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Assessing the climate change vulnerability of reptile and amphibian species found in Table Mountain National ParkHarper, Jack January 2020 (has links)
It is increasingly apparent that climate change and its associated impacts are a major threat to the rich biodiversity of the Cape floristic region. As the knowledge of the associations between biological traits and climate change impacts strengthens it has become clear that the assessment of climate change vulnerability is a key consideration in the management of biodiversity. This study is the first attempt to use a trait-based approach at the scale of a single national park, focusing on the climate change vulnerability of reptile and amphibian species found in Table Mountain National Park (including historically present species). The park and its immediate surrounding areas are home to a rich diversity of herpetofauna including the Critically Endangered Table Mountain ghost frog (Heleophryne rosei), Rose's mountain toadlet (Capensibufo rosei) and micro frog (Microbatrachella capensis), and the Endangered western leopard toad (Sclerophrys pantherina). Amphibian and reptile-specific assessment frameworks of biological and ecological traits were designed to identify the species most sensitive and least able to adapt to climate change pressures. Using a combination of a literature review and expert consultation, 18 species of amphibian and 41 species of reptile were assessed. The assessment highlighted that, in the worst-case scenario, 85% of the park's reptile species and 67% of the park's amphibian species are predicted to be highly vulnerable to climate change. The southern adder (Bitis armata), Cape long-tailed seps (Tetradactylus tetradactylus), Table Mountain ghost frog (Heleophryne rosei) and the Lightfoot's moss frog (Arthroleptella lightfooti) were identified as being the species most vulnerable to climate change within their respective taxa. All three of the Critically Endangered amphibian species were identified as having both high sensitivity and low adaptive capacity to climate change. Among the focal reptile species, climate change vulnerability was independent of current IUCN Red List status, highlighting that species currently not identified to be under threat by other anthropogenic pressures could imminently become threatened by climate change. Spatiallyexplicit presentation of the assessment output will help prioritise the management of areas within Table Mountain National Park that contain a high diversity of climate-vulnerable species. By reducing the threats from other human-associated impacts to these species, and by identifying when direct intervention is appropriate, the park's management can give these species the best opportunity of persistence in an uncertain climate future.
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Population crash of an endemic South African cyprinid: the role of non-native fish, drought and other environmental factorsCerrilla, Cecilia 10 September 2020 (has links)
Native freshwater fish are in decline worldwide due to human impacts including impoundment, changes to water quality, over-abstraction, climate change and the introduction of non-native species. South Africa's Cape Fold Ecoregion (CFE) harbours exceptionally high freshwater fish endemism, yet the majority of these species are threatened with extinction. The Clanwilliam sandfish (Labeo seeberi), an endangered cyprinid, has declined across its range in the CFE and currently exists in only a handful of tributaries of the Doring River in severely fragmented populations. The last remaining recruiting sandfish population occurs in the Oorlogskloof River, making this tributary one of critical conservation value. In this study, I analysed a six-year dataset comprising fish survey data from 38 sites along 25 km of the Oorlogskloof River to characterise spatio-temporal variation in sandfish abundance and size structure and evaluate the relative influence of different environmental factors on sandfish population trends. The environmental factors considered included other fish in the system, especially three non-native fishes (banded tilapia Tilapia sparrmanii, smallmouth bass Micropterus dolomieu and bluegill sunfish Lepomis macrochirus), temperature, precipitation, habitat characteristics and a range of physicochemical factors. The results show that sandfish have experienced a 93% decline in the sampled stretch of the Oorlogskloof River since 2013 and that the ongoing drought may be preventing recovery. They also suggest that banded tilapia do not adversely affect the Oorlogskloof River sandfish population, while predation of juveniles by smallmouth bass and/or bluegill sunfish apparently reduces the abundance of sandfish, especially of juveniles, where these non-native fish are present. Future studies should attempt to isolate the relative impacts of the different invasive fish species and examine habitat requirements of different sandfish life stages. Management of the river's sandfish population should focus on precautionary actions such as continued monitoring and landowner engagement, as well as clearing dams of non-native species high in the catchment, to prevent the further upstream invasion of smallmouth bass and bluegill sunfish. Proactive measures, such as eradicating smallmouth bass and bluegill sunfish from the Oorlogskloof River, are also necessary to restore connectivity of suitable sandfish habitat in the Doring River system.
