The Elodea canadensis Michx. records in Novosibirsk Region (Russia)

Elodea canadensis was found in July 2016 in the Ust-Tarksky district of Novosibirsk Region. In July 2016 and in July–August 2018, it was found in three bays of the Novosibirsk Reservoir: Ordynsky, Sharapsky, and Karakansky. In the Sharapsky Bay, elodea (Canadian waterweed) formed thickets of about 34 000 m2 in area, which were characterized by high productivity with a maximum aboveground phytomass ranging from 417 to 1352 g/m2 of absolute dry weight. The records appear to be the first confirmed data for Novosibirsk Region, because all earlier mentions are the result of an erroneous definition, or do not have any documentary evidence, or were cited from earlier publications. The reasons for the fact that E. canadensis has just begun its expansion on the territory of Novosibirsk Region with a significant area of 177 800 km2, while in many regions of Siberia it manifests itself as an active invasive species, are discussed. It was concluded that the leading factors limiting the distribution of E. canadensis in Novosibirsk Region include the composition and degree of mineralization of natural waters and a high representation of the local species Hydrilla verticillata in the water bodies, which are potentially suitable for the growth of elodea.