Abstract
Abstract : The degradation of aquatic resources has become an issue of great concern to authorities, interested and affected members of the public. Management actions implemented throughout the years for sustainable water use have failed and the ongoing impacts of anthropogenic activities can be reflected in the deterioration of aquatic ecosystems. The impacts of the physical and chemical alterations occurring in rivers can be integrated and reflected by the aquatic communities such as macro invertebrates, fish and riparian vegetation. The main aim of the study was to determine the current ecological state of the Klip River by measuring selected water quality variables; conduct an integrated habitat assessment and assess macro-invertebrate communities as ecological indicators. Six sites (K1-K6) were selected along the Klip River, upstream and downstream of identified point sources of pollution. The in situ water quality parameters measured included temperature, pH, and electrical conductivity as well as dissolved oxygen. Nutrient and metal concentrations were also measured at all study sites. The aquatic macroinvertebrate monitoring was conducted using the South African Scoring System version 5 (SASS5) and the assessment of habitat quality was conducted using the Integrated Habitat Assessment System (IHAS). The results from the study indicated the water quality to be poor as the concentration levels of all parameters from study site K1 to K6 exceeded the target water quality range (TWQR) for aquatic ecosystems. Site K1, at the source of the Klip River, recorded the highest levels of silver, iron, nickel and manganese and the levels of phosphate, chlorophyll-a, free and saline ammonia increased from K2 to K6 downstream of the waste water treatment works. The ecological classes for the macro-invertebrates from sites K1 to K6 were all in the category class E/F indicative of a critically modified state with low species diversity and the absence on sensitive species at all sites. This was also indicated by the low average score per taxa (ASPT) and SASS5 scores recorded at all sites. The habitat quality was only adequate at the upstream site K1 and in a poor, unacceptable state at sites K2 to K6. The principal component analysis (PCA) showed that sites K4 & K5 grouped together with DO, EC, pH. Chlorophyll-a, Total Phosphates, Nitrites and Nitrates grouped with sites K2 and K3. The PCA for metals and sampling sites indicated a grouping for Cobalt, Silver, Nickel and Iron with site K1. The metals Magnesium, Phosphorus, Boron, Silicon, Barium and Aluminium showed a grouping with site K6 and Potassium, Calcium and Sodium with sites K2 and K5. Site K1 grouped with the macro-invertebrates Culicidae and Amphipoda. Sites K3 and K6 grouped with the macro-invertebrate families Gerridae, Gyrinidae and Coenagrionidae. Sites K2 and K5 showed an association with macro-invertebrate families Baetidae, Gomphidae, Notonectidae, Dytisdae, Hydropsychidae and Belostomatidae. More of the families were recorded at sites below waste water treatment works (K2 & K5) and few families were recorded upstream at site K1.
M.Sc. (Aquatic Health)