Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: In this study the chromosomal arsenic resistance (ars) genes shown to be present in all Acidithiobacillus. caldus isolates were cloned and sequenced from At. caldus #6. Ten open reading frames (ORFs) were identified on a clone conferring arsenic resistance, with three homologs to arsenic genes, arsC (arsenate reductase), arsR (regulator) and arsB (arsenite export). This ars operon is divergent, with the arsRC and arsB genes transcribed in opposite directions. Analysis of the putative amino acid sequences of these arsRC and arsB genes revealed that they are the most closely related to the ars genes of Acidithiobacillus ferrooxidans. These ars genes were functional when transformed into an Escherichia coli ars deletion mutant ACSH50Iq, and conferred increased levels of resistance to arsenate and arsenite. ArsC was required for resistance to arsenate, but not for resistance to arsenite. None of the other ORFs enhanced arsenic resistance in E. coli. A transposon located arsenic resistance system (TnAtcArs) has been described for highly arsenic resistant strains of the moderately thermophilic, sulfur-oxidizing, biomining bacterium At .caldus #6. In the latter study it was shown that TnAtcArs confers higher levels of resistance to arsenate and arsenite than the chromosomal operon. TnAtcArs was conjugated into a weakly ars resistant At. caldus strain (C-SH12) and resulted in greatly increased arsenite resistance. RT-PCR analysis revealed that arsR and arsC are co-transcribed. Despite ORF1 (cadmium inducible-like protein) and ORF5 (putative integrase for prophage CP-933R) not being involved in resistance to arsenic, ORF1 was co-transcribed with arsRC and ORF5 with arsB. Using arsR-lacZ and arsB-lacZ fusions it was shown that the chromosomal ArsR-like regulator of At. caldus acts as a repressor of the arsR and arsB promoter expression. Induction of gene expression took place when either arsenate or arsenite was added. The chromosomal located ArsR was also able to repress TnAtcArs, but the transposon-located ArsR was unable to regulate the chromosomal system. / AFRIKAANSE OPSOMMING: In hierdie studie is die chromosomale arseen weerstandbiedendheidsgene (ars gene), teenwoordig in alle Acidithiobacillus caldus isolate, gekloon en die DNA volgorde daarvan vanaf At. caldus #6 bepaal. Tien oopleesrame (ORFs) is geïdentifiseer op ‘n kloon wat arseen weerstandbiedend is, met drie homoloog aan ars gene, nl. arsC (arsenaat reduktase), arsR (reguleerder) en arsB (membraan-geleë pomp wat arseniet uitpomp). Die ars operon is gerangskik met die arsRC en arsB gene wat in teenoorgestelde rigtings getranskribeer word. Analise van die afgeleide aminosuurvolgorde van dié ars gene het getoon hulle is naverwant aan die ars gene van Acidithiobacillus ferrooxidans. Die ars gene was funksioneel na transformasie na ‘n E. coli ars mutant (ACSH50Iq), en het ‘n hoër vlak van weerstand teen arsenaat en arseniet gebied. ArsC was nodig vir weerstand teen arsenaat, maar nie vir weerstand teen arseniet nie. Geen van die ander ORFs het arseen weerstandbiedendheid in E. coli bevorder nie. Voorheen is ‘n ars operon, geleë op ‘n transposon (TnAtcArs), in ‘n hoogs arseen-weerstandbiedende stam van die middelmatige termofiliese, swawel-oksiderende, bio-ontgunning (“biomining”) bakterie Acidithiobacillus caldus #6 beskryf. In laasgenoemde studie is gevind dat TnAtcArs hoër vlakke van weerstand bied teen arsenaat en arseniet as die chromosomale operon. TnAtcArs is na ‘n lae arseen-weerstandbiedende At. caldus stam (C-SH12) gekonjugeer. Die resultaat was ‘n groot verhoging in arseen weerstandbiedendheid. RT-PCR analise het onthul dat arsR en arsC saam getranskribeer word. Benewens die feit dat ORF1 (kadmium induseerbare protein) en ORF5 (afgeleide integrase vir profaag CP-933R) nie betrokke is in weerstand teen arseniet and arsenaat nie, is ORF1 saam met arsRC getranskribeer en ORF5 saam met arsB. Deur gebruik te maak van die fusie-gene arsR-lacZ en arsB-lacZ is bewys dat die chromosomale ArsR reguleerder van At. caldus as ‘n inhibeerder van die arsR en arsB promoter uitdrukking funksioneer. Indusering van geen uitdrukking vind plaas wanneer arseniet of arsenaat bygevoeg word. Die chromosomaal-geleë ArsR is ook in staat om TnAtcArs te inhibeer, terwyl die transposon geleë ArsR nie daartoe in staat is om die chromosomale ars sisteem te reguleer nie.

