Diatoms - A new dimension to water monitoring

Abstract

Water quality monitoring Diatoms – a new Dimension to water monitoring There is more to the brown, slimy stuff covering rocks and plants in rivers, wetlands and estuaries than meets the eye. Diatoms, the microscopic algae found in almost all aquatic and semi-aquatic habitats, are playing an increasingly important role in the assessment and monitoring of the health of South Africa’s water resources. Lani van Vuuren reports. D iatoms are one of the most common types of phytoplankton. They are delicate unicellular organisms that have a yellow-brown chloroplast (rather than a green chloroplast colour) that enables them to photosynthesise. Dr Bill Harding of DH Consulting, a phytoplankton ecologist, explains that the cell walls (‘skeletons’) of diatoms are made of silica, almost like a glass house. The construction of the cell wall, called the frustule, consists of two halves (known as ‘valves’) that fit into each other like a pillbox. These valves are ornamented by a variety of other structures. Diatoms were discovered shortly after the invention of the microscope.

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