Masters Degrees (Ecology)

Permanent URI for this collectionhttps://hdl.handle.net/10413/7488

Browse

Now showing 1 - 20 of 64

The effects of anthropogenic disturbances on vegetation, birds, and nearby communities in selected Southern Mistbelt Forests in South Africa.
(2025) Magoso, Siboniso.; Downs, Colleen Thelma.
Globally, forests are threatened by several disturbance factors. Most of these include anthropogenic activities such as deforestation, land use, agricultural conversion, and fragmentation, driven by poverty and rapid population expansion. These disturbances have a considerable impact on forest structure and composition. In eastern South Africa, most rural communities are located near natural forest patches and, if not, are within travelling distance, which allows for unlimited access to forest resources. Overexploitation and harvesting are common in these regions. Nevertheless, forests provide valuable ecosystem services to local communities, while they are also crucial for biodiversity as they host most species, regardless of the small space they take up on Earth. Therefore, understanding the trends of disturbance and future implications is necessary. We explored the benefits and costs of mistbelt forest disturbance to the nearby communities and biodiversity. We compared lower, medium, and highly disturbed mistbelt forests in three different areas in terms of (1) bird species diversity, forest structural complexity and heterogeneity, and (2) the impacts, values, and perspectives of the nearby communities. Firstly, we investigated the response of bird taxonomic and functional diversity to local and landscape characteristics. Bird species were sampled using fixed radius point counts at a distance of 200 m apart. The bird functional indices were quantified using the functional richness and functional evenness. The overall results showed a positive response of functional richness and evenness to structural complexity and heterogeneity. The categorical disturbance had a negative influence on the functional richness and evenness of the bird community, including the specialists and generalist bird species. However, we found that the functional richness and evenness in highly disturbed patches increased compared with medium disturbed patches. The results demonstrated the importance of microhabitat covariates in promoting species diversity and conservation of endangered and vulnerable species. Moreover, monitoring of recovering forest patches is crucial given their possible future role in biodiversity conservation. Secondly, we conducted a total of 360 interviews in seven villages/communities situated near indigenous forest patches using the questionnaires between October 2023 and January 2024. The overall results indicated that local community members benefit from forest resources such as firewood and traditional medicine. They use these resources to build houses, and fences, and generate sales. Furthermore, during the dry season, the forests become primarily important for foraging for their livestock. This prevents the use of expensive supplements to supplement their livestock. Therefore, human-nature interactions are an important step in balancing ecosystem services and conservation. In addition, forest ecosystems are crucial for the provision of ecosystem services for biodiversity and human livelihood. The proper management and conservation of the Mistbelt Forests is recommended for a long-term supply of resources and biodiversity conservation.
Presence and persistence of the Peregrine Falcon and Lanner Falcon in South Africa.
(2024) Govender, Kyle Trenton.; Downs, Colleen Thelma.
The Peregrine Falcon (Falco peregrinus) and the Lanner Falcon (Falco biarmicus) are small to medium-sized birds that display behavioural plasticity to diverse environments and are widely distributed throughout sub-Saharan Africa, where they occur sympatrically. Peregrine Falcons have an almost global distribution, and Lanner Falcons have an Afro-tropical distribution. The aim of this thesis was to determine the presence and persistence of the Peregrine Falcon and the Lanner Falcon across South Africa. This study leverages data from the Southern African Bird Atlas Project (SABAP1 and SABAP2), social media platforms (Facebook®, eBird®, and iNaturalist®), and literature (sourced from Google Scholar®, Web of Science®, Scopus®, and PUBMED®) to investigate the distribution and relative abundance of the Peregrine Falcon and Lanner Falcon across South Africa. Both species, often coexisting across sub-Saharan Africa, share similar habitat preferences and prey species selection. Peregrine Falcons’ behavioural plasticity to urban environments highlights its resilience, whereas Lanner Falcons displayed mixed responses suggesting targeted conservation strategies to mitigate the impacts of habitat fragmentation, land use changes, and urban encroachment. Peregrine Falcons had a more restricted distribution within South Africa than Lanner Falcons, and both species had distributions within urban areas. The presence of Peregrine Falcons negatively influenced Lanner Falcons distributions and abundance. Lanner Falcons were more frequently observed but remained understudied in comparison. Overall, both species are understudied in Africa, particularly in South Africa. Research on both falcons focussed on their breeding ecology and the health of the species with a focus on egg-shell thickness in response to environmental factors and parasitic studies. Research was primarily based in Europe and North America, and both species remain understudied in other regions of geographical distribution. Research techniques for monitoring and data collection relied on observational data and biological and genetic sampling. Established monitoring techniques are commonly used, and new novel approaches such as citizen science remain underutilised but with growing interest. The findings in this thesis highlight the complex relationship between urbanisation, species competition, social interactions, ecology, behaviour, and habitat preferences in shaping these falcons' distribution and population trends.
Aspects of the urban and rural ecology of Nile monitors (Varanus niloticus) in KwaZulu-Natal, South Africa.
(2024) Genevier, Euan Emmanuel Zinedine.; Downs, Colleen Thelma.
Changing land use, which is taking place globally at an unprecedented rate, generally has a negative impact on biodiversity. However, some species persist in or even exploit these anthropogenically modified environments. Little is known about how reptiles are affected by urbanisation, especially in the global South. Nile monitors (Varanus niloticus) are Africa’s largest lizard and are amongst the most exploited tetrapods on the continent, yet they can be found in highly urbanised and densely populated areas of KwaZulu-Natal, South Africa. They remain greatly understudied, with many gaps in even basic aspects of their ecology. They are projected to become threatened in parts of their range without successful management. This thesis focuses on two broad aspects of the ecology of Nile monitors in KwaZulu-Natal Province, South Africa. Namely, a) their distribution and persistence in a mosaic of land-use type and human population density in two focal areas and b) their population size and morphometrics in rural and urban areas. The aim was to fill important knowledge gaps in the ecology of this highly exploited, charismatic, and yet understudied species to make management recommendations and promote sustainable coexistence of people with Nile monitors in KwaZulu-Natal, South Africa. The first aim was to determine if Nile monitors occur in urban environments in KwaZulu- Natal and what land use types they are associated with. Using 419 Nile monitor sightings, two hotspots were found in the region, one dominated by protected land and the other dominated by mosaics of anthropogenic land use. They were found throughout regardless of human density. However, their use of residential areas was greater in the region with less available natural land. Increasing human density was positively associated with the use of more wooded habitats, except for planted forests, which were avoided systematically. Their association with water was confirmed; however, increased human density also increased their mean distance to rivers, likely reflecting their use of swimming pools, storm drains and other anthropogenic water features. Both managed and unmanaged green spaces (e.g., gardens, parks, golf courses) in urban mosaic landscapes are important features for the persistence of Nile monitors. The second aim was to estimate the Nile monitor population size using a mark-resight method with baited camera traps on a gradient of land use in three different specific sites and also compare urban and rural morphometrics throughout KwaZulu-Natal. Nile monitor limbs, body width, tail base, heads, and body mass were larger in rural areas but only marginally. Furthermore, we found greater population size estimates with increased habitat modifications (golf course > farmland > nature reserve), but the average estimated snout-vent length decreased. Reduced size may result from intraspecific or interspecific competition and different predation dynamics in urban and rural ecosystems. More independent trigger events of potentially competing diurnal mesocarnivores were recorded in the nature reserve and farmland than on the golf course. Despite the larger population size estimate of monitors, there was evidence of poaching at the golf course. One individual was stolen from a trap, and four instances of deployed snare traps were recorded. The inclusion of dead individuals for morphometrics has shed light on the added threats caused by domestic dogs (Canis lupus familiaris), people and vehicles for urban monitor populations. It is concluded that Nile monitors are successfully persisting in the mosaic urban landscapes of KwaZulu-Natal but are not as successful as some other urban varanids. The use of anthropogenic land-use, and thus conflict with people, will likely increase with continued land-use change. Future research should investigate Nile monitor interactions with people and pets as well as conflict mitigation strategies and both their urban and rural spatial ecology.
