The Drakensberg rock-jumper: ecology and genetic status of isolated montane populations
- Authors: Morris, Dale Brett
- Date: 2013
- Subjects: Passeriformes -- Drakensberg Mountains , Passeriformes -- South Africa , Passeriformes -- Lesotho , Passeriformes -- Ecology -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5828 , http://hdl.handle.net/10962/d1007696 , Passeriformes -- Drakensberg Mountains , Passeriformes -- South Africa , Passeriformes -- Lesotho , Passeriformes -- Ecology -- Africa, Southern
- Description: The Drakensberg rock-jumper (Chaetops aurantius) is a high-altitude passerine endemic to South Africa and Lesotho, living along a highly disrupted portion of the southern Great Escarpment from the Drakensberg highlands in the north-east to the Sneeuberg in the west, above an altitude of 1500 m. Along with the Cape rock-jumper (C. frenatus), this genus provides one of the stronger faunal links between the floristic biomes known as the Drakensberg Alpine Centre (DAC) and the Cape Floristic Region (CFR). Despite this, there is a significant lack of information regarding the species. The great majority of information is based on incidental observation, and no dedicated study has been undertaken. I conducted a series of field excursions between January 2011 and November 2012 in order to explore the rock-jumper’s feeding ecology, diet, habitat usage and genetic diversity. By trapping the birds, I was able to mark them individually with unique colour ring-combinations, and pluck a tail feather for genetic analyses. Observational data reveal that birds living close to their lower altitude threshold (c. 1500 m) are strongly habitat specific, living in boulder fields dominated by grassy vegetation. However, in areas at higher elevations (c. 2000 – 2500 m) this restriction seemed to fall away, possibly as a result of farming practices in those areas – higher grazing pressure results in shorter grass and less foraging effort for the birds. They live in groups ranging from pairs to small family groups of up to twelve individuals and maintain year round territories. Territory defence takes the form of calling and displaying from a prominent rock or boulder and becomes particularly noticeable just prior to, and during, the breeding period. No colour ringed individuals were ever spotted in boulder fields outside from where they had been initially ringed. This, coupled with the behaviour of territory maintenance, suggests a strongly sedentary lifestyle. Genetic inferences are constrained by a small sample size (only 25 birds were caught), but results indicate that some genetic isolation is occurring – a single haplotype was exhibited in birds from across the southern Escarpment, while seven private haplotypes show that any genetic mixing is likely to be historical rather than current. Historical gene flow would most probably have occurred during the last glacial maximum (18 000 years before present), when the cooler, drier conditions which are currently restricted to high peaks would have been much more extensive, thereby decreasing the distance required for effective dispersal. This is in agreement with the observation results, concluding that although there has been movement of birds across the southern Escarpment in the past, it does not appear to be occurring currently. However, this does leave plenty of scope for further work, particularly in the genetic diversity of the species, and in expanding the ecological observations to include the breeding biology.
