Garden ponds: hidden sources for plant invasions?

Private garden ponds are increasingly popular among homeowners and can, to some extent, compensate for the loss of natural habitats, but they may be sources of invasive species as pond owners often introduce alien ornamental species. We assessed the popularity, distribution and sources of six invasive macrophyte taxa (<i>Elodea spp., Eichhornia crassipes, Ludwigia spp., Myriophyllum aquaticum, Pistia stratoites, Vallisneria spp.</i>) in garden ponds across Hungary using citizen science. Using Species Distribution Modeling (SDM), we predicted the potential spread of these taxa into natural waters, comparing the results to confirmed occurrences in the wild. Based on 560 responses, we found that even banned invasive macrophytes remain highly popular and widespread. Pond owners purchase them from various sources, including garden centres, web stores and online communities, which represent routes hardly accessible for authorities. Our results highlight the need to raise awareness among garden pond owners and vendors about the threat of invasive species via extensive educational campaigns and outreach activities in addition to the existing policies on invasive species management.