Recruitment and presence of native migratory fish species in the uThukela River estuary and lower uMngeni River catchment, KwaZulu-Natal, South Africa
(2024) Africa, Leawin Virgenise.; Downs, Colleen Thelma.
African rivers provide significant sources of freshwater and are ecologically and economically important to human livelihoods, especially regarding income and food sources. In Africa, ~200 million people consume freshwater fish daily, and ~10 million people are gaining an income associated with freshwater fisheries. Unfortunately, African rivers are some of the most unpredictable rivers as they fall victim to extreme variability in precipitation. These rivers and streams are under threat to anthropogenic activities, such as the building of dams, weirs and locks, water extraction, modified river embankments, water quality issues, flow modifications from hydropower dams, and climate issues, that are significant threats to all fish species. Estuaries are unique and highly productive systems that are rich in biodiversity, as they are tidal-driven. An intricate flow dynamic connecting freshwater systems, estuaries, and the sea needs to be maintained for optimum ecosystem functioning. Thus, rivers are fundamental to the connectivity they provide. Physical barriers decrease the ecological connectivity of river systems. This has a major impact on various fish species, especially migratory fish. Migratory fish are major ecological drivers that can shape the structure and function of ecosystems. They are fundamental in maintaining food webs as predators or prey. Many flagship migratory species (i.e. yellowfish (Labeobarbus spp.) and eels (Anguilla spp.) in South Africa are prevented from reaching their breeding grounds. Four of the globally nine recognised species of anguillid eels are located and documented along the East flowing African Rivers, including those in South Africa. A few studies have been conducted on the recruitment of glass eels into the rivers and estuaries in the Western Indian Ocean. There are limited studies on the location of spawning areas of African freshwater eels. Relatively little is known about the migratory requirements of African fish species; only a few quantitative studies have been conducted to support the understanding of the migratory habits of these fish species and their dependency on free-flowing and connected rivers. This study investigated the recruitment of African freshwater glass eels into the uThuleka River. Environmental data were collected. Glass eel species were identified by their tail and caudal fin pigmentation together with DNA barcoding. The findings included seasonal variation in recruitment, but the majority of glass eels were caught in the wet season, in warmer temperatures, during high spring tides and at night. These findings should encourage more frequent sampling in estuaries across all seasons along the Western Indian Ocean coast, as the timing of glass eel recruitment can be used to locate where the African Freshwater glass eels’ breeding area is. Additionally, this study aimed to characterise the risk of multiple stressors, including instream anthropogenic barriers, on the ecology of fish communities and their environmental drivers in the lower part of the uMngeni River catchment. Various fish sampling methods were used to capture fish and investigate their species diversity and evenness. Statistical analyses were used to evaluate the relationship between fish communities and environmental variables, including barriers. The findings showed distinct fish community structures found across all sites in the catchment, which were susceptible to multiple stressors impacting migratory fish, especially velocity and mean depth. These stressors result in impaired river connectivity, which reduces a fish’s ability to recolonise a river's range sufficiently. Restoring and considering river connectivity in the lower uMngeni catchment can potentially improve fish communities.
An evaluation of present and potential inland fisheries in dams and rivers in the uThukela and uMngeni Catchments, KwaZulu-Natal, South Africa.
(2024) Makhathini, Ntandokayise.; Downs, Colleen Thelma.
Globally, freshwater systems and their biodiversity and ecosystem services are threatened. Freshwater fisheries in South Africa are understudied despite their economic importance to fishers, especially subsistence fishers. Little is known about the potential for rivers and impoundments to support subsistent fisheries and the resilience of native fish species impacted by invasive alien fish species. The main aim of this study was to address the lack of knowledge about economically and biologically important indigenous fish species that support inland fisheries in KwaZulu-Natal Province, South Africa. The composition and contribution of native and invasive fish species and their offtake by fishers were assessed. Fishers across the uThukela and uMngeni catchments were interviewed using in-person questionnaires. In addition, assessment of fish communities and population structures in Midmar Dam and Henley Dam, two selected dams on the uMngeni River, coupled with questionnaire data, were used to determine the offtake trends by fishers (subsistence and recreational). These will contribute to a potential subsistence fisheries management plan for these dams based on the findings to guide the development of the provincial and national inland fisheries plan. Firstly, in a systematic review, the present and potential inland fisheries in dams and rivers across Africa to guide inland fisheries in KwaZulu-Natal, South Africa, were assessed. The results showed diverse inland fisheries types with distinct characteristics and shared challenges. National and regional importance of African inland fisheries was found, but there was a lack of understanding of the definitions and boundaries between the categories of inland fisheries. Subsistence fisheries, focusing on local food provision through traditional methods, face threats like overfishing. Recreational fisheries, contributing to food, income, and recreation, require effective conservation in developing nations. Small-scale fisheries showcase resilience and successful conservation, emphasising adaptive management. Commercial fisheries involving professional fish exploitation encounter challenges, especially in regions like South Africa, demanding sophisticated approaches for long-term viability. Across Africa, common challenges such as overfishing and habitat destruction persist. In KwaZulu-Natal, a significant research gap exists, impacting sustainability. Addressing issues like monitoring systems, invasive species, and species knowledge is crucial for sustainable fisheries management in the region. Secondly, to address the paucity of knowledge of economically beneficial fish species and their offtake based on the perceptions of fishers present in selected sections of the uMngeni and uThukela catchments, KwaZulu-Natal, South Africa, a questionnaire interview method was used to obtain fishers' responses during 2021-2023. Findings from this study revealed difficulties in categorising fishers because of present inland water policies similar to the “fuzzy boundary” concept for inland fisheries globally, with some individuals identifying as recreational because of nondisclosure fears. Fishers’ knowledge illustrated the ecological imbalances between native (Labeobarbus natalensis) and invasive (Cyprinus carpio, Micropterus spp.) species, as well as the economic importance of fish based on market valuations, with C. carpio having a greater market value. Additionally, the results showed that subsistence fishers preferred river fishing compared with recreational fishers that targeted impoundments. Importantly, a considerable percentage of subsistence fishers ate fish mostly once a week or once a month. These results highlighted the importance of holistic management of water regulations, fish ecology, and economics to promote sustainable inland fisheries. Thirdly, an ecological assessment of fish communities in Midmar Dam and Henley Dam during the winter and summer seasons of 2022 and 2023 was conducted. Diverse fishing methods were used to capture a broad spectrum of fish species. Additionally, questionnaires were administered in selected areas of KwaZulu-Natal to gather complementary data on fish species in inland fisheries. A total of six fish species (three native species and three invasive species) were found in the two impoundments. Midmar Dam had significantly higher total fish catch than Henley Dam, highlighting the role of environmental factors such as dam size, depth, and temperature in shaping fish populations and influencing overall productivity. The KwaZulu-Natal yellowfish (L. natalensis) was significant to local inland fisheries, while invasive fish species posed challenges to maintaining the native fish species. These results emphasised that incorporating fish catch data into decision-making processes is crucial for making informed, science-based choices that ensure the long-term viability of fish populations and promote the overall health of freshwater ecosystems. In conclusion, the findings underscore the necessity for tailored fisheries management strategies that consider the unique environmental characteristics of each dam and the structures of fish populations. By integrating water quality data, catch-per-unit-effort (CPUE) results, and insights from fishers, decision-makers can formulate science-based approaches to preserve fish populations, support local livelihoods, and safeguard vulnerable communities dependent on subsistence fishing. Ultimately, successful conservation and sustainable management of fish populations hinge on informed decision-making prioritising ecosystem health and resilience across KwaZulu-Natal's freshwater habitats.
