Doctoral Degrees (Biological Sciences)

Permanent URI for this collectionhttps://hdl.handle.net/10413/12381

Browse

Now showing 1 - 20 of 42

Ecology of some mammals in relation to conservation management in Giant's Castle Game Reserve.
(1982) Rowe-Rowe, David Treloar.; Meester, Jurgens Anthonie Janse.
Abstract available in PDF.
A microbal study of water quality in the marine environment off Durban : 1964-1988.
(1989) Livingstone, Douglas James; Contrafatto, Giancarlo.
wastewater from the harbour mouth with the outgoing tides, while the discharge from a sewer on the Bluff into the surf-zone amounted to 20 x 103 m3 /day. In addition, there existed more than 90 beach pipes and storrnwater drains (not all of them legal) , about one third of which carried contaminative material on to the beaches and into the surf. Twenty-eight sampling stations were established between the Mgeni River and Isipingo and subjected to detailed bacteriological surveillance, prior to the construction of a pair of submarine outfalls to serve the region's disposal requirements . A microbial system of evaluating seawater quality was developed using Escherichia coli I, parasite ova, staphylococci, salmonellae (including Salmonella typhi) and the salinity as indicators. A comprehensive "before" picture was therefore created against which to measure future changes in the sea off Durban. In 1968/69 the pair of submarine pipelines was commissioned with their attendant treatment plants. The harbour effluent was diverted to the new complex , and pollution from the minor outfalls was progressively halted with their wastes similarly joined to the new works. The system of water quality gradation was applied to the surf-zone and out to sea to measure the efficacy of the new pipelines, providing an "after" picture . Throughout the subsequent engineering innovation of sludge disposa l via the outfalls (which proved successful), and during climatic extremes involving a severe drought (with stringent water consumption restrictions), cyclones and catastrophic floods, the classification system continued to function satisfactorily , covering 25 years in all: alterations in the water quality were shown to be invariably a consequence of changes effected upon the shore or meteorological events. The system has also proved useful in identifying and measuring the impact of contaminative foci in Cape waters and at Richards Bay. The relevant oceanography and current dynamics, the rationale for the selection of the indicators used and the methodology, along with more general aspects of marine pollution and associated risks are discussed. Finally, the feasibility is examined of curtailing the numbers of parameters measured and simplifying the classification system while retaining its usefulness and serviceability as an instrument for assessing the impact of domestic effluent on the marine environment off Durban.
Systematic revision of Southern African species in the genera Eptesicus, Neoromicia, Hypsugo and Pipistrellus (Chiroptera: Vespertilionidae).
(2005) Kearney, Teresa Catherine.; Contrafatto, Giancarlo.; Taylor, Peter John.
Abstract available in PDF file.
Studies on the biology, fungal contamination, and conservation of seeds of Welwitschia mirabilis Hook. fil.
(2006) Whitaker, Claire Rosalie.; Pammenter, Norman William.; Berjak, Patricia.
Abstract available in PDF file.
Grape fruit juice improves glycemic index and up-regulates expression of hepatic organic cation transporter protein (OCTI) in the rat
(2009-03) Owira, Peter Mark Oroma.; Ojewole, John Akanni Oluwole.
Abstract available in PDF file.
The challenges and opportunities in conserving wide-ranging cross-border species : a case study of the Greater Mapungubwe Transfrontier Conservation Area elephant population.
(2015) Selier, Sarah-Anne Jeanetta.; Slotow, Robert Hugh.; Page, Bruce Richard.; Di Minin, Enrico.
