Browsing by Author "King, Jackie"

Now showing 1 - 7 of 7
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    Defining flows to protect instream biota : a critique of the instream flow incremental methodology and the development of a hierarchical habitat-based approach, using the pennant-tailed catlet, Chiloglanis anoterus in the Marite River, South Africa
    (2001) Pollard, S (Sharon); King, Jackie; Davies, Bryan
    This thesis focusses on two approaches to determining Instream Flow Requirements (IFR) for regulated rivers, specifically in the sub-tropical eastern region of South Afiica using a flow-sensitive fish species, the pennant-tailed catlett 07iloglanis anoterus. In response to the diminishing and altered flow regimes of rivers, and the ecological consequences, a range of methodologies has evolved that attempt to quantify IFRs for rivers. One group of methods that attempts to do this are known as habitat-assessment approaches. They focus specifically on understanding how changes in river flow affect the quantity of physical instream habitat. The most widely used of these is the Instream Flow Incremental Methodology (lAM) and it's associated computer packages, PHABSIM II. More recently, South Africa has also turned its attention of ways to defining IFRs. Given lAM's prominence internationally, it was considered as one potential methodology. Nonetheless, its applicability to local conditions required testing. At the same time, the easterly-flowing rivers were under increasing development pressure, providing a particular immediacy to find appropriate means to define IFRs. Thus, my research was designed to assess the downstream effects of the Injaka Dam on the physical habitat of a flow-sensitive fish species of the Marite River. Specifically, it aimed to test the local applicability of lAM, based on the microhabitat requirements of C anoterus, and to explore an alternative approach if it were found to be unsuitable. Microhabitat is described on the basis of three hydraulic variables: depth, velocity and Channel Index (substratum and cover).
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    Design and prototype of an external quality assurance program for urine bicarbonate
    (2011) Benjamin, Ryan; King, Jackie; Berman, Peter
    This dissertation validates a Beckman-Coulter DxC(R) assay for total bicarbonate in urine and then proceeds to design, prototype and cost an inter-laboratory comparison (ILC) program for the above urine bicarbonate based on the validation. Furthermore, this work serves as a case study for how to establish proficiency testing - and thereby achieve accreditation - for tests without external quality assurance because of analyte instability.
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    Distributions of physical habitats and benthic macroinvertebrates in Western Cape headwater streams at multiple spatial and temporal scales
    (2005) Schael, Denise Marie; King, Jackie; Day, Jenny; Field, John G
    The research in this thesis examines the links between benthic macroinverebrate (invertebrate) distributions and aspects of the physical habitat at different spatial and temporal scales in mountain and foothill zones of rivers in the Western Cape, South Africa. A geomorphological hierarchy was used as the spatial template for studying invertebrate distributions. The different levels of the hierarchy are: catchment, segment, zone, reach, morphological unit and hydraulic biotype. Hydraulic biotypes are visually defined flow and substratum combinations. The hierarchical levels studied in this thesis were catchment, zone, reach and hydraulic biotype.
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    The influence of hydraulics, hydrology and temperature on the distribution, habitat use and recruitment of threatened cyprinids in a Western Cape river, South Africa
    (2008) Paxton, Bruce Randall; King, Jackie; Cambray, Jim
    This study aims to explore the relationships between river flow and fish ecology in the context of the riverscape model of river ecosystems by examining the seasonal distribution of two endangered fish species, i.e. the Clanwilliam yellowfish and Clanwilliam sawfin, in relation to their physical (structural) and hydraulic habitat requirements at several scales, and to assess the importance temporal changes in flow and temperature in relation to the timing of key life history events and recruitment. From these findings it aims to recommend water management strategies to ensure the persistence of remaining populations, as well as to suggest a way forward for fish habitat studies in South Africa. The study was conducted on the Driehoeks River, a tributary of the Doring River system, which rises in the Cederberg mountains of the Western Cape, South Africa. A 5.9 km segment of this river was selected for the study.
