Thesis (M. Sc. (Zoology and Entomology))--Rhodes University, 2006.

Os estudos em microbacias hidrográficas têm mostrado que as características físicas, químicas e biológicas das águas dos córregos e riachos possuem uma estreita relação com a composição do ambiente terrestre adjacente, refletindo as condições de uso e ocupação dos solos da bacia hidrográfica por eles drenada. A microbacia do Córrego do Cancã, localizada perpendicularmente ao Rio Monjolinho, situa-se em uma maior parte no município de São Carlos (SP), e foi estudada sob uma abordagem ecossistêmica. As coletas e análises de campo foram realizadas em sete transectos do córrego, em dois períodos hidrológicos distintos: seca e chuva. A caracterização física e química da água foi realizada através da análise do pH, da condutividade elétrica, da concentração de oxigênio, da temperatura, da concentração e da carga de nutrientes. Alguns dos parâmetros analisados foram comparados aos limites estabelecidos pela CONAMA segundo a resolução nº 20/1986. O córrego do Cancã, segundo a classificação proposta pela CONAMA, é um rio de classe-2. A água do córrego é levemente ácida tendendo à neutralidade em um gradiente da nascente à foz e caracteriza-se pela baixa condutividade elétrica. A temperatura variou entre os períodos avaliados e espacialmente foi influenciada pelos horários de coleta. As concentrações de nutrientes não foram elevadas, e das formas nitrogenadas as mais abundantes foram o nitrato (na estação mais impactada) e o amônio (após o represamento), com valores mais elevados no período de seca. A maior variabilidade foi observada para o nitrogênio total, sendo as maiores concentrações registradas na estação seca. Com base no índice de estado trófico, as águas do córrego do Cancã foram classificadas como mesotróficas. A forma da microbacia é irregular e ligeiramente alongada e pouco sujeita a enchentes. A área da microbacia foi determinada como sendo de 3,075 Km2. Na análise das comunidades planctônicas foram encontrados poucos representantes, distribuídos principalmente nas estações localizadas nos trechos inicial e médio do córrego, sendo, entretanto mais abundantes na nascente. Ocorreu predominância das clorofíceas e diatomáceas entre os organismos fitoplanctônicos e de rotíferos e cladóceros no zooplâncton. A microbacia está sujeita à práticas agrícolas e atividade pecuária semi-intensiva que alteram o balanço de massa dos principais nutrientes, contribuindo para o aumento da carga de nutrientes que são carreados do sistema terrestre para o aquático particularmente no período chuvoso. / The studies peformed in small hydrographic basins have shown that the physical chemical and biological characteristics of the water in springs and streams have a close relation with the composition of adjacent terrestrial ecosystems, reflecting the uses and activities in the soils in the basin drained by them. The microbasin of Cancã stream belongs to the Monjolinho river basin and is mainly located inside the district of São Carlos (SP). In this study It has been evaluated under the ecosystemic approach. Field sampling and analysis were carried out in seven transects of the stream at two distinct hydrological periods: dry and rainy seasons. Physical and chemical analyses of water were performed by mesuring the pH, electrical conductivity, dissolved oxygen and the nutrient concentrations and loads. The parameters obtained were compared to the CONAMA limits, act nº 20/1986. The Cancã stream according to CONAMA proposed system, is classified as a class 2 water. The pH of Cancã water is slightly acid and there a tendency to the neutral from the source to the mouse. It is also characterized by low electrical conductivity. Water temperature has changed between dry and rainy periods and spatially it was influenced by the sampling timing. Nutrient concentrations are low and the main nitrogen compounds present were nitrate and ammonium, at the most impacted site, with highest values in the dry season. The highest variability was obtained for the total nitrogenvariability with higher concentrations at the dry season. Based on the trophic state index. The water of Cancã stream was classified as mesotrophic. The hydrographic microbasin has a non-regular shape, being slightly elongated and it has low vulnerability to floodings. The area of the catchment was found to be 3,071 Km2. Planktonic communities were composed by few organisms mainly occuring at the upper and middle stream streches, being most abundant at the first stretch. Clorophyceans and diatoms were the dominant groups among phytoplankton and the rotifers and cladocerans among the zooplankton. Cancã microbasin is subjected to a variety of agriculture and semi-intensive cattle enterprises that have changed major nutrient mass balances, contributing to the increase in nutrient loadings mainly via surface terrestrial runoff.

