M.Sc. / The upper catchment of the Olifants River, from its origin near Bethal, to its confluence with the Wilge River, north of Witbank, as well as it tributaries, are being subjected to increasing afforestation, mining, power generation, irrigation, domestic and industrial activities. These activities have a profound effect on the water quality and the major point sources of pollution in this area include mines, industries and very importantly, combined sewage purification works, located alongside the river, which, in addition to oxidizable material contains detergents, nutrients, and metals. It was therefore necessary to determine the extent to which these activities affect the water quality of the system. The impact of these activities was therefore addressed by a Water Research Commision Project namely "Lethal and sublethal effects of metals on the physiology of fish" of which the present study investigated effects at two localities, namely in the Olifants River (locality OR1) before its confluence with the Klein Olifants River and a locality in the Klein Olifants River (locality KOR1). Apart from the field study, toxicity tests were also performed in a laboratory, in order to determine the effects of low pH and elevated aluminium concentrations on the haematology, osmoregulation and carbohydrate metabolism of the Mozambique Tilapia, Oreochromis mossambicus as the acidification of soil systems may cause the transfer of aluminium into aqueous solutions, where it may be present in different forms. During the field study, the chemical and physical characteristics of the river water were evaluated, with special attention to the concentrations of certain metals (manganese, copper, chromium, lead, nickel, zinc, iron and aluminium) in the water and sediment, as well as in fish, which are known to accumulate the elements supra and are therefore valuable as indicators of these pollutants. The two fish species used for the investigations were the African sharptooth catfish, Clarias gariepinus and the moggel, Labeo umbratus. Four tissue types were dissected, namely the muscle, liver, skin and gill tissues. The metal concentrations in these organs/tissues, as well as in the water and sediment, were determined in a laboratory with an atomic absorption spectrophotometer. Statistical analyses were performed on the results obtained from this study and the order and extent of bioaccumulation of these metals in the water and sediment were determined, as well as in the fish organs/tissues. Its dependence on the size, sex and species of the fish and the localities and seasons were investigated.

M.Sc. / Metal ions have become an increasing source of pollution in the natural waters of South Africa. This phenomenon is related to the rapid industrial, mining and agricultural activity growth along rivers, especially in the Upper catchment of the Olifants River, Mpumalanga. In general, metal ions have - negative effects on the physiology of fish and other aquatic biota in metal polluted waters. In this study. the sublethal effects of, manganese were determined by exposing the freshwater fish, Oreochromis mossambicus, to this metal in an experimental flow-through system. The exposure times were divided in acute (96 hours) and chronic (26 days) exposures, both at 23 ± 1°C. The results obtained showed changes in the general, haematological, metabolic, osmoregulatory variables, as well as the differential white blood cell counts. These changes indicated several effects in the physiology of a mossainblais after sublethal manganese exposure. Significant differences (P < 0.05) were found between the haematological variables of the control and exposed fish. During chronic exposure, an oxygen deficiency developed due to , the epithelial lifting of gill lamellae. As a result of hypoxia the red blood cell numbers, haemoglobin-, haematocrit and lactate concentrations increased to uplift the depleted oxygen situation. The significant differences (P < 0.05) found in the sodium, potassium,. calcium and chloride concentrations are mainly as a result of gill damage. Manganese showed a disruptive influence on the structural organization of the gill. The differential white blood cell counts performed , showed significant fluctuations. This leucocytosis and leucopenia are normal reactions of the fishes’ body against infections of foreign substances, such as metal ions. It was concluded that the general haematology, metabolism, osmoregulation and differential white blood cell counts can, be used as indicators in detecting the effects of sublethal manganese exposure on fish.