- Full Text:
- Date Issued: 2013
- Authors: Morris, Dale Brett
- Date: 2013
- Subjects: Passeriformes -- Drakensberg Mountains , Passeriformes -- South Africa , Passeriformes -- Lesotho , Passeriformes -- Ecology -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5828 , http://hdl.handle.net/10962/d1007696 , Passeriformes -- Drakensberg Mountains , Passeriformes -- South Africa , Passeriformes -- Lesotho , Passeriformes -- Ecology -- Africa, Southern
- Description: The Drakensberg rock-jumper (Chaetops aurantius) is a high-altitude passerine endemic to South Africa and Lesotho, living along a highly disrupted portion of the southern Great Escarpment from the Drakensberg highlands in the north-east to the Sneeuberg in the west, above an altitude of 1500 m. Along with the Cape rock-jumper (C. frenatus), this genus provides one of the stronger faunal links between the floristic biomes known as the Drakensberg Alpine Centre (DAC) and the Cape Floristic Region (CFR). Despite this, there is a significant lack of information regarding the species. The great majority of information is based on incidental observation, and no dedicated study has been undertaken. I conducted a series of field excursions between January 2011 and November 2012 in order to explore the rock-jumper’s feeding ecology, diet, habitat usage and genetic diversity. By trapping the birds, I was able to mark them individually with unique colour ring-combinations, and pluck a tail feather for genetic analyses. Observational data reveal that birds living close to their lower altitude threshold (c. 1500 m) are strongly habitat specific, living in boulder fields dominated by grassy vegetation. However, in areas at higher elevations (c. 2000 – 2500 m) this restriction seemed to fall away, possibly as a result of farming practices in those areas – higher grazing pressure results in shorter grass and less foraging effort for the birds. They live in groups ranging from pairs to small family groups of up to twelve individuals and maintain year round territories. Territory defence takes the form of calling and displaying from a prominent rock or boulder and becomes particularly noticeable just prior to, and during, the breeding period. No colour ringed individuals were ever spotted in boulder fields outside from where they had been initially ringed. This, coupled with the behaviour of territory maintenance, suggests a strongly sedentary lifestyle. Genetic inferences are constrained by a small sample size (only 25 birds were caught), but results indicate that some genetic isolation is occurring – a single haplotype was exhibited in birds from across the southern Escarpment, while seven private haplotypes show that any genetic mixing is likely to be historical rather than current. Historical gene flow would most probably have occurred during the last glacial maximum (18 000 years before present), when the cooler, drier conditions which are currently restricted to high peaks would have been much more extensive, thereby decreasing the distance required for effective dispersal. This is in agreement with the observation results, concluding that although there has been movement of birds across the southern Escarpment in the past, it does not appear to be occurring currently. However, this does leave plenty of scope for further work, particularly in the genetic diversity of the species, and in expanding the ecological observations to include the breeding biology.
- Full Text:
- Date Issued: 2013
The effect of elephants (Loxodonta africana, Blumenbach, 1797) on Xeric Succulent Thicket
- Authors: Knott, Edward Joseph
- Date: 2007
- Subjects: Addo Elephant National Park (South Africa) , African elephant , Elephants -- South Africa -- Eastern Cape , Elephants -- Nutrition -- South Africa -- Eastern Cape , Elephants -- Ecology -- South Africa -- Eastern Cape , Elephants -- Behavior -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Woody plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5674 , http://hdl.handle.net/10962/d1005359 , Addo Elephant National Park (South Africa) , African elephant , Elephants -- South Africa -- Eastern Cape , Elephants -- Nutrition -- South Africa -- Eastern Cape , Elephants -- Ecology -- South Africa -- Eastern Cape , Elephants -- Behavior -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Woody plants -- South Africa -- Eastern Cape
- Description: This study looks at the impact of elephant feeding on the Xeric Succulent Thicket component of Eastern Cape Subtropical Thicket (ECST) in Addo Elephant National Park (AENP). Observations of elephant feeding were carried out and vegetation transects were surveyed for impact of elephant feeding. The results indicated that the Nyati elephants spent the majority of their time grazing (nearly 90%), particularly the cow-young herds, and especially when the herd gathered in larger numbers. Browsing events were concentrated on Acacia karroo (81%) and there was no significant difference between the sexes in their preference for this species. Despite being subjected to most of the browsing, the majority of A. karroo trees were undamaged and the effect of elephants was generally light. It appears unlikely that, three years after re-introduction to Nyati, the elephants have had an effect on community structure of the vegetation. Surveys were conducted on stands of the alien invasive weed prickly pear Opuntia ficus-indica, and it was recorded that elephants in Nyati have had a dramatic effect on prickly pear, utilising all adult plants assessed and destroying 70% of them. This level of destruction in such a short period of time suggests that prickly pear is a highly favoured species. The results from the present study suggest that elephants can play a role in the control of prickly pear. Results are discussed in terms of elephants as both megaherbivores and keystone species, and as agents of intermediate disturbance.
