APPLICATIONS OF FRESH-WATER DIATOMS TO GEOGRAPHICAL RESEARCH

Diatoms (Bacillariophyceae) are a widely distributed group of microsco pic, unicellular algae that are characterized by siliceous cell walls (frustules). The size, shape and sculpturing of diatom frustules are t axonomically diagnostic. Moreover, because of their siliceous composit ion, diatoms are often well preserved in stratigraphic deposits, where they can be used to infer (quantitatively or qualitatively) past envi ronmental conditions. The sensitivity of diatoms to a wide variety of environmental variables provides geographers with a multitude of resea rch opportunities. This review focuses on palaeoecological reconstruct ions that are based on freshwater diatoms. Geographical applications i ncluding studies of climatology, hydrology, geomorphology, biogeograph y, and water-quality assessment and monitoring are discussed.