Doctoral Degrees (Biological Sciences)

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Aligning elephant conservation with societal aspirations.
(2022) Van de Water, Antoinette.; Slotow, Robert Hugh.
Protection of biodiversity and social development often seem at odds in the world of today. The aim of this thesis is to show that it does not need to be that way. Most global social compacts focus on either economic development, or biodiversity conservation. Few prioritise the needs, values and rights of local people living in or near conservationsensitive areas. If biodiversity and human well-being goals are to be realised simultaneously, we must find ways to increase land use for conservation purposes, while respecting the values and needs of local people and future generations. In an effort to contribute to this aim, this thesis explores and analyses how elephants are valued and perceived by a wide range of stakeholders; it investigates why narrow conservation approaches fail; and it uses the research outcomes to develop an alternative roadmap for conservation, one that realises beneficial outcomes for elephants, people and the environment. Through literature review, participatory workshops, questionnaires, interviews and reports provided by reserves and provincial government, I developed: (1) the TUSKER framework to reconcile integrity of nature with human well-being, (2) the pluralist elephant valuation system to incorporate all values of elephants that I have been able to uncover and provide insight into trade-offs associated with conservation decisions, (3) a theory of change for human-elephant coexistence and building common ground, and (4) a One Well-being framework to holistically assess and rank the consequences of elephant management interventions at different scales of animal, human and environmental well-being. The frameworks can be used in strategies that promote animal well-being and range expansion, while simultaneously empowering local communities and enhancing local economies. They may be employed by policymakers and managers to work towards ‘living-in-harmony’ conservation schemes, in which elephants and other iconic species do not represent a threat to humans but a chance for development and joy. Through ‘Living in harmony’, ‘convivial conservation’, and the incorporation of African philosophy Ubuntu (a philosophy that recognises moral values such as justice, dignity and rights), we will move towards a more ethical, just, and sustainable world.
Alleviating delayed field curing-induced deterioration in rice seeds by cathodic water invigoration: a comparison of seed and seedling responses in two upland rice species and their interspecific hybrid.
(2021) Bam, Raphael Kwame.; Varghese, Boby.; Naidoo, Sershen.; Pammenter, Norman William.
Rice constitutes the major source of the world’s food supply. A number of varieties are grown in many parts of the world, all which produce orthodox seeds that are usually stored between growing seasons. As in other crop species, storage-induced loss of seed quality (viability and vigour) is inevitable but considerable research effort has been invested in optimising seed bank storage protocols for rice to ensure acceptably high levels of seed germinability and seedling emergence. However, poor post-harvest practices such as delayed field curing before threshing in developing countries in the humid tropics, such as Ghana, result in curing-induced seed deterioration in the field prior to ex situ storage. Given that many rice growing regions are likely to experience significant levels of climate change, seed processing and storage induced declines in rice seed quality could exacerbate the crop losses incurred by rice farmers in these regions in the future. This motivated the present study which was designed around three aims: 1) to investigate how environmental conditions and the duration of field curing influenced seed macro-structural integrity, susceptibility to microbial infection, and seed germinability and vigour; 2) to identify macro-structural and ultrastructural indicators/ biomarkers of field curing and associated storage-induced stress/ damage; 3) to assess whether the invigoration of field-cured seeds with cathodic water (CW), an established antioxidant-based seed invigoration medium, and deionized water (DW) can alleviate the deteriorative effects of delayed field curing on rice seed cellular integrity, germination and subsequent seedling growth and biomass. The specific objectives of this comparative study, which involved an Asian (Oryza sativa L.) and African (Oryza glaberrima Steud) upland rice species and their interspecific hybrid (O. sativa × O. glaberrima), were as follows: a) to compare the impacts of delayed field curing in wet and dry environments on seed physical, physiological and pathological quality; b) to identify potential ultrastructural biomarkers of seed sensitivity to delayed field curing-induced stress/ damage in embryonic root meristematic cells using transmission electron microscopy (TEM); c) to assess whether CW invigoration alleviates cellular stress/ damage induced by delayed field curing using selected ultrastructural biomarkers of seed sensitivity to such curing-induced stress/ damage; and d) to assess whether invigoration with CW and DW