- Full Text:
- Date Issued: 2007
- Authors: Knott, Edward Joseph
- Date: 2007
- Subjects: Addo Elephant National Park (South Africa) , African elephant , Elephants -- South Africa -- Eastern Cape , Elephants -- Nutrition -- South Africa -- Eastern Cape , Elephants -- Ecology -- South Africa -- Eastern Cape , Elephants -- Behavior -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Woody plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5674 , http://hdl.handle.net/10962/d1005359 , Addo Elephant National Park (South Africa) , African elephant , Elephants -- South Africa -- Eastern Cape , Elephants -- Nutrition -- South Africa -- Eastern Cape , Elephants -- Ecology -- South Africa -- Eastern Cape , Elephants -- Behavior -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Woody plants -- South Africa -- Eastern Cape
- Description: This study looks at the impact of elephant feeding on the Xeric Succulent Thicket component of Eastern Cape Subtropical Thicket (ECST) in Addo Elephant National Park (AENP). Observations of elephant feeding were carried out and vegetation transects were surveyed for impact of elephant feeding. The results indicated that the Nyati elephants spent the majority of their time grazing (nearly 90%), particularly the cow-young herds, and especially when the herd gathered in larger numbers. Browsing events were concentrated on Acacia karroo (81%) and there was no significant difference between the sexes in their preference for this species. Despite being subjected to most of the browsing, the majority of A. karroo trees were undamaged and the effect of elephants was generally light. It appears unlikely that, three years after re-introduction to Nyati, the elephants have had an effect on community structure of the vegetation. Surveys were conducted on stands of the alien invasive weed prickly pear Opuntia ficus-indica, and it was recorded that elephants in Nyati have had a dramatic effect on prickly pear, utilising all adult plants assessed and destroying 70% of them. This level of destruction in such a short period of time suggests that prickly pear is a highly favoured species. The results from the present study suggest that elephants can play a role in the control of prickly pear. Results are discussed in terms of elephants as both megaherbivores and keystone species, and as agents of intermediate disturbance.
- Full Text:
- Date Issued: 2007
An assessment of the shore baitfishery in the Eastern Cape
- Authors: Mackenzie, Bernard Louis
- Date: 2005
- Subjects: Fishing baits -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fisheries -- South Africa -- Eastern Cape , Fishery -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5232 , http://hdl.handle.net/10962/d1005075 , Fishing baits -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fisheries -- South Africa -- Eastern Cape , Fishery -- Law and legislation -- South Africa
- Description: The collection of bait organisms goes hand-in-hand with shore-angling in South Africa, hence the level of bait-collection can be used as an indicator of fishing effort and vice versa. This emphasises the importance of understanding the fisheries for bait organisms. In 1998 the South African fisheries policy was revised, culminating in the Marine Living Resources Act No. 18 (1998) which supported sustainable development, equitable access to resources and stability of the industry. The policy also dealt with the needs of subsistence fishers who had previously been all but ignored. This study looks to continue in this direction by investigating the opportunities for the establishment and management implications of small-scale commercial baitfisheries in the Eastern Cape. Data were collected from eight clearly demarcated sampling areas using the roving survey method. A total of 97 survey trips were undertaken between September 2001 and April 2003 and 469 interviews were conducted on individual anglers. The data was analysed and discussed on the basis of three wider study regions and this allowed for a more accurate and focussed assessment of the fishery area and the potential for its formalisation. Recreational fishers (91.5%) dominated in each of the three regions surveyed. The low number of subsistence fishers encountered in this study is not a standard pattern throughout South Africa. The dominance of local residents in the shore-fishery could have an important impact on the success of a formalised baitfishery in that the greater proportion of the potential market is accessible throughout the year. Most recreational shore-anglers were middle-aged (43.8 years ± 12.9 years), and hence at the peak of their earning years and this may contribute towards the potential success of a small-scale commercial baitfishery. Most anglers and baitfishers were of the opinion that all South Africans owned and were responsible for managing the living marine resources. The vast majority of recreational users paid for and were in possession of valid permits and approved of the baitfishery regulations. This implies that the greater majority of users recognise that the state is the