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

Ph.D. / Except for agriculture, the mining industry is considered as not only the oldest but also the most important industry. Mining involves the removal of minerals from the earth's crust for usage by mankind. The disturbance during mining activities such as mining effluent has an effect on the natural aquatic environment. In any freshwater environment, the macroinvertebrates form a vital link between the abiotic envinronment and the organisms in higher trophic levels. It is thus true that specific environmental contaminants, such as mining effluent, may directly affect the survival of macorinvertebrates. The density and diversity of macroinvertebrates is in a direct relation with the water quality. For the purpose of this study, attention was given to the effects of gold and coal mine effluent on the macroinvertebrate fauna, as well as to the determination of metal accumulation from the water through the macroinvertabrates to fish. At Case Study Mine One, with an open water system, acidic conditions of the water caused a reduction in the number and diversity of macroinvertebrates. A closed water system, characteristic of Case Study Mine Two, presented a slightly more abudandant macroinvertebrate population than with the previous mine. The results lead one to conclude that the surface water in this study area is of a better quality. Case Study Mine Three had a complex water circuit and presented a greater number and diversity of macroinvertebrates, with the best water quality of the three mines investigated.

Acclimation temperature had a significant effect on the lethality of copper to fathead minnows in replicated 96-hour lethality tests. Lowest median lethal copper concentrations (LC50) were recorded at 12 and 22°C, with LC50s at 5 and 32°C at least 140 μg/1 higher. This research found LC50 copper concentrations in the 300 to 500 μg/1 range and a polynomial relationship between LC50s and acclimation temperature. Following a 24-hour exposure to three sublethal concentrations of copper, critical thermal maxima (CTMax) were tested in minnows acclimated to four temperatures. Sublethal exposure to copper significantly decreased the CTMaxs relative to controls at three of the four temperatures. Control CTMaxs ranged from 28.6 to 40.4°C and increased 0.46°C for each 1°C increase in acclimation temperature.

Normal ranges of values for hematological parameters of bluegill gathered seasonally from three lakes were determined. Sexual, seasonal, and inter-lake variations were found. Effects of 2-wk exposure to turbidity on blood parameters included an increase in rbc size and a decrease in small lymphocytes. Effects of 3-hr exposure were increases in rbc count, hemoglobin, and pH and decreases in PG2 and large lymphocytes. The effects of 0.44 and 0.88 ppm chloramines were an increase in blood pH, a decrease in MEV, and severe spastic reactions resulting in loss of equilibrium or death in 90% of the fish. Effects of Flexibacter columnaris included an increase in transformed lymphocytes and a decrease in small lymphocytes.

Ph.D. (Zoology) / The study concept was derived following an information requirement related to the need for the development of a scientifically sound technique to minimize illegal entries at major South African freshwater fishing tournaments. The hypothesis was that fish that are in equilibrium with the environment that they live in should reflect the chemistry of that environment. Therefore it would be possible to chemically link the fish to a specific impoundment and identify whether the fish are indeed from that impoundment or whether they were brought there to be illegally entered at a fishing tournament. The project area consisted of selected lakes within the Vaal, Mgeni, Crocodile (West) and Olifants River catchments in South Africa. The catchments were chosen to contain major sport fishing lakes and to have different sizes, different sources of pollution, different underlying geological compositions and different climates. Soil analyses data from the regional geochemical mapping program of the Council for Geoscience as well as lake sediment and lake water analyses were used to trace chemical elements during weathering, erosion and deposition. This was done to identify unique characteristics that are able to distinguish between water and sediment from individual lakes. It was found that Rb, Sr, Ba, Cu, Ni,Th, Pb, Sc, K, Mg and Ca could be effectively used as single elements or element ratios to distinguish between lakes. Large variation in sediment compositions within individual lakes limited this distinction. Anomalous catchment soil concentrations related to the underlying geology or anthropogenic contamination can however be traced to lake sediments. Rare earth elements are not uniformly distributed in lake sediments or lake waters and sampling localities should be carefully considered when comparing lakes. Leachable soil sulphate distribution patterns from coal mining areas above Lake Witbank and Lake Middelburg extend downstream through Lake Loskop to Lake Arabie (Flag Boshielo). Leachable fluoride, abundant in the Pilanesberg Alkaline Complex extends northwards along rivers draining the complex. The mineralogy of lake sediments was also compared with the major element composition of these sediments as well as with the anion composition of lake water. Genetic rock classification diagrams could be used effectively to show correlations between catchment soil and lake sediment samples both in terms of mineralogy and chemistry. Lake water and fish tissue samples were collected and analysed to investigate the link between element concentrations in lake water and otolith, fin spine, muscle, liver and gill tissues. Using the Sr/Ca elemental ratio, a species-specific correlation was identified between lake water, otolith, spine and gill tissue samples. The best discrimination between fish species was achieved using a Na/Ca versus Mg/Ca elemental ratio diagram of gill tissues. The best discrimination between fish from different lakes was achieved using a Ba/Mg versus Sr/Mg elemental ratio diagram for spine tissue. Sediments from most lakes in the project area showed elevated Hg values during the dry season as well as elevated Hg levels in sediments from the deeper/central part of these lakes. Lake Sterkfontein has a low sediment Hg concentration but contains fish with the highest Hg tissue concentration in the project area. When comparing the Hg distribution in fish muscle and spine tissue from the project area there is a better correlation with species than with location. The Sr isotope ratio of lake water shows a remarkable correlation with the Sr isotope ratio of fish from the same lake. Analytical data showed that fish within a specific lake all have the same Sr isotope ratio in their spines regardless of species, age, sex and condition. The Sr isotope ratio of water generally increases with distance from the source within tertiary catchments and is determined by the prevalent geology of the formations being weathered. In large rivers like the Vaal River where pollution also plays a role the pattern is much more complicated. The Pb isotopic composition of soil samples from Pretoria and the surrounding areas correspond well to the major underlying geological units. Superimposed on this pattern is an anomalous anthropogenic Pb component possibly related to leaded fuel, which extends from the Pretoria city center northwards along the road and railway networks. Water and sediments from Lake Bon Accord and Lake Marais also contain this anthropogenic signature. The hypothesis that fish, which are in equilibrium with the environment that they live in, should reflect the chemistry of that environment, is therefore not rejected since the results of analysing lake water and fish tissues from 23 South African lakes, within 4 major catchments showed definite correlations. Comparing single elements is the least effective method of establishing such correlations. Comparing elemental ratios is a much better method, while comparing isotope ratios is the most effective method.

