Indicative value of Pediastrum and other coccal green algae in palaeoecology

Sporopollenin layers in the cell wall of coccal green algae are responsible for the resistance of cell walls to destructive processes during fossiliza tion as well as during chemical preparation of samples for pollen-analysis. Pollen slides of samples from limnic sediments thus also contain some alga l cell walls. Although some pollen-analysts tried to stress this fact, the finds of algae in pollen slides have not been paid systematic attention yet , despite their potential use for a more accurate palaeoecological reconstr uction. The article summarizes the results of palaeoecological studies showing how the algae can be used in palaeoecological reconstruction of past environmen ts. The possibility of utilizing the indicative value of algal finds is dem onstrated on examples of algal communities from fossil, subrecent and recen t sediments from different longitudes, latitudes, and altitudes. The identi fication and indicative values of species and varieties of Pediastrum are i ncluded in a special review (KOMAREK & JANKOVSKA, Biblioth. Phycol., in pre ss). The contemporary knowledge of ecological requirements of the given tax a, completed by information from their fossil finds, makes possible the rec onstruction of trophic and temperature conditions and of the purity of the water environment of the past water biotopes.