ADAPTIVE REACTIONS OF THE ADVENTIVE SPECIES LEMNA GIBBA TO WATER POLLUTION

The study is devoted to adventive macrophyte Lemna gibba L. (duckweed) adaptive reactions to pollution of water by heavy metals. Under the high technogenic impact on aquatic ecosystems, some invasive species quickly spread and crowd out of native flora. In this regard, studies of the physiological and biochemical mechanisms of these species tolerance, contributing to their successful resettlement are of particular importance. The results of two years of research (July 2016–2017) on the study of accumulative abilities in relation to heavy metals (nickel, copper, zinc, manganese and iron) and some morphophysiological parameters of L. gibba – one of the adventive flora representatives of the Middle Urals is presented. Plant material and surface water samples were taken from two water bodies of the Sverdlovsk region, differing in levels of technogenic impact: the Iset River (Aramil town) and its tributary the Sysert River (Dvurechensk town). It was found that Cu, Ni and Mn concentration in the Iset River were on average 1.5 times and Zn – 4.0 times higher than that in the Sysert River. It was shown that the fronds of the studied macrophyte from the habitat with an increased water pollution (the Iset River) were distinguished by a more significant accumulation of metals, larger mesophyll cells, a higher content of photosynthetic pigments and increased activity of catalase and polyphenol oxidase enzymes compared to plants from the water body with a lower level of pollution (the Sysert River). It is concluded that the physiological and biochemical adaptations revealed in L. gibba increase its competitiveness and play an important role in the development of new territories, including technologically disturbed ones.