An assessment of the ecological integrity of Reed Pans on the Mpumalanga Highveld
- Authors: De Klerk, Arno Reed
- Date: 2011-05-16T07:53:33Z
- Subjects: Pans (Geomorphology) , Ecological integrity , Lake ecology , Aquatic invertebrates , Water quality biological assessment , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:7074 , http://hdl.handle.net/10210/3637
- Description: M.Sc. , Mpumalanga, “the place where the sun rises”, sets the scene for one of the rarest wetland types in South Africa. They are formed on one of the last remnants of the ancient African land surface, contain peat and together with a variety of other pan types make up the Mpumalanga Lakes District. Of these approximately 320 pans, only ±2.3% are reed pans. These endorheic wetlands are unique from other pan types and peatlands in South Africa and support an abundant biodiversity. They perform vital functions such as water storage, filtering out impurities and carbon fixation, which prevents an excess release of CO2 into the atmosphere. There is very little known about these endorheic wetlands and thus they are constantly being threatened by various activities such as agriculture, livestock and mining. The objectives of this study were to determine the spatial and temporal variation of macroinvertebrate community structures of reed pans and the environmental factors, such as water quality, responsible for the maintenance of these structures; to determine the best method for sampling aquatic invertebrates in reed pans; as well as to determine the relationship between aquatic invertebrates and the water, sediment and habitat quality of a reed pan. Together with this the amphibian diversity as well as the occurrence of other biotic components was determined. Four reed pans were assessed during four different seasons over a one year period to account for the different hydrological extremes. Sub-surface water samples were analyzed for their suspended solid content, nutrient levels, metals and chlorophyll-a concentrations as well as in situ water quality parameters. Sediment samples were analyzed for metal concentrations, organic carbon and water content, as well as sediment size distribution. Invertebrates were collected using the following sampling techniques: aquatic light trap, terrestrial light trap, emergent trap, sweep net, plankton net, as well as benthic sampling using an Eckman grab.
- Full Text:
- Authors: De Klerk, Arno Reed
- Date: 2011-05-16T07:53:33Z
- Subjects: Pans (Geomorphology) , Ecological integrity , Lake ecology , Aquatic invertebrates , Water quality biological assessment , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:7074 , http://hdl.handle.net/10210/3637
- Description: M.Sc. , Mpumalanga, “the place where the sun rises”, sets the scene for one of the rarest wetland types in South Africa. They are formed on one of the last remnants of the ancient African land surface, contain peat and together with a variety of other pan types make up the Mpumalanga Lakes District. Of these approximately 320 pans, only ±2.3% are reed pans. These endorheic wetlands are unique from other pan types and peatlands in South Africa and support an abundant biodiversity. They perform vital functions such as water storage, filtering out impurities and carbon fixation, which prevents an excess release of CO2 into the atmosphere. There is very little known about these endorheic wetlands and thus they are constantly being threatened by various activities such as agriculture, livestock and mining. The objectives of this study were to determine the spatial and temporal variation of macroinvertebrate community structures of reed pans and the environmental factors, such as water quality, responsible for the maintenance of these structures; to determine the best method for sampling aquatic invertebrates in reed pans; as well as to determine the relationship between aquatic invertebrates and the water, sediment and habitat quality of a reed pan. Together with this the amphibian diversity as well as the occurrence of other biotic components was determined. Four reed pans were assessed during four different seasons over a one year period to account for the different hydrological extremes. Sub-surface water samples were analyzed for their suspended solid content, nutrient levels, metals and chlorophyll-a concentrations as well as in situ water quality parameters. Sediment samples were analyzed for metal concentrations, organic carbon and water content, as well as sediment size distribution. Invertebrates were collected using the following sampling techniques: aquatic light trap, terrestrial light trap, emergent trap, sweep net, plankton net, as well as benthic sampling using an Eckman grab.