Ph.D. (Zoology) / The present study deals with the effects of metal-polluted aquatic habitats at five different localities on the Witwatersrand and the Orange Free State on the concentrations of lead, nickel, copper and cadmium in the organs and tissues of the Redknobbed Coot, Fulica cristata, the Sacred Ibis, Threskiornis aethiopicus, and the Reed Cormorant, Phalacrocorax africanus. The physical and chemical conditions of the water and the sediments which prevailed during the period of survey at the various sampling sites suggest that concentrations of parameters such as phosphates, nickel and lead in a number of cases exceeded the limits laid down by Kempster et at. (1980) for acceptable river water quality standards in South Africa. The major sources of pollution responsible for these conditions can primarily be related to sewage, mine and industrial effluents (urban) as well as agricultural practices (rural), respectively. Mining activities were largely responsible for the acidification and miniralization as well as metal pollution of the water and sediments, especially so at the Marievale Bird Sanctuary in the Blesbokspruit catchment area. However, automobiles are suspected to contribute much towards the lead concentrations in the water and sediments at all the sampling sites. Levels of cadmium were generally low and may be the only one of the four metals analysed which truly reflected unpolluted, environmental conditions for this metal in the water and sediments of all the sampling sites. The nutrient loads which suggest mild to moderate eutrophication of the water at all the localities can largely be attributed to sewage effiuents and surface runoff waters from the surrounding townships on the Witwatersrand as well as from inorganic fertilizers from farm lands in the vicinity of the Steynsrus and Senekal farm dams in the Orange Free State. These conditions resulted in the overall increase in primary and secondary production of the affected waters which also coincided with the development of submerged and floating water weeds such as Potamogeton pectinatus and Azolla filiculoides, respectively. The herbivorous Redknobbed Coot and to a lesser extent the piscivorous Reed Cormorant, benefitted directly or indirectly from these conditions. Data obtained during the investigation present a complex situation in terms of the environment and the biological availability of the four metals under discussion. A number of factors in both the abiotic and biotic components may have had an effect on fluctuations in metal concentrations. These may have acted individually and/or synergistically, making the interpretation of the data difficult. Cadmium occurred in the lowest concentrations of all four metals in all four the organs and tissues during all four seasons of investigation. In the case of the rest of the metals as well as the organs and tissues no specific, clear seasonal trend or sequence in the concentrations of the metals was discernible. Copper in the kidney and liver and lead in the bone and blood tissues had the highest mean concentrations over the four seasons of investigation. As far as the winter and summer seasonal tendencies are concerned, statistically significant differences occurred in the concentrations of some metals in specific organs and tissues between the winter and summer seasons, respectively. However, values recorded were not necessarily higher during a particular season. Lead (liver) and cadmium (kidney) concentrations were found to be significantly higher in winter 1991 whilst cadmium and copper (both in the blood) were significantly lower during this same season, compared to winter 1992. Concentrations of nickel did not differ significantly between organs and tissues such as the liver and blood for particular seasons. It was only nickel in the kidney and cadmium in the bone tissue which reflected definite seasonal trends for the four successive seasons of investigation.

M.Sc. (Botany) / Eight sampling points were selected on the Jukskei River so that the impact of inflows from various localities on the quality of the river water could be determined. Samples were taken every two weeks from the 4th April 1983 to 19th March 1984. The temperature, conductivity, dissolved oxygen and pH of the water were determined on site. Determinations of total phosphorus (as p-po1-), nitrate (NO), chloride (C11 and chlorophyll a were done. After filtration the water of each sample was inoculated with Euglena gracilis and incubated for four days under controlled conditions after which the Euglena chlorophyll-content, primary productivity and biological growth potential were measured...