M.Sc. / The recognition of the occurrence, importance and effects of contaminants on food chains and ecosystems has led to the development of biomonitoring programmes that use indicator species to estimate the levels in other parts of the ecosystem. There has been an increased awareness of potential pollution of ecosystems in Gauteng, South Africa, because of increased formal and informal urbanization, industrialization and mining activities. It is essential to obtain clear indications of metal pollution cause-effect relationships at ecosystem level in order to carry out effective management of these ecosystems. The objective was to investigate the application of an ecotoxicologically-based investigation of metals in selected bird species as bioindicators of metal pollution of ecosystems in Gauteng. Three passerine species were used, the Southern Masked Weaver (Ploceus velatus), the Red Bishop (Euplectes orix) and the Red-billed Quelea (Quelea quelea). The sites were selected to represent a theoretical pollution gradient from severely contaminated wetlands in the Vaal Triangle, to moderately contaminated wetlands in the Witwatersrand and Pretoria. A nature reserve in North West Province was chosen as reference site. The sites were Rietvlei in Tshwane, Roodekrans and Olifantsvlei in Johannesburg, Holfontein in the Vaal Triangle and Barberspan in North West Province. Two sampling surveys were carried out, one in 2002 and one in 2005. Feathers were collected for metal analyses. Blood samples were collected for biomarker (oxidative stress and DNA damage) and haematological analyses. The samples were digested using the microwave destruction technique. The metal analyses were carried out using ICP-MS. Oxidative stress enzymes (reduced glutathione content and catalase activity) were analysed in plasma samples and DNA damage was evaluated in red blood cells using the average base-pair length comparisontechnique. Haematological studies were done on the blood samples. The results were compared between the sites and surveys. The levels of stress correlated well with the levels of metals in the feathers. Sites with higher metal levels had higher levels of organism stress. Thus the study showed that the feathers can indeed be used in biomonitoring. Internationally there is a trend to incorporate Ecological Quality Objectives (EcoQOs) into legislation, especially when dealing with metal contamination. Within the framework of EcoQOs developed for birds the monitoring of contaminants forms a specific category of EcoQOs. However, due to a lack of available data, Reference and Target Levels still need to be set. The development of EcoQOs is especially important at this stage in South Africa. The recently promulgated National Biodiversity Act (10 of 2004) specifically provides for the preparation of conservation plans for identified ecosystems that are important because of their goods and services that they provide. Since there is no management tool available at present to develop a suitable management plan, the setting of EcoQOs that are in line with international standards and practices will be of immeasurable value to implementing the Act. Feathers from museum specimens were used to determine the Reference Levels for the various metals in the feathers. The Target Levels were calculated from the Reference Levels. These were compared to the Current Levels and the EcoQOs were determined for the metal levels in the feathers in weaver in Gauteng, South Africa. / Prof. V. Wepener

M.Sc. (Zoology) / Please refer to full text to view abstract

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M.Sc. / The water quality in the Vaal River system has deteriorated due to increasing industrial, mining and agricultural activities in the Vaal Dam and Vaal River Barrage catchment areas. This study was undertaken to determine the water quality in the Vaal Dam, and three localities within the Vaal River Barrage reservoir (i.e. the Riviera Aquatic Club, Abrahamsrust Pleasure Resort and at the Barrage structure). The objectives of this study, was to determine the fish population species composition, evaluate the general health of the selected fish species and obtain site specific metal bioaccumulation data for each locality. Suggestions and proposals for future monitoring and management of these waterbodies were also made. Metereological information on the Vaal River Barrage area was supplied by Rand Water, as well as physical and chemical data of fixed localities, sampled fortnightly (January 1997 to September 1998). In addition, water samples were collected at the Vaal Dam and the three Vaal River Barrage localities mentioned above, during February, May, August and November 1997. These samples were analysed by the Chemistry Department of the Rand Afrikaans University in accordance with standard methods. The chemical and physical characteristics and metal concentrations (aluminium, cadmium, calcium, copper, iron, magnesium, manganese, nickel, strontium and zinc) of these separate sets of data were then compared with Rand Water's Raw Water Quality Criteria. The aluminium, ammonia, chromium, copper, dissolved organic carbon, fluoride, iron, lead, manganese, nitrate, sulphate, total hardness and turbidity variables did not comply with the recommended guideline values. No guideline levels for strontium are available, however. Sedimentation, turbidity, salination and eutrophication within the Vaal River system play an important role in the bioaccumulation of metals by benthic organisms. Metals that adsorb to sediment particles, through various processes, are generally more persistent and less mobile than those in the overlying water and pose a severe long-lasting threat to the aquatic environment. Generally, the highest metal concentrations (AI, Cd, Cu, Fe, Mn, Ni, Pb, Sr and Zn) in the sediment samples collected at the four localities and seasons, were found in the finer sediment classes (class D). The Riviera Aquatic Club locality had the highest overall concentrations of the metals analysed. The adult fish communities within the Vaal Dam and Vaal River Barrage were assessed, as it is believed that the fish community structure is indicative of environmental conditions. Adult Labeo capensis, Labeo umbratus, Cyprinus carpio, Clarias gariepinus, Barbus aeneus and Micropterus sa/moides, were collected (using gill nets) to determine the adult fish community composition and age. When compared with a study conducted by Mulder (1971), it is clear that Labeo capensis has remained the most abundant species within the system, but that Barbus aeneus has now been replaced by Labeo umbratus as the second most abundant species. Furthermore, age determination tables (Mulder, 1971) were used to classify the fish population between the ages of 2 and 7 years. This indicates a healthy, dynamic community structure where recruitment is taking place. The Health Assessment Index (HAl) was used to determine the general health of the two fish species selected for metal analysis (i.e. Labeo capensis and Labeo umbratus). Except for moderate to severe gill damage recorded, no damage to external variables, were of concern. However, both Labeo capensis and Labeo umbratus had high percentages (89% and 93%, respecii tively) of abnormal livers. Using the Plascon Colour Chart (Watson, personal communication), these livers were classified as ranging from tan to "coffee with cream" in colour. High haematocrit and plasma protein levels were observed and could be due to environmental stress, while the White Blood Cell Counts were within normal ranges. Generally speaking, only mild to moderate parasite infections were observed and probably do not pose a serious health threat to the fish host. Total HAl values for Labeo capensis indicate that this this fish population was in relatively good health, but too few Labeo umbratus individuals were collected to make accurate assumptions about this population. Metal analysis (AI, Cd, Cu, Fe, Mn, Ni, Pb, Sr and Zn) was carried out on the tissues and organs (skin, muscle, gill filaments, gill arches, liver, hindgut content, gonads and vertebrae) of Labeo capensis and Labeo umbratus, collected during the study period. Only aluminium, iron and strontium are discussed. Aluminium concentrations were relatively high at all of the localities, but as pH values were mostly alkaline, aluminium is rendered biologically unavailable and as for iron, was mostly accumulated in the non-edible portion and viscera of the fish. Strontium accumulates in bony tissues due to its similarity with calcium, but is not essential for bone formation. The human health risks of these metals in the edible portion of the fish still have to be refined and communicated to the general public of South Africa. In conclusion, this baseline study has determined the metal concentrations in the aquatic environment (due to anthropogenic activities) that may be accumulated by fish and may affect the adult fish community structures and their general health.