improves seed germinability and emergence, and subsequent plant growth in field cured seeds, relative to non-invigorated (NI) dry seeds. For objective (a), seeds of both species and their interspecific hybrid were grown in Ghana, harvested, field cured in open (wet) and within ventilated rainproof containers (dry) for five weeks. Harvested panicles were sampled from the wet and dry cured environments at weekly intervals for 5 weeks, hand threshed, and depending on the moisture content (MC) at sampling, seed samples were further dried to 12% and stored hermetically at 4°C until used. Sub-samples of both species and the hybrid from the weekly samples were used for seed microflora studies and germination assay. Environmental parameters (temperature and relative humidity) were measured in wet (weather station) and dry (tiny tag data loggers) cured environments. Seed samples of both species and hybrid were taken daily from wet and dry cured environments at 08h00 and 15h00 during the 5 week period, equilibrated overnight at 20°C for seed MC and water activity measurements. Sub-samples of seed samples of both species and hybrid taken daily at 08h00 from the wet and dry cured environments were used to measure percentage of seeds with cracked endosperm. Results revealed that dry field curing delayed endospermic cracking and reduced crack frequency (10% in O. sativa; 40% in O. glaberrima; 36% in the hybrid), enhanced subsequent seed germinability (2%), and reduced subsequent seedling vigour (radicle length, 37%; seedling dry weight, 11%) relative to wet cured seeds across both species and hybrid. However, fungal infection was higher (22%) in dry than wet cured seeds: seeds infected with fungal species (e.g., Aspergillus flavus, Bipolaris oryzae, Curvularia lunata, Fusarium moniliforme and Phoma sp) was higher in dry cured O. sativa (22%) and the hybrid (31%) than the wet cured seeds. Seed germinability and seedling vigour declined with delayed field curing, but the decline was higher in the hybrid than in both species. For objective (b), seeds of both species and their interspecific hybrid field cured for different durations (0, 2 and 5 weeks) and hermetically stored at 4°C for 20 months were removed from storage, equilibrated overnight at 25°C and invigorated with DW for 18 h. Untreated dry (nonimbibed seeds, cured for different durations (0, 2 and 5 weeks) were used as the controls for this study. These controls were used for two reasons: 1) to establish whether ultrastructural abnormalities induced by curing are permanent or can be reversed/ repaired during imbibition; 2) to establish whether seed deterioration during curing leads to imbibitional damage. The severity of ultrastructural lesions related to cellular stress/ damage differed across species and the hybrid and progressed at a rate in agreement with the viability and vigour loss brought about by delayed field curing. These microscopy studies also served to identify useful ultrastructural biomarkers of field curing induced cellular stress/ damage in both rice species and the hybrid. These include marked abnormalities in cell wall and key organelle [nucleus (N), nucleolus (nu), mitochondria (M), lipids, vacuoles, plastids and amyloplasts] ultrastructural integrity with delayed field curing. This study suggests that these biomarkers may serve as useful screening tools for rice breeders looking to identify species/ varieties that produce seeds that are more resistant to field curing-induced deterioration. For objective (c), seeds of both species and their interspecific hybrid were field cured for different durations (0, 2 and 5 weeks), stored hermetically and removed from storage and equilibrated as in the experiment for objective (b). However, in the experiment designed to address this objective, seeds of both species and hybrid cured for different durations (0, 2 and 5 weeks) were invigorated with CW and DW for 18 h before comparing their ability to alleviate the effects of field curing induced cellular stress/ damage in terms of the ultrastructural biomarkers of such stress/ damage identified via objective (b). Seed germinability was significantly higher in CW invigorated 5 week cured seeds of both species and 2 and 5 week cured seeds of the hybrid than DW invigorated seeds suggesting that CW invigoration was more effective in alleviating curing-induced stress/ damage. Ultrastructural studies showed that CW invigoration of cured seeds of both species and hybrid appears to have enhanced the repair of damaged cellular components and/ or reduced the damage that ensues during imbibition in the deteriorated seed. More importantly, seeds subjected to CW invigoration exhibited more prominent signs [e.g., M exhibited elongated profile, homogenous matrix, well-differentiated cristae (Cr), and well-defined outer mitochondrial membrane (OM) and inner mitochondrial membrane (IM), and highly developed Golgi bodies (G)] of repair and germinative metabolism than those imbibed with DW. Interestingly, the degree of mitochondrial and G development in CW invigorated seeds was greater in the hybrid than the two species. The results obtained for these biomarkers indicated that CW invigoration can alleviate the cellular stress/ damaged induced by field curing and also point to superior restorative effects