rightful custodian of the resource and is responsible for management. No subsistence users were in possession of permits. Resource users in the Gamtoos to Tsitsikamma National Park region, where the inspection rate was highest, had the best knowledge of the regulations regarding both baitfishing (67.2% ± 38.8%) and angling (79.8 ± 21.4%). This substantiates the hypothesis that there is a direct correlation between knowledge of the regulations and the rate of inspection. About 475 000 angler-days/year were fished in the study area, with the highest number of angler-days recorded in or near urban and peri-urban areas. Bronze bream (65.9%) and dusky kob (61.1%) were the two most commonly targeted species, followed by white steenbras (31.7%), white musselcracker (31.4%) and blacktail (20.2%). A total of four purchased and 19 collected bait species was recorded during the study. Sardine, chokka and pink prawn were the most frequently encountered purchased bait. Red bait, sand prawn, mullet, siffie, sand mussel, bloodworm and saddleback were the most frequently encountered collected bait species. Sand prawn was identified as the preferred bait species for a wide range of angling species. The total quantity of bait organisms used per fishing trip was markedly less than the total amount collected per trip. The ban of off-road vehicles (ORV's) from beaches (20 January 2002) resulted in spatial shifts in angler effort in certain areas, suggesting that total effort has reduced in areas where ORV's were commonly used. Subsequent to the ban, fishers were encountered, on average, much closer to access points. The value of small-scale baitfisheries within the total study area was estimated at about R7 million per year. Across the entire study area red bait was identified as the most valuable bait in the rock-and-surf fishery in monetary terms, while sand prawn was also important. The findings led to the conclusion that small-scale commercial baitfisheries in the study area are potentially viable. Scenarios for the establishment of baitfisheries are suggested and discussed.
- Full Text:
- Date Issued: 2005
- Authors: Mackenzie, Bernard Louis
- Date: 2005
- Subjects: Fishing baits -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fisheries -- South Africa -- Eastern Cape , Fishery -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5232 , http://hdl.handle.net/10962/d1005075 , Fishing baits -- South Africa -- Eastern Cape , Fishery management -- South Africa -- Eastern Cape , Fisheries -- South Africa -- Eastern Cape , Fishery -- Law and legislation -- South Africa
- Description: The collection of bait organisms goes hand-in-hand with shore-angling in South Africa, hence the level of bait-collection can be used as an indicator of fishing effort and vice versa. This emphasises the importance of understanding the fisheries for bait organisms. In 1998 the South African fisheries policy was revised, culminating in the Marine Living Resources Act No. 18 (1998) which supported sustainable development, equitable access to resources and stability of the industry. The policy also dealt with the needs of subsistence fishers who had previously been all but ignored. This study looks to continue in this direction by investigating the opportunities for the establishment and management implications of small-scale commercial baitfisheries in the Eastern Cape. Data were collected from eight clearly demarcated sampling areas using the roving survey method. A total of 97 survey trips were undertaken between September 2001 and April 2003 and 469 interviews were conducted on individual anglers. The data was analysed and discussed on the basis of three wider study regions and this allowed for a more accurate and focussed assessment of the fishery area and the potential for its formalisation. Recreational fishers (91.5%) dominated in each of the three regions surveyed. The low number of subsistence fishers encountered in this study is not a standard pattern throughout South Africa. The dominance of local residents in the shore-fishery could have an important impact on the success of a formalised baitfishery in that the greater proportion of the potential market is accessible throughout the year. Most recreational shore-anglers were middle-aged (43.8 years ± 12.9 years), and hence at the peak of their earning years and this may contribute towards the potential success of a small-scale commercial baitfishery. Most anglers and baitfishers were of the opinion that all South Africans owned and were responsible for managing the living marine resources. The vast majority of recreational users paid for and were in possession of valid permits and approved of the baitfishery regulations. This implies that the greater majority of users recognise that the state is the rightful custodian of the resource and is responsible for management. No subsistence users were in possession of permits. Resource users in the Gamtoos to Tsitsikamma National Park region, where the inspection rate was highest, had the best knowledge of the regulations regarding both baitfishing (67.2% ± 38.8%) and