1834 research outputs found
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Characterisation of the glycoside hydrolase domain of a novel bi-functional metagenomic clone for use in the biofuel production industry
No full textNational Research Foundatio
Effects of melatonin on the histomorphometry of the pancreas, liver and kidney of rats on antiretroviral treatment
No full textNational Research Foundatio
Envisioning the Future of Aquatic Animal Tracking: Technology, Science, and Application
No full textElectronic tags are significantly improving our understanding of aquatic animal behavior and are emerging as key sources of information for conservation and management practices. Future aquatic integrative biology and ecology studies will increasingly rely on data from electronic tagging. Continued advances in tracking hardware and software are needed to provide the knowledge required by managers and policymakers to address the challenges posed by the world's changing aquatic ecosystems. We foresee multiplatform tracking systems for simultaneously monitoring the position, activity, and physiology of animals and the environment through which they are moving. Improved data collection will be accompanied by greater data accessibility and analytical tools for processing data, enabled by new infrastructure and cyberinfrastructure. To operationalize advances and facilitate integration into policy, there must be parallel developments in the accessibility of education and training, as well as solutions to key governance and legal issues
Shark spotters: successfully reducing spatial overlap between white sharks (carcharodon carcharias) and recreational water users in False Bay, South Africa
No full textWhite sharks (Carcharodon carcharias) are apex predators that play an important role in the structure and stability of marine ecosystems. Despite their ecological importance and protected status, white sharks are still subject to lethal control to reduce the risk of shark bites for recreational water users. The Shark Spotters program, pioneered in Cape Town, South Africa, provides a non-lethal alternative for reducing the risk of human-shark conflict. In this study we assessed the efficacy of the Shark Spotters program in reducing overlap between water users and white sharks at two popular beaches in False Bay, South Africa. We investigated seasonal and diel patterns in water use and shark presence at each beach, and thereafter quantified the impact of different shark warnings from shark spotters on water user abundance. We also assessed the impact of a fatal shark incident on patterns of water use. Our results revealed striking diel and seasonal overlap between white sharks and water users at both beaches. Despite this, there was a low rate of shark-human incidents (0.5/annum) which we attribute partly to the success of the Shark Spotters program. Shark spotters use visual (coloured flags) and auditory (siren) cues to inform water users of risk associated with white shark presence in the surf zone. Our results showed that the highest risk category (denoted by a white flag and accompanying siren) caused a significant reduction in water user abundance; however the secondary risk category (denoted by a red flag with no siren) had no significant effect on water users. A fatal shark incident was shown to negatively impact the number of water users present for at least three months following the incident. Our results indicate that the Shark Spotters program effectively reduces spatial overlap between white sharks and water users when the risk of conflict is highest
First record of the invasive Australian redclaw crayfish Cherax quadricarinatus (von Martens, 1868) in the Crocodile River, Kruger National Park, South Africa
No full textThe redclaw crayfish Cherax quadricarinatus (von Martens, 1868), a robust freshwater crayfish native to Australia and Papua New Guinea, has now been recorded from the Kruger National Park (KNP). Previously absent from the Crocodile River, SAN Parks received a report in February 2016 of redclaw crayfish below the Van Graan Dam on the border of the KNP. Here, we provide evidence of the presence of redclaw crayfish in the Crocodile River. A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the KNP and the Komati Catchment. The negative impacts of global crayfish introductions justify efforts to discourage further introductions and prevent their secondary spread.
Conservation implications: A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the Kruger National Park and the Komati Catchment
Land reform in South Africa is failing. Can it be saved?
No full textWhat is going wrong in South Africa’s post-apartheid land reform programme, and how can its failings be addressed? Twenty two years after the transition to democracy and the commencement of land reform, there is a great deal of lived experience to reflect upon and a rich literature to draw on. Here I offer a diagnosis of failures, suggest a new narrative for land reform, and offer some provocations around alternative policies. The paper argues that the logic of land reform as a whole needs to be re-thought, rather than merely tinkering with details.1
Land grabbing over nearly 350 years of South African history saw the loss of key productive resources by indigenous populations and erosion of their rights to land and natural resources (Hendricks 2013, Ntsebeza 2007, Platzky and Walker 1985). Women’s land rights were severely undermined, especially in areas where land was held and governed within systems informed by custom (Claassens and Ngubane 2008, Claassens and Mnisi 2009). Spatial inequalities defined by race were hard-wired into the South African capitalist economy from its very beginning, partly as the basis for a cheap-labour regime involving circular migration (Magubane 1979, Wolpe 1972). Social differences and inequalities based on a complex articulation of race, gender and class identities thus underpinned the unequal distribution of land and insecure rights to land. The legal system underwrote the unequal land dispensation: private property rights to land and housing were not on offer to most black South Africans, or were allowed on highly discriminatory terms, and the legal system helped to legitimise forced removals (Murray and O’Regan 1990).National Research Foundation (South Africa
Staying safe from top predators: patterns of co-occurrence and inter-predator interactions.
