Large scale spatio-temporal forcing of pelagic-coastal coupling: disentangling the effects of environmental change on intertidal invertebrate recruitment
- Authors: Muñiz, Carlota Fernández
- Date: 2019
- Subjects: Dinoflagellates -- South Africa , Coastal ecology -- South Africa , Climatic changes -- South Africa , Benthic ecology -- South Africa , Agulhas Current , Ocean temperature -- Agulhas Current , Ocean temperature -- Physiological effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/151541 , vital:39140
- Description: Marine systems are driven by the relationships among organisms and environmental conditions. Anthropogenic-induced changes during the past decades have started to alter climatic drivers which have the potential to alter the physical, chemical and biological environment. In coastal systems, biogeography is influenced by the temporal variability in the conditions of the water mass. In addition, many marine benthic organisms develop in the water mass and rely on the conditions that link the pelagic and benthic systems for population maintenance. Such pelagic-coastal coupling indicates that changes in the trophic system during development can be transferred to the adult populations through changes in propagule supply. Thus, changes in environmental conditions can influence benthic populations directly (e.g. through larval advection) or indirectly, through their influence on the phytoplankton community (e.g. through the development of HABs). The South African coastline shows clear alongshore patterns of faunal biomass and species richness. On the south coast, strong longitudinal patterns of recruitment of intertidal organisms exist, with areas of particularly high recruitment. HABs of unprecedented spatio-temporal magnitude have recently developed along the south coast, including the areas where benthic recruitment is most intense. The present thesis used these blooms to study changes in intertidal recruitment directly or indirectly associated with their occurrence. Using a combination of remote sensing data to study the environmental conditions of the water mass in the innermost part of the Agulhas Bank, and estimates of mussel and barnacle recruitment rates to integrate the effects of conditions in the water mass during larval development, this thesis aimed to: (1) understand the conditions that triggered the development of an HAB of the dinoflagellate Lingulodinium polyedrum during summer of 2014, (2) determine the direct or indirect effects of that bloom on recruitment of intertidal organisms, and understand the factors that affect recruitment along the coast, (3) determine if the environmental factors during bloom development produced any carryover effects on recruit growth and mortality, and (4) determine the factors that drive changes in community biomass and composition along the south coast, the long-term trends in those factors, and possible changes experienced in recent years. Water column stability during spring, before the development of the red tide, followed by alternating periods of upwelling and relaxation during summer and autumn, seemed to promote the development and persistence of L. polyedrum. Recruitment of mussels and barnacles was estimated during the reproductive season of mussels in 2014, coinciding with the red tide, and during the following year. Alongshore patterns in recruitment were found, with higher mussel recruitment in the absence of the red tide and the opposite pattern in barnacles. Alongshore patterns in SST and chlorophyll matching those of recruitment were also found, with higher SSTs and lower chlorophyll during the red tide than the following year. Growth and mortality rates in barnacles did not differ between years during the first five months after settlement. This suggests that the factors which produced differences in recruitment between years did not produce carryover effects detectable at the temporal scales studied. Further analysis of 15 years of satellite-derived environmental data showed significant cooling trends potentially driven by a long-term seasonal acceleration of the Agulhas Current in autumn around two upwelling centres on the south coast, coinciding temporally with the reproductive period of mussels and barnacles, and spatially with the areas of highest recruitment. In addition, the comparison of SST and chl-a conditions during the first and the second half of the period of study showed that seasonality of both variables has changed in large areas over the shelf, with increasing importance of shorter-term variability, which would in turn decrease environmental predictability. Thus, the conditions observed during the present study, particularly during 2015, when upwelling seemed to be more intense, may presage the potential effects of identified long-term cooling trends at the upwelling centres. Although the general trend shows cooling around those areas, conditions can vary greatly among years, favouring different taxa. Changes in the Agulhas Current System are affected by changes in distant areas in the Indian Ocean basin. Such tele-connection is unlikely to be unique to this system and indicates the importance of understanding trends in major large scale climatic drivers and their regional effects in order to make predictions about coastal systems.