Aspects of the ecology and conservation of vultures in South Africa.
(2024) Laurieston, Emma Beth.; Downs, Colleen Thelma.
Vultures play a crucial role in ecosystems as scavengers by consuming carcasses and preventing the spread of diseases. However, vulture populations worldwide face anthropogenic threats causing drastic declines, with several species now facing extinction. In response to this, various conservation efforts have been implemented to safeguard vultures. The overarching goal of this thesis was to evaluate the effectiveness of these conservation efforts through a comprehensive examination of vulture ecology and conservation strategies. We reviewed the use of questionnaires to understand stakeholder perceptions and global threats to vultures. Additionally, public attitudes towards wildlife marking techniques and the implications for vulture conservation were explored. Furthermore, we evaluated the effectiveness of vulture rehabilitation, release and monitoring initiatives by comparing the behaviour and survival of rehabilitated and wild vultures. The systematic review of questionnaire-based vulture research revealed critical insights into stakeholder perceptions globally. The study highlighted the multitude of threats facing vultures in different regions. We found worldwide misconceptions among stakeholders, including the belief that vultures attack livestock. These misconceptions exacerbate retaliatory killings, highlighting the need for focused education initiatives to protect vultures. Across Africa, poisoning, poaching, and cultural use of vultures pose significant challenges to their conservation. The exploration of public perception of wildlife marking techniques, particularly patagial tags on vultures, revealed predominantly positive attitudes towards marking wildlife. Despite broad support for wing-tagging vultures, variations in reporting vulture sightings highlighted the importance of promoting active monitoring and awareness. Analysis of the Endangered Wildlife Trust Vulture Resighting Database proved patagial tags valuable in collecting long-term data on vulture movements. However, concerns about the durability of tags and the high number of vultures not resighted after tagging raised questions about their potential impacts on vulture survival. The study of vultures treated at Moholoholo Wildlife Rehabilitation Centre indicated the successful reintroduction of poisoned and injured vultures into the wild despite challenges, including post-release mortality and possible behavioural impacts of the rehabilitation process. Future research should prioritise tailored conservation strategies, including stricter regulations to limit substances that are harmful to vultures and community-based initiatives for responsible carcass disposal. Increasing public awareness, citizen science projects, and advancements in tracking technology are crucial for improving conservation efforts and halting the decline of vulture populations.
Response to urbanisation: aspects of the ecology of the Western Cattle Egret (Bubulcus ibis) with notes on population estimates in the KwaZulu-Natal province and across South Africa.
(2024) Cele, Jennifer Zamathuli.; Downs, Colleen Thelma.
Human population growth continues in Africa, impacting its natural fauna and flora. South Africa is experiencing a growth in population and metropolitan areas. KwaZulu-Natal is a province with the second fastest growing population in South Africa, with ~11.4 million people. This growing population is concentrated around Durban and Pietermaritzburg, the largest and second-largest cities in the province, respectively. This study focused on the city of Pietermaritzburg in the uMgungundlovu District Municipality, and Durban in the eThekwini Municipality, and their surrounding periurban areas, including communal lands and farmlands. As the response of Western Cattle Egrets (Bubulcus ibis) and selected heron species to urban expansion in KwaZuluNatal Province context is poorly documented, the purpose of this study was to understand aspects of the ecology of Western Cattle Egrets in these urban mosaic landscapes. Firstly, a literature review of the Western Cattle Egret was undertaken. Secondly, a comparison of the first Southern African Bird Atlas Project (SABAP1 conducted from 1987-1992) to the second Southern African Bird Atlas Project (SABAP2 ongoing since 2007) allowed us to observe range distribution changes of the Western Cattle Egret across South Africa. There was a significant difference for all changes observed in reporting rates between SABAP1 and SABAP2. With the exception of the Northern Cape, with a 22% decrease, provinces showed more than 60% decrease in reporting rates for the species between the two project periods. This indicated that there has been a decrease in Western Cattle Egret abundance nationally. Changes in reporting rates between SABAP1 and SABAP2 indicated a change in distribution range possibly caused by land transformation. Thirdly, population estimates of Western Cattle Egrets in the uMgungundlovu (Pietermaritzburg) and eThekwini (Durban) Municipalities, KwaZulu-Natal, South Africa, were i conducted over a period of 18 months. These areas are both urban mosaic landscapes with some remaining natural green areas as well as managed green spaces with urban built. A population estimate of Western Cattle Egrets was conducted within these districts, and characteristics that allow for their urban persistence were identified. No significant difference in population size existed between the breeding (~230) and the post-breeding (~470) seasons. Western Cattle Egret colonies were within 10 km of a landfill, wetland, major road, river, and grassland. In addition, nesting sites were closer to a wastewater treatment facility than roosts without nests. The nests were found on 27 trees in both commercial and residential properties. Vachellia xanthophloea and Jacaranda mimosifolia were used on commercial properties. A significant difference was observed for the mean tree height. The tallest trees used for roosting were Eucalyptus spp. (20.23 m) and Jacaranda mimosifolia (19.52 m) found at Mpophomeni. Western Cattle Egrets have become cosmopolitan, undertaking various forms of migration to exploit available resources in the urban landscape mosaic. The trends showed Western Cattle Egrets roost in urban mosaic landscapes near water. In some areas, human-egret conflict was observed. Management recommendations are made for the persistence of Western Cattle Egrets in urban mosaic landscapes.