- Full Text:
Ecological integrity assessment of the Mvoti Estuary, KwaZulu-Natal, South Africa
- Authors: Swemmer, Riaan
- Date: 2011-06-29T06:54:01Z
- Subjects: Estuaries , Estuarine ecology , Ecological integrity , KwaZulu-Natal (South Africa)
- Type: Thesis
- Identifier: uj:7146 , http://hdl.handle.net/10210/3737
- Description: M.Sc. , Estuaries are regarded as South Africa's most productive ecosystems due to the important functions that they perform, such as providing nursery areas and feeding sites for juvenile macro-invertebrate and fish species. Furthermore, ecologically healthy estuaries are not only of critical importance since they facilitate the provision and recirculation of nutrients, they also provide conduits for catadromous or anadromous fish and act as buffers during floods. In South Africa these functions are continuously threatened by residential and/or industrial developments. It is thus essential to determine the ecological integrity (structure and function) of these systems. An ecological integrity study was carried out on the Mvoti Estuary, KwaZulu-Natal during 2004/2005. An ecological integrity study was also carried out on the Amatigulu/Nyoni Estuary, KwaZulu–Natal during the same period and was used as a reference study. The ecological integrity of the Mvoti Estuary was assessed in terms of the effects of selected abiotic drivers on specific biological responses. The study was carried out according to the guidelines of the ecological reserve determination methodologies and the resource directed measures for aquatic resources as set out by the Department of Water Affairs and Forestry. Surveys were carried out during low flow (September 2004) and high flow (March 2005) periods. Abiotic and biotic monitoring was carried out at four sites on the Mvoti Estuary and five sites on the Amatigulu/Nyoni Estuary. The abiotic components, such as the substrate composition and physico-chemical properties of the water and sediment, was analysed using standard methods. Biological monitoring included the study of the benthic macro-invertebrate-, ichthyofaunal- and avifaunal communities. The biotic and abiotic components were analysed using various indices, where applicable. The ecological integrity of a system can be assessed on the basis of its ability to carry out its natural functions. Results show that various anthropogenic activities in the upper reaches of the Mvoti River contributed to the highly modified state of the Mvoti Estuary. The abiotic drivers of the aquatic system that contributed to the modified state of the Mvoti Estuary is unacceptable water quality, a loss and/or modification of habitat and an altered hydrological pattern. As a result of the abiotic drivers, results show that the xi ichthyofaunal-, macro-invertebrate- and, to a lesser degree, the avifaunal communities also reside in a modified state. Physico-chemical, geomorphological and hydrological changes in this system resulted in the Mvoti Estuary suffering a loss in both its biological and ecological function as well as aesthetic value. It is apparent from the above that there is not only a need for rehabilitation, but also a need for an effective and continuous management strategy. This management strategy can only be successful if the biomonitoring of the system includes the effects at both economical and social levels.
- Full Text:
- Authors: Swemmer, Riaan
- Date: 2011-06-29T06:54:01Z
- Subjects: Estuaries , Estuarine ecology , Ecological integrity , KwaZulu-Natal (South Africa)
- Type: Thesis
- Identifier: uj:7146 , http://hdl.handle.net/10210/3737
- Description: M.Sc. , Estuaries are regarded as South Africa's most productive ecosystems due to the important functions that they perform, such as providing nursery areas and feeding sites for juvenile macro-invertebrate and fish species. Furthermore, ecologically healthy estuaries are not only of critical importance since they facilitate the provision and recirculation of nutrients, they also provide conduits for catadromous or anadromous fish and act as buffers during floods. In South Africa these functions are continuously threatened by residential and/or industrial developments. It is thus essential to determine the ecological integrity (structure and function) of these systems. An ecological integrity study was carried out on the Mvoti Estuary, KwaZulu-Natal during 2004/2005. An ecological integrity study was also carried out on the Amatigulu/Nyoni Estuary, KwaZulu–Natal during the same period and was used as a reference study. The ecological integrity of the Mvoti Estuary was assessed in terms of the effects of selected abiotic drivers on specific biological responses. The study was carried out according to the guidelines of the ecological reserve determination methodologies and the resource directed measures for aquatic resources as set out by the Department of Water Affairs and Forestry. Surveys were carried out during low flow (September 2004) and high flow (March 2005) periods. Abiotic and biotic monitoring was carried out at four sites on the Mvoti Estuary and five sites on the Amatigulu/Nyoni Estuary. The abiotic components, such as the substrate composition and physico-chemical properties of the water and sediment, was analysed using standard methods. Biological monitoring included the study of the benthic macro-invertebrate-, ichthyofaunal- and avifaunal communities. The biotic and abiotic components were analysed using various indices, where applicable. The ecological integrity of a system can be assessed on the basis of its ability to carry out its natural functions. Results show that various anthropogenic activities in the upper reaches of the Mvoti River contributed to the highly modified state of the Mvoti Estuary. The abiotic drivers of the aquatic system that contributed to the modified state of the Mvoti Estuary is unacceptable water quality, a loss and/or modification of habitat and an altered hydrological pattern. As a result of the abiotic drivers, results show that the xi ichthyofaunal-, macro-invertebrate- and, to a lesser degree, the avifaunal communities also reside in a modified state. Physico-chemical, geomorphological and hydrological changes in this system resulted in the Mvoti Estuary suffering a loss in both its biological and ecological function as well as aesthetic value. It is apparent from the above that there is not only a need for rehabilitation, but also a need for an effective and continuous management strategy. This management strategy can only be successful if the biomonitoring of the system includes the effects at both economical and social levels.
- Full Text:
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