Thesis (M.Sc. ( Physiology )) --University of Limpopo, 2011 / Refer to document / the National Research Foundation

A research program was developed to investigate basic and applied aspects of toxicity, both lethal and sublethal, of hemoxidants, particularly nitrite, on fish, non-fish aquatic vertebrates, and crayfish. The major objectives of this research were to determine A) acute and sublethal toxicity of nitrite to selected aquatic organisms: 1. aquatic salamander larvae, Ambystoma texanum, 2. swamp crayfish, Procambarus simulans, 3. bluegill, Lepomis macrochirus, 4. bullfrog, tadpoles, Rana catesbiana, 5. channel catfish, Ictalurus punctatus, B) the influence of environmental chloride on acute and sublethal exposures to hemoxidants: 1. on acute nitrite toxicity to salamander larvae, crayfish, and bluegill, 2. on nitrite-induced methemoglobinemia in bullfrog tadpoles, Rana catesbian, C) the effect of environmental hydrogen ion concentrations (pH) on acute nitrite toxicity 1. to the crayfish, Procambarus simulans, 2. to the bluegill, Lepomis macrochirus, D) the effect of temperature in sublethal exposures to nitrite 1. methemoglobin formation in channel catfish exposed at different acclimation temperatures, 2. recovery from methemoglobinemia at different acclimation temperatures, E) the effect of the fish anesthetic TMS-222 on nitrite-induced methemoglobinemia in channel catfish 1. supression of nitrite-induced methemoglobinemia, 2. dose-response curve for TMS-222 induced methemoglobinemia, and F) if a methemoglobin reductase system is present in channel catfish.

MSc. (Zoology) / The Albasini Dam was used as a reference site outside the DDT (1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane) - sprayed area in a previous survey conducted from 2006 to 2008. DDT, endocrine disrupting chemicals and inorganic chemicals were detected in the dam. A histological analysis of fish from the dam showed histological alterations in heart, liver, gills, and gonads. Therefore, it was necessary to follow up the health status of the dam by monitoring the levels of organic and inorganic chemicals and their effects on fish. The aim of the present study was to determine the health status of three freshwater fish species, Clarias gariepinus, Oreochromis mossambicus, and Coptodon (Tilapia) rendalli from the Albasini Dam, using fish histology as a biomonitoring tool. In total, 18 fish were sampled using gill nets; these included Clarias gariepinus (n=5); Coptodon (Tilapia) rendalli (n=4) and Oreochromis mossambicus (n=9). The histology-based fish health assessment included a standard fish necropsy; a calculation of blood parameters (haematocrit, leukocrit and total plasma protein); somatic indices and the condition factor and a qualitative and semi-quantitative histological assessment of five target organs: liver, heart, gills, kidney and gonads. Water, sediment and fish muscles samples were collected and analysed for inorganic chemicals and organic chemicals. Inorganic chemicals were analysed by means of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Optic Emission Spectrometry (ICP-OES). Organic chemicals in water and fish muscles were analysed using Gas Chromatography-Mass Spectrometry (GC-MS). Nutrients and physical parameters of water were also measured...

PhD. (Chemistry) / This thesis focuses on functionalising the silicone membrane by filling it with synthesised γ-Fe2O3 nanoparticles for the purpose of using it as a passive sampling device for monitoring microcystins and cylindrospermopsin in aquatic environments. The identity and purity of the synthesised nanoparticles was verified by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), surface zeta potential analyser and Brunauer-Emmet-Teller (BET). There was no chemical uptake of microcystin compounds into the silicone membrane without a suspension of maghemite nanoparticles. But, a linear uptake of microcystin compounds was observed into the functionalised silicone membrane passive sampler throughout the exposure period. These findings suggest that the silicone membrane filled with a suspension of synthesised γ-Fe2O3 nanoparticles can be an efficient, green and less costly instrument useful in estimating biotoxin concentrations in South African waters and the world at large.

M.Sc. (Aquatic Health) / The North West Province is mineral rich and known for its extensive mining and agricultural activities. These activities drain organic and inorganic pollutants in our waterways, possibly resulting in reduced water quality in dams. Organic and inorganic pollutants such as nutrients, organochlorine pesticides and metals may be present in unacceptable levels possibly affecting fish as well as human health. The North West dams are known for their high nutrient loads and are mostly classified as hypertrophic. In order to better understand the possible effects of the combined pollutant loads on fish health and edibility of fish, (1) a fish health assessment and (2) a human health risk assessment should be conducted. The fish health assessment and the human health risk assessment form an important role in the establishment of water quality standards or/and guidelines for acceptable levels of safe consumption of fish respectively. The aim of this study was to determine (1) if Oreochromis mossambicus from the Klipvoor -, Roodekopjes - and Vaalkop Dams show adverse effects and (2) if consumed, pose a human health risk. The results were compared to the reference site, the Marico-Bosveld Dam.