coaltech upper olifants river catchment wetland inventory ...

Sixteen fish species (four of which were exotic) were analysed for the presence of metals
and pesticides by Heath and Claassen (1999). Representative specimens in each of the
species were analysed. There is a dietary difference between species in different rivers, and
this may also influence comparisons between rivers. A marked difference exists between
accumulation of different metals in different tissues such as the liver, gills, ovaries and
testes. The different tissues were, therefore, analysed for each of the metals. The mean
metal value per tissue was converted to ųg/l as a common unit. The result of the study was
that fish can be used as indicators of pollution and that the bio-accumulation of metals and
pesticides is taking place in the Olifants River. The bio-accumulation of pesticides such as
DDT may be from past usage of the pesticide within the catchment (Heath and Claassen
1999).
3.8 Wetland inventories
3.8.1 National Landcover database
The wetland layer in the National Landcover was updated. The scale of the wetland cover is
approximately 1:250 000. The expected date of release to the public is not yet known,
however it is expected that the data will be released very soon, since the wetland layer was
completed in July 2006.
3.8.2 Endorheic pans (Allan et al 1995)
A synthesis of all literature on the pans in the Transvaal and Free State was compiled by
Allan et al (1995). The report included the definition, distribution, density and the size of
pans. The distribution map is on a very small scale (approximately 1:9 000 000), and is
therefore, difficult to identify the locations of pans in the UORC. The classification of pans
and the difficulties experienced in classifying pans are discussed, as well as, the possible
origin and maintenance of the pans. The report includes a section on the abiotic and biotic
characteristics of pans, as well as, a section on threats to the pans (Allan et al 1995).
Wetland Database for UORC - 59 -