M.Sc. / Pollutants present in minute concentrations in aquatic environments and which possess long residence times may be accumulated by aquatic organism such as fish, resulting in adverse affects. Bioaccumulation and biomarker responses are often used to qualify and quantify pollutant exposure and effect, and for this reason form a major part of many environmental assessments. To interpret bioaccumulation and biomarker responses the physico-chemical parameters of the environment should be known. This study aimed to spatially and temporally assess the environmental partitioning of heavy metals in three South African freshwater systems, namely the Pongolapoort Dam, Olifants and Luvuvhu Rivers, and to relate these concentrations to bioaccumulation and biomarker responses in tigerfish, Hydrocynus vittatus. This is because there is relatively little known about the bioaccumulation potential and stress responses of tigerfish to pollutants and they have recently become listed as a protected species. Result from this study showed that there were few differences between seasons in terms of metal bioaccumulation in the Pongolapoort Dam with the exception of Se, Zn and Fe. Selenium and Fe concentrations were linked to concentrations found in the environment, whereas Zn was attributed to a disruption in homeostasis within the fish. Increases in MT were found during the winter months and were attributed to increased metal concentrations at this time, namely Zn and Se, whereas decreases in CEA and PC were observed at this time and were linked to depleted energy reserves, stress and a reduction in the presence of pesticides as a result of decreased runoff during the winter months. It was found in the Olifants and Luvuvhu Rivers that there were no distinct decreases in metal concentrations as the rivers flowed through the KNP, and processes such as rainfall, remobilization of sediments, distance of the study area from the source and geology played a great role in the distribution of metals. Metal concentrations in the Olifants River water, sediment and fish were, for the most part, found to be lower than previous studies, possibly due to improvement in management strategies or increased buffering of this river. Only Al and As were significantly higher in tigerfish from the Olifants River, and this was reflected in high MT concentrations. It was suggested that tigerfish from the Olifants River have developed effective mechanisms for the excretion and detoxification of heavy metals that they are exposed to as a result of extended exposure. Concentrations of AChE were also significantly inhibited in tigerfish from the Olifants River which is indicative of greater concentrations of organophosphates and carbamate pesticides than the other sites. Tigerfish from the Pongolapoort Dam had signifcantly higher levels of MT and significantly inhibited concentrations of AChE in comparison to tigerfish from the Luvuvhu River. The tigerfish from the Luvuvhu River had significantly higher concentrations of Se in muscle tissue. Tigerfish from the Luvuvhu River, also experienced stress as a result of pollution as was apparent from significantly depleted energy reserves in comparison to the other sites under study, and higher concentrations of PC and CYP1A which are typical biomarkers responding to halogenated and aromatic pesticides, such as deltamethrin and endosulfan. It was recommended that further studies be done to assess the presence of pesticides within these systems to determine the contribution of these pollutants to the state of tigerfish

