Study Site
Paliastomi Lake was selected as a research site (Figure 1). Paliastomi Lake is a flowing lake located on the Odish-Guria lowland near the city of Poti. The surface area of the lake is 18.2 km2. Basin area - 547 km2, maximum depth - 3.2 m, average depth 2.6 m. The volume of water is 52 mln. m3. It is located 0.3 m below sea level. The Fichori River joins the lake, and the Kaparchina River flows out. The high-water level is characteristic in spring, summer, and autumn, and low in winter. Water temperature increases in July-August (25.1°C), and decreases in January (5.2°C). The lake is part of Kolkheti National Park (Aphkhazava et al., 1984).
According to the Ramsar Convention, Paliastomi Lake is a protected area of international importance and is part of the Kolkheti National Park. Ramsar site N° 893 “Wetlands of Central Kolkheti” consists of three different peat bog complexes (Anaklia-Churia, Nabada, and Fichora-Paliastomi), Paliastomi Lake, the surrounding sunken forests, the Black Sea coastal zone and the lower reaches of the Khobi (or Khobiskali) and Rion rivers. A total of 33,710 hectares (including the marine part of 55,500 hectares) in the central part of the Black Sea coastal plain, in Khobi and Lachkhuti administrative districts, and in the territory of Poti (Dassenakis et al., 2006).
Paliastomi Lake was considered one of the most highly productive reservoirs. The impact of environmental factors has led to the salinization of the lake with associated changes in water hydrology, and a sharp decrease in the biodiversity of the lake (the number of fish species has decreased from 40 to 24). The lake is fed by rainwater and tributaries.
Paliastomi Lake is separated from the sea by a 300-400 meter wide and 2-meter high sand section. The lake has a large amount of sediments and vegetation. Rivers (Fichori, Tkhorika, etc.) and lakes (Paliastomi, Imnati, Maltakva, etc.) receive water from large reservoirs, and the water level ranges from 0.2-0.7 m in swamps, 0.5-3 m in lakes, and 1- in rivers. 21 m. Until 1924, Paliastomi Lake was a freshwater lake: water flowed from the lake through the Kaparchina River, which originates near the northwestern shore of the lake. Leaving the lake, the river turns sharply to the south, runs almost parallel to the western shore, and flows into the sea 11 km from its source. Sea water freely flows into this strait during heavy storms and this has made the lake salty.