LAUSR

In 2020, the first record of Wolffia arrhiza was made in Novosibirsk region (Western Siberia) in a floodplain lake. Wolffia arrhiza formed vast stands with an area of hundreds of square meters and with high productivity. Besides monodominant communities, it was met as a component of the cenoses of such hydrophytes as Stratiotes aloides and Hydrocharis morsus-ranae, as well as of the helophyte communities formed by Typha latifolia and Eleocharis mamillata. According to local residents, Wolffia was observed as abundant for some years; thus, most likely, the population winters safely at the latitude of Novosibirsk. The most likely source of Wolffia arrhiza appearance in the lake was an accidental introduction from an aquarium, although the possibility of this plant entering the lake in high-water years from the wastewater of the municipal settling tank of Novosibirsk sewage waters also exists.