums. Bangia atropurpurea is distributed on every continent except Antarctica. Introductions are reported in North America (including in the Great Lakes), Italy, and Pakistan. Studies from the Great Lakes have shown detrimental impacts both ecologically (displacing a native species and contributing to hypoxic conditions) and through biofouling. Elsewhere, B. atropupurea appears to support a less diverse macroinvertebrate community, but the impact of this is unknown. For these reasons the history of invasiveness is High. The Climate 6 score for the contiguous United States was high, with a high to medium match across most of the contiguous United States. B. atropurpurea is already present in the Great Lakes and Pacific coastal areas and is possibly native in coastal areas of the Atlantic Coast. The certainty of assessment is medium because some impact studies were inconclusive and the taxonomy of B. atropurpurea is unresolved. The overall risk assessment category is High.