Reconstruction of temperature cycles and succession changes by diatomic complexes from bottom sediments: Case study of Lake Galichskoe

Diatomic complexes from bottom sediments of Lake Galichskoe (Kostroma Province) were analyzed. Samples of most recent sediments that formed during the past decades were studied. For the first time a large lake was studied by using a single reconstruction method based on the three major hydrological characteristics: the temperature, cation-anion balance, and nutrient concentration. The taxonomic composition of diatomic complexes was identified by the above-mentioned hydrological-environment parameters with account of the bioindication significance. A method developed by the author was used for graphic correlation of the structure of diatomic complexes. Cyclic variations were identified in the temperature regime of the lake in recent decades. The duration of cycles appears to be comparable with the 11-year cycle of solar activity. Correlation was found to exist in the dynamics of variations in all parameters involved in the analysis. Confirmation is given to the preliminary suggestions regarding the high rate of sedimentation at the last phase of the lake structure passing into the category of bog ecosystems.