The use of intestinal parasites as indicators of pollution has increased in Europe due to the fact that parasites accumulate more of the available metals than their hosts. Eighty Largemouth yellowfish, Labeobarbus kimberleyensis (Gilchrist and Thompson, 1913) were collected between April 2005 and February 2006 with gill nets at RAU Island (26° 52, 249’ S, 28 10, 249’ E) in the Vaal Dam. The fish were killed, weighed and their lengths determined. Muscle, liver and spinal cord tissues were collected from each fish and the intestines removed and opened to expose Bothriocephalus acheilognathi. The position of attachment of B. acheilognathi in the host’s intestine was recorded. Thereafter tapeworms were collected in glass bottles and frozen. Water and sediment samples were collected. Clossed vessel microwave digestion was used to digest liver, muscle and tapeworms with Suprapur Nitric acid, and spinal cord tissue with Suprapur Nitric acid and Suprapur Hydrochloric acid. Thereafter metal concentrations of twenty three elements (Lithium, Beryllium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Arsenic, Selenium, Molybdenum, Cadmium, Tin, Antimony, Tellurium, Barium, Mercury, Thallium, Lead and Uranium) were determined specifically for each tissue type with an ICP-MS. Certified dogfish liver (Dolt-3) was used as a quality control standard. Water quality data was provided by Rand Water and included. Statistical data were analyzed with ANOVA and post-hoc tests and parasite infection statistics were calculated. Seasonality and intensity of tapeworms were compared to the intestine and total lengths of the fish. All the tapeworms were identified as the Asian Tapeworm B. acheilognathi Yamaguti, 1934. Bothriocephalus acheilognathi attached between 10% and 20% from the anterior end of host intestine. A 100% prevalence of Asian tapeworm was recorded in all surveys and the highest mean intensity of 231.1 was recorded in autumn and the lowest mean intensity of 73.7 was recorded in summer. The fecundity of largemouth yellowfish was not influenced by the high infection rate of B. acheilognathi as young fish fry was collected during the summer survey and the fish condition was good. No correlation was observed between parasite intensity and total length of each fish. This indicates that intensity is not dependant on host size. Parasite numbers are higher and differ from a previous study. Water quality of Vaal Dam changed in summer, due to transferance of water from the Grootdraai Dam. Algal counts and secchi disk readings increased. This indicates that zooplanktonic intermediate hosts increased due to an increase in food availability and increased the chance of infection. Significant differences were recorded in one sample T-test comparisons, while ANOVA indicated that significant differences between tissue groups and seasons occurred. Bioaccumulation of metals occurred in tapeworms in Selenium, Mercury, and Lead during autumn, Copper, Zinc, Selenium, Cadmium, Antimony, Thallium and Mercury during winter, Lithium, Zinc, Selenium, Cadmium and Antimony during spring and Zinc during summer. The highest mean value was recorded in sediment, followed by water, tapeworms and then the host tissue. The general trend was sediment > water > tapeworms > liver > spinal cord > muscle. Die gebruik van intestinale parasiete as indikatore vir besoedeling het in Europa verhoog omdat die parasiete meer van die beskikbare metale as hul gashere akkumuleer. Tagtig Grootbekgeelvisse Labeobarbus kimberleyensis (Gilchrist en Thompson, 1913) was tussen April 2005 en Februarie 2006 met kieunette te RAU eiland (26° 52, 249’ S, 28 10, 249’ E) in die Vaaldam versamel. Die visse is doodgemaak, geweeg en hul lengtes bepaal. Spier, lewer en werwelkolomweefsel was versamel van elke vis en die intestinums verwyder en oopgemaak om Bothriocephalus acheilognathi bloot te lê. Die posisie van aanhegting van B. acheilognathi in die gasheer se intestinum is aangeteken. Daarna is die lintwurms in glasbottels versamel en gevries. Water en sediment was ook versamel. Geslote-flesmikrogolfvertering was gebruik om lewer, spier en lintwurms met Suprapur® Swaelsuur en werwelkolom met Suprapur® Swaelsuur en Suprapur® Soutsuur te verteer. Daarna is die metaalkonsentrasies van drie-en twintig elemente (Litium, Berillium, Titanium, Vanadium, Chroom, Mangaan, Yster, Kobalt, Nikkel, Kopper, Sink, Arseen, Selenium, Molibdenum, Cadmium, Tin, Antimoon, Tellurium, Barium, Kwik, Tallium, Lood and Uranium) spesifiek vir elke weefseltipe bepaal met ‘n IGP-MS. Gesertifiseerde haailewer (Dolt-3) was gebruik as ‘n standaard ter wille van kwaliteitskontrole. Waterkwaliteitsdata is deur Rand Water verskaf en word ingesluit. Statistiese data was geanaliseer met ANOVA en nagraadse toetse en parasiet infeksie statistieke was bereken. Seisonaliteit en intensiteit van die lintwurms was vergelyk met die totale lengtes van visse en intestinumlengte van die visse. Al die lintwurms was as Asiese lintwurms B. acheilognathi Yamaguti, 1934 geïdentifiseer. Bothriocephalus acheilognathi was tussen 10% en 20% vanaf die anteriorgedeelte van die gasheerintestinum geheg. ‘n 100% persentasiebesmetting was opgeteken in alle opnames met Asiese lintwurms en die hoogste gemiddelde besmettingsintensiteit van 231.1 was opgeteken in die herfs en laagste gemiddelde besmettingsintensiteit van 73.7 waargeneem in die somer. Die broeisukses van die Grootbekgeelvisse was nie beïnvloed deur die hoë infeksies met B. acheilognathi nie, soos blyk uit die feit dat jong vissies versamel is tydens die someropname en die viskondisie was ook goed. Daar was geen korrelasie waargeneem wanneer die parasietintensiteite en totale lengtes van die visse vergelyk is nie. Dit dui dat intensiteit nie afhanklik is van gasheergrootte nie. Die parasietgetalle is hoër en verskil van ‘n vorige studie. Die waterkwaliteit van die Vaaldam het verander gedurende somer a.g.v. die toevoer van water vanaf die Grootdraaidam. Die algtellings en die secchi-skyf lesings het dus verhoog. Dit dui dus aan dat die getal soöplanktoniese tussengashere verhoog het agv die verhoogde voedselbeskikbaarheid en ‘n hoër kans van infeksie vir visse. Betekenisvolle verskille was waargeneem wanneer enkel monster T-toets vergelykings gemaak is, terwyl ANOVA betekenisvolle verskille tussen groepe en seisoene gewys het. Bioakkumulasie van metale in lintwurms het in selenium, kwik en lood gedurende herfs, en in koper, sink, selenium, cadmium, antimoon, tallium en kwik in winter, en in litium, sink, selenium, cadmium en antimoon in lente en in sink gedurende somer voorgekom. Die hoogste gemiddelde waarde was waargeneem in sediment, gevolg deur water, lintwurms en gasheerweefsel. Die algehele akkumulasie verwantskap is sediment > water > lintwurms > lewer > werwelkolom > spier. / Prof. Annemarie Avenant-Oldewage

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.