of CW on viability, vigour and cellular integrity and metabolism in cured seeds compared with DW. For objective (d), endosperm integrity (i.e., nature/severity of physical damage to endosperm, caryopsis coat thickness, and presence of seed microflora) of stored (4°C for 20 months) NI seeds of both species and their interspecific was assessed using scanning electron microscopy (SEM). Seeds of both species and the hybrid stored for the same duration as in the SEM studies were also equilibrated overnight at 25°C and invigorated for 18 h in CW and DW before being sown in individual pots under greenhouse conditions. Untreated dry seeds, cured for different durations were used as the controls for this study. The uncured seeds (0 week) of both species and the hybrid did not exhibit macro-structural damage; however, 5 week-cured seeds exhibited deep cracks which exposed the aleurone cells (grains and lipid bodies) and facilitated fungal infection and insect damage which may have contributed to viability and vigour loss in cured seeds. Cathodic water invigoration significantly enhanced seedling emergence (17% in 5 week cured O. sativa; 23% in 5 week cured O. glaberrima; 16 and 19% in 2 and 5 week cured hybrid, respectively) in field cured seeds of both species and the hybrid than DW invigoration. Also, CW invigoration significantly produced taller seedlings in CW invigorated cured (2 and 5 weeks) seeds of both species and the hybrid than DW invigorated seeds. Across both species and hybrid, CW enhanced panicle biomass, although differences between CW and DW were not always significant. The invigorative effect of CW on plant growth from cured seeds was generally not observed in terms of total biomass yield and changes in biomass allocation to stem, leaves, and roots. Overall, the study has deepened our understanding of the physical, pathological, physiological, and ultrastructural lesions that contribute to loss of rice seed quality (seed viability and vigour) during delayed field curing. It has also served to identify a number of seed physiological, ultrastructural, and macro-structural biomarkers/ indicators that can be used by breeders for screening rice varieties for sensitivity/ tolerance to field curing. The results have also provided a basis for many new opportunities for research on alleviating seed processing- and storage - induced deterioration in crop seed quality through seed soaking/ invigoration treatments (particularly those involving CW and other antioxidant-based solutions), which is going to represent an increasingly important research area as the effects of climate change and developmental challenges threaten food security in many parts of the world. However, future studies must screen a larger number of rice genotypes to assess the plasticity of the biomarkers identified to be reliable indicators of curing-induced stress and stress recovery before they are adopted by the seed industry. Additionally, future studies must use biochemical, physiological, molecular, omic and biophysical approaches to fully understand the mechanism(s) of action of CW invigoration in deteriorated rice seed in order to extend this method to other crop species that experience a decline in seed quality during seed processing and or storage.
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.
Aspects of the ecology of spotted hyena (Crocuta crocuta) in relation to prey availability, land use changes and conflict with humans in western Zimbabwe.
(2018) Mhlanga, Mlamuleli.; Downs, Colleen Thelma.; Ramesh, Tharmalingam.
Patch selection by carnivores is affected by various factors including availability of prey and denning areas, extent of vegetation cover, competition from sympatric large carnivores and anthropogenic habitat change among other variables. Understanding the influence of such factors is fundamental in the management of the carnivores. The study investigated spotted (i) hyena occupancy and (ii) co-occurrence with mesocarnivores in Zambezi National Park, Matetsi Safari (hunting) Area and Dimbangombe Ranch (mixed livestock and wildlife) in western Zimbabwe during the dry and wet seasons of 2014 and 2015 using camera traps. First, habitat characteristics, potential major prey and possible disturbance factors were modelled using the occupancy modelling approach to quantify habitat occupancy of the spotted hyena. It was found that the spotted hyena mean site occupancy was high (ψ = 0.617, SE = 0.147 and ψ = 0.502, SE = 0.107 for wet and dry seasons respectively). Furthermore, spotted hyena habitat occupancy increased in clayey soil and grasslands in the national park and hunting area, a behaviour attributed to denning preferences and possibly prey movement. Management priorities should focus on improving habitats for wild prey outside protected areas while preserving clayey areas for enhanced productivity of the spotted hyena inside protected areas. Secondly, it was predicted that mesocarnivores would avoid habitats occupied by the spotted hyena resulting in seasonal variation in temporal overlap between the spotted hyena and mesocarnivores. The study found that the detection probability of the mesocarnivores varied in the presence of the spotted hyena as a function of the detection of the leopard, presence of rocky and mixed vegetation