angling (79.8 ± 21.4%). This substantiates the hypothesis that there is a direct correlation between knowledge of the regulations and the rate of inspection. About 475 000 angler-days/year were fished in the study area, with the highest number of angler-days recorded in or near urban and peri-urban areas. Bronze bream (65.9%) and dusky kob (61.1%) were the two most commonly targeted species, followed by white steenbras (31.7%), white musselcracker (31.4%) and blacktail (20.2%). A total of four purchased and 19 collected bait species was recorded during the study. Sardine, chokka and pink prawn were the most frequently encountered purchased bait. Red bait, sand prawn, mullet, siffie, sand mussel, bloodworm and saddleback were the most frequently encountered collected bait species. Sand prawn was identified as the preferred bait species for a wide range of angling species. The total quantity of bait organisms used per fishing trip was markedly less than the total amount collected per trip. The ban of off-road vehicles (ORV's) from beaches (20 January 2002) resulted in spatial shifts in angler effort in certain areas, suggesting that total effort has reduced in areas where ORV's were commonly used. Subsequent to the ban, fishers were encountered, on average, much closer to access points. The value of small-scale baitfisheries within the total study area was estimated at about R7 million per year. Across the entire study area red bait was identified as the most valuable bait in the rock-and-surf fishery in monetary terms, while sand prawn was also important. The findings led to the conclusion that small-scale commercial baitfisheries in the study area are potentially viable. Scenarios for the establishment of baitfisheries are suggested and discussed.
- Full Text:
- Date Issued: 2005
Effects of small-scale water movement on the settlement and growth rates of the brown mussel Perna perna, on the south-east coast of South Africa
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
The development of a baculovirus expression system for the production of Helicoverpa armigera stunt virus capsids for use in the encapsidation of foreign molecules
- Mosisili, Kekeletso Mpho Thakane
- Authors: Mosisili, Kekeletso Mpho Thakane
- Date: 2003
- Subjects: Helicoverpa armigera , Fall armyworm , Baculoviruses , Insects -- Viruses , RNA -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4088 , http://hdl.handle.net/10962/d1007700 , Helicoverpa armigera , Fall armyworm , Baculoviruses , Insects -- Viruses , RNA -- Analysis
- Description: The capsid protein of Helicoverpa armigera stunt virus (HaSV) a T=4 insect virus was expressed in Spodoptera frugiperda 9 cells using a baculovirus vector. When the insect cells were infected at a high MOl the expressed coat protein assembled into virus-like particles (VLPs) that spontaneously underwent maturation and were morphologically indistinguishable from wild-type HaSV. The VLPs were electron dense when viewed under EM and encapsidated their coat protein mRNA. When Sf9 cells were infected at a low multiplicity of infection (MOl) the expressed capsid protein assembled into procapsids that did not spontaneously undergo maturation. These procapsids underwent autoproteolytic maturation cleavage when they were treated with an acidic buffer. The procapsids were used in the encapsidation of a FITC labelled peptide. The peptide encapsidating VLPs showed an increase in their buoyant density that was not collaborated by an increase in the concentration of the FITC labelled peptide detected when these samples were compared to control samples with similar buoyant densities.
- Full Text:
- Date Issued: 2003
- Authors: Mosisili, Kekeletso Mpho Thakane
- Date: 2003
- Subjects: Helicoverpa armigera , Fall armyworm , Baculoviruses , Insects -- Viruses , RNA -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4088 , http://hdl.handle.net/10962/d1007700 , Helicoverpa armigera , Fall armyworm , Baculoviruses , Insects -- Viruses , RNA -- Analysis
- Description: The capsid protein of Helicoverpa armigera stunt virus (HaSV) a T=4 insect virus was expressed in Spodoptera frugiperda 9 cells using a baculovirus vector. When the insect cells were infected at a high MOl the expressed coat protein assembled into virus-like particles (VLPs) that spontaneously underwent maturation and were morphologically indistinguishable from wild-type HaSV. The VLPs were electron dense when viewed under EM and encapsidated their coat protein mRNA. When Sf9 cells were infected at a low multiplicity of infection (MOl) the expressed capsid protein assembled into procapsids that did not spontaneously undergo maturation. These procapsids underwent autoproteolytic maturation cleavage when they were treated with an acidic buffer. The procapsids were used in the encapsidation of a FITC labelled peptide. The peptide encapsidating VLPs showed an increase in their buoyant density that was not collaborated by an increase in the concentration of the FITC labelled peptide detected when these samples were compared to control samples with similar buoyant densities.
