Based on previous necropsy results, Microcystis blooms in constructed water impoundments in the Kruger National Park (KNP) have been identified as a cause of wildlife mortality. In response to wildlife mortality during 2007, water samples, containing algal bloom material, were collected during February 2007 and July 2007 from four dams (Nhlanganzwani, Mpanamana, Makhohlola, and Sunset) in the southeastern part of the KNP as part of the follow-up investigation. The toxicity of the Microcystis blooms was determined using the enzyme-linked immunosorbent assay (ELISA), protein phosphatase inhibition (PPI) assay, mouse bioassay, and African sharptooth catfish (Clarias gariepinus) primary hepatocytes. Both the ELISA and PPI assays indicated that the water sample collected during February 2007 from the Nhlanganzwani Dam, and samples collected from the Nhlanganzwani and Sunset dams in June 2007, were toxic. These dams, exhibiting the toxic Microcystis blooms, were also associated with the wildlife mortality. Mice injected intraperitoneally with water samples from Nhlanganzwani Dam (February 2007) induced hepatotoxicity and mortality within 1 hr. Primary hepatocytes from the sharptooth catfish exposed to samples from these dams gave similar results. This laboratory investigation and results strongly incriminate the toxic Microcystis blooms as the cause of the wildlife mortality. Eutrophication and bloom formation appear to have been the consequence of the high numbers of hippopotami (Hippopotamus amphibius) in specific dams.

The toxicity of purified microcystin-LR (MC-LR) and algal material collected during the winter and summer seasons (2005/2006) from the Hartebeespoort dam, South Africa, was investigated using the enzyme-linked immunosorbent assay (ELISA), mouse bioassay, catfish primary hepatocytes (in vitro assay) and protein phosphatase inhibition (PPi) assays. Microcystis aeruginosa, known producer of microcystins, was the dominant cyanobacteria present in the water samples. Exceptionally high cell numbers per millilitre were observed, especially with the summer samples (~1.442 × 10 8 cells/ml), indicating a severe algal bloom in the dam. The toxin concentration as detected by ELISA and PPi assay in the winter and summer extracts was at least 1000 times more than the provisional guideline value (1 mg/l) set by the World Health Organization (WHO) for MC-LR in drinking water. Hepatotoxic effects and death of mice were observed after dosing with the summer extracts, while no hepatotoxic effects were observed with winter extracts. The EC 50 values obtained after exposure of the catfish primary hepatocytes for 72 h to MC-LR, winter and summer extracts was about 0.091, 0.053 and 0.014 mg/l, respectively. Similar toxicity results were obtained when the mouse bioassay and primary hepatocytes were used. Keywords: Catfish primary hepatocytes; Mouse bioassay; ELISA; Protein phosphatase inhibition; AssayIn South Africa and other parts of the world, livestock, waterfowl, wildlife and game animals have died after drinking water containing heavy blooms of blue-green algae (Steyn, 1945;Soll and Williams, 1985;Bell and Codd, 1994;Harding et al., 1995;Van Halderen et al., 1995;Kellerman et al., 2005). Records of poisoning incidents that can be attributed to cyanobacteria in South Africa date back to the 1920s, when mass mortalities of thousands of cattle, sheep, horses and rabbits around pans in the south-eastern Transvaal were reported (Steyn, 1945;Soll and Williams, 1985;Harding and Paxton, 2001). According to a report published by the Department of Water Affairs and Forestry (DWAF, 2002), many South African surface water resources exhibit high nutrient enrichments and eutrophication-related problems. About 80 dams were monitored between October 2002 and September 2003 in South Africa (Van Ginkel, 2003. Eleven per cent of the monitored dams were hypertrophic (showing serious water quality problems), 23% were eutrophic (showing increasing signs of water quality problems) and 25% were mesotrophic (showing emerging signs of water quality problems). Microcystin levels detected in the hypertrophic dams ranged from1 to 28 930 mg/l (Wicks and Thiel, 1990; DWAF, 2002;Van Ginkel, 2003). Given the current status of algal blooms in the impoundments of South Africa, sensitive and specific monitoring assays for cyanotoxins are required. Toxicity testing is important to ensure good water quality for human and animal consumption, and for recreational activities. For many years the mouse bioassay has been used to determine toxicity of blooms (Carmi...

Background: South African universities face a challenge of low throughput rates, with most students failing to complete their studies within the minimum regulatory time. Literature has begun to investigate the contribution of well-being, including mental health, with depression among students being one of the most common mental disorders explored. However, locally relevant research exploring associations between depression and academic performance has been limited. This research hypothesizes that the presence of depression symptoms, when controlling for key socio-demographic factors, has an adverse impact on student academic outcomes and contributes to the delay in the academic progression of students. Methods: The study used a cross-sectional design. Data were collected in 2019 from first-time, first-year undergraduate students using a self-administered online questionnaire. In total, 1,642 students completed the survey. The Patient Health Questionnaire-9 (PHQ-9) was used to screen for depression symptoms. Data on students’ academic performance were obtained from institutional records. Bivariate and multivariate regression analyses were used to examine associations between depression symptoms and academic performance. Results: Most participants (76%) successfully progressed (meeting the requirements to proceed to the second year of university study). Of the participants, 10% displayed symptoms of severe depression. The likelihood of progression delay (not meeting the academic requirements to proceed to the second year of university study) increased with the severity of depression symptoms. Moderate depression symptoms nearly doubled the adjusted odds of progression delay (aOR = 1.98, 95% CI: 1.30-3.00, p = 0.001). The likelihood of progression delay was nearly tripled by moderate severe depression symptoms (aOR = 2.70, 95% CI:1.70–4.36, p < 0.001) and severe depression symptoms (aOR = 2.59, 95% CI:1.54–4.36, p < 0.001). The model controlled for field of study, financial aid support as well as sex and race. Conclusion: Higher levels of depression symptoms among first-year university students are associated with a greater likelihood of progression delay and may contribute to the low throughput rates currently seen in South African universities. It is important for students, universities and government departments to recognize student mental wellness needs and how these can be met.