Assemblage-based monitoring of the uMsunduzi River, using biotic and abiotic lines of evidence.
(2024) Ngozi, Lwandile.; Downs, Colleen Thelma.
Globally, urbanisation and industrialisation activities result in a multitude of impacts on freshwater ecosystems. Generally, frequent pollution of rivers from industrial effluents and sewage channels has caused the deterioration of the water quality of rivers. The availability of healthy, clean, and good-quality drinking water is a matter of concern in urban areas, particularly in developing countries such as South Africa. The instream physical barriers that lack fish ladders, development of industrial complexes adjacent to the river banks, extensive agricultural activities, abstraction of water for domestic and industrial use, and ageing sewage networks, as well as periodic industrial spills, have worsened the ecological well-being of the two socio-economically important rivers in the KwaZulu-Natal Province, South Africa, the uMsunduzi River a tributary of the uMngeni River. The present study evaluated the recovery of the uMsunduzi River, and efforts were made to improve fish population structures following a fish kill event using biotic and abiotic lines of evidence. It was hypothesised that water quality characteristics and biological communities would exhibit improvement since the occurrence of the spill. Abiotic lines of evidence included water quality and habitat characteristics, whereas biotic lines of evidence involved fish communities and fish population attributes of the indigenous KwaZulu-Natal yellowfish (Labeobarbus natalensis), macroinvertebrates, and benthic diatoms. The research was carried out quarterly from 2022 to 2023 at selected sections of the uMsunduzi system, with sites for fish collection upstream of the spill point and re-introduction sites downstream of the spill point. After the mixed product spill and fish kill in the Baynesspruit and uMsunduzi Rivers, nine sites were considered for fish community assessment and ecological monitoring. This included how assemblages respond to a wide range of environmental variables and for fish using the Fish Response Assessment Index (FRAI). The results showed that the uMsunduzi River is heavily polluted, and the stressors impact water quality, fisheries and habitat availability. The multivariate analyses indicated that the anthropogenic stressors that drive the ecological well-being and fish community structures of the uMsunduzi River could be related to changes in water quality and instream habitat modifications. The identified environmental modifications can be directly linked to human activities and flow modifications along the uMsunduzi system. Assessment of attributes of fish communities along the uMsunduzi catchment, with a focus on the KwaZulu-Natal yellowfish as an indicator species, showed a declining state of fish communities in terms of species richness and abundance. The poor fish communities include the fish collection sites upstream of the spill point selected for fish collection. The downstream site, further away from the city, showed some improvement in fish communities. The poor water quality and fish stock for collection sites highlight poor water quality and the impact of stressors on fish communities. The outcomes of this study can contribute to the holistic management, monitoring, and rehabilitation strategies for the uMsunduzi River after a fish kill event. The pre-spill fish data from (Dlamini et al. 2019) showed fish to be slowly recovering to attain the pre-spill abundances. Furthermore, biological stressors should be minimised, particularly inputs of toxic industrial effluents from industrial complexes, sewage from poorly maintained sewage systems and instream physical barriers that fragment fish populations and reduce environmental flows required by indigenous fishes. The development of evidence-based rehabilitation strategies is recommended to attain ecological health for the uMsunduzi River. Removing obsolete instream barriers and incorporating fishways on operational barriers is recommended to allow the movement of migratory fish between upstream and downstream niches. Moreover, inter-system translocation of the KwaZulu-Natal yellowfish from adjacent catchments with healthy breeding populations, such as the uMngeni River, should be collectively decided by the relevant stakeholders to improve population attributes of the yellowfish in the uMsunduzi River. The fisheries management could benefit local subsistence fishermen and improve river conditions. Before this, the genetics of the species need to be determined so as not to jeopardise the genetic fitness or resilience of the existing population. The existing legislative framework for environmental protection should be enforced for industrial and municipal operations to render minimal degradation to freshwater ecosystems. Conservancies should be established to strategically manage and protect freshwater resources and potential fisheries along the uMsunduzi system.
The impact of land-use change on arthropod diversity along an arid elevational gradient.
(2022) Mkhungo, S'phesihle.; Munyai, Thinandavha Caswell.; Foord, Stefan Hendrik.
Land-use change is a major threat to global biodiversity. The rapid growth of the human population has resulted in increased landscape modifications and habitat loss. The impact includes reduced species diversity, ecosystem instability, altered species interactions and altered food webs. Land-use has increased drastically in mountainous areas, mainly through agriculture and human settlements. Mountains support approximately one-third of the terrestrial diversity and host half of the global biodiversity hotspots. The high variation in habitat structure and microclimates, within short distances allows mountains to support high species diversity. This study aimed to investigate the impact of increasing land-use change, elevation, and season on selected arthropod diversity, and community composition along the Western Soutpansberg mountain range in Limpopo province of South Africa. The objectives of the study were to determine spider and ant diversity patterns along the mountain. Secondly, to determine the role of land-use, elevation, and season in structuring the diversity of both taxa. Lastly, to compare the composition of spider and ant assemblages across the various sites and identify indicator species for monitoring land-use change in the study area. A standardized pitfall trap survey was used to sample ants and spiders along an elevational transect that stretches across the southern and northern aspects of the mountain. The elevational transect (800 m a. s. l – 1700 m a. s. l) was made up of 18 sites, some of which have undergone human transformation mainly through agriculture and settlements. Sampling took place during the dry season (September 2019) and wet season (January 2020). Generalized linear mixed models with Poisson error distributions were used to determine the impact of land-use, elevation, season on spider and ant species richness and activity. Community composition was analyzed using NMDS (non-metric multidimensional scaling), PERMANOVA and ANOSIM analyses. Land-use had a positive effect on spider and ant diversity as the transformed sites had significantly higher species richness and activity for both taxa, particularly the agricultural sites and human settlement. However, species evenness was significantly lower in the transformed sites and higher in the natural sites. Species richness and activities for both taxa were highest at the low elevations. Spider diversity was higher in the dry season, but ants peaked in the wet season. Spider and ant assemblages were highly distinct between the land-use types and elevations. Ant assemblages remained similar between the seasons, while spider composition was slightly different across the two seasons. Spider and ant assemblages in the transformed sites were highly uneven which indicates a large disproportion in the number of individuals within the species found in transformed sites. It also indicates high species dominance, which is driven by the disturbance-tolerant species. One spider species, Copa flavoplumosa, was identified as an indicator species for the Eucalyptus plantations. All land-use types had an ant indicator species, which was either Monomorium damarense and/or Lepisiota sp.02 (spinosior gp.). High species dominance displayed by spider and ant assemblages in the modified habitats might have adverse effects on native and endemic communities. Because dominant and disturbance-tolerant species are likely to increase if more natural land is converted. This study was the first to investigate the impact of land-use changes at the Soutpansberg mountain range. The results indicate that landuse change had a positive effect on arthropod species richness and activity. However, species evenness was negatively affected. Although the land-use changes at Soutpansberg can increase the diversity of certain species, the potential to sustain the populations over the long term is unknown. Therefore, further assessments and monitoring of diversity in the region is recommended to understand the long-term impact of land-use and for informed decision making and strategy in conservation efforts.