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How air temperature affects flight initiation distance in arid-zone birdsPistorius, Penny January 2016 (has links)
Arid zones, such as the Kalahari in southern Africa, are experiencing an increase in the number of hot days, as well as in the intensity of heat waves. Research is being conducted to try and understand how increasing temperatures will impact bird communities and population persistence in these areas. Understanding the mechanisms through which birds are vulnerable to climate change is key to answering these questions. This study investigated how changes in air temperature affect arid-zone birds' response to predators. The flight initiation distances (FID), i.e. the distance from a predator when the prey initiates escape, of eight bird species in the Kalahari were measured over a range of air temperatures during October and November 2015. The results from this study show a negative relationship between air temperature and FID. This relationship was weak across the full range of temperatures observed during the study period (11.9 ⁰C - 40.4 ⁰C), with a large amount of variability in FID not explained by air temperature. However, high air temperatures (> 35 ⁰C) were important in explaining some of the variation in FID. Starting distance, time of day, bird species, plant species, bird location (on the ground / in the canopy / at the top of the tree / in a dead tree), bird exposure (whether the bird was in the sun or in the shade) and bird activity (whether mobile / stationary) were consistently found to explain some of the variation in FID in this dataset. The relationships between the behavioural variables (plant species, bird location, bird exposure and bird activity) and air temperature were investigated and revealed a potential mechanism through which air temperature may also indirectly be affecting FID. The reduction in FID at high air temperatures, and thus the potentially increased risk of predation, may have negative consequences for these species in the Kalahari in light of rising air temperatures associated with climate change
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Resurrection ecology of invertebrates in temporary wetlands in the Cape Floristic region: effects of urbanisation and fireBlanckenberg, Michelle January 2017 (has links)
Despite their importance to regional biodiversity, temporary wetlands and their invertebrate communities are generally understudied and under-conserved. Resurrection ecology is used to study the communities present in the dry phase of temporary wetlands to gain a better understanding of the functioning and health of these systems. The hatching success of invertebrate propagules in dried soil sediments, collected from temporary wetlands in Cape Sand Fynbos regions of Cape Town, were investigated in 2016. Soil samples were collected from conserved and urban sites (during May and June 2016) using a standard soil auger method and complemented with monthly aquatic phase sampling using standard sweep net methods (during September and October 2016). The effects of fire were tested, on hatching success by staging vegetation fires over the collected soil samples for five temporary wetland areas in the same region. Mann-Whitney U tests were used to test differences in abundances between treatments, whereas for comparison of taxon richness, Shannon diversity and Pielou's evenness linear mixed effect models (LMER) were used. Non-metric multidimensional scaling (nMDS) plots were used to graphically visualize the community composition between the different treatments, with 'adonis' analysis used to test their statistical significance. Results found a total of 18 invertebrate taxa hatched, while a total of 27 taxa were identified from the wet phase. Results from hatching assays showed no significant differences in diversity patterns of invertebrates between conserved and urban areas in the dry phase. However, wetlands that were in the conserved area supported higher invertebrate diversity during the wet phase, although not significant (lmer, Z = -1.75, p = 0.08). These results suggest that human activity (alien vegetation, littering and polluting) in the area did not impact the ability of invertebrate propagules to emerge, but did slightly affect the natural aquatic phase. Fire had a significantly negative impact on invertebrate diversity measures (lmer, p < 0.001) and community composition (adonis, F = 24.494, p = 0.001) during hatching assays. Management of unpredicted and uncontrolled fire in urban areas is essential to ensure future protection of critical biodiversity areas created by these temporary wetlands. More research should focus on the impact of increasing fire frequency and intensity on these systems to understand the management challenges in a changing climate.
