The use of thermal modelling in improving rural subsistence aquaculture
- Authors: Bailey, Dylan Francis
- Date: 2007
- Subjects: Sustainable aquaculture -- South Africa , Aquaculture industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10715 , http://hdl.handle.net/10948/473 , Sustainable aquaculture -- South Africa , Aquaculture industry -- South Africa
- Description: There has been a long history of attempts to promote subsistence rural aquaculture within South Africa. Many of these attempts have failed due to inadequate support from government and support agencies. There has been a recent revived interest in promoting rural aquaculture development. Presented in this project are six scenarios demonstrating the potential application of thermal modelling techniques to improving subsistence rural aquaculture. These scenarios were based on a model validated against a real life system, and run with environmental data for the year 2005. Bovine manure, grass thatch, cereal straw and Typha spp. water reeds were tested for thermal performance. These results were then applied to the scenarios. The open and kraal enclosed pond scenarios yielded the widest deviation in temperatures throughout the year, with an average temperature of 3.8oC and 6.0oC above ambient and a temperature range of 10.6oC and 12.4oC for the year respectively. Eliminating solar radiation and reducing wind speed resulted in an average difference of 1.5oC below ambient and a temperature range of 7.5oC for the year. When completely enclosed in a well-sealed traditional Xhosa style hut, the pond had an average difference of 5.6oC below outside ambient temperature, with a range of 7.8oC for the year. A passive solar heating scenario added to the sealed hut scenario, which when run continuously maintained an average difference of 34.7oC above outside ambient temperatures, with a range of 56oC for the year. When a hypothetical 25oC temperature control was included in the model, the system maintained an average of 7.1oC above ambient outside temperatures, with a temperature range of 0.8oC throughout the year. The wider range of temperatures made available through the use of thermal modelling approaches provides a more diverse range of species available for subsistence rural aquaculture at any site, significantly improving its potential.
- Full Text:
- Date Issued: 2007
- Authors: Bailey, Dylan Francis
- Date: 2007
- Subjects: Sustainable aquaculture -- South Africa , Aquaculture industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10715 , http://hdl.handle.net/10948/473 , Sustainable aquaculture -- South Africa , Aquaculture industry -- South Africa
- Description: There has been a long history of attempts to promote subsistence rural aquaculture within South Africa. Many of these attempts have failed due to inadequate support from government and support agencies. There has been a recent revived interest in promoting rural aquaculture development. Presented in this project are six scenarios demonstrating the potential application of thermal modelling techniques to improving subsistence rural aquaculture. These scenarios were based on a model validated against a real life system, and run with environmental data for the year 2005. Bovine manure, grass thatch, cereal straw and Typha spp. water reeds were tested for thermal performance. These results were then applied to the scenarios. The open and kraal enclosed pond scenarios yielded the widest deviation in temperatures throughout the year, with an average temperature of 3.8oC and 6.0oC above ambient and a temperature range of 10.6oC and 12.4oC for the year respectively. Eliminating solar radiation and reducing wind speed resulted in an average difference of 1.5oC below ambient and a temperature range of 7.5oC for the year. When completely enclosed in a well-sealed traditional Xhosa style hut, the pond had an average difference of 5.6oC below outside ambient temperature, with a range of 7.8oC for the year. A passive solar heating scenario added to the sealed hut scenario, which when run continuously maintained an average difference of 34.7oC above outside ambient temperatures, with a range of 56oC for the year. When a hypothetical 25oC temperature control was included in the model, the system maintained an average of 7.1oC above ambient outside temperatures, with a temperature range of 0.8oC throughout the year. The wider range of temperatures made available through the use of thermal modelling approaches provides a more diverse range of species available for subsistence rural aquaculture at any site, significantly improving its potential.
