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A research study was conducted to examine the relationship between speciation of heavy metals (Zn, Cd, Pb, Cu) and their biotoxicity. Therefore, static bioassay experiments were designed to determine LC-50 values for those metals on mosquitofish, Gambusia affinis. The standard bioassay scheme consisted of twelve 16-liter all-glass aquaria that provided duplicates of five different metal concentrations and a control for each run. Deionized tap water and filtered retention/detention water from Maitland Pond were used for bioassays. The effects of various physiochemical parameters such as pH, alkalinity, hardness and organic complexation on metal toxicity were determined. Also, synergistic and antagonistic effects resulting from metal mixtures were examined. It was concluded that metals in pond water were considerably less toxic than in deionized water for mosquitofish. Also, copper was consistently the most toxic metal tested for both deionized water and pond water.

The brain of fish, as in other vertebrates, is responsible for many functions basic to life and is also thought to be an anoxia-sensitive tissue. Therefore, during anoxia, the maintenance of energy within the brain is of paramount importance to the survival of the animal. Studies concerning energy levels and storage and the use of anaerobic metabolism in fish brains following exposure to anoxia are lacking. Rainbow trout (<u>Salmo gairdneri</u>) and brown bullhead catfish (<u>Ictalurus nebulosus</u>) occupy ecologically distinct habitats. Their tolerance of anoxia is different; trout survived l2 minutes while bullhead survived 62 minutes in anoxic water. Brains from control and anoxiaâ exposed trout and bullheads were analyzed using enzymatic assays and high pressure liquid chromatography (HPLC). Control bullhead brains had higher concentrations of glycogen, ATP, CrP, and glucose than control trout. With anoxia, bullheads showed a significant decrease in ATP, CrP, and glycogen with no change noted for glucose, ketone bodies (betaâ hydroxybutyrate and acetoacetate), or alternative anaerobic endproducts (succinate, alanine, propionate, isobutyrate, isovalerate, and ethanol). Lactic acid increased two-fold with anoxia. The bullhead was able to generate ATP by depleting its CrP stores and through classical anaerobic glycolysis. Death was most likely due to an inability to maintain ATP levels. Catfish may survive anoxia longer than trout in part due to greater fuel stores. Rainbow trout brain stored approximately one sixth the amount of glycogen as bullheads. With anoxia, these stores were depleted but there was no significant decrease in ATP, CrP, or glucose; the alternative endproducts also did not change. There was a l00% increase in lactic acid, suggesting that anaerobic glycolysis helped maintain ATP levels. Death may be due to factors other than ATP depletion such as lactic acid injury and increased intracellular free calcium. / Master of Science

Three nontaxonomic indices; ATP/Chlorophyll <u>a</u>(ATP/Chla), ATP/ADP, and Chlorophyll <u>a</u>/Pheopigment (Chla/Pheo) were compared to the taxonomic measures of species diversity (d) and species richness as indicators of stress in aquatic environments. Field and laboratory microcosm responses of indigenous microbial communities exposed to municipal sewage treatment plant (STP) effluent were monitored. The STP effluent produced increased adenylate concentrations, ATP/ADP and ATP/Chla ratios, and decreased Chla, Chla/Pheo, d, and species richness relative to upstream reference communities. Nontaxonomic responses were consistent in four separate field tests. Significant differences in responses were discernible in 3 d when communities were transferred from reference to polluted sites. Chla/Pheo decreased more rapidly than other measurements. The predictive capability of laboratory flow through microcosm tests was examined by simultaneously transferring communities from upstream reference sites to downstream field sites and to various dilutions of field effluent in the laboratory. / Master of Science

M.S.

Bluegill were exposed to 3 and 30 pg/L lindane and 20 and 200 pg/L naphthalene to determine uptake rate constants, K1 depuration rate constants, K2, and bioconcentration factors, BCF. Correlations were determined between lipid normalized and non-lipid normalized BCFs, and between observed Kl, K2 and BCFs and predicted values. The K1 values for both chemicals and concentrations were similar. The K2 values were different (1.04 day~1, 0.46 day 1). Naphthalene was more rapid. BCFs for lindane (315) and naphthalene (98) were different. Lipid normalized BCFs for naphthalene were more variable than non-lipid normalized BCFs. The reverse was observed for lindane BCFs. Predicted K1, K2 , and BCFs were in agreement with observed values.