Irgarol 1051 is a common antifoulant toxic to certain marine organisms. Submerged aquatic vegetation (SAV) are exposed to this herbicide when it leaches into the marine environment from painted structures, making SAVs ideal candidates to function as sentinel indicator of contamination. In the initial stage of this study, Coconut Grove and Key Largo Harbor were assessed for environmental exposure to Irgarol. Water, sediment and SAVs were collected, the latter two subject to automated solid phase extraction, and all samples analyzed by GC/MS-SIM for Irgarol and its metabolite, M1. Of the vegetation analyzed, Halodule and Syringodium had the highest capacity to bioaccumulate Irgarol and M1. The root system and leaf contributed negligibly and significantly, respectively, to Irgarol uptake. In the final stage, a transplant between Coconut Grove and Chicken Key showed that the biota Thalassia and Halodule were able to uptake and depurate Irgarol, respectively, over a period of 30 days.

O consumo de peixes e frutos do mar está associado à manutenção de uma dieta saudável em função da sua proteína de elevado valor biológico, da presença de ácidos graxos poli-insaturados e de importantes nutrientes como selênio, ferro, cálcio e fósforo. No entanto, esses organismos representam uma importante fonte de elementos-traço contaminantes para os seres humanos em função da bioacumulação desses elementos que também podem biomagnificar ao longo da cadeia alimentar. Apesar da ocorrência natural de elementos-traço no meio ambiente, sua concentração nos ecossistemas costeiros tem aumentado drasticamente em função de atividades antropogênicas, fazendo com que os organismos marinhos atuem como um elo da contaminação ambiental à contaminação humana. O presente trabalho avalia a concentração de elementos-traço em diferentes tecidos de organismos marinhos sob dois aspectos: (1) o risco alimentar associado ao consumo das espécies analisadas e (2) a bioacumulação dos elementos em diferentes tecidos. Para isso foram analisadas três espécies de peixes comercializadas na cidade de Santos (SP): Sphyraena guachancho (bicuda), Priacanthus arenatus (olho de cão) e Genidens genidens (bagre) e três espécies coletadas em diferentes pontos do Sistema Estuarino de Santos (SP): Callinectes danae (siri azul), Mytella guyanensis (mexilhão) e Mugil curema (parati). O hábito alimentar foi o principal critério para seleção das espécies. O risco alimentar, calculado pelo Índice Provisório de Risco (PHI) e pelo Índice Provisório de Risco Total (PTHI), apresentou valores elevados para Sphyraena guachancho (espécie piscívora) e para peixes e siris coletados no Sistema Estuarino de Santos. A bioacumulação foi associada à espécie, tecido e tipo de elemento avaliado. A espécie piscívora apresentou elevada concentração de Ba, Hg e Ag no tecido muscular, indicando a potencial biomagnificação desses elementos ao longo da cadeia alimentar. Genidens genidens, espécie detritívora, apresentou elevada concentração de Ba, Cd e Pb na nadadeira, possivelmente associado às estratégias de detoxificação da espécie, por meio da imobilização desses contaminantes no esporão ósseo. / The consumption of fish and seafood is associated with the maintenance of a healthy diet due to its protein of high biological value, the presence of polyunsaturated fatty acids and important nutrients as selenium, iron, calcium and phosphorus. However, these organisms represent an important source of contaminant trace elements for humans due to the bioaccumulation of these elements in tissues that can also biomagnify along the food chain. Despite the natural occurrence of trace elements in the environment, its concentration in coastal ecosystems has increased dramatically as a result of anthropogenic activities, causing marine organisms to act as a link between environmental and human contamination. The present work evaluates the concentration of trace elements in different tissues of marine organisms under two aspects: (1) the food risk associated with the consumption of the species analyzed and (2) the bioaccumulation of the elements in different tissues. Three species of fish commercialized in the city of Santos (SP) were analyzed: Sphyraena guachancho (bicuda), Priacanthus arenatus (dog eye) and Genidens genidens (catfish) and three species collected at different points of the Santos Estuarine System (SP): Callinectes danae (blue crab), Mytella guyanensis (mussel) and Mugil curema (parati). The eating habit was the main criteria for selection of the species. The food risk, calculated by means of the Provisional Hazard Index (PHI) and the Provisional Total Hazard Index (PTHI), presented high values for the piscivorous species Sphyraena guachancho and for fish and crabs collected in Santos Estuarine System. The bioaccumulation was associated with the species, tissue and type of element evaluated. The piscivorous species had a high concentration of Ba, Hg and Ag in muscle tissue, indicating the potential biomagnification of these elements along the food chain. Genidens genidens, a detivorous species, presented a high concentration of Ba, Cd and Pb in the fin, possibly associated with the detoxification strategies of the species, through the immobilization of these contaminants in the bone spur.