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Burning for birds : the response of bird communities to recent fire history in the Serengeti ecosystemKinsey, Elliot January 2014 (has links)
Includes bibliographical references. / Fire is a ubiquitous ecosystem process with important implications for savanna ecology and conservation. In this study we aimed to explore the short-term and long-term effects of recent fire history on bird communities in the greater Serengeti savanna ecosystem in Tanzania. The study investigated the influence of immediate fire event history ( < one year), cumulative fire regime history (over 14 years), and fire seasonality on bird assemblages. We predicted that the occurrence of recent fire events and cumulative fire regime history would influence bird communities, particularly through its impact on vegetation structure. We mapped fire activity from remote sensing data (2000-2013) and extracted mean rainfall and nitrogen estimates from interpolated maps. We conducted field sampling of bird community composition and vegetation structure at 207 sample sites distributed across the western Serengeti ecosystem. We tested the structuring effect and regression trends of recent fire event occurrence, cumulative fires regimes, rainfall, and nitrogen on bird community structure and vegetation, and tested the response of birds to vegetation. Despite a high degree of variation in bird communities and vegetation structure, our results suggested that fire regimes do indeed impact bird communities with important conservation implications. We detected the strongest changes in bird community structure, diversity, and density in response to the immediate impact of a fire event and post-fire regeneration processes, and weaker effects to cumulative fire regime history. Short fire season burning (Feb-April) appears to have significant influence on birds and vegetation structure, and these preliminary findings warrant further investigation. While our findings do not have alarming conservation implications, the effects of seasonality and frequency of fires are not negligible. We recommend against extensive burning practices over short periods to allow continuity in the landscape. We recommend greater forethought among conservation managers, bearing in mind both short-term and longterm habitat changes caused by burning and the consequent bird assemblages impacted. We advise focused research on species and functional groups of conservation interest.
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Using real-time forest loss alerts and global deforestation maps to assess the effectiveness of Africa's tropical protected areasBowker, Jenna January 2015 (has links)
Tropical rainforests harbor a significant portion of the world's remaining biodiversity. Having undergone rapid changes in forest cover over the last two decades, a large amount of irreplaceable biodiversity has been lost. The establishment of protected areas has been a key strategy to hinder the loss of tropical forests and biodiversity. However, the effectiveness of designating protected areas has been called into question, particularly in regions such as tropical Africa where widespread conditions of poverty, rapid population growth and political instability are evident. Quantitative measurements of park effectiveness for forest conservation are urgently needed, however accurate inferences concerning park effectiveness across broad regions is difficult. Whilst remote sensing techniques have been proposed as a practical solution, the intensity of data processing has made it untenable until recently. Here, I use remote-sensing methods to analyze high-resolution satellite imagery of tropical forest loss (as a proxy for tropical deforestation) within and outside 224 parks across 23 countries in Africa. I compare the extent of tropical forest loss inside parks to outside of them to show that the majority of African parks in the Subtropical and Tropical Moist Broadleaf forest biome are effective in curbing forest loss within park boundaries. However, certain parks were more effective in forest conservation than others. Whilst smaller parks were less effective at preventing forest loss inside park boundaries than larger parks, older parks were less effective than younger parks. Furthermore, parks of varying IUCN management categories exhibited negligible differences in forest loss between one another. Lastly, significant geographical variations in park effectiveness existed: West African parks exhibited the most forest loss within park boundaries and Central African parks exhibited the least. My results demonstrate the complexity of factors which influence a park's ability to curb forest loss within its boundaries. Furthermore, this study is the first bioregional-wide assessment of park effectiveness using remote sensing. These results supplement scarce literature on tropical deforestation in Africa and demonstrate the potential of using remote satellite imagery for measuring the relative impact of park establishment on forest conservation in this region.