Ph.D. (Zoology) / Please refer to full text to view abstract

Ph.D. / The primary objective of the study was to determine the ecological integrity of the Klip River. The protocols applied during the study gave a reliable and good reflection of the overall ecological integrity, as well as the state of different components determining the overall integrity. The ecological integrity of the most recent assessment (February 1999) is summarized in Figure 8.2. It was decided to keep the different components determining ecological integrity (physico-chemical, physical, biological) separate and not to combine everything into one score. When expressed separate, such as in the case of Figure 8.2, it is possible to observed deterioration in overall ecological integrity at a site, and it is also evident which of the components are responsible for the degradation. As mentioned previously, biological communities, and thus biotic integrity, are the best indicators of overall ecological integrity, due to the fact that they integrate both water and habitat related stresses over time. Habitat and water quality assessments are indications of the conditions prevailing at the time of sampling, while biota give an indication of the conditions prevailing over the long term. Invertebrates have shorter life cycles, and in many cases have a terrestrial phase, therefore they recolonise quicker than fish may be able to do after a pollution incident. Invertebrates can therefore be seen as indicators of short-term biological integrity, while fish indicate long-term biological integrity of a river. / Prof. G.J. Steyn

Colonisation theory relative to introduced populations was examined with a view to determining the usefulness of theoretical concepts in the prediction of the success of an invasion by a species. To this end, the Great Fish River, with reference to species introduced by the Orange/Fish Tunnel, was used as a case history. It was concluded that theoretical descriptions of population growth, control and decline are useful only when considering individual ecosystems or species. The highly variable nature of species and environments nullifies attempts to simplify behavioural characteristics into a predictive framework. There is an abundance of terminology associated with introduced organisms and frequently many of these terms are used synonymously. Eleven terms have been defined in this thesis with a view to standardising terminology. Characteristics of species and environments which enhance their susceptibility to invasions by exotic ichthyofauna were discussed and summarised. Distribution data concerning exotic fish introduced into the Great Fish River by the Orange/Fish Tunnel has demonstrated that, with the exception of Clarias gariepinus, all remaining exotics have restricted distributions. Only Barbus aeneus appears to be extending its range down the drainage. Age, Growth, reproduction and condition data support the conclusion that, excluding B. aeneus and C. gariepinus, invasive species in the drainage are not performing well. Of the five invasive species (B. aeneus, Labeo capensis, L. umbratus, Gephyroglanis sclateri and Cyprinus carpio), only two have established populations (B. aeneus· and C. gariepinus). Labeo umbratus and C. carpio were present on the Great Fish River prior to the construction of the tunnel and populations of the species could not be distinguished. It was concluded that there is no evidence to suggest that exotic species introduced into the Great Fish River are having a deleterious effect on indigenous, endangered ichthyofauna. Monitoring of the drainage should be continued to ensure that a danger to indigenous species does not develop.

M.Sc. (Zoology) / Ari investigation was made into the biological control of the submerged aquatic weeds Potamogeton pectinatus, Lagarosiphon major and L. muscoides in the Florida Lake, Transvaal using the Chinese grass carp Ctenopharyngodon idella (Val.) as biological control agent. The physical, chemical (including selected heavy metals), faunal and bacteriological conditions were also investigated over a period of one year. The total standing crop of P.pectinatusand Lagarosiphon spp, were reduced from an initial 0,193 kg m" 2 (wet mass) in March 1990 to 0,0338kg m-2 (wet mass) in March 1991. Reductions in the densities of the macrophytes coincided with a corresponding increase in chIorophyll-a values in the water columm of the lake. Abnormally high concentrations of the heavy metals copper, manganese, iron, nickel chromium, zinc and lead were found to occur in the lake sediments, aquatic macrophytes, ftlamentous algae, macroinvertebrate fauna as well as in organs and tissues of the perch Perea fluviatilis. These metals could be related to gold mining activities which occurred in the vicinity of the lake some years ago. Faecal bacterial counts of the water in the lake point towards the possible contamination of the lake water with domestic sewage. Ari analysis of the faeces of the numerically dominant birds which occur at the lake i.e. the coot Fulica aistata and the egyptian goose Alopochen aegyptiacus suggest that the main cause of faecal contamination of the lake's water possibly originates from these and other water birds frequenting the lake. By using the results on the physical-chemical conditions in the lake, conditions which presently prevail can be summarized as being largely that of a mesotrophic impoundment with strong tendencies towards eutrophic conditions. Secondary effects of the grass carp on the lake ecosystem was the progressive decline of weed eating birds and a slight increase in the numbers of piscivorous birds, both of which could be linked to the drastic reduction in the standing crop of the submerged weeds in the Lake. The present survey confirms the value of the Chinese grass carp as biological control agent in the management of excessive growths of submerged aquatic weeds in lakes and reservoirs in South Africa...

