First report of Hydrocharis laevigata in Spain
Hydrocharis laevigata (Hydrocharitaceae: synonym Limnobium laevigatum) is a floating aquatic plant which is native to South and Central America. It has been introduced into a number of countries worldwide, including Australia, the USA (California), Japan, Indonesia (Java), Zambia and Zimbabwe. A risk assessment conducted by the United States Department of Agriculture (USDA), scored the species as a high risk for the USA. It can form massive floating mats which can block light and have negative impacts on native biodiversity. Additionally, it can negatively impact ecosystem services by altering carbon and nutrient cycles. Hydrocharis laevigata is a popular aquatic plant for aquariums and ponds and it is readily available on the internet. In the EPPO region, H. laevigata has been reported as a casual in Belgium, Hungary and Poland (EPPO RS 2021/114). In the case of Belgium, several small populations (with at least 100 individuals) were discovered in 2013 in a small river near Ganshoren. In Spain, two individuals of H. laevigata were discovered in 2021 in the Martín Gonzalo stream, below the dam of the same name, in the province of Córdoba, which constitutes a novel finding for the flora of Andalusia. The two plants were not flowering, and it is not clear if the species can persist to form an established population. Previously, H. laevigata has been reported from the province of Madrid. H. laevigata is a species of concern as it could have environmental impacts similar to that of other mat forming aquatic species such as Pontederia crassipes and Pistia stratiotes. Surveys should be conducted in the wider region where the species has been recorded and the phytosanitary risk to the EPPO region should be assessed.
Sources
Martinez-Sagarra G, Garcia Murillo P, Devesa JA (2021) Hydrocharis laevigata (Humb. & Bonpl. Ex Willd.) Byng & Christenh (Hydrocharitaceae), novedad para la flora de Andalucia (España). Acta Botanica Malacitana 46. http://doi.org/10.24310/abm.v46i.11403