- Full Text:
- Date Issued: 2007
The zooplankton of Mngazana estuary
- Authors: Louw, Liezel
- Date: 2007
- Subjects: Marine zooplankton -- South Africa -- Mngazana Estuary , Mngazana Estuary (Eastern Cape, South Africa) , Estuarine ecology -- South Africa -- Mngazana Estuary , Estuarine area conservation -- South Africa -- Mngazana Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10707 , http://hdl.handle.net/10948/702 , Marine zooplankton -- South Africa -- Mngazana Estuary , Mngazana Estuary (Eastern Cape, South Africa) , Estuarine ecology -- South Africa -- Mngazana Estuary , Estuarine area conservation -- South Africa -- Mngazana Estuary
- Description: The zooplankton community of the main channel of the Mngazana estuary was investigated on six occasions over one year. Spatial and temporal variability in zooplankton abundance and distribution were sampled using two slightly modified WP2 plankton nets of 200 μm mesh and 57 cm mouth diameter. Nets were fitted with calibrated Kahlsico 005 WA 130 flow meters. A set of environmental variables were also measured at each site. The water column of the main channel of Mngazana estuary was stratified in summer but well mixed in winter. Temperature progressively increased from the lower stations to the upper reaches of the estuary. Maximum vertical temperature differences occurred in the middle estuarine reaches. Salinity progressively decreased from the lower reaches to the upper reaches, but was generally above 26 from Station 3 to Station 8. Only during November 2005, were salinity readings low due to heavy rains. Summer salinity values were always lower than the winter salinity values as a result of summer rainfall. A total of 76 zooplankton taxa were identified. The estuarine copepods Acartia natalensis and Pseudodiaptomus hessei dominated the assemblage, with maximum abundances in the middle to upper reaches. Acartia natalensis reached high densities in winter (> 50 000 m-3) although lowest abundances were recorded when maximum rainfall was received (November 2005). Wooldridge (1977) and Deyzel (2004) recorded maximum densities during summer. Pseudodiaptomus hessei reached high densities (> 17 000 m-3) during the highest rainfall month. Previous studies indicated that this pioneer species is able to recover quickly after a flood and subsequently increase rapidly in numbers. The mysid, Mesopodopsis africana reached high densities (> 5 000 m-3) in the middle estuarine reaches during summer. Ichtyofauna, brachyura and anomura were important contributors to the merozooplankton component of the community. The maximum number of species was recorded during winter in the lower estuarine reaches, when vertical differences in salinities were minimal.
- Full Text:
- Date Issued: 2007
- Authors: Louw, Liezel
- Date: 2007
- Subjects: Marine zooplankton -- South Africa -- Mngazana Estuary , Mngazana Estuary (Eastern Cape, South Africa) , Estuarine ecology -- South Africa -- Mngazana Estuary , Estuarine area conservation -- South Africa -- Mngazana Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10707 , http://hdl.handle.net/10948/702 , Marine zooplankton -- South Africa -- Mngazana Estuary , Mngazana Estuary (Eastern Cape, South Africa) , Estuarine ecology -- South Africa -- Mngazana Estuary , Estuarine area conservation -- South Africa -- Mngazana Estuary
- Description: The zooplankton community of the main channel of the Mngazana estuary was investigated on six occasions over one year. Spatial and temporal variability in zooplankton abundance and distribution were sampled using two slightly modified WP2 plankton nets of 200 μm mesh and 57 cm mouth diameter. Nets were fitted with calibrated Kahlsico 005 WA 130 flow meters. A set of environmental variables were also measured at each site. The water column of the main channel of Mngazana estuary was stratified in summer but well mixed in winter. Temperature progressively increased from the lower stations to the upper reaches of the estuary. Maximum vertical temperature differences occurred in the middle estuarine reaches. Salinity progressively decreased from the lower reaches to the upper reaches, but was generally above 26 from Station 3 to Station 8. Only during November 2005, were salinity readings low due to heavy rains. Summer salinity values were always lower than the winter salinity values as a result of summer rainfall. A total of 76 zooplankton taxa were identified. The estuarine copepods Acartia natalensis and Pseudodiaptomus hessei dominated the assemblage, with maximum abundances in the middle to upper reaches. Acartia natalensis reached high densities in winter (> 50 000 m-3) although lowest abundances were recorded when maximum rainfall was received (November 2005). Wooldridge (1977) and Deyzel (2004) recorded maximum densities during summer. Pseudodiaptomus hessei reached high densities (> 17 000 m-3) during the highest rainfall month. Previous studies indicated that this pioneer species is able to recover quickly after a flood and subsequently increase rapidly in numbers. The mysid, Mesopodopsis africana reached high densities (> 5 000 m-3) in the middle estuarine reaches during summer. Ichtyofauna, brachyura and anomura were important contributors to the merozooplankton component of the community. The maximum number of species was recorded during winter in the lower estuarine reaches, when vertical differences in salinities were minimal.