Investigating the effectiveness of a simple water-purifying gadget made of Moringa oleifera seeds as the active beads.
(2023) Raphasha, Dineo Gladys.; Tsvuura, Zivanai.; Ndhlala, Ashwell Rungano.; Mbendana, Dambudzo.
Abstract available in PDF.
Evaluating multiple stressors on aquatic ecosystems in an urban environment.
(2024) Ngcobo, Nolwazi Blessed.; Downs, Colleen Thelma.
The issue of compromised aquatic ecosystems is a global dilemma; with existing and new stressors emerging, freshwater ecosystems continue to degrade tremendously. Multiple stressors exist in aquatic ecosystems, from invasive species to overexploitation of aquatic resources, habitat degradation, flow modifications and pollution. The uMsunduzi catchment in Pietermaritzburg, KwaZulu-Natal Province, South Africa, is one such stressed freshwater body. The present study was undertaken to determine the major threats to aquatic ecosystems and the possible strategies to mitigate the factors that compromise freshwater biodiversity, health, and ecological status. The first problem was to investigate the impact of anthropogenic barriers along the longitudinal pathway of the rivers. Hence, an extensive literature review on managing river barriers was conducted. This systematic review showed a need for river connectivity restoration projects in Africa, particularly in South Africa. The Northern Hemisphere countries are more advanced in restoring river connectivity by removing barriers or retrofitting fishways. A prevalence of physical barriers in the uMsunduzi catchment was found, and most barriers did not have fishways or fish passage structures. The fish communities, together with their associated habitat features, within the uMsunduzi mainstem and tributaries, were assessed to deduce which environmental factors influence the fish communities' structures in the system. There was a clear indication of a decline in species diversity and deterioration of the ecological health of the uMsunduzi catchment. Of the 18 expected fish species, according to the Freshwater Biodiversity Information System (2023), only 50% of these were caught. This is concerning, especially as the “near threatened” (IUCN status) Enteromius gurneyii (redtail barb) was not caught, and Amphilius natalensis (Natal mountain catfish) was caught once in low abundance. The uMsunduzi River had a highly deteriorated ecological integrity per the Fish Response Assessment Index (FRAI) scores, especially close and downstream of the city centre where the industrial areas are concentrated. Similarly, there is a great deal of microbial contamination, putting the uMsunduzi River in a matter of public health. There was also a significant presence of magnesium, calcium and fatty acids. In conclusion, the connectivity, ecological health and water quality of the uMsunduzi catchment were compromised, giving a clarion call for mitigation and management actions on the systems.
Effects of land restoration on the habitat integrity of rivers based on biological water quality and habitat condition assessments with a focus on the eThekwini Municipality, Durban, South Africa.
(2024) Magudu, Kholosa.; Downs, Colleen Thelma.; Burnett, Matthew James.
Riparian ecosystems are natural areas that offer an extensive range of ecosystem services. Their functionality aids in diverting and mitigating the impacts of surface water runoff, thereby reducing soil erosion. Riparian ecosystems also play an important role in sequestering nutrients and organic matter. The degradation of river systems impairs riparian ecosystem health and results in dysfunction, lack of ecosystem services provision and other deleterious effects. This study examined the effect of restoring riparian habitats across two study sites in Durban, Ethekwini Municipality, South Africa. The study aimed to a) measure and assess habitat integrity across three river systems as a result of reforestation efforts, and b) monitor the biological water quality using the Mini Stream Assessment Scoring System (MiniSASS) and the Index of Habitat Integrity indices. In addition, a systematic review was undertaken to provide an introduction and background to ecological restoration work involving freshwater ecosystems in the general South African context. The Index of Habitat Integrity and MiniSASS data were collected over ten months at two sites reforested by eThekwini Municipality, which were compared with data collected from a third river site used as the reference. Two sampling points were selected per site (namely upstream and downstream). It was predicted there would be a significant difference in MiniSASS scores between river sites under reforestation and reference sites not exposed to reforestation. However, it was found that MiniSASS and Index of Habitat Integrity scores differed between and across sites. The reference site had the highest scores. The sites with greater habitat integrity had improved ecological conditions based on macroinvertebrate responses to anthropogenic disturbances. This study highlighted the important role of naturally functioning riparian habitats in cleaning water and provides a baseline for reforestation impact monitoring, as well as informing local governance strategies for restoring degraded rivers in urban areas.
Community diversity and composition of ground-dwelling arthropods in major habitat types of the KwaZulu-Natal Sandstone Sourveld.
(2023) Mhlongo, Nokukhanya.; Tsvuura, Zivanai.; Munyai, Thinandavha Caswell.
Grasslands constitute over 25% of the global land surface and close to one-third of southern Africa. Natural and semi-natural grasslands are recognized globally for their high biodiversity value and their important contribution to the provision of ecosystem services, including provisioning services such as carbon sequestration, water catchments, and grazing for livestock and wildlife. Nonetheless, grasslands are consistently reduced and threatened by anthropogenic activities and invasive alien plants. Invasive alien plants may hinder the growth of natural vegetation by overconsumption of resources. The impact of invasive alien plants on natural vegetation may indirectly affect plant-to-animal interactions such as specialized pollination and seed dispersal syndromes which may ultimately disturb ecosystem processes. The Sandstone Sourveld in KwaZulu-Natal province of South Africa is a threatened grassland ecosystem as a result of various anthropogenic disturbances. Knowledge of arthropod response to differences in habitat types may be essential for an improved understanding of the structure and functioning of ecosystems, which is relevant for informing conservation practice. The aim of this study was to investigate the composition and diversity patterns of ground-dwelling arthropods (ants, beetles, Orthopterans, and spiders) in three habitat types (forest, intact grassland, and disturbed grassland) at Springside and Tanglewood Nature Reserves, which occur in the KwaZulu-Natal Sandstone Sourveld (KZNSS). The objectives were: (i) to document the response of the ground-dwelling arthropod community in different habitat types, (ii) to determine the impacts of seasonal change on the abundance and richness of ground-dwelling arthropods at the two sites, and (iii) to determine the correlation between the distribution of ground-dwelling arthropods and soil characteristics in the KZNSS. Ground-dwelling arthropods were sampled in Springside and Tanglewood Nature Reserves using pitfall traps in each habitat type. Soil parameters in the habitats were also assessed. Analysis of variance was used to test for differences in arthropod morphospecies richness and abundance viii across the habitat types and between seasons. The Shannon-Weiner diversity index was computed and used to compare the diversity of ground-dwelling arthropods between the two sites and among habitat types. Ground-dwelling arthropods showed varying patterns in response to habitat characteristics and the disturbance gradient at Springside and Tanglewood. Intact grassland was the most diverse habitat in both Springside and Tanglewood. In Tanglewood, the abundance of ants was greater in disturbed grassland which consisted of a variety of alien invasive shrubs, the high abundance was explained by the “intermediate disturbance hypothesis”. However, alien invasion showed more negative than positive impacts on the abundance and composition of ground-dwelling arthropods when there was a significant decrease in the abundance and composition of ants, beetles and spiders. Species richness of ants and beetles was higher in the wet than dry season whereas Orthopterans and spiders showed no significant difference between seasons. In all arthropod groups, a greater number of species were correlated to soil potassium, soil pH, and soil bulk density. Overall, the intact grassland had the highest species richness and abundance followed by the forest and lastly the disturbed grassland. The greater abundance of ants, beetles, and spiders in the pristine grasslands of KZNSS shows that there is still a need to conserve the remnants of the KZNSS vegetation. Therefore, the conservancy management is urged to consider the eradication of alien invasive plants. Future studies are recommended to consider the volant and vegetation canopy arthropods as they are all interdependent with ground-dwelling arthropods to form a whole community of arthropods in an ecosystem.
