Browsing by Author "Naidoo, Samantha."

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The effect of wastewater treatment works on foraging ecology, haematology, detoxification organs and reproduction in an urban adapter, the banana bat (Neoromicia nana).
(2015) Naidoo, Samantha.; Schoeman, Marthinus Cornelius.; Mackey, Robin L.; Vosloo, Dalene.
Natural land is rapidly becoming urbanized. Wastewater Treatment Works (WWTWs) are a ubiquitous component of this urban landscape. WWTWs may provide profitable foraging areas for insectivorous bats because of their association with a high abundance of pollution-tolerant chironomid midges (Diptera). However, bats that feed on these insects may also accumulate metal pollutants in their tissues, with acute or chronic effects on their health. There have been no studies to investigate whether African bats utilize these WWTWs as foraging grounds, and the potential physiological impacts from foraging at such sites. The aim of this study was to investigate the impact of WWTWs on foraging ecology and multiple tiers of physiology (haematology and genotoxicity, detoxification organs and reproduction) in an urban adapter, the banana bat (Neoromicia nana, family Vespertilionidae) in KwaZulu-Natal, South Africa. N. nana exhibited a significantly higher abundance and feeding activity at wastewaterpolluted sites than at unpolluted reference sites. Additionally, the most abundant insect order at wastewater-polluted sites and in the diet of resident bats was Diptera, compared to a diverse insect diet at unpolluted sites. Thus, WWTWs provide an optimal food resource to bats in the short-term. However, I found significantly higher levels of essential and non-essential metals at WWTW-polluted sites, and in the tissues of WWTW bats than at unpolluted sites. Further, I found sub-lethal haematological and genotoxic responses related to increased metals in WWTW bats. Specifically, N. nana at WWTWs had significantly lower antioxidant capacity and significantly higher levels of DNA damage and haematocrits than bats from unpolluted sites. An accumulation of DNA damage, especially from double-stranded breaks ultimately leads to tissue damage and disease. These longer-term effects of chronic pollutant exposure should be most evident in the organs involved in detoxification, the liver and kidneys. Indeed, I found evidence of disrupted balance of essential metals and mineral nutrients, histopathological tissue damage and whole organ effects in the liver and kidneys. Finally, I found reproductive system alterations in male N. nana at WWTWs. Although I did not find significant effects on the sex organs, testosterone hormone concentrations were significantly lower in male N. nana at WWTWs than in males from unpolluted sites. In addition, body condition indices for N. nana from the WWTWs were significantly lower than at unpolluted sites, suggesting lower quality male bats at WWTWs. Taken together, these results suggest the potential for serious long-term health risks, negative fitness implications and ultimately, population effects for these top predators within the urban landscape.
The effect of wastewater works on foraging behaviour and metal content of Neoromicia nana (Family : Vespertilionidae)
(2011) Naidoo, Samantha.; Schoeman, Marthinus Cornelius.; Vosloo, Dalene.; Mackey, Robin L.