habitats and road network. The high temporal coefficients of overlap for all pairs of species implied high chances of co-detection at the same sites. It was recommended that land management and top predator introductions should consider how optimal use of the habitat by small carnivores is affected. In addition, the study (iii) determined spotted hyena prey selection by comparing differences in frequency of occurrence of prey remains in their scats from a hunting area (117 scats) and a national park (137 scats). Small, medium and large-sized mammalian prey contributed 19.8 %, 41.9 % and 19.8 % to the diet of the spotted hyena in the safari area, compared with 34.3 %, 24.0 % and 35.9 % in the national park, inclusive of domestic stock (10.3 % in the safari area; 12.0 % in the national park). The difference in diet composition of the spotted hyena between the two land-uses was attributed to the ability of the species to shift between prey species in relation to the availability. Furthermore, a questionnaire survey was done (iv) to assess the attitudes and perceptions towards the spotted hyena of people (n = 353 households) in communities living at various distance categories within 0 - 20 km from the protected area boundary. It was found that livelihood source and extent of livestock loss had an influence on perceptions about the spotted hyena. The study recommended development of a modified incentive driven model that will encourage human-wildlife coexistence. Bushmeat harvesting is thought to affect prey distribution for the carnivores and a questionnaire survey was done on 355 households (v) to determine the factors driving bushmeat activities in the area in relation to conservation efforts. Bushmeat availability was highly influenced by scarcity of protein sources and season (dry). The dry season peak in bushmeat availability was attributed to increased demand that coincided with a period of low protein availability in the villages. The hunting zone (distance from protected area boundary) was the most influential predictor of how communities viewed illegal bushmeat harvesting in relation to conservation efforts. Mitigating illegal activities would likely be effective when started in settlements that are inside wildlife zones. Insights on community perceptions towards conservation may help in managing edge effects around PAs.
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.
Cathodic water invigoration of deteriorated orthodox seeds – implications on subsequent plant growth.
(2020) Fatokun, Kayode.; Beckett, Pichard Peter.; Varghese, Boby.; Pammenter, Norman William.
Orthodox seeds deteriorate even when kept under the best of conditions leading to loss of germination, poor seedling growth. In this study, a novel approach via the use of cathodic water, an electrolysed form of calcium magnesium solution, was used to invigorate fresh and controlled deteriorated seeds of wild (Bolusanthus speciosus (Bolus) Harms, Combretum erythrophyllum (Burch.) Sond., Erythrina caffra Thumb.) and agricultural (Pisum sativum L., Cucurbita pepo L.) species. Other treatment solutions investigated alongside cathodic water were un-electrolysed calcium-magnesium solution and deionized water. Fresh seeds of the test species were controlled deteriorated to 50% germination (P50) at 40°C and 100% relative humidity. Thereafter, the seeds were invigorated with the treatment solutions. Fresh and un-primed controlled deteriorated seeds served as the control. In addition, to study the mechanism of invigoration, the effects of priming on the membrane stability index (MSI), amylase activities, lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) were investigated. The effects of priming on the reactive oxygen species (ROS) scavenging enzymes superoxide dismutase, and catalase and DNA (concentration and purity). All priming treatments improved germination, emergence, growth parameters and subsequent seedling photosynthesis relative to the unprimed seeds. In general, cathodic water was most effective at invigorating seeds in the all test species. Also, controlled deteriorated seeds benefitted more than the fresh seeds treatments. Analyses of the lipid peroxidation products and antioxidant enzyme activities in invigorated seeds provided support for the hypothesis that the effectiveness of cathodic water in the invigoration of debilitated orthodox seeds derive from its ability to act as a potent antioxidant. This study, which is a novel approach at bringing the concept of electrochemistry into germplasm conservation via the use of cathodic water, has also confirmed the efficacy of cathodic water in invigorating debilitated seeds. This is especially critical for seeds containing traits that may be under the threat of being lost due to various reasons. The current study reinforces the strong potential of cathodic water in the recovery of aged germplasm and improved yield of orthodox seeded species.
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.
Comparative studies of the ultrastructure of Entamoeba histolytica and Entamoeba coli.
Proctor, Eileen Margarita.; Elsdon-Dew, R.
No abstract available.
Concurrent spatiotemporal ecology of African lions and spotted hyenas and the potential for inter- and intraspecific interactions in semi-arid and wetland ecosystems.