- Full Text:
- Date Issued: 2007
Towards knowing through doing : improving the societal relevance of systematic conservation assessments
- Authors: Knight, Andrew Thomas
- Date: 2007
- Subjects: Conservation of natural resources -- Planning , Nature conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10598 , http://hdl.handle.net/10948/711 , Conservation of natural resources -- Planning , Nature conservation -- South Africa
- Description: Systematic conservation assessments are spatially-explicit techniques for prioritising areas for the implementation of conservation action. There has been considerable reference in the peer-reviewed literature as to the usefulness of these tools, which appear to be primarily used by academics for theoretical research. A literature review and author survey reveals the peer-reviewed literature is largely theoretical, although conservation action results more frequently than reported. The effectiveness of these interventions is generally described as only ‘fairly effective’. This general trend, coupled with previous personal failures in translating systematic conservation assessments into effective conservation action triggered an explicit process of social learning implemented as action research. It examined the workings of the Subtropical Thicket Ecosystem Planning (STEP) project, which included development of a systematic conservation assessment. Systematic conservations assessments simply provide information on where action should be implemented, and so are only useful if situated within broader operational models for conservation planning. Most operational models presented in the peer-reviewed literature are primarily focused upon the testing ecological data, not upon the delivery of conservation action. A new operational model for conservation planning is presented which more accurately reflects the ‘real-world’ process of conservation planning. An implementation strategy is an essential complement to a systematic conservation assessment. It describes how specific, explicitly-stated goals will be achieved, who is accountable for undertaking these activities, and the resources required. As the Implementation Specialist for the STEP Project, I co-lead the collaborative development of an implementation strategy with stakeholders that aimed to mobilise resources towards achieving common goals. Whilst the development and initial uptake of the strategy was good, subsequent implementation has flounder. The reasons for this are explored. The ultimate pragmatic goal of a conservation planning process is the establishment of effective social learning institutions. These develop common visions, mobilise collective action, and adaptively learn and refine their conservation activities. Thicket Forum is one xi such institution established through the STEP Project. My involvement with Thicket Forum since 2004 in implementing an adaptive learning approach facilitates collaboration between land managers, government and research organisations. Systematic conservation assessments evolved in response to the ad hoc way in which protected areas were implemented, leaving unrepresentative, biased protected area networks. Most research is theoretical and without an intimate understanding of the social-ecological system of a planning region, notably opportunities and constraints for implementing conservation action. Highlighting the importance of an approach which is flexible, not only in space, but in time, which can capitalise upon implementation opportunities, is important for stemming the myth that opportunism is the nemesis of systematic conservation assessments. To this end, conservation planners have been slow to include factors influencing effective implementation in systematic conservation assessments. Many studies which identify candidate protected area networks, first, fail to identify the specific instrument(s) to be applied, and second, assume all intact land is available. Having mapped the willingness of land managers in the Albany District, South Africa, to sell their land, it is demonstrated the majority of targets fail to be achieved because land managers will not sell. Knowing this, the current focus of gathering ever-more ecological data is misplaced. Human, social and economic factors influence target achievement, efficiency and spatial configuration of priority areas. Selecting important areas for conservation, particularly at the local-scale, requires the mapping of factors which define opportunities for conservation. Land manager willingness to collaborate and participate, entrepreneurial orientation, conservation knowledge, social capital, and local champions were applied using a method of hierarchical clustering to identify land managers who represent conservation opportunities for private land conservation initiatives.
