Evaluation of the fish health assessment index in the Olifants River system, South Africa

  • RM Watson
  • D Crafford
  • A Avenant-Oldewage

Abstract

The fish health assessment index (HAI) biomonitoring technique, developed in the USA and subsequently tested in South Africa, was re-evaluated in the Olifants River system using Clarias gariepinus, Oreochromis mossambicus and Labeobarbus marequensis during drought and flood conditions in 1994–1997 at the same sample sites in the Kruger National Park as used previously, as well as at Loskop Dam and Bronkhorstspruit Dam in the upper catchment. Parasite numbers recorded from Clarias gariepinus supported the HAI hypothesis that higher endoparasite and lower ectoparasite numbers occur at highly impacted areas. The apparent effects of pollution type on the ratio between ectoparasites and endoparasites are discussed. Environmental stressors such as flood conditions resulted in immunological responses, reflected statistically as changes in white blood cell percentage (WBC%). It is suggested that endoparasite and WBC% data provide the best overall assessment of fish condition in the Olifants River system. Modifications made to the HAI included further development of the original parasite presence/absence component into a more extensive parasite index component. The modified HAI index shows promise as a long-term biological monitoring tool in South Africa.

Keywords: biomonitoring, Clarias gariepinus, health assessment index, heavy metals, Labeobarbus marequensis, Oreochromis mossambicus, parasites, pollution

African Journal of Aquatic Science 2012, 37(3): 235–251

Author Biographies

RM Watson
Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, Johannesburg 2001, South Africa; Current address: Bohlweki-SSI Environmental, PO Box 867, Gallo Manor 2050, South Africa
D Crafford
Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, Johannesburg 2001, South Africa; Current address: Clinvet International (Pty) Ltd, PO Box 11186, Universitas, Bloemfontein 9321, South Africa
A Avenant-Oldewage
Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, Johannesburg 2001, South Africa
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Articles

Journal Identifiers


eISSN: 1727-9364
print ISSN: 1608-5914