The South African National Water Act (NWA) (No. 36 of 1998) recognises that in order to sustain the goods and services that are provided by rivers and their associated biological communities, it is necessary to conserve the entire aquatic ecosystem. Conservation and maintenance of ecosystem functioning entails the protection of the biotic components (i.e. fish, macroinvertebrates, riparian vegetation, etc.) and ensuring that the abiotic driver aspects (i.e. required amount and variability of flow, water quality and fluvial geomorphology) are addressed and met (Malan and Day, 2003). According to the Reserve Determination methodology (DWAF, 2003), sustainable utilisation of the river resources requires proper, responsible management and that exploitation without understanding or limits, impacts negatively on the ecological processes, functions and communities, both in the present and the future. Manipulation of the flow regimes of rivers, to provide water when and where people need it, has resulted in a growing deterioration in the condition (health) of riverine ecosystems (King et al., 2000). Stressors on aquatic ecosystems originating from these anthropogenic activities, include point and non-point loadings, land use influences and changes, and stream modification. These are usually defined by the drivers of aquatic ecosystems namely the geomorphology, hydrology and water quality. In turn, the effects on the physical habitat and water quality have both direct and indirect effects on the biotic communities present and are usually defined by biological responses to these changes (Kleynhans et al., 2005). There is currently limited data available to formally propose a methodology to quantify the significance of altered flows in riverine ecosystems brought about by the abstraction or excessive release of water by industrial activities on a reach scale. The aim of this study was to determine the degree and magnitude of habitat-flow alterations caused by pulp and paper mill activities in the Elands and Mvoti Rivers and to link the related biological responses to them. / Prof. V. Wepener
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:7739 |
| Date | 15 August 2008 |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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