The Spatial and Temporal Variations of Ichythyofauna and Water Quality in the Crocodile River (East), Mpumalanga, South Africa

Abstract

The Crocodile River is situated in the north east of the Republic of South Africa. It is a large river basin with a total length of 320 km and draining a catchment of 10,450 km 2 . The water quality of this river is of high importance in sustaining the people and businesses relying on the sustainability of the river. The aim of the study was to use fish and water quality data to determine the present ecological state of the river and identifying the possible sources of pollution in the river. Multivariate statistical analysis was used to identify the main contaminants in the river at the various sections of the river. The results obtained indicated that species richness and diversity are high during low flow condition and the lower reaches had high species richness and diversity compared to the middle and upper reaches. The Fish Response Assessment Index indicated that the Ecological Class for the Crocodile River is mostly at C class beginning from the Kwena Dam downstream. Water quality constituents such as total dissolved solids and electrical conductivity increase with the increase in river distance in the downstream reaches. It was evident from this study that anthropogenic activities along the Crocodile River play a role in water quality deterioration and the subsequent distribution of fish during high and low flow conditions. The main sources of the pollution are believed to be agricultural activities in the upper reaches and a combination of industrial, domestic and agricultural activities in the middle and lower reaches of the Crocodile River.