No full textTop predators often have cascading effects on mesopredator communities by driving behavioural changes. Using camera-trapping surveys, we explored the site-detection probability of sympatric predators and temporal overlap and examined behavioural patterns to explore hypotheses of carnivore guild interactions between and within large and small predators in the presence/absence of lion (Panthera leo) in open and closed habitat cover. We used single-season two-species occupancy models to test inter-predator interactions at 205 camera sites spread across five Protected Areas of the Maputaland Conservation Unit, South Africa. These data showed the respective associations between the presence of large carnivores and smaller carnivores. We observed that leopard (Panthera pardus) and hyena (Crocuta crocuta) tended to avoid interference encounters, as they were less likely co-detected at the same sites. There was a decrease in detection of leopard and hyena as a function of lion presence. Small predators such as the group honey badger (Mellivora capensis)-striped polecat (Ictonyx striatus) and the slender mongoose (Herpestes sanguineus) were detected less often at cameras where leopards were detected. Detection probabilities of the group badger-polecat and slender mongoose were much higher in the closed habitat than in open habitat where leopards were detected. At camera sites where hyenas were detected, badger-polecat and genet (Genetta tigrina) detection probability was much higher in the closed habitat than open habitat. Slender mongoose overlapped less temporally with large predators while others did not. Our study showed that large predator guilds can affect the probability of detecting subordinate mesopredators; therefore, reintroduction of large carnivores can have a cascading effect on subordinate carnivores, and it is necessary to consider this effect when planning recovery programmes for carnivore conservation.National Research Foundation (South Africa
Health Risk Perception Related to Fracking in the Karoo, South Africa
No full textShale gas exploration involving hydraulic fracturing (fracking) has been on South Africa's energy agenda since 2010 as a potential alternative to coal. Internationally, the desirability of fracking has been under debate, due to increasing evidence of associated environmental and health risks. There is limited research related to the public's knowledge and risk perceptions of fracking, and none whatsoever from South Africa. This cross-sectional study explored, through a household survey, knowledge of, health risk perceptions of, and information sources related to fracking of 102 Central Karoo residents. Our results indicated that 40% of the participants do not know what fracking is or the potential risks and benefits thereof. The media is participants' main information source (59.8%), and only half of the participants trust their information sources. Those with more trust in their information sources perceived fracking as posing a greater risk. Those believing fracking poses a low risk were more likely to trust the government and oil and gas companies. More than half of the participants (52.9%) believe that fracking poses an extreme health risk, and 78% think that fracking will harm their health. Despite this, 45% of the participants indicated a willingness to work in the fracking industry. The most commonly listed reasons for why fracking would make Karoo residents sick included water pollution (47.4%) and air pollution (19.6%). This study found high levels of risk uncertainty related to fracking among Central Karoo residentsNational Research Foundation (South Africa
Predicted decrease in global climate suitability masks regional complexity of invasive fruit fly species response to climate change
No full textClimate change affects the rate of insect invasions as well as the abundance, distribution and impacts of such invasions on a global scale. Among the principal analytical approaches to predicting and understanding future impacts of biological invasions are Species Distribution Models (SDMs), typically in the form of correlative Ecological Niche Models (ENMs). An underlying assumption of ENMs is that speciesenvironment relationships remain preserved during extrapolations in space and time, although this is widely criticised. The semi-mechanistic modelling platform, CLIMEX, employs a top-down approach using species ecophysiological traits and is able to avoid some of the issues of extrapolation, making it highly applicable to investigating biological invasions in the context of climate change. The tephritid fruit flies (Diptera: Tephritidae) comprise some of the most successful invasive species and serious economic pests around the world. Here we project 12 tephritid species CLIMEX models into future climate scenarios to examine overall patterns of climate suitability and forecast potential distributional changes for this group. We further compare the aggregate response of the group against species-specific responses. We then consider additional drivers of biological invasions to examine how invasion potential is influenced by climate, fruit production and trade indices. Considering the group of tephritid species examined here, climate change is predicted to decrease global climate suitability and to shift the cumulative distribution poleward. However, when examining species-level patterns, the predominant directionality of range shifts for 11 of the 12 species is eastward. Most notably, management will need to consider regional changes in fruit fly species invasion potential where high fruit production, trade indices and predicted distributions of these flies overlap.National Research Foundation (South Africa
Solving resource allocation problems in cognitive radio networks: a survey
No full textCognitive radio networks (CRN), in their quest to become the preferred next-generation wireless communication paradigm, will depend heavily on their ability to efficiently manage the limited resources at their disposal in meeting the demands of their numerous users and driving their operations. As a result, a considerable amount of research work has been recently dedicated to investigating and developing resource allocation (RA) models that capture the essentials of CRN. The various ideas put forward by researchers to address RA problems in CRN have been somewhat diverse, and somehow, there seem to be no links that bring cohesion and clarity of purpose and ideas. To address this problem and bridge the gap, in this paper, a comprehensive study on the prevalent techniques developed for addressing RA problems in CRN is carried out, with an intent to put some structure, relevance and meaning to the various solution approaches. The solution models are therefore grouped and/or classified based on certain outstanding criteria, and their strengths and weaknesses highlighted. Open-ended problems are identified, and suggestions for improving solution models are given. The study therefore gives good directions for further investigations on developing RA solutions in CRNNational Research Foundation (South Africa