- Full Text:
- Date Issued: 2007
- Authors: Knight, Andrew Thomas
- Date: 2007
- Subjects: Conservation of natural resources -- Planning , Nature conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10598 , http://hdl.handle.net/10948/711 , Conservation of natural resources -- Planning , Nature conservation -- South Africa
- Description: Systematic conservation assessments are spatially-explicit techniques for prioritising areas for the implementation of conservation action. There has been considerable reference in the peer-reviewed literature as to the usefulness of these tools, which appear to be primarily used by academics for theoretical research. A literature review and author survey reveals the peer-reviewed literature is largely theoretical, although conservation action results more frequently than reported. The effectiveness of these interventions is generally described as only ‘fairly effective’. This general trend, coupled with previous personal failures in translating systematic conservation assessments into effective conservation action triggered an explicit process of social learning implemented as action research. It examined the workings of the Subtropical Thicket Ecosystem Planning (STEP) project, which included development of a systematic conservation assessment. Systematic conservations assessments simply provide information on where action should be implemented, and so are only useful if situated within broader operational models for conservation planning. Most operational models presented in the peer-reviewed literature are primarily focused upon the testing ecological data, not upon the delivery of conservation action. A new operational model for conservation planning is presented which more accurately reflects the ‘real-world’ process of conservation planning. An implementation strategy is an essential complement to a systematic conservation assessment. It describes how specific, explicitly-stated goals will be achieved, who is accountable for undertaking these activities, and the resources required. As the Implementation Specialist for the STEP Project, I co-lead the collaborative development of an implementation strategy with stakeholders that aimed to mobilise resources towards achieving common goals. Whilst the development and initial uptake of the strategy was good, subsequent implementation has flounder. The reasons for this are explored. The ultimate pragmatic goal of a conservation planning process is the establishment of effective social learning institutions. These develop common visions, mobilise collective action, and adaptively learn and refine their conservation activities. Thicket Forum is one xi such institution established through the STEP Project. My involvement with Thicket Forum since 2004 in implementing an adaptive learning approach facilitates collaboration between land managers, government and research organisations. Systematic conservation assessments evolved in response to the ad hoc way in which protected areas were implemented, leaving unrepresentative, biased protected area networks. Most research is theoretical and without an intimate understanding of the social-ecological system of a planning region, notably opportunities and constraints for implementing conservation action. Highlighting the importance of an approach which is flexible, not only in space, but in time, which can capitalise upon implementation opportunities, is important for stemming the myth that opportunism is the nemesis of systematic conservation assessments. To this end, conservation planners have been slow to include factors influencing effective implementation in systematic conservation assessments. Many studies which identify candidate protected area networks, first, fail to identify the specific instrument(s) to be applied, and second, assume all intact land is available. Having mapped the willingness of land managers in the Albany District, South Africa, to sell their land, it is demonstrated the majority of targets fail to be achieved because land managers will not sell. Knowing this, the current focus of gathering ever-more ecological data is misplaced. Human, social and economic factors influence target achievement, efficiency and spatial configuration of priority areas. Selecting important areas for conservation, particularly at the local-scale, requires the mapping of factors which define opportunities for conservation. Land manager willingness to collaborate and participate, entrepreneurial orientation, conservation knowledge, social capital, and local champions were applied using a method of hierarchical clustering to identify land managers who represent conservation opportunities for private land conservation initiatives.
- Full Text:
- Date Issued: 2007