Invasive aquatic plants in the aquarium and ornamental pond industries: a risk assessment for southern Ontario (Canada)

An assessment of the invasive risk associated with the establishment and dispersal of plants available in the aquarium and ornamental pond industries in the Greater Toronto area (Canada) was made. In the risk model, sales volumes of individual taxa were used as a proxy for propagule pressure, to assess pathway risk potential. Organism risk potential, the ability to become established and disperse associated with a release, was assessed using an analysis of the biological traits of the species. Discriminant correspondence analysis was used to predict which biological traits were useful in discriminating native plants from alien invasive plants and alien non‐invasive plants. Importantly, a relatively small number of biological traits appear to be useful in predicting whether an alien aquatic plant had the characteristics that would support establishment and/or dispersal in new environments. Aquatic plants distributed by the industries that are cold tolerant, able to propagate by fragments and use a number of dispersal methods are of particular concern as potential invaders. The model identified 11 alien plants in the trade that have a high risk of becoming invasive, and an additional 52 with moderately high risk.