published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

Toxic/mutagenic potentials of Gambierdiscus toxicus (GT) and Prorocentrum lima (PL) methanol extracts (CME) were determined using brine shrimp (Artemia salina), mouse, chicken embryo and Salmonella microsomal assays. PL-CME and GT-CME were toxic to shrimp and mice. Isolation and separation were accomplished using ether/water, hexane/methanol partition and butanol extraction. Toxic fractions were purified using column and thin layer chromatography (TLC). GT-CME showed low levels of mutagenic potential. For GT isolated fractions and PL-CME, no mutagenic effects were observed. Both CMEs showed embryotoxicity, with no teratogenic effects. Ether/methanol and water/butanol fractions showed shrimp toxicity. These fractions were purified by treatment with warm/cold acetone. Acetone insoluble precipitates were obtained. Ether soluble acetone filtrate (ESAF) and butanol soluble acetone precipitate (BSAP) showed shrimp and mouse toxicity. GT-BSAP produced temperature depression in mice. Three toxic isolates were obtained from PL-ESAF, four from GT-ESAF and one from both BSAPs columns. TLC preparative plates showed at least 12 toxic isolates for PL-ESAF, 8 for GT-ESAF and 4 for GT-BSAP.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

M.Sc. (Aquatic Health) / The Bojanala Platinum District (BPD) in North West Province (NWP) is a well-established mining and agricultural region of South Africa. These activities result in surface runoffs that are likely to pollute nearby freshwater impoundments, including the Roodekopjes (RD) and Vaalkop Dams (VD). These impoundments support subsistence fishing, where the fish caught, are often the sole source of dietary protein for local communities. The aim of this study was two-fold: firstly, to assess the health status of the fish in these impoundments by (i) conducting a necropsy-based macroscopic evaluation, (ii) calculating appropriate biometric indices, and by (iii) performing a semi-quantitative histology-based fish health assessment (HBFHA) on selected target organs of two freshwater fish species, namely Clarias gariepinus (Sharptooth Catfish) and Cyprinus carpio (Common Carp). Secondly, the edibility (safe for human consumption) of these fish species was to be determined by (i) quantifying the bioaccumulation of selected organic and inorganic toxicants within the muscle of the fish collected and (ii) assessing the resultant potential health risk/s through consumption toward consumers of these fish. In addition, in situ physico-chemical parameters were measured and samples of water and sediment were collected for laboratory analysis at each of the assessed impoundments. Otoliths and scales were also collected for age estimation. Tissue samples for histology were fixed in formalin (liver, kidney & heart) and Bouin’s (gills, gonads & skin) solution and processed for light microscopy analysis using standard histological techniques. Water, sediment and muscle samples were analysed for organic and inorganic toxicants by accredited laboratories using ICP-MS & ICP-OES. Results from the two assessment sites (RD & VD) were assessed against a reference site, the Marico-Bosveld Dam (MBD).