We assessed the status of Littorella uniflora (L.) Aschers. population and its habitat based on long-term studies (2000–2023). It is an extremely rare, endangered, protected species for Belarus. Lake Svityaz is the only known location of L. uniflora habitat in Belarus. The species cenotic role in the community, its dynamics depending on biotopic, ecotopic and anthropogenic factors were revealed. The boundaries of the species distribution within the lake were determined. We assessed the changes in lake overgrowth and physicochemical indicators of the water over the long-term observation period. Major threats have been identified and measures to restore the L. uniflora habitat are proposed. Signs of progressive eutrophication are detected: decreased nitrogen compounds and the absence of phosphates in the surface water layer due to the phytoplankton active development; hydrosulphuric zone in the hypolimnion; a decrease in the dissolved oxygen content and transparency of water to 2–3 m; water “blooming”; an increase in the reed beds’ density and extent (up to 52 % of the coastline); rapid degradation of the hydrophytic vegetation belt (the depth of maximum growth of submerged plants decreased from 7.0 to 2.5 m over a 40-year period). Analysis of the higher aquatic vegetation species composition showed its reduction from 14 to 8 species due to the loss of a number of submerged plant species. The above indicates a structural restructuring of plant communities towards helophytic vegetation and deterioration in water quality. Littorella uniflora dominates in underwater communities, but its abundance is declining. Excessive recreational load and changes in hydrological regime degrade the Lake Svityaz and the L. uniflora population. We proposed some measures to regulate recreational load, improve the sanitary condition of the coast and a number of internal measures. The recommendations are aimed to stabilize the lake ecological status, to conserve the sustainability of its ecosystem and to protect the L. uniflora unique population.
ISSN 1995-4301
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