The Indicator value of the stones-in-current fauna of the Jukskei-Crocodile river system, Transvaal, South Africa

Abstract

This study is an evaluation of the relationships between the stones-incurrent fauna of a river system and variations in water quality influencing it. The value of the biota in indicating short term and subtle changes in water quality when the reactions of whole communities and not just single taxa are examined is shown by the results. These results suggest that misrepresentation of conditions can result from the more rigid methods of biological classification found in many biotic and diversity indices. This is shown by examples of unsuspected contamination of water resulting in misleading faunal associations. The system derived in this study requires the definition of regionally and locally controlled taxa and their division into dominant and sub-dominant associations. No single taxon has a rigidly defined indicator function. These results are applicable to this river system only but further studies should show their applicability to other systems.