Comparing stable isotope ratios and metal concentrations between components of the benthic food web: a case study of the Swartkops Estuary South Africa
- Authors: Ndoto, Asiphe
- Date: 2024-04
- Subjects: Swartkops River Estuary (South Africa) , Estuarine ecology -- South Africa -- Swartkops River Estuary , Fishes -- Ecology -- South Africa -- Swartkops River Estuary
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64256 , vital:73669
- Description: Estuarine systems are highly productive ecosystems; however, they are subjected to high anthropogenic pressure such as metal contamination and: increased nutrient loads. The contamination sources of metals and nutrients in urban estuaries are derived: from industrial waste. agricultural and urban runoff that flows into estuaries. An example of such a system is the Swartkops Estuary. industry and three wastewater treatment plants within the Swartkops River catchment are major sources of metal. and nutrient pollution, respectively. The metals accumulate in the environment, are biomagnified up the food web, and transferred from one trophic level to another. At lethal concentrations, metals pose a threat to organisms using the estuary by affecting their physiological and biochemical processes. Stable Isotope analysis has proven to be an effective tool for investigating, trophic linkages in the food chain from a variety of environments. By assessing both metals and stable _isotopes in the. estuary it can provide a more robust understanding of the pathway metals accumulate, biomagnified, and transfer from the environment through the estuarine food web. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
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- Date Issued: 2024-04
Sediment characteristics and hydrodynamic conditions of the Swartkops estuary, Eastern Cape Province of South Africa
- Authors: Best, Lutho https://orcid.org/0000-0001-6400-9061
- Date: 2021-11
- Subjects: Geology, Stratigraphic , Estuarine oceanography , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22611 , vital:52596
- Description: This study is a part of an environmental research project aimed at providing assessment information to the grain-size distribution, mineral compositions, sedimentary structures and coastal erosion and rehabilitation methods along the Swartkops estuary, a recent developing industry area of South Africa. The methodologies used in this study comprise desk study of literature, field geological investigation and sampling, and laboratory analyses including grainsize analysis, thin section microscope study, XRD mineral composition study and SEM-EDX grain surface texture and composition analyses.The basement and surrounding areas of the Swartkops estuary consist of three formations: the Enon Formation of mainly conglomerate, the Kirkwood Formation of sandstone and mudstone, and the Sundays River Formation of dominantly mudstone with sandstone, which integrated as Uitenhage Group of Cretaceous sequence with modern estuarine sand and alluvial sediments filled in the entire basin. Grain size analysis is a useful tool to assess hydrodynamic environments. The grain size parameters showed that most of the Swartkops estuary sediments are moderately sorted with very few well and poorly sorted, coarse to fine skewed in grain size distribution.Whereas the Bluewater Bay beach sediments are mostly fine grained, well sorted, fine to coarse skewed in grain size distribution. The bivariate scatter plots are an indication of shallow marine environment by beach and coastal processes with the influence of water flow and wind influence during transportation and deposition processes. Mineralogy studies revealed that the Swartkops estuary sediments are dominantly composed of minerals such as: quartz, calcite, feldspar (orthoclase and plagioclase), aragonite, clay minerals (smectite and illite), and salts such as NaCl and MgCl2. Skeletal carbonate minerals (shell fragments) are more than chemical precipitated carbonate minerals. Quartz is the most abundant detrital mineral observed in all the sediments and it comes from inland and transported into the estuary and the beach by fluvial streams, whereas skeletal calcite/aragonite is the most abundant biogenic carbonate derived from sea side and transported by marine currents. The study shows that grain surface textures reveal the existence of several features that reflect the depositional environments. Observed grain surface textures by microscope and SEM include V-shape pits, upturned pits caused by mechanical crashing and corrosion during transportation; crystalline precipitation of calcite, quartz, salt and clay by chemical precipitation and crystallization; dissolution pits and pores formed by dissolution, and burrow and boring by biogenetic activities. The grain surface morphologies are closely linked to different formation mechanisms and depositional environments. Well-developed sedimentary structures have been found in the beach and estuary, including sand dune, sand ridge, straight and sinuous ripple, ripple marks, aeolian nail marks, high angle tabular cross bedding, antidune, rill mark, rhomboid mark, swash line, mud crack, gravel pavement, interfering ripples, flat topped ripple mark, linguiod mark, asymmetric sinuous ripples, dendritic pattern on sandy beach, boring and bioturbation, burrows desiccation cracks and water escape hole. Different sedimentary structures are reflective of different hydrodynamic conditions and depositional environments. Coastal erosion is a major problem for damage of road, bridge and properties in the industrial areas in Swartkops, which is also a task for this study. The author had suggested some practical mitigation-methods to local government, such as groins, revetments, shoreline hardening, planting of vegetation, and vertical walls, bulkheads, sills, which could be useful for the protection of coastal erosion. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
