Abstract
M.Sc. (Zoology)
The catchment area of the Olifants River is being subjected to increased agricultural
and mining activities, industrial development and urbanisation. As a result of this, the
water quality 'of the Olifants River and some of its tributaries (e.g. Selati River) has
been deteriorating since 1983. This causes reason for concern as one of the
downstream water users in the Olifants River catchment is the Kruger National Park,
which requires of good quality to sustain its terrestrial and aquatic ecosystems
It was therefore necessary to determine what extent activity midstream-or--tlie I
Olifants River, especial y in the Phalaborwa area, influenced the water quality of the
Olifants River. In this study, an evaluation was done of the water quality (physically
and chemically of the Lower Olifants River inside of the Kruger National Park, as well
as the Lower Selati River, a tributary of the Olifants River which flows through the
Phalaborwa area. Special attention was paid to the metal concentrations in the water,
sediment and fish.
Water and sediment were sampled every alternate month from April 1990 to February
1992 at six sampling sites along the Lower Olifants River and one in the Selati River.
Standard methods were used to determine the physical and chemical characteristics
(e.g. pH, TDS, etc.) of the water. The fish species Barbus marequensis was also
sampled every alternative month, but only at three sampling sites along the Olifants
River and one in the Selati River. Organs and tissues that were dissected, included the
gills, fat, liver, gonads, gut, muscle, skin, blood, vertebrae, kidney and bile, as well as
the gut contents. In February 1992, additional sampling was performed at Pioneer
Dam, a natural reference point used in this study. Atomic absorption
spectrophotometry was used in the laboratory to determine the Cr, Cu, Fe, Mn, Ni, Pb,
Sr and Zn concentrations in the water, sediment and fish samples.
(The water quality of the Selati River was found to be stressful to aquatic life, especially
.) with regard to the sodium, fluoride, chloride, sulphate, potassium, total ~dissolved salts 1 and metal concentrations (except strontium). The Selati River also influenced the
': water quality of the Olifants River after the Selati-Olifants confluence. Most of the
:. time the water quality of the Lower Olifants River in the KNP did, however, comply
With the recommended guideline limits, except for the metal concentrations. The high
metal concentrations detected in the water (in some cases sub-lethal levels) indicated
some degree of metal pollution, but, due to the hardness of the Olifants River water,
conditions were not necessarily toxic to the aquatic life. The accumulated metals in
the organs and tissues of marequensis gave a good indication of the metal levels to
which the fish were exposed. More metals were taken up by the fish from April 1990
to February 1991 than from April 1991 to February 1992. The various metals were
. distributed differently to the tissues of B. marequensis, with the highest zinc
concentrations being accumulated by the skin and ovaries; the highest copper and iron
by the liver, kidney and gut; the highest chromium and nickel by the blood; and the
highest manganese, lead and strontium by the vertebrae and gills. These results
afforded guidelines as to the types of tissue which should be sampled as the most
suitable for the analysis of the various metals in polluted waters.