Transfrontier conservation areas potentially play a key role in conserving biodiversity and promoting socioeconomic development. However, socio-political factors often affect their effectiveness in achieving biodiversity conservation and sustainable development objectives. Following a transdisciplinary approach, I assessed the challenges and opportunities in conserving and managing the African elephant (Loxodonta africana) population within the Greater Mapungubwe Transfrontier Conservation Area (GMTFCA) in Botswana, South Africa and Zimbabwe, southern Africa. The results showed that the current rate of offtake of bull elephant in the GMTFCA is unsustainable. At current rates of hunting, in fact, trophy bulls were predicted to disappear from the population in less than 10 years. Elephant densities were higher in South Africa and Botswana where the gross domestic product is higher. In addition, elephant densities were higher at sites where the proportion of agricultural land around them was the lowest and where vegetation productivity was the highest. Trophy hunting, as well as other localised human activities, also affected the distribution of elephant within sites, forcing them to trade-off between disturbance avoidance and the availability of food and water. While at the international level, a significant body of law and policy relevant to elephant conservation exists, I found that there was little cooperation among Botswana, South Africa and Zimbabwe, and a lack of implementation of these provisions on a national and trilateral level. Overall, this study confirmed that poverty was an important factor affecting elephant abundance at the country level, but highlighted that, at the site level, anthropogenic disturbance played a crucial role. A revision of the current hunting quotas within each country and the establishment of a single multi-jurisdictional (cross-border) management authority regulating the hunting of elephant is needed. Further, to reduce the impact of increasing human populations and agricultural expansion, the development of coordinated legislation and policies to improve land use planning, and the development of conservation corridors to link current protected areas, is needed. The issues regarding the management of this elephant population illustrate the significant challenges involved in achieving a comprehensive, consistent and effective implementation of a transboundary population approach. Southern African countries make an important contribution to elephant conservation and could soon become the last stronghold of elephant conservation in sub-Saharan Africa. Therefore, immediate actions are needed to reduce pressures from human activities in order to enhance the long-term persistence of the species.
Socio-economic and environmental deteminants of malaria in four malaria endemic provinces of Zambia.
(2015) Shimaponda, Nzooma Munkwangu.; Mukaratirwa, Samson.; Gebreslasie, Michael Teweldemedhin.; Tembo-Mwase, Enala.
A large fraction of the global malaria burden occurs in sub-Saharan Africa and its endemicity depends on the interaction of environmental factors, vectors, parasites and the host. In Zambia, the negative effect of the break in interventions experienced in the late 2000s varied by regions. Therefore, it was necessary to determine the malaria determinants through the study of: statistical models that have been employed; knowledge of the community in malaria management and control; prevalence of malaria and presence of social and community-related factors influencing malaria control in selected communities; contribution of other social and environmental determinants of malaria from the household point of view; and also socio-economic and climatic determinants of malaria at provincial level, in Zambia. This work was achieved through a number of methods beginning with a systematic review of studies that have identified socio-economic and eco-environmental determinants of malaria through the use of statistical models in malaria burden determination and prediction in southern Africa. We also conducted a cross-sectional survey employing a simple random sampling technique to administer questionnaires to 584 household heads from selected communities, on the following components: knowledge, attitude and practices in malaria control; the role of social and community-related structures in malaria burden and control; and water sources and practices as well as housing structures in relation to self-reported malaria infections. Malaria testing was also performed using a rapid diagnostic test (RDT) in 756 individuals sampled from the 584 households. The household-level data was analysed in STATA and WinBUGS whereas the provincial-level malaria cases, government socio-economic and remotely-sensed climatic data were analysed in STATA, WinBUGS and also in R- integrated Nested Laplace (R-INLA) The focus of the studies conducted in southern Africa reviewed, has mainly been on malaria determinants related to intervention strategies and climatic factors. Additionally, the use of Bayesian statistical modelling was quite low (29.2%) in the studies reviewed. The community knowledge study showed that although knowledge levels in malaria were high they were not interrelated with attitudes and practices. In the malaria testing survey, a higher infection rate was seen in children and the highest RDT malaria prevalence was recorded in communities of Luapula province. Relating malaria burden with the role of community health workers (CHWs) in malaria control, malaria prevalence was inversely related with CHWs presence in Western Province. On the other hand, relating malaria burden with water practices and housing structures, “river” as a water source was the main predictor. The Bayesian hierarchical (or Generalised Linear mixed model) and R-INLA based models showed that region on one hand and region, time and precipitation on the other, were strong predictors of malaria incidence. More research in the area of statistical modeling as well as in other areas such as behaviour change, strengthening of existing CHW and exploring new avenues with regards to community social structures and ecological and climatic factors by locality is a great need.
Spatio-temporal analysis of woody vegetation data at various height classes within a semi-arid savanna : insights on environmental drivers, distributions and dynamics.
(2015) Scholtz, Rheinhardt.; Kiker, Gregory Alan.; Scharler, Ursula Michaela.; Mwambi, Henry Godwell.; Smit, Izak P. J.