Importance of freshwater systems and eels in the uMngeni and uThukela catchments, KwaZulu-Natal, South Africa: community perspectives.
(2023) Nkomo, Mxolisi Nhlakanipho.; Downs, Colleen Thelma.
Globally, the conservation status of inland fishery resources and freshwater systems is vulnerable, threatening communities' livelihoods dependent on freshwater harvested species. Few studies have reported on the economic and cultural contributions of catadromous eels (Anguilla spp.) in southern Africa, particularly in South Africa. Beyond using freshwater systems for domestic purposes and meeting basic needs, people use rivers for socio-cultural purposes such as; cultural (cleansing), spirituality (healing), and religion (baptism). This study was undertaken to determine if human activities impact the African anguillids eel populations in the local communities of uThukela and uMngeni catchments and management areas in KwaZulu-Natal. A systematic review was conducted on global studies, with an emphasis on southern Africa, that report on the human perspective on the value of anguillid eels when in freshwater systems. In the southern African region, the available literature focused on the distribution of anguillid eels, habitat loss, and a report on the drastic decline of anguillid eels in KwaZulu-Natal's freshwaters where the Anguilla marmorata, A. mossambica, A. bengalensis, and A. bicolor occur. The studies from the northern hemisphere were rich in reports of eel harvesting (wild catches) and export, which was lacking in the southern African region. The systematic review showed a scarcity of knowledge regarding anguillid eels’ association with spirituality, spirituality, culture, and subsistence in South Africa. Secondly, people’s perceptions of the importance of eel species in freshwater fisheries were assessed using a questionnaire along water courses in the uMngeni and uThukela catchments and ecological management areas, KwaZulu-Natal. A total of 154 people were interviewed (66% males, 34% females); the majority of these participants were isiZulu-speaking, which contextualises the findings to the area of KwaZulu-Natal, uThukela and uMngeni management ii areas in particular. The fishing of eels was found in both catchments, with 74% (of the n = 102) being subsistence fishers (with only one female fisher), and 41% of these subsistence fishers specifically targeted eels. All the fishers that targeted eels depended on freshwater eel catches for income because of the relatively high demand and value. Some fishers caught and sold eels to traditional healers who used their products of medicinal products for different uses. Thirdly, the use of freshwater eels (Anguilla spp.) was assessed beyond harvesting them to sell or consume. In particular, using a questionnaire, the spiritual and cultural values of African freshwater eels and their associated freshwater environment in the uMngeni and uThukela catchments were investigated. A total of 154 people from different communities were interviewed along these river systems during 2021 and 2022. In the different communities within catchments, participants reported a number of different beliefs associated with eels and rivers. The responses showed that people valued clean rivers for various cultural, religious, and recreational activities. Some valued eels as they were associated with their beliefs. People who use freshwater for their respective cultural and spiritual, fishing, and domestic purposes voiced a considerable challenge in using freshwater systems, water pollution and water contamination from industrial waste or eutrophication from agricultural waste. Without community participation, there is no guaranteed sustainability of the water resources for the spiritual and cultural values of freshwater eels and freshwater systems. Community leaders and water management bodies must engage with communities in identifying important river uses (domestic, fisheries), and their contribution to spiritual and cultural practices. This will ensure long-term sustainable use and protection of inland water and fisheries resources associated with cultural and spiritual beliefs in KwaZulu-Natal. Freshwater eels hold a crucial aspect in the lives of traditional healers, some local fishers, and the general public, iii those that have knowledge of the use of these species. The study has shown that these species are still under-studied in KwaZulu-Natal, and most people have little understanding of the economic and cultural values, leading to less appreciation of these species by most people, mostly nonfishers.
Monitoring the efficacy of a lowland instream barrier on the lower uThukela River and the importance of river connectivity.
(2023) Van Zyl, Bradley Bruce.; Downs, Colleen Thelma.