(2022) Barker, Nancy Ann.; Slotow, Robert Hugh.
Intraguild interactions among apex predators can potentially influence carnivore population densities and distribution, which may have profound effects on trophic processes within ecosystems. Coexisting carnivores are able to mitigate such interactions through behavioural mechanisms that promote spatiotemporal separation. Despite increasing research which highlights the occurrence and prevalence of competitive interactions between African lions (Panthera leo) and spotted hyenas (Crocuta crocuta), studies that incorporate the effects of such interactions on lion and hyena space use patterns are limited. Interactions among sympatric carnivores reveal how predators utilize spatial and temporal partitioning strategies within jointly used areas, and elucidate the spatiotemporal patterns enabling species coexistence between them. Thus, an understanding of how inter- and intragroup interactions drives the movement responses of apex predators has important implications for the structure and function of large carnivore communities, and their conservation. We used remote tracking data to investigate aspects of the ecology and behaviour of lions and spotted hyenas, with an emphasis on the spatiotemporal patterns among coexisting populations. Both lions and spotted hyenas mediated the potential for interference competition through subtle differences in temporal activity, fine-scale habitat use differentiation, and localized reactive-avoidance behaviours. Recursivity to, and duration of time at, locales of high competitor probabilities, were similar among female lions and both sexes of hyenas, but different for male lions. Our findings of lion space-use patterns across arid and mesic environments indicated the seasonal influences of competitive interactions with competitors (spotted hyenas), in that lions selected for, and chose to move through areas with a lower probability of competitors during the dry season. Dyadic interactions among lions and spotted hyenas illuminates how hyenas effectively reduced their potential of interactions with lions by utilizing spatiotemporal partitioning strategies and local reactive avoidance behaviours within shared space use areas. Quantifying the types of movement behaviour between competitors highlights the type of interaction occurring in a dyad and enhances our understanding of the potential effects of interspecific interactions among large carnivore space-use patterns within an apex predator system. Both lions and spotted hyenas exploit different behavioural strategies resulting in fine-scale spatiotemporal segregation among shared space-use areas enabling the two species to co-exist, and show adaptability across heterogeneous and homogeneous environments. Such findings are essential in understanding the behavioural choices made by members of a guild that subsequently affects population dynamics and community structure of multi-species food networks.
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.
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.
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.
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.
The effects of sexual dimorphism on the movements and foraging ecology of the African elephant
Graeme, Shannon.; Slotow, Robert Hugh.
Abstract available on PDF file.
A genetic approach to the biodiversity of shallow water alcyonacea in South Africa.
(2018) Etsebeth, Kerry-Lee.; Macdonald, Angus Hector Harold.
The cnidarian order Alcyonacea (Octocorallia) represents a diverse group of marine invertebrates that are dominant taxa on shallow and deep reefs. These organisms constitute sensitive indicators of climate change and have bioprospecting potential. In South Africa, alcyonacean soft corals form the dominant faunal component of the high latitude marginal reefs on the east coast, an understudied region of interest that forms some of the southernmost distribution limits for key taxa in this order. Globally, soft corals are understudied whereby systematic, ecological, and biochemical studies are challenged by inconclusive taxonomy. This is in contrast to the growing understanding of the necessity for genetics in the systematics of Scleractinia, where large scale reclassification has been successful in reconstructing more accurate phylogenies of the order. The knowledge deficit in the systematics and evolution of Alcyonacea is paralleled in South African taxa. An integrative assessment using morphological classification in combination with phylogenetics of Alcyonacea is the most promising approach to assess their biodiversity in South Africa. Accordingly, the aims of these studies were to advance the taxonomic knowledge of soft corals in South Africa; assess species richness and provide a national checklist; and investigate evolutionary relationships between taxa. In so doing, this thesis also aimed to support the global taxonomy of Alcyonacea. Particular attention was given to Alcyonacea that dominate the reef biota in the UNESCO world heritage site, the iSimangaliso Wetland Park (iSWP). Three genetic markers, cytochrome c oxidase I (COI), bacterial MutS homolog (MutS) and nuclear 28S ribosomal RNA (28S rRNA) were used to determine genus and species boundaries in the closely related Alcyoniidae genera; Cladiella, Aldersladum and Klyxum. The use of these genes corroborated taxonomic analyses and demonstrated