Savanna vegetation is regulated by bottom-up (e.g. soil and rainfall) and top-down (e.g. fire and herbivory) factors. Little is known about how these factors influence biodiversity at regional scales, particularly spatial patterns of woody plant cover, species richness, distribution and composition at various height classes. Vegetation studies are often restricted to hillslope or catchment-level scales due to time and/or logistical constraints, however there is a need to understand patterns of vegetation dynamics at regional scales as well. The main aim of this thesis was to better understand the factors (bottom-up and top-down) that influence vegetation structural dynamics in terms of species richness, distribution, composition and woody cover at regional scales. Using a rapid data collecting technique within n>1800 field sites across the entire Kruger National Park, South Africa, woody species were identified and categorized into one of three height classes; shrub (0.75m – 2.5m), brush (2.5m-5.5m) and tree (>5.5m). From this, several vegetation attributes were collated; such as species composition, richness and woody cover at each height class. A range of covariates related to disturbance (i.e. fire frequency and elephant density), landscape (e.g. aspect, altitude) and climate (temperature, rainfall) were used to identify which covariates were significantly associated with each attribute of interest. A primary finding of this research highlights the importance of bottom-up factors, such as geology and rainfall, for woody vegetation spatial distribution at regional scales. However, depending on the response variable (e.g. species richness, woody cover, species distribution), the various height classes were not influenced equally by each specific environmental factor. Overall, both climatic and non-climatic factors were highly associated with species distribution and richness, but top-down factors such as fire and herbivory were significantly associated with maintaining plant structural variation. This influenced species community composition but not species richness at each height class. Similarities in composition were related to degree of disturbance rather than the disturbance alone at specific height classes. Therefore, while species distribution and woody cover were spatially regulated by specific climatic and non-climatic factors, top-down disturbances were essential in preserving structural heterogeneity. Future vegetation monitoring campaigns in disturbance-driven systems should be cognizant of the importance of vegetation structure.
The effect of wastewater treatment works on foraging ecology, haematology, detoxification organs and reproduction in an urban adapter, the banana bat (Neoromicia nana).
(2015) Naidoo, Samantha.; Schoeman, Marthinus Cornelius.; Mackey, Robin L.; Vosloo, Dalene.
Natural land is rapidly becoming urbanized. Wastewater Treatment Works (WWTWs) are a ubiquitous component of this urban landscape. WWTWs may provide profitable foraging areas for insectivorous bats because of their association with a high abundance of pollution-tolerant chironomid midges (Diptera). However, bats that feed on these insects may also accumulate metal pollutants in their tissues, with acute or chronic effects on their health. There have been no studies to investigate whether African bats utilize these WWTWs as foraging grounds, and the potential physiological impacts from foraging at such sites. The aim of this study was to investigate the impact of WWTWs on foraging ecology and multiple tiers of physiology (haematology and genotoxicity, detoxification organs and reproduction) in an urban adapter, the banana bat (Neoromicia nana, family Vespertilionidae) in KwaZulu-Natal, South Africa. N. nana exhibited a significantly higher abundance and feeding activity at wastewaterpolluted sites than at unpolluted reference sites. Additionally, the most abundant insect order at wastewater-polluted sites and in the diet of resident bats was Diptera, compared to a diverse insect diet at unpolluted sites. Thus, WWTWs provide an optimal food resource to bats in the short-term. However, I found significantly higher levels of essential and non-essential metals at WWTW-polluted sites, and in the tissues of WWTW bats than at unpolluted sites. Further, I found sub-lethal haematological and genotoxic responses related to increased metals in WWTW bats. Specifically, N. nana at WWTWs had significantly lower antioxidant capacity and significantly higher levels of DNA damage and haematocrits than bats from unpolluted sites. An accumulation of DNA damage, especially from double-stranded breaks ultimately leads to tissue damage and disease. These longer-term effects of chronic pollutant exposure should be most evident in the organs involved in detoxification, the liver and kidneys. Indeed, I found evidence of disrupted balance of essential metals and mineral nutrients, histopathological tissue damage and whole organ effects in the liver and kidneys. Finally, I found reproductive system alterations in male N. nana at WWTWs. Although I did not find significant effects on the sex organs, testosterone hormone concentrations were significantly lower in male N. nana at WWTWs than in males from unpolluted sites. In addition, body condition indices for N. nana from the WWTWs were significantly lower than at unpolluted sites, suggesting lower quality male bats at WWTWs. Taken together, these results suggest the potential for serious long-term health risks, negative fitness implications and ultimately, population effects for these top predators within the urban landscape.
