This article presents the hydrographic and hydrochemical characteristics of this lake. Lake Jazerske is located in the Western Carpathians (Spiš Magura) in northern Slovakia. It occupies a depression that was formed at the foot of the main scarp of a landslide. Below the lake, there are small intercolluvial depressions that have been transformed into wetlands (peat bogs). The studied lake is very small. Its area is 3600 m2 and its length is 85 m. The maximum depth of the lake is 7.2 m and its capacity is 17 000 m3. The lake is supplied by an inflow of groundwater via fractured aquifers. During periods of heavy rainfall and snow melting, the lake is also supplied by the water from surface runoff. On the main slope of the landslides, traces of ephemeral courses were also found. During the periods of increased supply (spring snow melting, summer rainfall), the outflow of water from the lake occurs both on the surface and underground. In terms of its hydrochemistry, the lake water represents the four-ion type - bicarbonate-sulphate-calcium-magnesium. The concentrations of various ions is characteristic of the shallow groundwater of the Carpathian flysch. The predominant cation, the average concentration of which is 52 mg dm-3, is calcium. The dominant anion is carbohydrates with an average concentration of 163 mg dm-3. What is interesting is the very low levels of chlorides, which do not exceed 2 mg dm-3. The electrolytic conductivity of the water flowing out of the lake ranged from 290 to 328 μS cm-1.
Dependence between occurrence of selected species of psammic rotifers and phytopsammon abundance
Correlations between densities of dominant species of psammic (i.e. sand-loving) rotifers and densities of cyanobacteria and algae were studied on beaches of 16 natural lakes and 11 artificial water bodies. The lakes are located in the Bytów, Drawsko and Wielkopolska Lakelands (NW Poland), while the artificial water bodies, on the Silesian Upland (SW Poland). The psammon was dominated by diatoms and green algae in lakes of the Bytów and Drawsko Lakelands, and by cyanobacteria and diatoms, in lakes of the Wielkopolska Lakeland. In artificial water bodies in Upper Silesia, diatoms and cyanobacteria were the most abundant. Rotifer densities differed significantly between zones of the psammolittoral. Densities of some rotifer species were significantly correlated with the abundance of chlorophytes.
Environmental repercussion of subsidence reservoirs reclamation
Subsidence basins filled with water are being formed above exploitation fields also in woodland areas leading to changes in water relations simultaneously affecting creation of environmental islands characterized by higher biodiversity in comparison with adjacent areas.
Unfortunately, these types of water reservoirs from the legal point of view are considered mining damage and should thus be reclaimed. Reclamation usually consists in gravitational drainage and filling up with barren rock, appropriate relief forming and afforestation. So performed reclamation practices lead to negative effects both within the subsidence and in adjacent areas. The objective of this work was to determine the impact of reclamation based on filling subsidence with barren rock on changes in hydrology and biodiversity of nearby forest communities. For the purpose of the study two objects were selected: the existing water body and former water reservoir - at present filled with barren rock. Both are situated in Ślαskie voivodship (the territory of Mysłowice and Katowice). Within the two objects, hydrological studies at two sampling points in each of the objects and vegetation sampling were performed. The DCA of 12 transects (6 in each object) and statistical analyses of vegetation showed differences between two objects in species composition, especially due to higher abundance and coverage of invasive and expansive species in reclaimed areas. Chemical analyses showed high contamination of surface waters (by e.g. SO42-, Cl-, Na+) caused by waste deposition in barren rock and the negative effect of coal mine waters supplying the area of reclaimed reservoir.