Alien Express: The threat of aquarium e-commerce introducing invasive aquatic plants in Brazil

Aquarium market is one of the main causes of exotic species dispersion, as it promotes the introduction of potential invaders on natural environments. In this scenario, e-commerce provides easy access of invasive plants from around the world. Despite the economic importance of this trade, few studies have addressed the patterns and extension of environmental problems associated with this market. Using search engines and specialized literature, we characterized the e-commerce of freshwater aquarium plants in Brazil, including its commercial flow, traded species and invasive potential of exotic species. We observed that Brazilian e-commerce provides easy access to multiple aquatic plants, which are generally sold at low cost and as vegetative parts. From the 287 species of aquatic plants for sale, distributed in 58 families, 188 were exotic species, originated from Oriental biogeographic region. The trade of exotic species is a potential problem if they (1) are recognized as highly invasive in many parts of the world, (2) belong to genera and families very distinct from native species and could occupy empty niches, and (3) may hybridize with native species, creating lineages with increased potential for invasion. Although Brazilian laws regulating the trade of exotic species are adequate, there is a widespread illegal e-commerce of aquatic plants. The invasive potential of aquarium plants species traded via e-commerce should be a major concern and become the focus of increasing inspections and law compliance.