The invasion risk of Myriophyllum heterophyllum in Portugal
Myriophyllum heterophyllum (Haloragaceae: EPPO A2 List) is an aquatic plant native to North America. It is established in a number of countries in the EPPO region and further spread is likely. Dense mats in rivers and lakes can degrade habitats reducing biodiversity and the ecological status of water bodies. Currently, M. heterophyllum is absent from Portugal though it is present in neighbouring Spain and there is the potential for introduction with connecting waterbodies. The invasion risk of M. heterophyllum to Portugal was estimated using models predicting environmental suitability and the risk of human-mediated introduction. Climatic and environmental variables, and global occurrence data of M. heterophyllum were used in the model to predict environmental suitability, and density of aquarium stores were used to give a measure of the risk of human mediated introduction. The model predicts areas of environmental suitability mainly in temperate climate regions along central and northern coastal areas in Portugal. Areas at risk of invasion are concentrated in the Portuguese central and northern coasts and in the two main metropolitan areas, Lisbon and Porto. Within these regions at risk, there are a number of protected areas and therefore it is important to conduct surveillance to confirm the absence of the species and to enable a rapid response in the event of an invasion.
Sources
Diogo I, Sillero N, Capinha C (2024) Predicting the risk of invasion by broadleaf watermilfoil (Myriophyllum heterophyllum) in mainland Portugal. Heliyon 10, e34201. https://doi.org/10.1016/j.heliyon.2024.e34201