DEVELOPMENTS IN TWENTY-FIVE YEARS OF DIATOM (BACILLARIOPHYCEAE) RESEARCH IN SOUTH AFRICA

SUMMARY

Diatom research in South Africa can be divided into four distinct periods. The first period covers a span of some seventy years, beginning with Shadbolt's (1854) account of diatoms from Port Natal, and continuing with brief notes and reports on odd specimens found in various samples sent to the leading diatomists of the day. The second period spans the time between the two world wars and is characterized by accounts of diatoms found in algological surveys made by a number of algologists, notably F.E. Fritsch, Florence Rich and Edith Stevens. The real study of diatoms in South Africa, however, commenced on the arrival of Dr B.J. Cholnoky in the country in 1952. Through his intensive and extensive taxonomic and ecological studies he built up the diatom collection of the National Institute for Water Research (now the Division of Water Technology) making the latter the centre of diatom research in this country. During this third period he also trained his successors, Dr Schoeman and the author in the taxonomy and ecology of freshwater diatoms and encouraged Professor Giffen in his studies of the marine littoral and estuarine diatoms. Following Cholnoky's death in 1972, the fourth period saw a very fruitful partnership between Dr Schoeman and the author in which new approaches to the taxonomy of diatoms were made. The two most important changes were verification of identifications by comparison with type material, and the use of electron microscope to study the detail of valve morphology and fine structure. Two lines of research were followed: - (a) taxonomic and morphological study of individual species, and (b) studies of the diatom communities from various regions or specific environments. Outside the NIWR (DWT) relatively little work on freshwater diatoms has been undertaken. This has been mostly of an ecological nature. Some marine work has also been done involving mainly surf zone diatoms or phytoplankton (largely diatoms) productivity.

KEYWORDS:

• Diatoms
• taxonomy
• slide collection
• electron microscopy