The effects of petroleum hydrocarbon contamination on selected intertidal macrophytes and meiofauna.
(2015) Naidoo, Krishnaveni.; Naidoo, Gonasageran.; Naidoo, Yougasphree.
The effects of bunker fuel oil on the growth of A. marina, B. gymnorrhiza and R. mucronata were investigated in glasshouse and field experiments. The effects of oil on community structure in micro-organisms were also investigated in microcosm glasshouse experiments. The differences in oil tolerance of the three mangroves were compared in propagule and sediment oiled treatments and growth monitored for 13 months under glasshouse conditions. In propagule oiled treatments, various portions of the propagule were coated with oil. In the sediment oiled treatments, 50ml oil were added to the sediment in each pot. In oiled treatments, plant height, number of leaves and chlorophyll content were significantly reduced in all species compared to the control. In A. marina and R. mucronata, oiling resulted in growth malformations such as abnormal phyllotaxy and deformity of leaves and stems. The effects of oil on root growth were investigated in rhizotrons for 245 and 409 days respectively. In oiled treatments, root growth rate, length and volume were significantly reduced in all species. In A. marina and B. gymnorrhiza oil increased root diameter. In another series of experiments, PAH accumulation in roots and leaves of the three species were determined in one year old seedlings subjected to oiling for 21 days. The concentrations of 15 PAHs in roots and leaves were determined by gas chromatography / mass spectrometry. The highest total concentration of PAHs was accumulated in oiled roots of A. marina (44,045.9μg/kg), followed by B. gymnorrhiza (10,280.4μg/kg) and R. mucronata (6,979.1μg/kg). In oiled treatments, the most common PAHs in roots of all species were fluorene and acenaphthene (two rings), phenanthrene and anthracene (three rings), pyrene and chrysene (four rings) and benzo[a]pyrene (five rings). In the leaves of all species in oiled treatments, the common PAHs were naphthalene and acenapthene (two rings) and phenanthrene (three rings). To test for living and dead root tip cells and to compare the effects of oil on cell ultrastructure in roots and leaves of the three species, one year old seedlings were subjected to a control and sediment oiled treatments for seven days. Control root tips, stained with fluorescein diacetate, exhibited green fluorescence in living cells of the meristematic and conducting tissue in all species. Oiled root tips, stained with propidium iodide, exhibited red fluorescence, indicating cell death or dead cells. Transmission electron micrographs revealed that oil damaged cell ultrastructure in root tips and leaves in all species. Anatomical changes induced by oil included, disorganization of cells in the root cap, epidermis and meristem. Oil also induced loss of cell contents and destruction of organelles in root tissue. Oil damaged chloroplasts and cell organelles in spongy mesophyll and palisade cells of leaves. To compare the effects of oil on the ability of the three species to tolerate salinity, healthy one year old seedlings were subjected to 10% and 50% seawater in control and sediment oiled treatments for 12 months. In the oiled treatments, 200ml oil were added to the soil in each pot. Oil significantly reduced growth in the 50% seawater treatment in all species. Results suggested that oil reduces salt tolerance in the three species. The effects of oil on salt secretion in A. marina were investigated by subjecting one year old seedlings to sediment oiling treatments at 0%, 10% and 50% seawater for three weeks. Sodium accumulated in the leaves of oiled seedlings at 10% and 50% seawater. The effects of oil on salt secretion in A. marina in the light and dark were compared in one year old seedlings subjected to oiling treatments for seven days. Sodium accumulated in the leaves of oiled seedlings in the light and dark within 11 hours. Oil reduced secretion rates of Na⁺, K⁺, Ca²⁺ and Mg²⁺ in all treatments. The effects of oil on species abundance, richness and community structure of soil micro-organisms were determined by subjecting microcosms to oiling treatments with or without fertiliser for four weeks. In the oiled treatments, 15ml oil and 5ml/L fertiliser were added to 200g soil. Fertiliser consisted of 4% N, 2% P and 5% K. Nematodes were extracted after the experimental period and identified to genus or species level. Oil significantly reduced species abundance and richness. Oil also eliminated sensitive species and altered the abundance of dominant species thereby altering the free living nematode community structure. Addition of fertiliser increased richness and dominant species in oiled treatments. The effects of oil coating on leaves and internodes on growth of the three mangroves were investigated in field experiments for 48 weeks. Oiling of the leaves resulted in leaf abscission and decreased leaf production in all species. The effects of sediment oiling (at a dose of 5Lmˉ²) on the three species were also investigated in a field study for 53 weeks. In A. marina, oil caused adventitious roots to develop on the stem, about 10-15 cm above the soil surface after 38 weeks of treatment. In oiled treatments, plant mortality occurred after 53 weeks in all three species. The ability of B. gymnorrhiza and R. mucronata to exclude PAHs from sensitive root tissues probably accounted for the higher oil tolerance than A. marina. The capacity of the species to adapt to residual oil contamination by increasing root diameter (A. marina and B. gymnorrhiza), producing adventitious roots (A. marina), increasing root/shoot ratio (R. mucronata) and abscising oiled leaves (all species) probably contributed to oil tolerance.