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The birds, the bees and Erica: vulnerability of plant-pollinator communities in fragmented fynbos landscapesAngoh, Siow Yan Jennifer January 2016 (has links)
Habitat fragmentation has been identified as a major cause of pollination mutualism collapse that can eventually impinge on plants' reproductive success (e.g. through pollen-limitation). Agriculture, timber plantations, invasion by alien trees and the urbanisation of the southern Cape lowlands have transformed and fragmented large parts of the former distribution range of many Erica species. Recent evidence suggests that in the Fynbos biome, small remnants of natural and disturbed vegetation are likely to display depauperate plant communities. In the present study, it was found that Erica species richness declined significantly as patch size decreased. Limited nectar resources available on those small 'islands' might not be enough to attract essential bird and insect pollinators. Insect-pollinated species were more impacted by reduced patch size than the bird-pollinated ones. Further investigation using Erica discolor showed that for this widespread ornithophilous species, pollination mutualism still occurred in smaller fynbos patches. These findings stressed the importance of conserving small fragments for maintaining remnant plant populations, which can act as reliable food sources for avian pollinators. In addition, to cope with the effects of pollen limitation, highly resilient plant species have evolved and adopted different compensatory mechanisms. From a short-term perspective, adopting compensatory reproductive strategies (e.g. autonomous self-pollination, vegetative growth, and generalised pollination systems) could reduce dependence on specific pollinators and increase the chances of a species being able to persist through a period of low-pollinator abundance. The prevalence of autogamy and geitonogamy as alternatives to xenogamy was assessed in six different obligate seeder Erica species in the eastern coastal part of the Cape Floristic Region. Despite the long history of plantation-based timber production that fragmented the study area, and the subsequent possible pollinator loss, none of the species analysed in this study have adopted autonomous self-fertilisation as a response mechanism. Erica sessiliflora was the only species that showed a high compatibility for self-pollen. The species under investigation in a breeding system conducted here were also incapable of vegetative propagation and were plants targeting specific animal taxa (e.g. birds or insects) for successful pollination. Having limited compensatory mechanisms, further degradation of their habitat and weakening of their ecological interactions could be extremely detrimental to these Erica species' reproductive success.
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The Vulnerability of the Coast of Liberia to Marine Oil Spills: Implications for Biodiversity and Renewable Natural Resource UtilizationTuagben,Darlington Saykay January 2012 (has links)
Includes bibliographical references. / The West African coastline has become a "hotspot" for oil production, and 17 oil exploration blocks have been designated off the Liberian coast. Liberia's 579 km coastal zone supports almost 60% of the country's human population and is endowed with natural resources of both biological and socioeconomic significance, leading to the potential for conflict between oil production, existing human activities and biodiversity. The aim of this study was to establish the level of dependency of coastal rural households of Liberia on the natural resources of the marine and coastal environment, and to assess the relationship between coastal people, biodiversity conservation and the oil industry of Liberia with an overall goal of contributing to biodiversity conservation efforts in Liberia. Fieldwork was conducted from 19 September to 10 December 2011. Two aspects were assessed. A biological component focused on the biodiversity of the marine and coastal environments, and a socioeconomic component, which focused on natural resource utilization by, and the socio-cultural environment of, the coastal inhabitants of Liberia. A comprehensive review of published information was used to assess the vulnerability of the biotic and abiotic components of the coastal and marine environment to oil spills. Household surveys were conducted to assess the dependency of rural households on renewable coastal and marine resources and consequently, the potential threats to their livelihoods in the event of an oil spill. The surveys (N=316) were conducted in seven coastal counties adjacent to ten of the offshore oil exploration blocks that have been contracted for oil exploration activities. The coastline was divided into three regions with a total of 316 households surveyed: Western (N=76), Central (74) and Eastern (166). Average household size (N=10) was similar in all regions. The coastal zone of Liberia comprises sensitive environments including estuaries, coastal lagoons, mangroves, sandy beaches and rocky shores, all of which are vulnerable to oil pollution to varying degrees. Mangroves, estuaries and coastal lagoons are important spawning, roosting and breeding sites for fish and other wildlife, whereas sandy beaches are used for recreation and serve as breeding grounds for five species of marine turtles. Coastal inhabitants rely heavily on the utilization of coastal and marine resources for their livelihoods and income. Fishing was most important, contributing 70% of income across all households, followed by farming (19%) and mangrove harvesting (8%). The remaining income was derived from hunting, petty trading, gathering of wild resources and sand mining. The number of households engaged in fishing and non-fishing activities differed between the three regions. There was more fishing in some regions than others. The Eastern Region constituted the greatest (87%) proportion of fishing households and derived the highest monthly proportional income from all livelihood activities. The Western Region constituted the highest (71%) proportion of farming households by region and derived the lowest monthly income among the regions. Fishing and several other sources of income might be lost in the event of a large oil spill, increasing poverty and food insecurity in the region. There is urgent need for the development of an oil spill contingency plan and a waste management plan for the oil industry. Local inhabitants also need to be trained so that they can respond to minor spills and related forms of pollution.
