This paper presents the results of Cladocera subfossil analysis using material obtained from five paleolakes of the Eemian Interglacial located in central and north-eastern Poland. Analyses of Cladocera subfossils in Poland and other parts of the world have revealed detailed results covering the last 13,000 years. Cladocera subfossils from sediments older than the last glaciation have been analysed occasionally. The first analyses of older sediments were conducted in Denmark by Frey in 1962. In Poland, the first analyses of this type were conducted on material obtained in Konin. The Eemian lakes subject to the study were formed at the end of the Warta Glaciation in tunnel and kettle holes. A continuous record of environmental changes throughout the Eemian Interglacial until the early Vistulian Glaciation has been preserved in lake sediments. The bottom part of the profile consists of sands and silts, followed by gyttja and peat. The upper part of the profile contains peat and organic shales. Cladocera subfossils found in Eemian sediments were thinner and their structure was more damaged. The low degree of subfossil preservation forced a change in the method of preparation of subfossils for microscopic analysis as required by IGCP Project 158. Cladocera species determined within the studied paleolakes correspond to the present-day species inhabiting the area of Poland and Europe. The species composition and the variability in the frequency of Cladocera specimens made it possible to distinguish discrete phases of lake development associated with changes in temperature and water level, trophic state and the presence of macrophytes. The results of Cladocera analysis are well correlated with data obtained in pollen analyses.
Wacław Florek, Jerzy Jonczak, Monika Niska and Iwona Pasamonik
Interdisciplinary studies on environmental evolution during the last 650 years based on the analysis of mill pond deposits have been conducted in the valley of the Jarosławianka Stream (left-bank tributary of the River Wieprza). According to historical data, confirmed also by radiocarbon dating, the water mill was located in the valley in 1351 and operated until the 1960s. The sequence of stratified deposits with a thickness of up to about 2 metres was accumulated in mill pond basin during this period. The vertical variability in the physical and chemical properties of these deposits reflects temporal environmental changes in the catchment, particularly the intensity of chemical and mechanical denudation and human activity. Analysis of subfossil Cladocera suggests four phases in the development of the mill pond. Changing along with the intensity of the pond basin water flow, redox and nutritional conditions are reflected in the spatial variability of deposits, especially their textural parameters, pH and abundance in organic carbon, nitrogen and carbonates.