that morphologically aberrant members of the genus Cladiella should be reassigned to another as yet undescribed genus. The undescribed genus, Beta6, is characterised by an absence of platelet sclerites in the polyp region, features that demonstrate major distinctions from the genera Cladiella, Aldersladum and Klyxum. The species richness of 67 Sinularia specimens in the iSWP was estimated 6 Beta was selected as a placeholder name until the full taxonomic descriptions of this new genus and any of its associated species are published. using DNA barcoding (MutS and concatenated MutS+28S respectively). Phylogenetics and species delimitation methods were used to infer identifications for 63% of the specimens in the study, including a new record for Sinularia grandilobata. In addition, 16 putative species of Sinularia were discovered that are considered potentially undescribed or new records that require further taxonomic investigation by an octocoral expert. Furthermore, S. brassica exhibited two distinct morphotypes that were genetically differentiated and indicative of two distinct species. Taxonomic boundaries were investigated using integrative taxonomic approaches for 239 specimens of Alcyonacea from the iSWP. Specimens were assigned to ~61 putative species that were inferred from phylogenies, divergence estimates, colony photographs and sclerite characters for taxa in this study. Molecular evidence supported the reassignment of non-S. brassica congeners of Sinularia to an undescribed genus due to significant large scale polyphyly. Furthermore, this study reported new records for three genera; Scleronephthya, Paraplexaura, and Chironephthya and an undescribed species of Lobophytum. The results of this study, in conjunction with previously published records, contributed towards revised species estimates for the iSWP that increased from 37 to 81 species (with 12% endemism), 11 to 47 genera and 4 to 17 families. An updated checklist of the Alcyonacea across South Africa was compiled using records from chapters 2 to 4 in this thesis and published records. Two hundred and twenty-six different species from among 89 genera and within 25 families of Alcyonacea were reported. Seventy-five of these species are endemic to South Africa (33%). This represents a substantial increase from the last published estimates in South Africa of 130 species of Alcyonacea. This body of research represents a significant advancement in the knowledge of the biodiversity of an important group of marine invertebrates in South Africa. It provides resolution within some problematic identification assignations (Cladiella, Sinularia brassica). Sinularia, Beta and the Lobophytum-Sarcophyton complex require further taxonomic work for a better perspective on the diversity of this complex, marginal and neglected aspect of South Africa’s marine heritage.
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.
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.
Influence of human-associated tsetse habitat degradation on tsetse fly (Diptera: Glossinidae) populations and prevalence of infection with trypanosomes in North-Eastern Zambia.
(2021) Chilongo, Kallinga.; Mukaratirwa, Samson.
African trypanosomiasis is among the most important parasitic diseases of livestock and humans caused by several species of trypanosomes, and the disease occurs in 36 countries in sub-Saharan Africa. Human African Trypanosomiasis (HAT) causes a considerable public health burden on rural populations, and Animal African Trypanosomiasis (AAT) is an important constraint to livestock production and full utilization of land for agricultural production, such that if not controlled the disease can induce important losses through limiting crop production and access to land, and diminishing income from meat, milk and other livestock products, consequently resulting in poverty. In Zambia, approximately 40% of the country’s land is tsetse-infested and the infestation in the Luangwa valley is among the most important with respect to occurrence of both human and animal trypanosomiais. In affected areas, occurrence of trypanosomiasis in humans and in livestock normally correlates with the prevalence of trypanosome infection in tsetse flies. Laboratory studies have shown that among the major factors that affect such trypanosome infection in tsetse flies, is occurrence of stress in tsetse flies. Occurrence of stress in wild tsetse fly populations is associated with unfavourable environmental conditions for the flies, and this is usually a consequence of tsetse habitat degradation. In many parts of Zambia’s eastern tsetse belt, human-associated degradation of the tsetse habitat has been on the increase over the last decades. This suggests that research to determine the effects of such human-associated tsetse habitat degradation, on tsetse populations and prevalence of trypanosome infection in the tsetse population in the area, could provide some insights into the epidemiology of trypanosomiasis in the area. In this study undertaken in three sites, Mpika, Lundazi and Rufunsa sites, in north-eastern Zambia (in parts of the eastern tsetse belt), the objectives were, to determine and measure (i) variation in size, age and hunger stages in tsetse flies and (ii) variation in prevalence of trypanosome infection in the tsetse flies, with increase in distance away from the edge into the inner parts of tsetse belt, and in