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Environmental predictors of Carcharodon carcharias presence at two popular beaches in False Bay, South Africa using acoustic telemetryVan Beuningen, Dave 14 February 2019 (has links)
By understanding when white sharks (Carcharodon carcharias) are likely to be at certain popular beaches, it is possible to predict when the risk of overlap between water users and white sharks is highest, and to convey this information to the public so they can make informed decisions about using these areas. Previous studies have shown that white shark presence near popular recreational beaches in False Bay, South Africa, is influenced by a range of environmental variables. These studies have relied on land-based observers (shark observers), whose ability to detect sharks is subject to the depth at which the sharks swim and a suite of environmental conditions that influence water visibility, including cloud cover, wind speed and ambient light levels. In this study, I use passive acoustic telemetry on 56 tagged white sharks to determine whether the same or other environmental variables explain variation in white shark presence at the same beaches. A total of 13 803 and 1 481 white shark detections were recorded between April 2005 and December 2007 at Muizenberg and Fish Hoek beaches, respectively. This represented 32 and 16 individual white sharks with a median number of 32.5 (range 5.5 – 57.8) and 7 (range 4 – 14.8) detections per shark at Muizenberg and Fish Hoek beach, respectively. The low number of detections at Fish Hoek resulted in the data being highly zero-inflated with the result that the subsequent modelling of the data with environmental covariates did not converge, and hence I focused solely on Muizenberg beach. The probability of detecting a white shark at Muizenberg beach was modelled using binomial generalised additive mixed models (GAMMs) with water temperature, wind speed, wind direction, cloud cover, lunar phase, tide height, barometric pressure, year, season and time of day as predictor variables. Water temperature was a significant predictor of white sharks at Muizenberg beach during summer, autumn and winter while wind speed, time of day and barometric pressure were significant predictors of shark presence during the summer and autumn months. There was significant inter-annual variability in white shark detections and a strong seasonal relationship, with presence being highest during spring and lowest during winter. Encouragingly, the findings from this study support some of the key findings of previous studies using observational data, including the significant positive effects of increasing temperature, year, season and time of day.
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The influence of vulture restaurants on breeding success and nestling body condition of Gyps vulture populations across southern AfricaZimunya, Tapiwa 22 February 2019 (has links)
Vulture populations in many parts of the world continue to decline owing to numerous threats, such as lack of adequate food sources, poisoning and collisions with power-lines. Worldwide, supplementary feeding sites (hereafter, vulture restaurants) have been used as a conservation tool aimed at supporting vulture populations. However, in many parts of the world there is little scientific evidence about their effectiveness in aiding vulture populations. Here, I assessed the relationship between chick condition (African White-backed Vultures) and breeding success (Cape Vultures/African White-backed Vultures) in relation to a variety of variables which described levels of access to vulture restaurants. My data suggest the potential of vulture restaurants to increase breeding success in vulture populations. Breeding success generally increased for nests closer to vulture restaurants. There was a significant positive correlation between African White-backed Vulture breeding success and proximity to vulture restaurants (p< 0.05), but little evidence to support such a relationship for Cape Vultures (p> 0.05). Nestling body condition of African White-backed Vultures was also not influenced by proximity to vulture restaurants (p> 0.05). Findings of this study provide motivation on the use of vulture restaurants as a conservation strategy across southern Africa. The current study informs future conservation efforts on the use of vulture restaurants across the region, particularly in countries where a network of vulture restaurants is still being established.
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