VASCULAR PLANTS OF IMANDRA LAKE
Vascular aquatic flora of Imandra Lake is studied. Imandra is the largest oligotrophic reservoir in the North-West Russia located in the central Kola Peninsula. Being under antropogenic pressure since the middle of the 20th century, several parts of its aquatorium (bays, basins, river estuaries) are eutrophicated and (or) polluted. Total vascular flora of the lake comprises 59 species from 21 families. Data on the species distribution, frequency, environmental and biotopical preferences are given in the annotated species list. Species distribution in different parts of the waterbody depends on various natural factors: depth, bottom composition, wind and wave activity, water purity, etc. The most favourable conditions for macrophyte cover are in quiet bays with sandy or mud bottom at the depth 0.5-2.5 m down to 3-4.5 m. Species diversity in such areas varies from 8 to 11 species, pondweed colonies and well-developed bottom Isoetetum echinosporae communities being frequently observed. Species lists of eutrophicated bays reach 16 species, broad-leaveed pondweeds are abundant, but bottom vegetation is poor and lacking in isoetids. Under combined impact of eutrophication and industrial pollution, the marcophyte flora becomes poorer down to vanishing. Peculiarities of aquatic plants distribution in different areas of Imandra are discussed in the context of anthropogenic impact on the lake ecosystem.