ETD Collection
Permanent URI for this collectionhttps://wiredspace.wits.ac.za/handle/10539/104
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Item Functional ecology of afrotropical freshwaters in the Republic of Congo, west-central Africa(2024) Walsh, GinaCharacterising functional freshwater biodiversity patterns and understanding community determinants can aid in predicting changes and prioritising specific conservation management actions. Afrotropical freshwater systems support diverse ecological communities, including many taxonomically undescribed species, yet few studies have been undertaken in this region and they remain poorly understood. Additionally, an overwhelming amount of research on north temperate streams has given rise to widely used lotic conceptual models which are superimposed over freshwaters globally, though the theory governing the structure of Afrotropical lotic communities remains largely unexplored. In this thesis I explored different aspects of the biodiversity, trophic ecology and functional diversity of an Afrotropical system in the Republic of Congo (west Central Africa) through a series of field studies. I formally describe two new to science fish species collected in the region, and use fish functional traitbased approaches to explore the functional diversity of fish assemblages and test selected expectations of riverine conceptual models in this regional setting. Following, I used carbon and nitrogen stable isotopes (δ13C, δ15N) from samples collected along a continuum of a coastal river in the Republic of the Congo to show temporal and spatial patterns of trophic diversity and basal carbon resource use. In addition to uncovering new fish diversity, I established that whilst tenets of certain conceptual models such as the River Continuum Concept and the River Habitat Template were supported by fish trait-environment relationships, unique patterns of functional diversity also exist which are scale dependent and result in different functional strategies driving communities between upper and lower positions in the basin. At sub-basin scale, headwater zones harbour substantial functional diversity in relation to upstream catchment size, and results suggest that historical forest refugia may play a role in the high functional richness at high elevations of the region. Isotopic analysis revealed that river order and season are important drivers in consumer trophic strategies along a river continuum in the wet Afrotropics, and that riparian forest sources are key basal carbon resources supporting consumers. Isotopic work reiterated that headwaters are distinctive in terms of trophic and functional diversity. I discovered potential evidence for methanogenic pathways in lateral swamp forests that may subsidize instream food webs. The outcomes of this work demonstrate that existing river conceptual models only partially explain patterns of richness and functional diversity of river systems in this region, and highlights the importance of understanding mechanisms structuring regional functional diversity (e.g. nestedness and turnover) in efforts to conserve freshwater systems. It also emphasizes the need for swamp forest- and riparian specific policies in central Africa to be incorporated into freshwater conservation plans and strategies for forested regions of the Afrotropics.Item Expecto patronum(2020) Edery, KyleOur natural world is currently undergoing a drastic and radical transformation! Human agency has led to the erosion of the very foundations of our livelihoods, economies, food security, health and quality of life. Ecosystems, which form our life support systems and our safety nets are shrinking and collapsing. At the heart of this collapse are pollinators, such as butterflies and bees, key species responsible for maintaining these vital ecosystems, whose very existence is being threatened by human activity. This thesis depicts a series of explorations, re-defining the environment and surface needed for pollinators in this new age of man vs nature, before manifesting and putting forth the creation of a version of an artificial envi-ronment. This version of an artificial environment is presented as a solution to sustain and revive endangered pollinators and the degrading context of the proposed site.This thesis looks at how architecture, in its physicality, can not only assist eco-systems and pollinators in their fight for survival but also act as a catalyst for a process of awakening and awareness. The intervention proposed in this thesis aims to create a space that negotiates between the two worlds of pollinators and humans, at the intersection of the built form and the natural environment. In doing so, this will ensure a space that benefits both people and pollinators, at their respective scales. The design of this new surface / artificial environment aims to aid pollinators year-round both naturally and through artificial means, while also showcasing their contribution to human life and research to aid their survival. The thesis demonstrates the demise of nature, illustrating the impact humanity, as a species, has had and continues to have on the natural world, primarily on the lives of pollinators. A focus on the demise of pollinators is addressed, as their brink of extinction stresses a fundamental link between the two causes of collapse and how by saving pollinators, nature in turn can be revived. By doing the above, this thesis will advocate for the creation of an artificial environment as an effective solution to sustain and revive South Africa’s endangered pollinators