An approach to the recent environmental history of Pilica Piaski spring (southern Poland) using diatoms

Diatom floras from springs have received little attention until recently, despite the fact that springs provide specific conditions that cannot be found in any other aquatic system, and remain of great importance in terms of general environmental changes. Due to pollution of the Kraków-Częstochowska upland aquifers, the chemical composition of spring waters in the area is anthropogenically modified, and far from the natural state. In order to generate a baseline diatom flora for springs, a paleolimnological study was applied as one of the best recognized and applied methods used to track long-term environmental changes worldwide. Little is known, however, about the direction and nature of such changes in aquatic environments fed by springs. The present article focuses on shifts in diatom assemblages preserved in sediments collected from a small pond, situated close to several spring outlets. They were interpreted as a record of environmental changes that had taken place during the last century. For most of the history of the pond—as recorded in this 84 cm long core—the diatom assemblage was dominated by small Fragilaria spp. The major shifts in species composition began in a core depth of 65 cm with a decline in Fragilaria construens var. venter (Ehrenberg) Grunow and Fragilaria pinnata Ehrenberg complexes, and a concurrent increase in Achnanthidium minutissimum (Kützing) Czarnecki. The second change was recorded at the depth of 45 cm with a sharp decline of A. minutissimum, which again was replaced by the small Fragilaria spp. In recent years, further changes in the diatom assemblage occurred, with a notable increase in Cyclotella delicatula Hustedt. The assemblage shifts recorded at this site appear to be consistent with environmental changes triggered by land use (e.g. agriculture intensity) and/or possible changes in spring water discharge. Guest editors: K. Buczkó, J. Korponai, J. Padisák & S. W. Starratt Palaeolimnological Proxies as Tools of Environmental Reconstruction in Fresh Water