Freshwater is the key to life on earth, with rivers being the pathway that allows it to run from mountains to the ocean, performing many important functions along its way. Humans rely on the many ecosystem services that freshwater provides, such as water quantity provision for domestic, industrial, and agricultural processes, food supply, water purification, and recreation and tourism, to name a few. Water-scarce countries, such as South Africa, are particularly vulnerable to water shortage issues and require many water supply solutions, like dams, weirs, and transfer schemes, to harvest the available rainfall. The uThukela River in KwaZulu-Natal is not only an important resource within its catchment but also to external catchments through inter-basin water transfer schemes, including that of the Thukela-Vaal transfer, which feeds the economically important hub of South Africa, the Gauteng Province. The lower uThukela River is a highly stressed system, with synergistic effects from multiple stressors relating to water quality, water quantity, habitat alterations, and wildlife disturbance affecting it. Additionally, the Lower Thukela Bulk Water Supply Scheme (LTBWSS) weir was recently constructed in its lower reaches, approximately 20 km upstream of the uThukela Mouth to the Indian Ocean, to provide bulk water to surrounding local municipalities. Due to the rich diversity of fish species in the region, particularly those with marine, estuarine, and freshwater migratory patterns, a fishway was incorporated into the design of the weir to facilitate fish movements over the weir. This study evaluated the impact that the LTBWSS weir has on fish community structures in the region and additionally assessed the efficacy of the fishway in allowing fish movements through it. Various sites were selected upstream, downstream, and on the tributary Mandeni ii Stream to assess environmental variables driving fish community structures, with passive and active sampling methods used to assess the fishway's functionality. Fish collection occurred at three sites upstream of the LTBWSS weir, four sites downstream of it on the uThukela River, and two sites on the Mandeni Stream. Abiotic variables relating to water quality, velocity, depth, and habitat were collected along with fish to determine which environmental variables were driving the fish communities at these sites. Multivariate analyses indicated that available substrate and cover, the average depth, and temperature were drivers of the fish communities in the study. Upstream sites showed lower species richness compared with downstream sites, with fish communities largely made of freshwater species and few euryhaline species. Additionally, individual species showed different responses to different environmental variables. Furthermore, since the construction of the LTBWSS, the loss of previously highly abundant cichlid species has occurred in the region. This is likely because of the synergistic effects of stressors created by it, such as the disruption of fine sediment transport, water abstraction, and pollution. Passive assessment of the fishway's efficacy in catering for migratory species used PIT telemetry. Budget constraints only allowed the installation of a single PIT antenna at the upstream entrance of the fishway, which was able to assess the upstream migration of fish from downstream. The results found that only eight individuals representing three species managed to navigate the fishway during the study successfully. This included Oreochromis mossambicus, Labeo molybdinus, and Clarias gariepinus. Active sampling involved electrofishing three key locations in the fishway on a monthly basis. Results showed that small-size classes of fish largely dominated the fishway and that the downstream entrance had the highest abundances and species richness. Further research on the role of the fishway in maintaining river connectivity is recommended. iii The outcomes of this study showed the importance that water resource managers have in maintaining the resource for humans and the environment. Knowing individual species' responses to environmental variables allows their populations to be better managed. Additionally, the outcomes of this study showed the importance of river connectivity past a barrier and highlighted the need for effective fish passage solutions in South Africa. It emphasised the need to better understand the migratory requirements of local fish to build better fish passage structures. Major stressors to be addressed include the impacts caused by barriers relating to flow releases, migration blocks, and habitat alteration upstream and downstream of them. Furthermore, the proper management of fish passage structures is essential to their functionality, which includes regular monitoring of the fishway for issues such as debris blockages and swiftly finding solutions to them to ensure that no undue delays or stress may occur for migratory fish.
Aardvark and people: can a shy species be widely known in a localised area?
(2022) Makwati, Nolutho.; Kraai, Manqhai.; Tsvuura, Zivanai.
The increase in human populations has led to humans sharing space with wild animals even in the natural habitats of the animals. Conflicts may arise when people and wildlife attempt to fulfill their needs which can be detrimental to one or both parties, and this type of conflict is called human-wildlife conflict (HWC). The human needs include people hunting wild animals for consumption of the animal and trading in animal body parts.Hunting is one of the factors that decreases populations of numerous animal species, and it occurs in many parts of the world e.g. in Africa, Asia and South America, where it contributes to extinction of species. The conservation and management of burrowing animals is a major challenge due to their elusive and nocturnal behaviour. The aardvark is an African medium-sized, burrowing mammal whose conservation status has not been updated recently due to the difficulties associated with studying nocturnal animals. Aardvarks may play a significant ecological role in the ecosystems in which they occur, such as by changing the landscape through their digging activities, or through affecting the dispersal of seeds. Therefore, the aim of this study was to explore the influence of humans on population trends and activity patterns of aardvarks outside protected areas, and to determine people’s perceptions about the animal. The study was conducted in Ncunjane village in Msinga Local Municipality, KwaZulu-Natal Province of South Africa. To understand people’s perceptions about aardvark in their community, I used a semistructured questionnaire survey. I asked personal information of the participants (sex, level of education and age), and questions related to people’s perceptions about the aardvark, such as people’s knowledge, myths, and their uses of the animal or its body parts. To determine activity patterns of the animal, I focused on aardvark foraging activities in a semi- arid savanna ecosystem that is also used as a communal rangeland over eight months between 2020 and 2021. I measured and quantified aardvark foraging holes using 53 50 m × 10 m transects where there was evidence of aardvark activity. In addition, I quantified aardvark burrowing of dens in the dry, wet and early dry seasons using walking transects guided by a research assistant who knows the area. I found that people have different perspectives about aardvark with the majority (78%) of respondents having strongly positive perceptions. The positive perceptions arise from aardvark not causing physical harm to people, and fleeing away upon sighting people. I found that aardvarks were mainly hunted for meat while some animal body parts were sold to traditional healers for traditional medicine. All seasons consisted of a greater number (> 51%) of old than new and very old foraging holes.The surface area of new, old, very old holes differed significantly with season (P < 0.0001) and the depth of new, old and very old holes also varied with season (P < 0.0001). In addition, the contents of foraging holes varied with age of the hole and season in that new holes lacked evidence of plant life across seasons. Aardvark dens were used by other animals such as spiders, wild cats, Cape porcupines and snakes. Hence, an increase in aardvark holes can be associated with significant landscape heterogeneity for vegetation and animal life. Aardvarks in Ncunjane fed close to their dens presumablyto mitigate against human predation through hunting threats, which may directly affect the extent of aardvark digging activities. These results show that aardvarks may be categorised as ecosystem engineers as the burrows provide shelter for other animals, also, their effects on other animals are disproportionate to their abundance. These results highlight that aardvarks are threatened by human uses and may decline in abundance in the area. Finally, aardvarks remain poorly studied in landscapes shared with humans. Further studies to assess aardvark numbers in human-dominated landscapes are required which can raise awareness and play a significant role in conservation of aardvarks.
The prevalence and implications of non-native wild boar Sus scrofa in KwaZulu-Natal, South Africa.
(2023) James, Claudette Njabulo.; Downs, Colleen Thelma.
Humans’ introduction of species into areas where they do not naturally occur has led to ecological and economic havoc. Introduced species can become invasive, exerting negative pressures on native species and the environment. Wild boar (Sus scrofa) is distributed worldwide except for Antarctica. The species is highly destructive and has been regarded as an invasive alien species in many parts of the world. Researchers have done many studies on wild boar investigating various aspects of the species, such as its biology, biochemistry, ecology, epidemiology, genetics, and archaeology. Invasive animals' effects on the environment and ecological systems were explored and focused on the impacts of exotic mammals, with wild boar as the species of interest. The potential for invasive spread by the European wild boar in South Africa was assessed by determining potentially suitable habitats using bioclimatic variables and the maximum entropy model, and then related to the present distribution records of the species in the country. Wild boars were found to have great potential to extend their invasive distribution range in South Africa. The prevalence of feral wild boar in KwaZulu-Natal (KZN) Province, South Africa, was investigated using camera trap surveys. The camera trap surveys revealed that there were no feral wild boar populations in the Midlands of KZN, but in other parts of KZN. The selling of wild boar in relation to the present legislation on wild boar in South Africa is illegal. The selling of wild boar contributes to the spread of the species in the country, as determined in this study. We recommend that the sale of wild boar should be monitored in South Africa by conservation authorities and the animals confiscated from the offenders and euthanised to prevent the further uncontrolled spread of the species. Moreover, we recommend the revision of the legislation regulating wild boar in South Africa to prevent the uncontrolled spread of the species in the country.