Ecology and conservation of the African golden cat Caracal aurata.
(2015) Bahaa-el-din, Laila.; Slotow, Robert Hugh.; Macdonald, David Whyte.; Hunter, Luke Thomas B.
Aspects of the molecular systematics, taxonomy and population genetics of Otomops (Chiroptera: Molossidae) in Africa and Madagascar.
(2015) Ralph, Taryn Marietta Cecilia.; Lamb, Jennifer Margaret.; Taylor, Peter John.; Goodman, Steven Michael.
Abstract available in the print copy.
Development and utilization of a river system model to integrate human and ecological water requirements in a southeastern United States river basin.
(2016) Leitman, Steven.; Kiker, Gregory Alan.
Abstract available in PDF file.
Applied carnivore management in a data deficient world: leopard Panthera Pardus as a case study.
(2016) Ross, Tyzack Pitman.; Slotow, Robert Hugh.; Hunter, Luke Thomas.
Large carnivores are vital to biodiversity at a global scale, through their role as keystone species, but also present significant challenges for conservation and management due to the lack of basic information on carnivore abundance and distribution, particularly at regional and sub-continental scales. Consequently, large-scale carnivore management decisions are seldom supported by science-based evidence. In this thesis, I use leopards Panthera pardus as a model large carnivore, in Limpopo Province, South Africa, to investigate and address some of the fundamental components that underpin wildlife management and conservation in a landscape dominated by people. Furthermore, I develop practical and scientifically justified methods to facilitate accurate and efficient management of the species at a scale that is meaningful to leopard conservation. I begin by developing a model approach to leopard management, particularly in the context of trophy hunting, using data that are currently available to management authorities, and provide management recommendations to improve leopard population persistence. Next, I focus on the game ranching industry—the primary driver responsible for lethal leopard control—and assess the relationship between game ranchers and free-ranging wildlife. I then explore the evolution of game ranching practices to better understand the concomitant change in game rancher tolerance of free-ranging wildlife, and integrate this mechanistic understanding into the challenges facing conservation policy making more generally. Given the challenges faced by leopards across Limpopo (e.g., high levels of trophy hunting, statesanctioned population control, and illegal killing), I then set out to investigate leopard resource use and landscape connectivity across Limpopo to better understand leopard space use in the region. I present an efficient method of integrating connectivity within wildlife management, and in doing so, identify key conservation priorities. Lastly, given that so little is known about how species respond to hunting, I present a simulation study focused on assessing biological sustainability of leopard hunting. I demonstrate that the sustainable hunting of leopards remains a challenging objective given the high degree of additive anthropogenic mortality (i.e., illegal killing and state-sanctioned problem animal control) and challenges associated with accurately aging leopards in the field. The findings presented in this thesis provide valuable information and novel guidance that could benefit the management and conservation of leopards across the region, and further afield.
The silencing of HER2/neu gene expression in a breast cancer cell model using cationic lipid based delivery systems.
(2016) Balgobind, Adhika.; Singh, Moganavelli.; Ariatti, Mario.
Abstract available in PDF file.
Use of invertebrates to evaluate the threat of water resource use on the wellbeing of selected river dominated estuaries in KwaZulu-Natal, South Africa.
(2017) Vezi, Madonna Sduduzo.; Downs, Colleen Thelma.; O'Brien, Gordon Craig.; Wepener, Victor.