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- Date Issued: 2021-11
Livelihood implications of a possible Ramsar declaration of the Swartkops estuary, Eastern Cape, South Africa
- Authors: Vembo, Glen Muchengeti
- Date: 2020
- Subjects: Swartkops River Estuary (South Africa) , Livelihood , Ramsar Convention , Estuaries Management , Poor Attitudes
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164715 , vital:41157
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Environmental Science, 2020 , Estuaries are key ecosystem resources but are increasingly coming under threat from human activities which requires their protection. However, livelihood implications resulting from a change in management of natural resources need to be anticipated and factored in conservation planning. The Swartkops estuary in the Eastern Cape Province of South Africa is currently ‘open access’ but there are plans to protect it through a Ramsar declaration. Using household surveys and key informant interview, this study examines the direct and indirect uses of the Swartkops estuary, perceptions held towards state and management of that estuary, and future visions held by different users of the estuary, as a basis for informing future management options. One hundred and forty people were surveyed using a questionnaire, consisting of both closed- and open-ended questions. Of this sample, 47 respondents were direct users and 93 household survey respondents, chosen from neighbouring residential areas. Overall, the findings suggest multiple uses of the estuary. Subsistence fishing and selling of bait organisms were key livelihood sources, providing cash income, supplementing dietary requirements and in some instances satisfying cultural values attached to the natural resources in the Swartkops estuary, especially for the poor. The well-off respondents tended to value the estuary for its recreational functions like boating and fishing. Perceived threats to the estuary included lack of visible management and clear policing of natural resources management but these were mainly cited by the more affluent users. Disservices of the estuary mentioned include breeding of mosquitos, drowning and a perceived crime hotspot. Concerning views for the future, improved management of the estuary was consistent between user groups, whilst a potential Ramsar declaration gained majority support. As expected, future visions were proposed with varied expected benefits, with results suggesting the wealthier user groups more concerned about conserving the ecological aspect of the Swartkops. However, due to limited livelihood opportunities, lower income user groups expected an improvement of their livelihoods, including continued access to natural resources in the Swartkops estuary. Such access would be important for crafting novel interventions that could reduce conflict levels between conservation agencies and local communities and in a broader sense; improve the relationship between the state and its citizens. This study concludes that any conservation proposition that advocates for restriction or limited use of natural resources without providing alternative livelihood options will be faced with difficulty. Consequently, the study proposes a pro-poor approach; whereby marginalised communities are supported with capacity building to make decisions and are integrated in any proposed conservation plans for the estuary.
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- Date Issued: 2020
Aspects of the ecology and biology of Gilchristella aestuarius (G & T) (Pisces: Clupeidae) in the Swartkops estuary, Port Elizabeth
- Authors: Talbot, Marie Marcel Jean-Francois
- Date: 1982-12
- Subjects: Fishes -- Ecology -- South Africa -- Swartkops River Estuary , Swartkops River Estuary (South Africa)
- Language: English
- Type: Master's theses , Manuscripct
- Identifier: http://hdl.handle.net/10948/52352 , vital:43613
- Description: The Department of Zoology at the University of Port Elizabeth has an ongoing programme on the Swartkops estuary with the eventual aim of drawing up the energy pathways of the system. Marais (1976) has investigated the nutritional ecology of the grunter Pommadasys cormersoni while Melville-Smith (1978) and Melville-Smith and Baird (1981) reported on the ecology of larval fish. Winter (1979) studied the ecological parameters of fish populations, but this work was not a detailed account of each population. Wooldridge (1979) studied components of the 3 zooplankton community in some detail. It became evident that there was a significant lack of understanding of the ecological relationships between plankton and piscivorous fish, which was crucial to the elucidation of the interactions and trophodynamics of the Swartkops estuarine system. Since G. aestuarius is an important link in the energy pathway from the plankton to the nekton, and in terms of numbers dominates the seine net catches made in the estuary (Winter, 1979), this study was motivated. The aim was to investigate the important biological parameters of the estuarine round herring population namely the population structure, distribution and abundance, individual growth rate from field data, the food and feeding habits, reproduction and respiration, all of which are essential for the understanding of the dynamics of a species. These parameters were later converted into energy terms and the construction of an energy budget was attempted. , Thesis (MSc) -- Faculty of Science, 1982
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- Date Issued: 1982-12