- Full Text:
- Date Issued: 2003
Studies on the bioactivities of selected Eastern Cape seaweeds
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
The tectono-metallogenesis during the irumide and pan-African events in South West Africa/Namibia
- Authors: Tregoning, Trevor Denzil
- Date: 1987 , 2013-03-05
- Subjects: Orogeny -- Namibia , Ore deposits -- Namibia , Mines and mineral resources -- Namibia , Geodynamics , Rifts (Geology) -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4922 , http://hdl.handle.net/10962/d1004490 , Orogeny -- Namibia , Ore deposits -- Namibia , Mines and mineral resources -- Namibia , Geodynamics , Rifts (Geology) -- Namibia
- Description: A large portion of South west Africa/Namibia is underlain by 2 great orogens. They are the Irumide (Sinclair/Rehoboth) and Damara Orogenies. The L-shaped Irumide Province forms part of a belt which extends over the subcontinent from Namaqualand to as far as Zambia. The volcano-sedimentary sequences of the Irumide are believed to have formed in intracratonic rifts and pull-apart basins during the period 1400 to 900 Ma. The evolution of the NW trending Sinclair Group proceeded by means of 3 major cycles each beginning with the emplacement of basic to intermediate magmas followed by felsic ones. The cycle ended off with subsidence, deposition of immature clastic debris and final tilting of the volcano-clastic sequence. It was suggested that the extensive calc-alkaline lavas present, developed within a magmatic arc above a subduction zone, but this proposal has not been generally accepted. The NE trending Klein Aub-Witvlei Basins consist essentially of red bed alluvial fans and lacustrine sediments with minor volcanics near the base. The red beds and aeolian sediments were deposited in an arid climatic condition. The regional greenschist facies metamorphism and deformation is attributed to a major tectono-thermal event at 1100 Ma. The Damara Orogen (900 - 550 Ma) forms part of the Pan-African mobile belt system of global proportions. The NE trending intracontinental branch (aulacogen) and 2 coastal branches constitute a triple junction with its focal point near Swakopmund. The NE extension of the intracontinental belt has been linked with the Lufilian Arc hosting the renown Zambian Copper Belt deposits. In South West Africa/Namibia this belt hosts many different mineral occurrences which can be grouped into rift and collision related deposits. The tectonic history of the Damara Orogen supports a geodynamic-evolution-with-time hypothesis and represents a transitional phase in which limited Wilson Cycle Tectonics was active. The Theory of Mantle Advection is invoked to explain rifting, thinning and subsidence. Extensive ensialic rifting resulted in a relatively stable Northern Carbonate Platform and several deep troughs hosting turbiditic sequences. Crustal rupture in the Khomas Trough allowed for the emplacement of ocean floor tholeiites known as the Matchless Amphibolite Belt. Subsequent ocean closure and collision resulted in deformation, metamorphism and generation of predominantly S-type granites. The southern continental plate was partially overridden by the northern plate during final collision at 550 Ma. These low angle thrust faults allowed for the emplacement of the Naukluft Nappe Complex on top of younger Nama sediments. The break up of Gondwanaland during the Mesozoic with the splitting of the Atlantic Ocean was responsible for the intrusion of anorogenic alkaline ring complexes along the extension of the NE trending transform faults within the intracontinental branch of the Damara Orogen. A close relationship between the tectonic setting and mineral deposits has been recognized in both the Irumide and Damara Orogenies. In the Irumide, stratiform syngenetic copper deposits are hosted by alluvial fan, playa and lacustrine sediments. The uninterrupted sedimentation from the Irumide to Damara Orogen resulted in similar stratiform copper deposits during the early stages of rifting. In the Damara Orogen the rifting (extensional) phase is characterized by 4 main mineralizing systems: diagenetic/syngenetic (Kupferschiefer-type), epigenetic/hydrothermal Cu-Pb-Zn (Mississippi Valley-type), volcanogenic cupriferous pyrite (Besshi-type) and volcano-exhalative Pb-Zn (Red Sea-type). The collision (compressional) phase was accompanied by 4 main mineralizing processes: epigenetic/hydrothermal Cu-Pb-Zn, hydrotheral/metasomatic Sn-W-rare earth, metamorphogenic Au and U-bearing anatectic melts. The key to the selection of viable exploration targets lies in the understanding of the field evidence and the geodynamics modelling to explain the evolution of the orogen and its associated mineral deposits.