The primary objective of this work was to determine the tissue-specific bioconcentration factors (BCFs) of the selected pharmaceuticals: norethindrone (NET), ibuprofen (IBU), verapamil (VER), clozapine (CLZ) and fenofibrate (FFB) in two freshwater fishes: fathead minnow and channel catfish. BCF tests on fathead followed the standard OECD 42-day test while a 14-day abridged test design was used in catfish exposures. Additional objectives included a) comparing the measured BCFs to the US EPA's BCFWIN model predicted values, b) comparing the BCF results from the standard and reduced tests, and c) prediction of chronic risk of the pharmaceuticals in fish using the human therapeutic plasma concentrations. Each test included uptake and depuration phases to measure tissue-specific kinetic BCFs. The results indicated that all the pharmaceuticals, except IBU, have the potential for accumulation in fish. Estimated BCFs for NET, VER and FFB may not be significant in view of the current regulatory trigger level (BCF &#8805; 2000); however, CLZ's BCF in the liver had approached the criterion level. Significant differences were noticed in the tissue-specific uptake levels of the pharmaceuticals with the following general trend: (liver/kidney) > (gill/brain) > (heart/muscle) > plasma. IBU uptake was highest in the plasma. When compared to the measured BCFs, predicted values for NET, IBU, VER and FFB were slightly overestimated but did not differ largely. However, the measured BCF of CLZ in the liver was approximately two-orders of magnitude higher than the predicted level. The tissue-BCFs for the two species were not widely different indicating the potential usefulness of the reduced BCF test. Comparison of fish and human plasma levels indicated that NET, CLZ and VER have the potential to cause chronic effects in fish.

Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2018 / This study aimed to determine the effects of water and sediment quality on fish and the effects of land-use on the water and sediment quality of the Steelpoort River system. To achieve these aims, a few objectives had to be met. The water and sediment quality, the level of metal bioaccumulation of two fish species, the level of acetylcholine esterase inhibition in fish brain tissue, as well as changes in land-use over time. The study adds value in the scientific knowledge of the Steelpoort catchment given that there’s little information about it. It is thus a good baseline, which gives direction for further studies conducted within this catchment. The Steelpoort River, is a tributary of the Olifants River system. The Olifants River (Mpumalanga and Limpopo provinces) is a river stressed by anthropogenic activities with the Steelpoort River being a major sub-catchment. The Steelpoort catchment is filled with mines, agricultural activities, and other developments, such as, the construction of a new dam (De Hoop Dam opened 2014), residential areas and malls. The mines within the catchment are mostly platinum and chrome mines. Sampling was conducted for high and low flow at five sampling sites: Two upstream sites, 1 and 2, and three downstream sites 3, 4, and 5. Site 1 is the reference site for the study as this section (ecoregion) was described as “least threatened”. It was hypothesised that high concentrations of metals and nutrients would be present in the water and sediment, and that the metal would be present in fish tissue and would have an effect on human health, that the biomarker AChE would show signs of inhibition within brain tissue, and lastly that land-use characteristics would have an effect on the water and sediment quality, and inhibition of AChE. Water and sediment samples were collected quarterly over a period of a year at five sites, whereas fish samples (Chiloglanis pretoriae and Labeobarbus marequensis) were only collected bi-annually at three sites. The physico-chemical, nutrients, cations and ions, and metals and metalloids were determined. The two fish species were used for metal bioaccumulation and AChE analyses. Human health risk and bio-concentration factor (BCF) analyses were conducted. Using the land-cover details obtained from South African National Biodiversity Institute (SANBI), Department of Environmental Affairs (DEA) and The Council for Scientific and Industrial Research (CSIR), land-use characteristics were determined and evaluated. The in-situ physico-chemical parameters assessed in this study were found to be within acceptable limits of the Target Water Quality Range (TWQR) at all the sites. The Electrical Confuctivity (EC) and Total Disolved Solids (TDS) parameters were highest at Site 5 and lowest at Site 1, this could be due to Site 5 being the last site before the Steelpoort River connects to the Olifants River, hence this site recieves all the ions and solutes from upstream; and the lowest value at Site 1 could be attributed to this site having the least number of lan-use effects. For nutrients, the highest total nitrogen concentration was recorded at Site 5 and the highest phosphate concentration at Site. This river is mesotrophic according to both the total inorganic nitrogen and phosphorus levels. Metals in the water column that were above DWAF guidelines for Aquatic Ecosystems were Al, Ba, Mn and Zn. In the sediment the following metals were above the Canadian sediment quality guidelines: Cd, Cu, Cr and Zn, which can pose a threat to the health of fish through biomagnification through the food chain. Both C. pretoriae and L. marequensis had bioaccumulated metals from the river system. The concentrations of metals in the muscle tissue of C. pretoriae where higher and this could be due to the fact that unskinned samples were used in the case of C. pretoriae. A variety of metals were present in both fish species but Al, Fe, Sr and Zn were present in higher concentrations. Concentrations of metals were highest in samples from Site 5 The human health risk assessment revealed that Pb could cause health related impacts to the humans who consume a single 150 g fish meal once a week in C. pretoriae; and that Co could cause potential risks in the near future. The BCF values revealed that there were more bioconcentrated metals in C. pretoriae than in L. marequensis and this could also be due to different diets. The AChE activity was higher for L. marequensis during high flow at all sites and higher at Site 1 during low flow but lower at Site 5 and equivalent at Site 2 than the AChE activity recorded for C. pretoriae. This could be due to the ability of L. marequensis to expel pesticides from their system before the pesticides affect brain activity by decreasing the function of AChE. Both fish species had more AChE activity during low flow for sites 1 and 2 than during high flow. The high flow AChE activity was higher for Site 5 in both fish species. The results confirm the hypotheses were that metals would be present in fish tissue and would have an effect on human health; and that the biomarker AChE would show signs of inhibition within brain tissue. The agricultural activity has decreased over time within the catchment, from 2000 to 2014 and this could be due to a decrease of fertile land. There has also been a decrease in the mining activity from 2000 to 2009 and then an increase during 2014, where the decrease could be due to the closure of mines at the end of their life span; and the increase in 2014 could be due to the opening of new mines. Residential areas have increased from 2000 through to 2014. The availability of water decreased from 2000 to 2009, and then increased drastically in 2014. The drastic increase is due to the multiple dams that have been built over time in order to provide water resources to the increased population, and also for mining and irrigation purposes. The water quality showed an increase in the NO3, SO4 and PO4; meanwhile the EC has decreased over time. The decrease in EC means that there are fewer ions in the river. The increase in phosphates and nitrates could mean there is a lot of fertilizers and pesticides being used in agriculture even with the decrease in agricultural land-use over the years. The pesticides can also be due to the increase in residential areas, where pesticides are also used to get rid of pests.

Four experiments were carried out with broiler chicks from day-old to three or four weeks of age to assess the effects of nitrates and nitrites from calcium, potassium, and sodium salts in the drinking water of broilers on growth, body weights, feed utilization, blood chemistries, liver tissues, and lipid oxidation of breast and thigh tissues. Body weights were lower (P<.05) among chicks consuming calcium nitrate than those of chicks consuming sodium nitrate or the control. Chicks consuming calcium nitrate (Ca(NO���)���) at 1000 ppm had lower (P<.05) body weights than those drinking Ca(NO���)��� at 0, 50, or 200 ppm. Broilers receiving 1000 ppm of calcium nitrite (Ca(NO���)���) had depressed body weights when compared to chicks consuming 0, 50, or 200 ppm of Ca(NO���)���. Consumption of sodium nitrate (NaNO���) at 2033 ppm reduced (P<.05) broiler weights in comparison to broilers ingesting 0, 111, or 427 ppm of NaNO���. Feed utilization was less efficient (P<.05) by chicks ingesting Ca(NO���)��� and calcium, potassium, or sodium salts of nitrite when compared with the control. / Graduation date: 1996