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- Date Issued: 2019
Approaches to detecting and assessing patterns, processes and responses to change in South African estuaries
- Authors: Van Niekerk, Lara
- Date: 2018
- Subjects: Estuaries -- South Africa , Climatic changes -- South Africa
- Language: English
- Type: Thesis , Doctoral , PHD
- Identifier: http://hdl.handle.net/10948/45491 , vital:38621
- Description: The research presented indicates deep knowledge of estuary pattern-process-function across a broad range of estuary types. This study successfully developed and applied approaches to detect change at varying temporal and spatial scales in South African estuaries. This assessment was based on the physical characteristics of estuaries and predicted or measured change in the drivers of estuary health. This is the first study in the country to review and synthesise the vulnerability of South African estuaries to Climate Change on a regional scale. Through sound scientific approaches this research has advanced our knowledge on complex estuarine systems and made a significant contribution globally to approaches for the conservation and management of estuaries.
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- Date Issued: 2018
Integrating Climate Change Adaptation (CCA) and Disaster Risk Reduction (DRR) for greater local level resilience: lessons from a multi-stakeholder think-tank
- Authors: Pereira, Taryn , Shackleton, Sheona E , Donkor, Felix Kwabena
- Date: 2017
- Subjects: Climatic changes -- South Africa , Climatic changes -- South Africa -- Eastern Cape -- South Africa
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/62027 , vital:28097
- Description: The last few years have seen one of the most severe droughts in recent times in the southern African region, and news headlines are increasingly full of warnings about heavy storms, fires and floods. There is no doubt that extreme hydro-meteorological events, and their multiple and potentially disastrous impacts, are at the forefront of the public consciousness at the present time and are one of the key concerns regarding the impacts of climate change in the region. While the links between extreme climate events, disaster risk reduction (DRR - see Box 1) and climate change adaptation (CCA - see Box 2) are recognised in the South African Climate Change White Paper, this is not the case for the whole region. Furthermore, even if there is national recognition of the need to synergise these two spheres of endeavour, this does not always trickle down to effective policy, planning and implementation at the local level.
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- Date Issued: 2017
Barriers to and enablers of climate change adaptation in four South African municipalities, and implications for community based adaptation
- Authors: Spires, Meggan Hazel
- Date: 2015
- Subjects: Climatic changes -- South Africa , Climatic changes -- Risk management -- South Africa , Climatic changes -- Social aspects -- South Africa , Climate change mitigation -- South Africa , Climatic changes -- Government policy -- South Africa , Municipal government -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4787 , http://hdl.handle.net/10962/d1018913
- Description: The focus of this study is on understanding the multiple and interacting factors that hinder or enable municipal planned climate change adaptation, here called barriers and enablers respectively, and their implications for community based adaptation. To do this I developed a conceptual framework of barriers to and enablers of planned climate change adaptation, which informed a systematic literature review of barriers to planned community based adaptation in developing countries. In this framework barriers were grouped into resource, social and physical barriers. I then conducted empirical case study analysis using qualitative research methods in four South African municipalities to understand what barriers and enablers manifested in these contexts. In light of the reflexive nature of my methodology, my framework was adjusted based on my empirical findings, where contextual barriers were found to better represent the empirical results and subsumed physical barriers. I found my framework useful for analysis, but in the empirical cases, barriers and enablers overlaid and interacted so significantly that in reality it was often difficult to separate them. A key finding was that enablers tended to be more about the way things are done, as opposed to direct opposites of barriers. Comparison of barriers and enablers across the case studies revealed a number of key themes. Municipalities struggle to implement climate change adaptation and community based adaptation within contexts of significant social, economic and ecological challenges. These contextual barriers, when combined with certain cognitive barriers, lead to reactive responses. Existing municipal systems and structures make it difficult to enable climate change adaptation, which is inherently cross‐sectoral and messy, and especially community based adaptation that is bottom‐up and participatory. Lack of locally applicable knowledge, funding and human resources were found to be significant resource barriers, and were often underlain by social barriers relating to perceptions, norms, discourses and governance challenges. Enablers of engaged officials, operating within enabling organisational environments and drawing on partnerships and networks, were able to overcome or circumvent these barriers. When these enablers coincided with windows of opportunity that increased the prioritisation of climate change within the municipality, projects with ancillary benefits were often implemented. Analysis of the barriers and enablers identified in the literature and case studies, informed discussion on whether municipalities are able to implement community based adaptation as defined in the literature, as well as the development of recommendations for how municipal planned climate change adaptation and community based adaptation can be further understood and enabled in the future. These recommendations for practice and research include: (a) To acknowledge and understand the conceptual framings of municipal climate change work, as these framings inform the climate change agenda that is pursued, and hence what municipal climate change adaptation work is done and how it was done. (b) The need for further research into the social barriers that influence the vital enablers of engaged officials, enabling organisational environments, and partnerships and networks. (c) To learn from pilot community‐level interventions that have been implemented by municipalities, as well as from other disciplines and municipalities. (d) To develop top‐down/bottom‐up approaches to enable municipal planned climate change adaptation and community based adaptation, that benefits from high level support and guidance, as well as local level flexibility and learning‐by‐doing. (e) To develop viable mechanisms for municipalities to better engage with the communities they serve.