relation to the distribution of human settlements; and (iii) to detect, assess and evaluate the contribution and importance of existing agricultural and other forms of ecosystem utilization, to tsetse-habitat degradation in the three sites. Three study sites were selected based on level and pattern of human settlement, i.e. Mpika and Rufunsa sites with human settlement concentrated at or close to the edge of the tsetse belt, and Lundazi site with human settlement evenly distributed from the edge into the innermost parts of the tsetse belt. Samples of two species of tsetse flies found in the sample sites, i.e. Glossina morsitans morsitans and G. pallidipes, were collected and (i) size, age and hunger stage in the tsetse flies were recorded and assessed with reference to distance away from the edge of the tsetse belt; (ii) variation in prevalence of trypanosome infection in the tsetse population in the study sites, with reference to distance away from the edge of the tsetse belt, and in relation to distribution of human settlements; and (ii) key land-use and socioeconomic factors in the human settlements, with reference to human-associated tsetse habitat degradation in the study sites. Trapping of the tsetse flies was done in defined sample points, identified with use of a Global Position System (GPS) unit, in the transect line, with use of the Black-screen fly round (BFR) and Epsilon traps. From the sampled flies, the following were recorded; species of fly, sex, body size, age and hunger stage (as indicators of levels of occurrence of stress), and screening for trypanosome infection using microscopy and the loop-mediated isothermal amplification (LAMP). A semi-structured questionnaire was administered in each of the settlements within our study location, and national land cover maps for the years 2000 and 2010, produced by the country’s Forest Department, were used to estimate vegetation cover change during the period 2000 to 2010 in each of the sites. Regression models were applied to determine and measure the level of association of the distance from the edge into the inner parts of the tsetse belt with; size, age and hunger stages of tsetse samples, and prevalence of trypanosome infection in the tsetse flies. In each settlement, data were collected on key land-use and socio-economic factors that may be linked to human-associated habitat degradation and changes in the vegetation cover during the period 2000 and 2010, was calculated in QGIS. The results showed that in the Mpika and Rufunsa sites, the number of Glossina morsitans morsitans tsetse flies caught increased along with the increase in distance from the edge into the inner parts of the tsetse belt. This was also associated with increase in the body size (p < 0.0001 in both sites), and reduction in the age (p < 0.001 in each site) and the hunger stages (p < 0.0001 in both sites), and reduction in the prevalence of trypanosome infection (p = 0.024 and p = 0.012 in the case of all sub-species of trypanosomes tested for in the Mpika and Rufunsa sites respectively; and p = 0.013 and p = 0.025 in the case of only nannomonas sub-species in the two sites, respectively). The level of vegetation cover change was insignificant in each of the sites, such that it was unlikely to have had any significant impact on the quality of the tsetse habitat in each of the sites. In the Mpika and Rufunsa sites, human activities associated with access to resources might have had significant effect on the distribution of wild mammals that served as tsetse hosts in the area, such that numbers (of wild mammals) were low in locations that were close to the settlements and high in locations that were furthest from the settlements – giving rise to a gradient of increasing levels of availability of tsetse hosts with increase in distance away from the human settlements. This same trend was observed with regard to the distribution of body size of the flies, age, hunger stages, and prevalence of nannomonas and trypanozoon trypanosome infection, in G. m. morsitans in the Mpika and Rufunsa sites. This was indication that (in the Mpika and Rufunsa sites) increase in the levels of availability of tsetse hosts was associated with increase in levels of tsetse wellbeing – in turn associated with increase in levels of tsetse habitat quality. With regard to the findings in the Lundazi site (where human settlement was evenly distributed in transect line), the absence of any such variation (in each of the respective attributes in G. m. morsitans) with distance from the edge of the belt, could be taken as supportive to the reason indicated above as the likely basis for the existence of a gradient of reducing levels of tsetse habitat degradation in the Mpika and Rufunsa sites. In the case of G. pallidipes, the results showed no variation in the respective features in the tsetse flies, with increase in distance from the edge of the tsetse belt, and factors such as the relatively fewer numbers of the species caught, and a large proportion of the transect length not having registered any catch of the species, in each site in the study, likely contributed to this outcome.
An investigation into the protein requirement of a marine prawn Fenneropenaeus indicus (H. Milne Edwards)
Sara, Joseph Roderick.; Forbes, Anthony Tonks.; Gous, Robert Mervyn.;
Abstract available in PDF file.

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