Assessing the trade of reptile species in the South African pet trade.
(2021) Mantintsilili, Asekho.; Downs, Colleen Thelma.; Shivambu, Tinyiko Cavin.; Shivambu, Ndivhuwo.
Despite the negative impacts that the pet trade has on the native and non-native biodiversity, economy and human health, the research suggests that the demand for pets and the extent of trade in live animals as pets has increased dramatically over the years. As a result, many species, including reptiles, have been translocated and introduced into new or non-native environments. Some of these have established feral populations, become invasive and are causing significant environmental and socio-economic impacts on non-native environments. Reptiles are among the most popular groups of animals in the pet trade industry globally. Trade in pet reptiles in South Africa is large and one of the major pathways through which non-native species, including invasive species, are introduced into the country. Despite this, little is known about the dynamics of the wildlife trade in pet reptiles globally. To understand the dynamics of the global trade in pet reptiles, we carried out a comprehensive literature search to gather relevant information from reptile pet trade-based publications. We further compiled a list of traded pet reptiles from all South African physical pet stores and online advertising websites to determine which species are traded, pose an invasion risk and have potential environmental and socio-economic impacts. We found a total of 39 publications based on the reptile pet trade from 1994 – 2021 worldwide. Our analyses revealed that the research effort was not uniform globally, with the majority (63.6%) of all relevant studies originating from three continents (Asia, Europe, and North America). Moreover, the United States of America (North America) and Indonesia (Asia) produced the greatest research outputs (12.1% each) compared with other countries across the world. We found at least 1140 reptile species belonging to 60 families involved in the global pet trade, with invasive red-eared slider Trachemys scripta elegans being the most frequently studied species (number of studies = 23/39). Of the recorded species, at least 79 are invasive, 46 endangered, 29 critically endangered, while only 546 are CITES-listed. In terms of reptile species sold in South Africa, we recorded a total of 2771 individuals representing 88 unique reptiles, 69 from physical pet stores and 18 from online advertising websites. KwaZulu-Natal, Gauteng and Western Cape Provinces had the highest number of pet stores and online advertising websites; therefore, they subsequently recorded the highest number of pet reptiles compared with other provinces. Physical pet stores were found to have the highest number of species compared to online trade. Of the recorded species, 76 are nonnative, and 15 of these are invasive to South Africa. Moreover, only 32 pet reptiles are listed under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). For current distributions, red-eared slider Trachemys scripta elegans, P. guttatus, and Western diamondback rattlesnake Crotalus atrox had the largest predicted climatic suitability. The future predictions for the latter two species were predicted to increase, while red-eared slider suitability shifted. Some species, such as Burmese pythons Python bivittatus, showed low invasion risk based on climatic suitability. However, given their large body size, history of invasion and their popularity in the pet trade, they are most likely to escape or be released from captivity and become invasive. A total of 76 reptile species were assessed for environmental and socio-economic impacts using the Generic Impact Scoring System (GISS), Environmental Impact Classification for Alien Taxa (EICAT), and Socio-Economic Impact Classification for Alien Taxa (SEICAT). Using GISS, we found that 13 species had environmental impacts (E_GISS), while 11 species had socio-economic impacts (SE_GISS). For EICAT and SEICAT, 13 species had environmental impacts, and eight had socio-economic impacts, respectively. The most popular pet species, red-tailed boa Boa constrictor, green iguana Iguana iguana, P. bivittatus, T. elegans, and central bearded dragon Pogona vitticeps had impacts in all the three scoring schemes. The later species and corn snake (Pantherophis guttatus) scored the highest for all impact schemes. Species sold in high numbers, with large climatically suitability and potential impacts, are more likely to establish feral populations and become invasive should they escape or be released from captivity. We, therefore, recommended that the trade in pet reptiles should be constantly monitored to avoid new introductions and the implications that the pet trade may have to the country.
Development and application of novel ornithological survey methods for the detection of cryptic avian indicator species that predict grassland health.
(2021) Beaumont, Stuart Nicholas.; Downs, Colleen Thelma.
The anthropogenic pressure on South African grasslands to meet the needs of the burgeoning human population has exposed them to extensive permanent transformation and degradation. Indicator species may identify changes in the grassland ecosystem. One such indicator species for natural sourveld grassland condition in South Africa is the red-winged francolin (Scleroptila levaillantii), whose population density is negatively correlated to grazing intensity and annual burning. Pointing dogs (Canis lupus familiaris) have been used extensively to aid ecologists in detecting these and other cryptic gamebirds to establish abundance. Here, a reliable method was developed to count cryptic gamebirds in the Greater uMgeni Vlei Expansion Area, KwaZulu-Natal Midlands, South Africa, where the route through a survey site was flexible. A variation to the existing distance sampling technique was proposed where the dog global positioning system (GPS) track was the transect line. The study investigated the effect of varying environmental conditions on the distance from which a pointing dog could reliably and consistently detect a bird and allow calculating a detection distance based on influential environmental variables. Between March – October 2021, using pointing dogs fitted with GPS devices, controlled and uncontrolled trials were conducted on Japanese quail (Coturnix japonica) and red-winged francolin in their natural habitat, respectively, to establish the environmental conditions that affect detectability and the detection distance from which a dog can detect a bird of known location. A total of 21 surveys were conducted (August 2020 – October 2021), on four survey sites by one or two pointer dogs fitted with GPS devices, to establish the population densities and territory of red-winged francolin. Individual area of search, established from the detection distance based on nominal wind speed and GPS track, was calculated. The redundancy in area of search enabled the evaluation of relative proficiency of detection of red-winged francolin. Of the environmental variables monitored, only nominal wind speed significantly influenced detection distance, where an increase of one-knot wind strength resulted in an increase in detection distance by 0.64 m. This enabled an area of search, considerate of influential environmental conditions, to be derived and the probability of detection within that search area = 1. Results showed significantly better precision and accuracy when surveying with two dogs when compared with one dog. The calculation of detection distance, where the probability of detecting a bird at this distance = 1, addresses the bias of varying scenting conditions. The established area of search, where the probability of detecting a bird within this area = 1, addresses the situation where known coveys in an area of known size remain undetected. Since the area of search is independent of time spent searching and normalised for redundancy, the bias introduced by varying physical aptitude is mitigated. Consideration for the application of this method should be given to the environmental conditions under which the surveying is planned since the detection distance function is derived for conditions at the present study sites. These techniques, based on a variable survey route through the survey site, may be used by citizen scientists to assist land managers, conservationists, and ecologists in establishing the abundance of red-winged francolin, contributing to burning and grazing regime management to enhance conservation efforts for the species.
Interactive effects of fire history and elevated 2 temperature on aboveground productivity in a high 3 altitude mesic grassland in South Africa.
(2021) Mvelase, Thembeka Ayanda.; Tedder, Michelle Jennifer.; te Beest, Mariska.
Abstract available in PDF.

Browse

Recent Submissions