Anthropogenic disturbance from urbanization has introduced a range of contaminants into freshwater ecosystems. Wastewater Treatment Works (WWTW) in particular, deposit effluent with high metal concentrations directly into rivers. These pollutants may affect river biota directly or through modifications to habitat and prey. Therefore, the impact of metal pollution through a food chain should be evident in high trophic level predators such as Neoromicia nana. N. nana is a small, insect-eating bat that occurs in forest and riparian habitats in Africa. Most importantly, it is an urban exploiter, i.e. a species that takes advantage of anthropogenic food and habitat resources. I investigated the foraging behaviour and metal content of N. nana at wastewater-polluted sites (WWTW sludge tanks and sites downstream of wastewater discharge into the rivers) and unpolluted sites (sites upstream of wastewater discharge) at three urban rivers in Durban, South Africa, during winter and summer. To assess water quality, I determined cadmium, copper, chromium, iron, nickel, zinc and lead concentrations using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). To investigate the foraging behaviour of N. nana, I quantified relative N. nana abundance, and feeding activity from recorded echolocation calls. Using ICP-OES, I quantified metal concentrations in three tissues (liver, kidney and muscle). My results show that concentrations of most metals were generally lowest upstream, intermediate at downstream sites and highest at the tanks. The relative abundance and feeding activity of N. nana were significantly higher at wastewater-polluted sites than at upstream sites, despite there being significantly more insect orders upstream. However, pollution-tolerant Chironomidae (Diptera), were significantly more abundant at wastewater-polluted sites. Indeed, at wastewater-polluted sites, Diptera represented the highest percentage of insects in the diet of N. nana. Essential metals (copper, zinc and iron) were detected in all tissue samples of N. nana. In contrast, the toxic metals cadmium, chromium and nickel were present in tissue of bats only at wastewater-polluted sites (except one upstream occurrence of cadmium). This suggests that these metals may accumulate in tissue through the ingestion of pollutant-exposed prey. Thus, metal pollution from WWTWs affects not only water quality of rivers, but also the diversity of resident aquatic insects and ultimately the ecology of N. nana populations, which may pose serious long-term health risks for these top predators.
The social work profession in South Africa : Quo Vadis?
(2004) Naidoo, Samantha.; Kasiram, Madhubala Ishver.
The overall aim of this study was to research the status of social work in South Africa by examining what factors contribute towards social workers in South Africa leaving their country to seek employment in the UK. Further, current frustrations, problems and needs of social workers in South Africa and those working in the UK were investigated. The benefit of the study therefore was to evaluate the status of the social work profession at present, and to expand future professional services. The study utilised both the qualitative and quantitative research methods. The research was undertaken in two phases utilising three different sample groups. The two phases were: (1) Phase One - in which the researcher quantitatively researched social workers frustrations, problems and needs in South Africa and (2) Phase Two - in which the researcher qualitatively explored the difficulties, experiences and accomplishments of South African social workers who have relocated to the UK. In sample group 1 in Phase One of the study, eighty social workers who had applied to work in the UK were selected. While, in sample group 2, in Phase One of the study, eighty social workers who were remaining in South Africa, were randomly selected. In sample group 3, in Phase Two of the study, thirty social workers were derived from the social work relocation list of a known Recruitment Agency. The research tool was a mailed questionnaire for the two sample groups in Phase One of the study. Reasons to relocate or remain were asked of both sample groups, along with their suggestions for improving the image of social work in South Africa and contributing to its survival. In Phase Two of the study the researcher chose the qualitative method of data collection, namely focus group interviews. Within the focus group interviews social workers in the UK were able to share their experiences of relocation. Focus group thematic questions guided the group discussions to generate a rich understanding of the social workers' experiences and beliefs. In this study, research evidence was provided on the concerns plaguing the profession such as safety and security, service conditions, poor salaries, staff turnover, lack of supervision and support from agencies, ineffective graduates/educators, curriculum change, and continuing education. Alongside this research results also indicated that culture, family, social ties and climate were significant factors preventing social workers from leaving the country. Recommendations were made by social workers to improve the image of social work as a way of contributing to its survival. These recommendations included a unifying role to be played by the Council of Social Service Professions to tackle cogent issues such as service conditions; staff development/training in accord with the need for continuous professional development; relevancy of training curricula to the new developmental paradigm; competent educators; research, and using auxiliary workers in service delivery. These recommendations need to be incorporated into policy/plans set up to address relevancy, image and survival issues facing the profession. Other general recommendations for the profession to survive, was the need for a partnership to be established between employers, workers and educators working together to create new supportive structures and develop knowledge and skills on an on-going basis. A further component to consider in addressing the exodus of social workers was for policy-makers, employers, educators and the South African Council of Social Service Professions (SACSSP) to prevent any further under-valuing of the profession and its practitioners. Social workers need to be presented as valued and crucial role players in our newly developed democracy.