Changes in ecological relationships in a group of eight shallow lakes in the Polesie Lubelskie region (eastern Poland) over forty years

Abstract

The changes in 33 factors in 8 shallow lakes and their catchment areas were studied over a 40 year period. Large-scale changes in ecological conditions were present in the region studied: a disappearance of about 30% of wetlands, a reduction in the surface area of lakes by about 15%, and an increased forest cover in the region by about 26%. Six lakes showed increasing transparency and nutrient concentration, while two changed in the opposite direction. Various reactions were observed in zooplankton and zoobenthos. Generally, patterns for the reactions of lake ecosystems were found to vary individually, even in very similar lakes. The character of some changes might indicate a modular type of biocoenosis reaction. The character and rate of the overgrowing of the open waters of lakes depend to a high degree on the species composition and the predominating structure of the plants in the lake and its drainage basin. To avoid an incorrect prediction of the reactions of lake ecosystems, it is recommended that multifactor analysis be used for drainage basins over long periods of time.