M.Sc. (Zoology) / Concern has been shown by Ezemvelo KZN Wildlife for the state of the Lower Pongolo River and Floodplain due to the ever increasing urban and industrial development in the area. This increase in development poses a threat to the fish populations within the system and their ability to support the surrounding communities. Continued spraying of pesticides e.g. DDT within the area are adding to stresses placed on the fish populations through decreasing water quality. The effectiveness of environmental water flows suggested by White et al. (1984), have never been assessed by conservation authorities. This means that the authorities have been unable to fulfil their legislative obligations to establish management and conservation plans (Hughes et al., 2001). Work on the biological responses of fish to anthropogenic stressors such as organic pollutants and metals; have been conducted by a group of experts in the field of ecological health. This section of the project focusses on two fish species, Hydrocynus vittatus and Synodontis zambezensis, sampled within the study area and used for biomarkers and tissue chemical level determination. Standard techniques were applied for Organochlorine Pesticide (OCP) analysis according to Yohannes et al. (2013) and these results have been compared to biomarker responses which have also been completed following standard protocols. Results found within both fish species, show the relationship between accumulation of toxicants and biomarker responses. The highest levels of ΣOCPs where found within H. vittatus at (Mean ± SE) 1101.61 ± 610.97 ng/g lipid weight, the highest constituent being technical grade Dichlorodiphenyltrichloroethane (DDT). High levels of ΣDDT were also found in S. zambezensis, but were lower than levels in H. vittatus and these levels correspond with positioning of each species within the food web. H. vittatus occupies a much higher level in the food web as they are top predators and S. zambezensis falls lower down on the food web due to their reliance on detritus and only small invertebrate species for food. Biomarker responses are clearly affected by bioaccumulation levels and this is especially evident within H. vittatus as Achetylcholinesterase (AChE) is greatly inhibited by high levels of ΣDDT. Changes in the level of biomarker responses are not as apparent in S. zambezensis and this is believed to be food web linked, due to differences in bioconcentration. Data collected during this study will contribute to baseline data on S. zambezensis and add to already accumulated data on H. vittatus. This new data will also help with the improvement of or alteration to already present monitoring programmes in the study area.

Amphibians are regarded as sensitive indicators of environmental change and are therefore excellent subjects for use in ecotoxicology. The Phongolo River floodplain is South Africa’s most diverse natural floodplain system and hosts more than 40 frog species. It is also a malaria endemic region and is subjected to active spraying with Dichlorodiphenyltrichloroethane (DDT) through means of indoor residual spraying over the summer months. The upper Phongolo River runs through agricultural landscape and is subjected to runoff from forest plantations, orchards and sugar cane plantations. In this study residue levels of 22 different organochlorine pesticides (OCPs) were analysed in selected amphibian species from in and around the Ndumo Nature Reserve coupled with 12 different biomarker response assays to determine environmental exposure levels and possible sublethal effects in amphibians from the lower Phongolo River floodplain. Seasonal change, direct influence of anthropogenic activity and the influence of species’ aquatic preference in habitat selection were all factors considered during this assessment. Stable Isotope analyses were performed on 11 different food web components In order to determine the food web structure pertaining to Xenopus muelleri (Müller's platanna). Samples were collected during both high and low flow seasons from inside and outside Ndumo Nature Reserve. Organochlorine pesticide bioaccumulation was analysed in whole frog samples using a GC-μECD. Results indicated significant seasonal variation in OCP levels and exposure composition. Significant differences between inside and outside sites were also noted. Dichlorodiphenyltrichloroethane in its different isomer forms and their metabolites along with the hexachlorocyclohexane (HCH) isomers was the two main contributing OCP groups detected. Total OCP levels from all sample sets ranged between 8.71 ng/g lipid and 21,399.03 ng/g lipid. An increase in OCP accumulation was observed for X. muelleri over a period of one year. Organochlorine pesticides are known to have neurotoxic effects causing imbalances in Na+, K+, and Ca+ ion exchange. Hyperactivity has been reported in Rana temporaria (European Common frog) tadpoles exposed to p,p-DDT concentrations above 110,000 ng/g lipid. Despite OCP levels measured in frogs from this study being lower than reported toxic levels, the biomarker response assays indicated definite oxidative stress responses correlating to OCP bioaccumulation, with other minor responses shown. Cellular energy allocation showed a shift in the main energy source type from proteins to lipids correlating to increased OCP bioaccumulation. A slight inhibition response was noted in the hepato-somatic index correlating to γ-HCH bioaccumulation. Stable isotope analyses indicated food web structure differences between inside and outside the reserve, with outside showing less clear distinction between trophic groups and nitrogen enrichment of primary producers. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Amphibians are regarded as sensitive indicators of environmental change and are therefore excellent subjects for use in ecotoxicology. The Phongolo River floodplain is South Africa’s most diverse natural floodplain system and hosts more than 40 frog species. It is also a malaria endemic region and is subjected to active spraying with Dichlorodiphenyltrichloroethane (DDT) through means of indoor residual spraying over the summer months. The upper Phongolo River runs through agricultural landscape and is subjected to runoff from forest plantations, orchards and sugar cane plantations. In this study residue levels of 22 different organochlorine pesticides (OCPs) were analysed in selected amphibian species from in and around the Ndumo Nature Reserve coupled with 12 different biomarker response assays to determine environmental exposure levels and possible sublethal effects in amphibians from the lower Phongolo River floodplain. Seasonal change, direct influence of anthropogenic activity and the influence of species’ aquatic preference in habitat selection were all factors considered during this assessment. Stable Isotope analyses were performed on 11 different food web components In order to determine the food web structure pertaining to Xenopus muelleri (Müller's platanna). Samples were collected during both high and low flow seasons from inside and outside Ndumo Nature Reserve. Organochlorine pesticide bioaccumulation was analysed in whole frog samples using a GC-μECD. Results indicated significant seasonal variation in OCP levels and exposure composition. Significant differences between inside and outside sites were also noted. Dichlorodiphenyltrichloroethane in its different isomer forms and their metabolites along with the hexachlorocyclohexane (HCH) isomers was the two main contributing OCP groups detected. Total OCP levels from all sample sets ranged between 8.71 ng/g lipid and 21,399.03 ng/g lipid. An increase in OCP accumulation was observed for X. muelleri over a period of one year. Organochlorine pesticides are known to have neurotoxic effects causing imbalances in Na+, K+, and Ca+ ion exchange. Hyperactivity has been reported in Rana temporaria (European Common frog) tadpoles exposed to p,p-DDT concentrations above 110,000 ng/g lipid. Despite OCP levels measured in frogs from this study being lower than reported toxic levels, the biomarker response assays indicated definite oxidative stress responses correlating to OCP bioaccumulation, with other minor responses shown. Cellular energy allocation showed a shift in the main energy source type from proteins to lipids correlating to increased OCP bioaccumulation. A slight inhibition response was noted in the hepato-somatic index correlating to γ-HCH bioaccumulation. Stable isotope analyses indicated food web structure differences between inside and outside the reserve, with outside showing less clear distinction between trophic groups and nitrogen enrichment of primary producers. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

MSc (Zoology)) / Department of Zoology