Vanishing world: alkaline, saline lakes in Central Europe and their diatom assemblages

Abstract

European shallow, alkaline, saline lakes are potential indicators of climate change. Diatoms have often been reported as valuable proxies for different kinds of anthropogenic activities. Diatom assemblages and 14 environmental variables from shallow, alkaline lakes from 2 different regions of the Carpathian basin (Europe) were investigated for 3 years to (1) elucidate the physical and chemical parameters and diatom assemblages of these lakes, (2) select the principle variables affecting the diatom communities, and (3) show the relevance of diatoms as ecological bioindicators. Water chemical characteristics of the lakes in the 2 regions differ significantly in anion concentrations (HCO3−, SO42−, and Cl−), platinum (Pt) units (colour), and oxygen saturation. Dominance by the stress-tolerant, motile diatom ecological guild, represented mainly by Nitzschia and Navicula species, was characteristic in these saline, turbid environments. Indicator species of the 2 regions were found to be different. Diatom assemblage composition was chiefly determined by conductivity and HCO3− and SO42−concentrations. Nutrient loads, extreme weather events, and consequences of habitat maintenance management were unequivocally identifiable by variations in the benthic diatom assemblage composition. Diatoms are valuable indicators for assessment of ecological status of these saline, alkaline lakes. Including these organisms in ecological status assessments of inland saline lakes may improve the effectiveness of directives for conservation management and might be useful in preserving these pristine habitats that depend on natural hydrological processes.