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    Modelling and managing the effects of trout farms on Cape rivers
    (1998) Brown, Catherine Anne; King, Jackie; Field, John G
    The south-western Cape is currently responsible for 45% of the total annual trout production in South Africa and further expansion of this industry in the region is likely. A pilot study of seven trout farms situated on the upper reaches of rivers in the south-western Cape was undertaken to determine whether there was a common trend in their effect on the rivers. Results indicated that the impact of the farms on the benthic invertebrate communities of the rivers ranged from mild to severe, based on the degree of change in the structure of the communities form upstream to downstream of the effluent outlets. Those farms situated on mountain streams had the greatest impact and those on the downstream foothill had a lesser impact. The reduced impact in the foothill zone was probably because these reaches were already disturbed by other catchment activities. Of the three farms that were situated on mountain streams and source areas, two used plastic portapools and the third earth dams. There was a substantial increase in the number of oligochaetes downstream of both 'portapool' farms and yet, despite being situated in the same sensitive river zone, this did not occur downstream of the farm that used earth dams. The general impact of trout farm effluent on the mountain-stream and source zones was to eliminate or greatly reduce the number of Limnichidae, Helodidae, Plecoptera, Elmidae, Heptageniidae and Ephemerellidae, and, in the case of portapool farms, to replace these with Naididae, Lumbriculidae, Chironomidae and Planaria. Once-off chemical samples were also collected at each site and, acknowledging the limitations of the sampling strategy, results showed that the particulate fraction of the effluent was probably responsible for the recorded reaction of the biota.
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    The relationship between periphyton, flow and nutrients in foothill rivers of the south-western Cape, South Africa
    (2012) Ewart-Smith, Justine L; King, Jackie; Day, Jenny
    This thesis examines spatial and temporal patterns in periphyton community composition and biomass and the environmental factors responsible for shaping these communities in south-western Cape rivers. The study focused on two prennial foothill rivers in the south-western Cape: the Berg River, which is oligotrophic but has a large dam (The Berg Dam) situated in its upper reaches; and the Molenaars River, which has a natural flow regime but is moderately enriched by trout farm effluent. Two site on the Berg River (one upstream and one downstream of the Berg Dam) and two on the Molenaars River (one upstream and one downstream of the Du Toit's Kloof trout farm) were used to study temporal dynamics in periphyton communities over a 21-month period between September 2007 and May 2009.
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    Spontaneous succession of riparian vegetation and aquatic macroinvertebrates along the Silvermine River, South Africa, after fire and clearing of exotic plant species
    (2008) Reinecke, Michiel Karl; King, Jackie
    Spontaneous succession, as a method to restore degraded riverine habitats, was assessed for three different components of the Silvermine River ecosystem over one year. These were the state of the physical habitats (biotopes) available to aquatic organisms, changes in the community composition of riparian vegetation, and changes to aquatic macroinvertebrate assemblages present in the river. Data were collected during two successive summer-sampling periods (200 I and 2002) at three study sites along the river. Site I was situated in the mountain stream zone, while Sites 2 and 3 were situated in the foothills. Changes in the riverine ecosystem and its associated habitats were compared to reference condition data for each of the three components from each study site. There were no large changes to the macro-channel banks of the river over the one year study, other than where a meander cut-off occurred at Site 2. Changes over the year in the proportions of flow at the three sites revealed a lack of faster-flow types, which would normally characterise mountain stream and foothill reaches, at all three study sites. Measurements of the proportions of substratum types at the three sites revealed there was an unusually high proportion of fine substratum types present. In the foothills, this was attributed to erosion of the unstable bank at Site 2, which continued to deposit an excess of fine sediment that was transported downstream. In the vegetation study, most species that came to dominate the mountain stream (Site I) and the foothill (Sites 2 and 3) riparian communities emerged from the seed bank within the first two years after the fire. Thus, using the presence or absence of characteristic riparian vegetation species it is possible to determine whether there is a need to augment the recovery process after two years. The aquatic macroinvertebrate communities of the mountain stream differed clearly from those in the foothill. The differences were attributed to a combination of the channel type and the longitudinal position of the sites along the river, both of which dictated the physical habitats available. There were clear differences in the potential for recovery at each of the three study sites. It was shown that non-intervention will not support successful recovery in the short to medium term for any of the measured three components of this river. A blanket policy of non-intervention cannot address site-specific differences, be they natural or artificial, which pose different challenges to restoration. There were zonal differences in the availability of substrata and flow types. There were also other differences that were attributed to water abstraction and the presence of different woody exotic trees. Recovery of the mountain stream was being hampered by the presence of the reservoir and the history of water abstraction while recovery of the foothill was being retarded by erosion from the massive sediment deposit at Site 2. Plans to restore the river, that took into account these inter-site differences, were proposed.