Metal concentrations in water, sediment and sharptooth catfish Clarias gariepinus from three peri-urban rivers in the upper Manyame catchment, Zimbabwe

  • T Nhiwatiwa
  • M Barson
  • AP Harrison
  • B Utete
  • RG Cooper

Abstract

Concentrations of zinc, cadmium, chromium, nickel, lead, copper and iron were measured in flowing water, riverbed sediments and tissues of sharptooth catfish Clarias gariepinus from three rivers in the upper Manyame catchment over seven months in 2008–2009. The Manyame and Mukuvisi rivers are severely polluted by industrial and domestic effluent, whilst the Gwebi River is not influenced by urban effluent. Key water quality parameters, including dissolved oxygen and conductivity, clearly showed a pollution gradient in the Mukuvisi and Manyame rivers, but water quality in the Gwebi River was good. Levels of zinc, iron, copper, nickel and lead in fish tissues from the three rivers sampled were unusually high, with zinc and iron concentrations being the highest in all the tissues. This was also positively correlated with the concentrations of these metals in water and sediments. Notable differences existed between the water (zinc and copper) and sediments (iron and zinc) of each river. The relatively high metal concentrations in the Gwebi River, as well as conductivity and dissolved ions, were explained by the geological influence of the Great Dyke in its subcatchment. Metals are bound in the sediment but these can be rapidly mobilised into water if environmental changes occur, therefore efforts to monitor and prevent further water quality deterioration are required. The results of this study may have significant negative implications for aquatic organisms and for human health through fish consumption and therefore risk assessment investigations are imperative. 

Keywords: bioconcentration, metal pollution, tissues, water

African Journal of Aquatic Science 2011, 36(3): 243–252

Author Biographies

T Nhiwatiwa
Department of Biological Sciences, University of Zimbabwe, PO Box MP167, Mt Pleasant, Harare, Zimbabwe
M Barson
Department of Biological Sciences, University of Zimbabwe, PO Box MP167, Mt Pleasant, Harare, Zimbabwe
AP Harrison
Department of Animal and Veterinary Basic Sciences, Copenhagen University, 1870 Frederiksberg C, Copenhagen, Denmark
B Utete
Department of Biological Sciences, University of Zimbabwe, PO Box MP167, Mt Pleasant, Harare, Zimbabwe
RG Cooper
Division of Physiology, Birmingham City University, 704 Baker Building, Franchise Street, Perry Barr, Birmingham B42 2SU, UK
Published
2012-01-24
Section
Articles

Journal Identifiers


eISSN: 1727-9364
print ISSN: 1608-5914