First record of Eurasian Water-milfoil, Myriophyllum spicatum, for the Saint John River, New Brunswick

Résumé

Eurasian Water-milfoil (Myriophyllum spicatum L.) is regarded by conservation practitioners as one of the most challenging invasive aquatic plants to manage. Owing to its broad tolerance to environmental conditions, vegetative propagation, and rapid establishment and growth, M. spicatum introductions have the potential to drastically alter macrophyte species assemblages via a loss of native species and their respective ecosystem functions. Following the discovery of a single specimen of M. spicatum in the Saint John River, near Fredericton, New Brunswick (Canada) we further investigated the localized distribution of this nonindigenous species. Thirteen areas were identified as potential M. spicatum habitat and were surveyed by wading or snorkeling. Specimens of M. spicatum were collected and morphological identifications were verified through genetic analyses (ITS2; rbcLa). The results of our investigation confirm the presence of M. spicatum at six different locations within the Saint John River. Here we discuss the implications of this discovery in the context of the contiguous aquatic habitats along a large river system.