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- Date Issued: 2015
Development role players' knowledge of ecological infrastructure in Eden district, South Africa
- Authors: Crisp, Abigail Gilmour
- Date: 2015
- Subjects: Climatic changes -- South Africa , Environmental management , Coastal engineering
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8725 , vital:26424
- Description: Coastal disasters have been increasing in intensity and frequency around the world causing loss of life and millions of Rands’ worth of damage to infrastructure. Coastal communities are growing as more people are drawn to urban areas. These people depend on the services the coastal ecosystem provide but through degradation and land use change the supply of services is reduced. The ability of these communities and landscapes to bounce back from disturbance has been severely hampered. As a result communities are looking for ways in which they can protect their lives and their assets and become more resilient. Through development planning structures such as coastal foredunes, that offer a buffering capacity against storm surges, can be used to strengthen the resilience of coastal communities. The type of defences used in communities would be dependent on the knowledge of the decision makers. This study explores the discourses and practices that are present in development processes regarding ecological infrastructure (in its buffering capacity for risk reduction) as an option for adaptation to global environmental change in the coastal areas of Eden District. Qualitative data collection and analysis techniques were used. In-depth interviews were used to collect data, which was transformed into frequency data using content analysis. Descriptive statistics was then applied to the coded frequencies. The interpretation of the data was presented alongside the frequency data, via the descriptive statistics and quotations from interviews. It was determined that role players in development processes are aware of the complexities surrounding coastal social-ecological systems and understand the role foredunes play as ecological infrastructure within this system. Those who lack knowledge are aware of their knowledge gaps. Participants believe the study area is at risk due to human impacts and overall, participants felt that there is a general lack of awareness with regard to issues affecting our coastline, compounded by the absence of an enabling environment brought about by a lack of finances and time.
- Full Text:
- Date Issued: 2015
Indicators of household-level vunerability to climate change in three topographically diverse rural villages
- Authors: Sotsha, Kayalethu
- Date: 2013
- Subjects: Poverty -- South Africa , Land tenure -- South Africa , Climatic changes -- South Africa , Farms, Small -- South Africa , Rural poor -- South Africa
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11212 , http://hdl.handle.net/10353/d1016204 , Poverty -- South Africa , Land tenure -- South Africa , Climatic changes -- South Africa , Farms, Small -- South Africa , Rural poor -- South Africa
- Description: Climate change has become a major concern globally and it clearly exerts a profound influence on the lives of poor rural populations who depend on agriculture for livelihoods.Generally, agriculture is more at risk from weather, pests and diseases than is industry or trade. Furthermore, many farming units are at low levels of development with little technological input in their production systems. This makes them vulnerable to any exposure to climate and environmental variation, given that there is little capacity for the system to adjust to change. Most at risk are the rural poor with low levels of development and limited ability to adapt to and overcome the effects of climate change. Using data from a sample survey of 120 households this study attempts to assess and compare indicators of vulnerability to climate change. The comparison was made at household level between three typical villages, an inland, a river catchment and a coastal village. This idea of comparison arises from the general understanding that different variables affect different regions differently so that the impact of and vulnerability to climate change differs across regions, areas and populations. The data was obtained using a questionnaire that was administered through face-to-face interviews. Given that sensitivity and adaptive capacity of farming systems to climate change is shaped by both socioeconomic and institutional factors, a multiple regression model was used to test the relationship between indicators of vulnerability and household socioeconomic and institutional characteristics. Indicators were selected based on significant statistical relationships. This means that the statistical procedure for selecting indicators involved relating a large number of variables to vulnerability in order to identify statistically significant factors. The results showed reliability of income and reliability of water resources to be good indicators of vulnerability. Many statistically significant variables as well as respective R2 of 0.988 and 0.825 confirm the foregoing. Another indicator was the Simpson index that measures diversification of agricultural production. The results show that vulnerability to climate change was highest for the households near the river and lowest for the inland village. Moreover, the results confirmed that most blacks that are practicing agriculture receive little if any support largely because available resources are highly skewed towards certain farmers rather than others.
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- Date Issued: 2013