- Full Text:
- Date Issued: 1987
- Authors: Tregoning, Trevor Denzil
- Date: 1987 , 2013-03-05
- Subjects: Orogeny -- Namibia , Ore deposits -- Namibia , Mines and mineral resources -- Namibia , Geodynamics , Rifts (Geology) -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4922 , http://hdl.handle.net/10962/d1004490 , Orogeny -- Namibia , Ore deposits -- Namibia , Mines and mineral resources -- Namibia , Geodynamics , Rifts (Geology) -- Namibia
- Description: A large portion of South west Africa/Namibia is underlain by 2 great orogens. They are the Irumide (Sinclair/Rehoboth) and Damara Orogenies. The L-shaped Irumide Province forms part of a belt which extends over the subcontinent from Namaqualand to as far as Zambia. The volcano-sedimentary sequences of the Irumide are believed to have formed in intracratonic rifts and pull-apart basins during the period 1400 to 900 Ma. The evolution of the NW trending Sinclair Group proceeded by means of 3 major cycles each beginning with the emplacement of basic to intermediate magmas followed by felsic ones. The cycle ended off with subsidence, deposition of immature clastic debris and final tilting of the volcano-clastic sequence. It was suggested that the extensive calc-alkaline lavas present, developed within a magmatic arc above a subduction zone, but this proposal has not been generally accepted. The NE trending Klein Aub-Witvlei Basins consist essentially of red bed alluvial fans and lacustrine sediments with minor volcanics near the base. The red beds and aeolian sediments were deposited in an arid climatic condition. The regional greenschist facies metamorphism and deformation is attributed to a major tectono-thermal event at 1100 Ma. The Damara Orogen (900 - 550 Ma) forms part of the Pan-African mobile belt system of global proportions. The NE trending intracontinental branch (aulacogen) and 2 coastal branches constitute a triple junction with its focal point near Swakopmund. The NE extension of the intracontinental belt has been linked with the Lufilian Arc hosting the renown Zambian Copper Belt deposits. In South West Africa/Namibia this belt hosts many different mineral occurrences which can be grouped into rift and collision related deposits. The tectonic history of the Damara Orogen supports a geodynamic-evolution-with-time hypothesis and represents a transitional phase in which limited Wilson Cycle Tectonics was active. The Theory of Mantle Advection is invoked to explain rifting, thinning and subsidence. Extensive ensialic rifting resulted in a relatively stable Northern Carbonate Platform and several deep troughs hosting turbiditic sequences. Crustal rupture in the Khomas Trough allowed for the emplacement of ocean floor tholeiites known as the Matchless Amphibolite Belt. Subsequent ocean closure and collision resulted in deformation, metamorphism and generation of predominantly S-type granites. The southern continental plate was partially overridden by the northern plate during final collision at 550 Ma. These low angle thrust faults allowed for the emplacement of the Naukluft Nappe Complex on top of younger Nama sediments. The break up of Gondwanaland during the Mesozoic with the splitting of the Atlantic Ocean was responsible for the intrusion of anorogenic alkaline ring complexes along the extension of the NE trending transform faults within the intracontinental branch of the Damara Orogen. A close relationship between the tectonic setting and mineral deposits has been recognized in both the Irumide and Damara Orogenies. In the Irumide, stratiform syngenetic copper deposits are hosted by alluvial fan, playa and lacustrine sediments. The uninterrupted sedimentation from the Irumide to Damara Orogen resulted in similar stratiform copper deposits during the early stages of rifting. In the Damara Orogen the rifting (extensional) phase is characterized by 4 main mineralizing systems: diagenetic/syngenetic (Kupferschiefer-type), epigenetic/hydrothermal Cu-Pb-Zn (Mississippi Valley-type), volcanogenic cupriferous pyrite (Besshi-type) and volcano-exhalative Pb-Zn (Red Sea-type). The collision (compressional) phase was accompanied by 4 main mineralizing processes: epigenetic/hydrothermal Cu-Pb-Zn, hydrotheral/metasomatic Sn-W-rare earth, metamorphogenic Au and U-bearing anatectic melts. The key to the selection of viable exploration targets lies in the understanding of the field evidence and the geodynamics modelling to explain the evolution of the orogen and its associated mineral deposits.
