Macroinvertebrate and diatom assemblage responses to pollution, with emphasis on salinity, in the Kat River, Eastern Cape South Africa
- Authors: Mgaba, Ntombekhaya
- Date: 2018
- Subjects: Water -- Pollution -- South Africa -- Kat River , Stream salinity -- South Africa -- Kat River , Sewage disposal plants -- South Africa , Environmental monitoring -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , South African Scoring System version 5 (SASS5) , Macroinvertebrate Response Assessment Index (MIRAI)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63279 , vital:28389
- Description: Salinity has been implicated as one of the major contributors to deteriorating water quality of freshwater ecosystems around the globe. In South Africa, anthropogenic activities such as mining, agriculture, industry and wastewater treatment works (WWTWs) are the major sources of increasing salinity levels of freshwater resources. The main focus of this study was to assess the impact of salinity on water quality of the Kat River using macroinvertebrates and diatoms as bioindicators. Biomonitoring using macroinvertebrates and diatom communities and concurrent sampling of water physicochemical variables were conducted bi-monthly from December 2015 to November 2016.This period covered summer and winter, and the study was conducted at five selected sites (Sites 1, 2, 3, 4 and 5) along the length of the Kat River. For macroinvertebrates biomonitoring, the South African Scoring System version 5 (SASS5) and Macroinvertebrate Response Assessment Index (MIRAI) were applied to collect and analyse data, while the Taylor et al (2006) protocol for collecting and analysing diatom assemblages was modified and used for diatom collection and analysis. Water physicochemical variables, including hydrogen ion concentration (pH), electrical conductivity (EC), dissolved oxygen (DO), temperature, turbidity and stream flow were determined in situ using appropriate multiprobe meter and/or techniques. Nutrients (NO3-N, NO2-N, NH4-N and PO4-P) were analysed in the laboratory using appropriate analytical methods. All data were subjected to appropriate statistical analyses and statistical decisions were made at an alpha value of 0.05. Particularly, multivariate analyses of both macroinvertebrates and diatoms assemblages were conducted using canonical correspondence analysis and Bray-Curtis similarity analysis, while indicator species analysis was used to determine which species is/are more significant with respect to biomonitoring in the Kat River. Biotic diversity indices were also measured and used to discriminate between least and most impacted sites. The Kat River water quality was found to have experienced a varying degree of modification compared to Generic Resources Water Quality Objectives limits. Change in DO, stream flow, EC, nutrients and turbidity exerted the greatest influenced on the macroinvertebrates assemblage structure, with organisms at Sites 4 and 5 (downstream sites) showing more significant negative impact compared to organisms at Sites 1, 2 and 3 (upstream sites). Analysis of the diatom biomonitoring showed more negative impact at Sites 2, 4 and 5 compared to Sites 1 and 3. Fort Beaufort Wastewater Treatment Works and small-scale farming activities, as well as leaking of pipes carrying sewage, were found to be the likely major sources of anthropogenic activities responsible for the observed increased salinity and other pollutants in the Kat River. Overall, this study found macroinvertebrates (identified up to the family level) as good for biomonitoring to assess or predict water quality of the Kat River, while diatoms were found to be most suitable for biomonitoring to assess salinity in the Kat River.
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- Date Issued: 2018
Generation of New Ecotoxicity Data for Salts Using Indigenous South African Freshwater Macroinvertebrate: Updating the National Salts Toxicity Database
- Authors: Mensah, Paul K , Mgaba, Ntombekhaya , Griffin, Neil J , Odume, Oghenekaro N , Palmer, Carolyn G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/437854 , vital:73417 , ISBN 978-1-4312-0747-3 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV%20353.pdf
- Description: Scherman and Palmer (2013) reviewed the historical and current trends of Environmental Water Quality (EWQ) in South Africa. Based on the review, they identified research gaps for which they proposed a co-ordinated set of projects that need to be commissioned and executed to fill these gaps. These co-ordinated set of projects include update of TEACHA (Tool for Ecological Aquatic Chemical Habitat Assessment); update of the national salt toxicity database; integration of Resource Directed Measures (RDM) components (ie Ecological Reserve, Re-source Quality Objectives (RQOs) and Classification); integrating water quality and quantity; evaluation of the RDM participatory process based on research and current understandings of complex social-ecological systems and ecosystem services; and integrating RDM and SDC (Source Direct Control) to ensure coherent link between the two. The overarching aim of the above set of projects is to support implementa-tion of the National Water Resource Strategy 2 (NWRS2). Therefore, the main objective of this project to contribute to addressing the second research gap listed above (ie updating the national salt toxicity data-base). Noting that the database contains only data on single salts with nothing on salt mixtures, the project also generated binary salt mixtures data for the database, in addition to generating data for single salts.
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- Date Issued: 2016