Ecological Risk Screening Summary - South American Spongeplant (Hydrocharis laevigata) - High Risk

Species that are considered high risk have a well-documented history of invasiveness in at least one location globally and are of establishment concern for the contiguous United States based on a climate matching analysis.

Hydrocharis laevigata, South American Spongeplant, is a floating, freshwater aquatic herb native to Mexico, Central and South America and the Caribbean, including Puerto Rico. H. laevigata is commonly traded around the world for aquariums and aquascapes and reportedly has a potential role in bioremediation. It has been introduced to and become established in many areas, including California and Washington in the United States, multiple regions of Australia, and in Indonesia and southern Africa. There are documented impacts from these introductions including obstruction of waterways, reduced water quality, and decreased biodiversity. H. laevigata is regulated in three U.S. States. The history of invasiveness is classified as High. The climate matching analysis for the contiguous United States indicates establishment concern for this species, with a medium to high match across much of the country. The certainty of assessment is Medium because much of the information on impacts comes originally from non-peer-reviewed sources. The Overall Risk Assessment Category for Hydrocharis laevigata in the contiguous United States is High.