The Best PhD Thesis in the Faculties of Dentistry, Engineering, Medicine and Science (University of Hong Kong), Li Ka Shing Prize,1999-2001 / published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

A dissertation submitted to the Faculty of Science, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science. Johannesburg 2015 / Exposure to inorganic and organic pollutants residues causes negative effects to human health. They can cause damage to the living organism as well as to the environment. Humans take up these pollutants through skin absorption, respiration and ingestion of contaminated food and also the drinking water as a potential contaminants exposure route for inorganic and organic pollutants to humans. Studies have shown that inorganic and organic pollutants can be retained in food crops at higher than the permissible levels, thus posing some health risks to consumers. This study sought to assess the potential risk posed by inorganic and organic pollutants to human health as a result of consuming raw food and processed food cooked in traditional utensils. The food samples and the traditional utensils were collected in Kinshasa and Johannesburg markets. In total ninety- two food samples were assessed. The food crops included: cabbage, cassava, beans, beef meat and fish (tilapia). Ten trace elements, namely: Al, As, Cd, Cr, Cu, Hg, Mn, Pb, Se and Zn were analysed in raw food samples using ICP-OES, ICP-MS and mercury analyser. These metals were also analysed in food cooked with the traditional utensils. The health risk indices calculated were: Daily Intake of Metal (DIM) and Hazard Index (HI). The results obtained reveal that the raw food collected in Johannesburg markets contained a significant (p ˂ 0.05) higher concentration in all elements than the food samples collected in Kinshasa markets. Hg was detected only in fish samples. It was observed that cooking utensils can leach some significant quantities of trace elements into food during processing, hence resulting increase the concentration of these metals in processed foods. The DIM exceeded the oral reference dose (Rfd) and the HI were ˃ 1 in all the food cooked. The results of metal found in this current investigation were above the standard permissible limit set by FAO/WHO. On the other hand, the levels of 17 organochlorine pesticides were assessed in uncooked and cooked beans, cabbage, cassava, fish and beef meat collected in Kinshasa and Johannesburg markets. It was noticed from the results recorder that the mean concentration of organochlorine pesticides in uncooked food collected in Johannesburg market were significantly high (p ˂ 0.05) than the uncooked food from Kinshasa markets. DDE recorded its highest mean level (253.58±4.78 μg kg-1) in beef meat samples collected in Johannesburg markets. The results from the current study revealed that after cooking the amounts of organochlorines were significantly reduce than the uncooked food. Residue amounts of organochlorine pesticides found in this study are considerably lower than the recommended amount of organochlorines set by WHO/FAO (300 μg kg-1). / MT2016

It has been suggested that fruit features such as nutrient content, size and colour have co-evolved with dispersal agent behaviour, physiology and morphology. Avian nectarivore feeding ecology is relatively well studied; however, less is known about fruit selection in avian frugivores. Previous work highlights the importance of individual factors that contribute towards fruit preferences, but few studies bring these factors together. Consequently the aim of this dissertation was to attempt this in terms of frugivory by investigating behavioural, physiological and morphological aspects of fruit selection in generalist avian dispersers. This was achieved by manipulating the nutritional content, size and colour of fruits (artificial fruits) under controlled conditions. The first part of the dissertation addresses physiological aspects of fruit selection in Red-winged Starling Onychognathus morio, Speckled Mousebird Colius striatus and Dark-Capped Bulbul Pycnonotus tricolor. Assimilation efficiency of birds fed glucose and sucrose diet treatments of varying concentration was observed. All study species showed high apparent assimilation efficiency irrespective of artificial fruit sugar concentration and type (with the exception of Red-winged Starlings on an all sucrose diet). The second part of the dissertation addresses behavioural aspects of fruit selection in the same three species by observing selective preferences between glucose and sucrose fruits of varying concentration and molarity. While Mousebirds displayed no preference for any of the diet treatments, Bulbuls occasionally favoured glucose diets over sucrose diets and Starlings always favoured glucose diets over sucrose diets. Another behavioural aspect of fruit selection was addressed in the third part of the dissertation. Colour preferences of Red-winged Starling and Speckled Mousebird were observed. Although study species did not conform to trends by favouring black and red fruits, they did show avoidance of green fruits and (Starlings) presented evidence of learning. A morphological aspect of fruit selection is presented in the fourth part of the dissertation. Starlings, Bulbuls and Mousebird beak morphology was measured to investigate if this has an effect on fruit size preferences. Starlings with the largest beak dimensions were more selective of fruit size classes than Bulbuls and Mousebirds which displayed the importance of feeding method (thrashing/swallowing/mashing) to compensate for larger fruit sizes. The final section of this dissertation is a synthesis of the observed behavioural, physiological and morphological aspects of fruit selection in Red-winged Starlings, Dark-capped Bulbuls and Speckled-Mousebirds. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.