Abstract available in PDF file.
Structure, biology and chemistry of plumbago auriculata (plumbaginaceae).
(2017) Singh, Karishma.; Naidoo, Yougasphree.; Baijnath, Himansu.
Plumbago auriculata Lam. is endemic to South Africa and is often cultivated for its ornamental and medicinal uses throughout the world. Belonging to the family Plumbaginaceae this species contains specialized secretory structures on the leaves and calyces. This study focused on the micromorphological, chemical and biological aspects of the species. Micromorphological studies revealed the presence of salt glands on the adaxial and abaxial surface of leaves and two types of trichomes on the calyces. “Transefer cells” were reported for the first time in the genus. The secretory process of the salt glands was further enhanced by the presence of mitochondria, ribosomes, vacuoles, dictyosomes and rough endoplasmic reticulum cisternae. Histochemical and phytochemical studies revealed the presence of important secondary metabolites that possess many medicinal properties which were further analyzed by Gas chromatography-mass spectrometry (GC-MC) identifying the composition of compounds in the leaf and calyx extracts. A novel attempt at synthesizing silver nanoparticles proved leaf and calyx extracts to be efficient reducing and capping agents that further displayed good antibacterial activity against gram-positive and gram-negative bacteria. Biological studies revealed for the first time the presence of three variants of flower colour (white, pale blue and deep blue) and each colour had a characteristic sex-morph described as “Pin” or “Thrum.” Due to the “Pin” and “Thrum” scenario, plants are reported to be self-incompatible. However, the findings of this study suggested that plants were also self-compatibile. Graphical demonstration of calyx trichomes showed their involvement in insect entrapment often resulting in the death of the insect due to the struggle to free itself. This study concludes that P. auriculata is of good medicinal value and can contribute towards drug development and other medicinal uses in traditional markets as well as in the cosmetic and pharmacological industries. This species has striking morphological and biological features and possesses good value for future perspectives.
Structural, chemical and physiological investigations of bilirubin found in seed arils of strelitzia nicolai.
(2017) Dwarka, Depika.; Baijnath, Himansu.; Thaver, Veneesha.; Naidu, Mickey.
In 2009, a team of researchers from the Florida International U niversity discovered bilirubin which is an animal compound in the se ed arils of Strelitzia nicolai , commonly known as the White Bird of Paradise plant. Bilirubin is an endogenous yellowish compound that is formed following the standard catabolic pathway by the breakdown of haem. This catabolism is an essential practice in the human body as it allows for the elimination of waste products. Bilirubin is formed in humans some vertebrates and invertebrates. Previously thought to be a toxic compound if accumulated, recent ad vancements in medical sciences show bilirubin as an eff ective antioxidant. This study describes novel protocols to reveal new insights into the presence of the only animal pigment found in S. nicolai arils, the potential advantages of bilirubin found in a plant and its therapeutic value indications. In vitro a nd in vivo experim ents using the aril extract was conducted in order to assess the antioxidant , anti cancer and toxicity dosage of S. nicolai aril extract. In vitro studies showed that S. nicolai aril extract caused apoptosis in 52% of Hela cancer cell lin es. These results indicate that S. nicolai aril s extract possess conceivable chemo preventive properties. In vivo results in a rat model showe d no acute toxicity nonetheless, t hese results were inconclusive as a lengthier chronic study needs to be conducte d in order to completely rule out toxicity. An ultrastructure study of the seed arils was embarked in order to integrate supplementary knowledge The developing seeds were grouped in five stages according to seed maturity and aril colour. The arils were an alysed using light and electron microscopy. The Hall’s staining which is generally used on human tissue was modified to detect bilirubin on the surface of the aril tissue. Light microscopic results showed that as the aril matures it undergoes an atypical c olour change from opaque to yellow and finally a deep orange. This colour change might be attributed to the accumulation of bilirubin in the aril tissue. This hypothesis was further justified by cryo SEM and TEM which shows the trend of an accretion of a p igment as the aril matures. In addition, the inclination of aril maturity in S. nicolai follows an analogous prototypical pathway to that of bilirubin catabolism in humans. This study consequently highlights the potential use of S. nicolai aril extract co ntaining bilirubin and also attempts to relate aril structure with impending function.
Urban ecology of the Vervet Monkey Chlorocebus pygerythrus in KwaZulu-Natal, South Africa.