The use of biomarkers in assessing the health of aquatic ecosystems is widely being used. Biomarkers have been proposed as sensitive early warning tools for biological measurement in environmental quality assessment. In this study, DNA damage, HSP 70 expression, Lactate dehydrogenase and alkaline phosphatase were evaluated for their usefulness and applicability in the active biomonitoring of the Rietvlei system using Melanoides tuberculata and Oreochromis mossambicuss as test organisms. Levels of DNA strand breakage were measured in the exposed test organisms and the references that were kept in the laboratory under unpolluted environment. Different levels of DNA damage were recorded in M tuberculata that were exposed during high-flow and those from the low-flow exposure period. There was no difference in DNA between the control and high-flow exposure M. tuberculata but the low-flow exposure duration had significantly higher DNA damage for all the three sites when compared to the high-flow and the controls. There was no difference in the amount of DNA damage in both exposed and control O. mossambicus. Fish samples were only available for the high-flow four weeks exposure because of the test organisms dying during the low-flow exposure. Heat shock protein 70 expression was determined in O. mossambious only and significant differences in expression between sites were demonstrated with highest expression at site 1 decreasing down stream at sites 3 and 5. The activity of LDH in M. tuberculata was not different in both control and exposed fish at all the sites. There was no difference in the activity of LDH between the high-flow and low-flow exposure groups in M. tuberculata. In O. mossambicus, the activity of LDH was significantly inhibited at site 1 with the effects of the contaminants decreasing downstream at sites 3 and 5 where LDH activity did not differ from the controls. There was no alkaline phosphatase activity in both exposed and control M. tuberculata but in O. mossambicus alkaline phosphatase was significantly inhibited at the three sites although inhibition did not differ from site to site. This suggests that LDH and alkaline phosphate are not sensitive biomarkers in M. tuberculata in the Rietvlei system but are sensitive in O. mossambicus. DNA damage was shown to be a sensitive biomarker using M. tuberculata but it was difficult to assess this in O. mossambicus since fish were only available during the 4 weeks high-flow exposure, which did not show any differences from the control. The lack of DNA damage in O. mossambicus maybe a result of low concentration of contaminants during high-flow or because this biomarker is not sensitive in fish. / Prof. J.H.J. Van Vuren

M.Sc. (Zoology) / Suidwes-Afrika is. tn land van kontraste. Dit is tn dorre gebied waar water die paspoort is tot lewe. Die jaarlikse reenval is betrekIik laag (280mm, Dept. Waterwese. 1972) sodatdie natuurlike dreineringsisteme vir die grootste gedeelte van die jaar bree sandslote is. Tydens die kort reenseisoen verander dit egter in bruisende watermassas, wat afloop om uiteindelik in die see, moerasse .of die sand van die Kalahari te verdwyn. Die bou van groot opgaardamme soos die Hardap-, Naute- en Von Bachdam het hierdie watermassas vir mens en dier opgegaar. Die vraag ontstaan egter of water, wat vir mens, dier en op besproeiingslande beskikbaar gestel is, ten volle benut word…