- Full Text:
- Date Issued: 1987
Studies in ionospheric ray tracing
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Lambert, Sheridan
- Date: 1978 , 2013-10-21
- Subjects: Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5501 , http://hdl.handle.net/10962/d1006906 , Ionosphere -- Research -- Graphic methods , Ionospheric radio wave propagation -- Research , Ionograms , Ray tracing algorithms
- Description: The use of ray tracing in the analysis of certain daytime ionograms recorded at Grahamstown is discussed in this thesis. A computer program has been modified and used to trace rays in the frequency range 1 - 30 MHz. Vertical, short distance oblique, and long distance oblique ionograms have been synthesized from the results and compared with experimental ionograms for Grahamstown, the Alice - Grahamstown transmission path (64 km), and the SANAE - Grahamstown transmission path (4470 km) respectively. Ray paths have been calculated and related in detail to the models of the ionosphere and geomagnetic field. The main features of the vertical and short distance oblique ionograms can, in general, be reproduced using spherically stratified ionosphere models with electron density profiles derived from vertical ionograms. A suitable model for the geomagnetic field is a tilted dipole equivalent to the actual field at Grahamstown. The two-hop mode is shown to be, usually, the lowest on the long distance oblique records. The ionosphere model is the principal limiting factor in reproducing such ionograms, and the most satisfactory results have been those obtained with a model in which electron density is assumed to vary linearly with latitude between the profiles at SANAE and Grahamstown. The promising results obtained by ray tracing with normal ionospheric conditions indicate that the method has further possibilities which could usefully be explored. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
A gas chromatographic study of oils from some Agathosma species (family Rutaceae)
- Persicaner, Peter Henry Robert
- Authors: Persicaner, Peter Henry Robert
- Date: 1972 , 2013-11-13
- Subjects: Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3837 , http://hdl.handle.net/10962/d1007634 , Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Description: From Introduction: Buchu leaf is a very widely used household medicine in South Africa, and is usually administered in the form of a brandy tincture or a vinegar, known as "buchu brandy" and "buchu vinegar" respectively. These preparations have a great reputation in curing diseases of the kidney and urinary tract, and in addition are employed as local applications to bruises, and for the relief of rheumatic pains. We owe its introduction into medicine to the Hottentot, who gave the name "buchu" or "bookoo" to any aromatic herb or shrub which they found suitable for use as a dusting powder.
- Full Text:
- Date Issued: 1972
- Authors: Persicaner, Peter Henry Robert
- Date: 1972 , 2013-11-13
- Subjects: Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3837 , http://hdl.handle.net/10962/d1007634 , Rutaceae , Rutaceae -- Therapeutic use , Gas chromatography
- Description: From Introduction: Buchu leaf is a very widely used household medicine in South Africa, and is usually administered in the form of a brandy tincture or a vinegar, known as "buchu brandy" and "buchu vinegar" respectively. These preparations have a great reputation in curing diseases of the kidney and urinary tract, and in addition are employed as local applications to bruises, and for the relief of rheumatic pains. We owe its introduction into medicine to the Hottentot, who gave the name "buchu" or "bookoo" to any aromatic herb or shrub which they found suitable for use as a dusting powder.
- Full Text:
- Date Issued: 1972
- «
- ‹
- 1
- ›
- »