(2017) Patterson, Lindsay Leigh.; Downs, Colleen Thelma.; Kalle, Riddhika Vinod.
The spread of development globally is extensively modifying habitats and often results in competition for space and resources between humans and wildlife. For the last few decades a central goal of urban ecology research has been to deepen our understanding of how wildlife communities respond to urbanisation. In the KwaZulu-Natal Province of South Africa, urban and rural transformation has reduced and fragmented natural foraging grounds for vervet monkeys Chlorocebus pygerythrus. However, no data on vervet urban landscape use exist. They are regarded as successful urban exploiters, yet little data have been obtained prior to support this. This research investigated aspects of the urban ecology of vervet monkeys in three municipalities of KwaZulu-Natal (KZN), as well as factors that may predict human-monkey conflict. Firstly, through conducting an urban wildlife survey, we were able to assess residents’ attitudes towards, observations of and conflict with vervet monkeys, investigating the potential drivers of intragroup variation in spatial ecology, and identifying predators of birds’ nests. We analysed 602 surveys submitted online and, using ordinal regression models, we ascertained that respondents’ attitudes towards vervets were most influenced by whether or not they had had aggressive interactions with them, by the belief that vervet monkeys pose a health risk and by the presence of bird nests, refuse bins and house raiding on their properties. Secondly, to investigate the vervet monkeys perceived negative impact on urban nesting birds, 75 artificial nests were deployed, and monitored by camera traps. Overall, 17 were depredated, 15 by monkeys and two by domestic cats Felis catus. It was determined that future experiments on natural nest predation are essential for comparison. Thirdly, by collecting observational data on 20 vervet monkey troops living in a variety of developed landscapes within KZN, it was found that the key landscape features influencing vervet monkey troop-level visitation rates, durations and observed foraging in residences were the absence of dogs, presence of supplementary food provisioning, fruiting trees, trees taller than two meters, and a high percentage of tree coverage. Data analysis revealed higher visitation rates during winter, in gardens with higher tree density, and the highest foraging rates in gardens closer to main roads, where supplementary provisioning and bird feeders were present. Furthermore, gardens with greater canopy cover had higher rates of feeding, grooming and playing, which all decreased with increasing troop size, while resting rates decreased with increasing distance from indigenous forest patches and main roads. Gardens experiencing comparatively low levels of visitation experienced high levels of raiding. The combination of these variables appears to provide monkeys with predictable, accessible, indigenous, exotic and anthropogenic food sources in human-modified habitats within close proximity to suitable sleeping sites and safety. Lastly, we examined vervet monkey space use using GPS/UHF telemetry data from 10 vervet monkeys across six troops over nine months within a 420 ha eco-estate. We documented a mean home range of 0.99 km2 (95% MCP) and 1.07 km2 (95% FK) for females (n = 6), 1 km2 (95% MCP) and 1.50 km2 (95% FK) for males (n = 4) and 0.87 km2 (95% MCP) and 1.12 km2 (95% FK) for troops (n=6), respectively, indicating that males and larger troops had larger home ranges. These relatively small home ranges included shared territorial boundaries and high home range overlap. Vervet monkey movements indicated higher morning activity levels and habitat selection indicated significantly more use of golf course, urban residential and forest, thicket and woodland areas, and avoidance of wetland, grassland and shrub, and urban built-up areas. Our results suggest that modified-habitat use by vervet monkeys is a consequence of behavioural facilitation to access highly-available food resources, thereby facilitating their persistence in developing ecosystems in South Africa. Therefore, conflict management is dependent on the conservation of sufficient natural habitats and food resources, to minimize their dependence on manmade resources and consequently reduce human-monkey conflict. The results contributed to an understanding of the drivers of urban vervet monkey spatial ecology within a transformed landscape. This hopefully will assist in determining the most sustainable way to mitigate conflict and manage vervet monkeys in these municipalities. In a broader context, this study highlights the value of citizen science and wildlife spatial ecology studies in providing mechanisms for identifying priority management and conservation efforts at the highly complex human-wildlife interface.
Impacts of anthropogenic disturbance on persistence patterns of forest mammals in an urban-forest mosaic of eThekwini Municipality, Durban, South Africa.
(2018) Zungu, Manqoba Moses.; Downs, Colleen Thelma.; Kalle, Riddhika Vinod.; Tharmalingam, Ramesh.
The burgeoning human population size and the consequent land development pressures to meet its various needs has led to an unparalleled increase in the rates at which natural environments are converted for anthropogenic purposes. Among the major drivers of landscape modification by humans, urbanisation is arguably the most damaging, persistent and rapidly expanding across the globe. With the expansion of urbanisation, an increasing proportion of global biodiversity will be affected. The Ethekwini Municipality Area (EMA) is an urbanised landscape with high levels of biodiversity in South Africa. However, this area has a relatively large human population (~3.5 million), most of which is poor. Furthermore, it is located within a region (KwaZulu-Natal) undergoing rapid landscape changes. High development pressures, unauthorised development practices, conflicting governance systems and the preponderance of development priorities over environmental concerns has subjected most of the EMA to human activity. Considering these pressures, it is important to understand how wildlife adapt and persist in this human dominated landscape in order to guide conservation action. The aim of this study was to assess the impacts of anthropogenic disturbance on persistence patterns of forest mammals (excluding bats) in an urban-forest mosaic in the EMA, Durban, South Africa. The objectives were to: (1) determine factors affecting the occupancy of forest mammals; (2) determine the effects of landscape context on mammalian richness; (3) determine the effects of patch attributes and species’ ecological and life-history traits on nestedness patterns and (4) determine the effects of anthropogenic disturbance and abiotic factors on activity patterns and temporal niche overlap of mammals. Between May–September 2016 and December 2016–April 2017, mammalian surveys were conducted in forest patches within the study area using remote-triggered camera traps. Furthermore, data on vegetation structure at each camera trap location was recorded in order to better understand the habitat requirements of species. The results showed varying responses of mammals to landscape and habitat structural variables. The blue duiker (Philantomba monticola), bushbuck (Tragelaphus scriptus), bushpig (Potamochoerus larvatus), and Cape porcupine (Hystrix africaeustralis) were negatively affected by the loss and degradation of forest habitat and the increase in matrix development intensity whereas the large-spotted genet (Genetta tigrina) and vervet monkey (Chlorocebus pygerythrus) were relatively unaffected by such changes. Among habitat variables, an intact undergrowth and a high density of large trees were found to be important for the occurrence of many species found in this area as they provide sufficient breeding, roosting and browsing resources for specialist species that respond negatively to urban development. The results also demonstrated the importance of habitat area and its spatial configuration to the occurrence and persistence of mammals in this area. Patches that supported a high diversity of mammals were significantly larger, closer together, more contiguous and less separated by roads and urban development than patches that supported fewer species. The mammalian assemblage in the EMA was found to be significantly nested, with nestedness patterns related to patch size and isolation. This suggested that both the ability of species to persist on patches of various sizes and the ability to move to patches with different degrees of isolation affects the distribution and abundance of mammals in this area. Ecological specialists were found to be under more severe threat from further loss of forest habitat, which will likely threaten the long-term ecosystem functioning of forest habitat. When the activity patterns of species in the EMA were compared with activity patterns of the same species occurring in a less-disturbed landscape (Isimangaliso Wetland Park), no significant shifts in activity patterns were observed for most species except for common duiker (Sylvicapra grimmia), vervet monkey and Cape porcupine. Furthermore, there was only partial support for higher temporal overlap in activity patterns of ecologically similar species in the highly-disturbed EMA. Overall, the results presented in this thesis have provided insights into the persistence abilities of mammal species found in the EMA. The results have also provided basic ecological information on poorly known taxa, which will advance our understanding of their ecology locally and regionally. To ensure the continued persistence of mammals in the EMA, conservation efforts should prioritise the prevention of further loss of habitat, particularly large tracts of contiguous habitat. Furthermore, measures aimed at improving matrix permeability (e.g. stepping stones or corridors) should be promoted. This will help in reducing the negative effects of roads, which will ultimately increase landscape connectivity. Nevertheless, this is a metropolitan area with high development pressures, which are expected to increase even further in the future given the rapid population growth rate and the need to provide basic services to the people. Therefore, town planners, land owners, ecologists, and other decision makers need to consider the whole landscape, including the matrix, in the planning phase of future development projects in this area in order to minimise potentially negative effects on biodiversity.

Browse

Browsing Doctoral Degrees (Biological Sciences) by Issue Date