Microphytobenthos (MPB), a mixed community of microscopic, photosynthetic organisms, algae and cyanobacteria, inhabiting the top few millimetres of bottom sediment, is a key component of intertidal mudflats. It accounts for a significant proportion of estuarine primary production, forms the base of the food chain and influences sediment distribution and resuspension (through production of extracellular polymeric substances (EPS)). Diatoms dominate the microphytobenthos community in the mid-latitudes of the Northern Hemisphere. Estuarine sediments, are a sink for metal contaminants derived from fluvial, marine and atmospheric sources. Whilst metal releases to estuaries have declined in recent years due to increased regulation and declining industrial activity, metals previously discharged and which are now locked up in saltmarsh sediments remain a concern. For example, there are indications that saltmarshes are already being eroded, due to climate change related sea level rise, in some locations. This erosion may result in the redistribution of historically contaminated sediment to locations, such as the mudflats, where it is more available to biota, such as the MPB. In addition to causing redistribution, climate change effects, such as increasing temperatures and storminess, may also alter the bioavailability of metals to MPB. Increased concentrations of metals within the MPB could potentially increase their transfer to higher organisms through the food chain with potential impacts for biota. Whilst planktonic algae have been well studied with respect to metal uptake from the water column, there has been little research involving MPB and uptake of metals from sediment. The extent to which contaminant uptake by microphytobenthic algae occurs and under what conditions is therefore poorly understood. The research presented uses laboratory, mesocosm and field studies, to gain an understanding of processes governing metal bioavailability and mechanisms for uptake from sediment to the diatoms of the MPB under the complex and variable conditions of intertidal mudflats. A laboratory study using a single diatom species Cylindrotheca closterium found that uptake of cadmium (Cd) varied with sediment properties revealing the importance of sediment particle size and organic matter content in metal bioavailability to diatoms. Additionally, this study showed that the presence of diatoms altered Cd partitioning between sediment, overlying and pore water. Specifically there was an increase in Cd in the overlying and pore water when diatoms were present, indicating that diatoms mobilise metals from the sediment to the water column potentially increasing metal bioavailability to other biota. A study was conducted using an intertidal mesocosm to increase the realism of the study system and examine uptake to a natural MPB community. Diatoms were found to have higher concentrations of all the metals analysed (except tin) than other types of algae (filamentous and sheet macroalgae), confirming their importance as a study organism with respect to metal uptake and potential mobilisation through the food chain. Sediment disturbance was shown to increase metal uptake (iron, aluminium, vanadium and lead) from the sediment to algae. This is of concern due to predicted increases in storminess which are likely to increase sediment disturbance, with the likelihood that uptake of metals to diatoms will increase in the future. However, there were also indications of an antagonistic effect of temperature on disturbance, whilst disturbance increased bioavailability and uptake, increasing temperatures reduced uptake of some metals. This highlights the importance of considering the effects of multiple stressors in complex systems. Field studies showed that concentrations of some metals were related to their position on the mudflat whilst others were related to sampling date, indicating that there may be seasonal controls, such as to the presence of greater diatom biomass in spring and autumn, on metal uptake from the sediment. The research conducted has increased understanding of metal uptake to microphytobenthic diatoms from sediment and the influence they have in transferring metals from sediment to water, however the research also raises a number of new questions. For example, there appeared to be a link between sediment organic matter content and bioavailability of metals to diatoms, although the relative contribution of the diatoms, other algae, cyanobacteria and EPS to the sediment organic matter warrants further investigation. Furthermore, it has shown that the use of laboratory and mesocosm studies for this type of research can produce similar outcomes to those observed in the field but under more controlled and easily manipulated conditions, although field studies will continue to be vital in improving understanding of metals availability and transfer.

D.Phil. / The entire Olifants . River Catchment is subjected to increasing afforestation, agricultural, domestic, mining, industrial, irrigation and urbanisation activities. These activities have a profound effect on the water quality of the river and its tributaries. This is cause for concern for the water users in the upper catchment, and because the Kruger National Park, one of its downstream water users, is extremely dependent on water of a satisfactory quality to sustain its various ecosystems. It is therefore vitally important to determine to what extent activities in the Upper Catchment of the Olifants River (Mpumalanga), especially in the Witbank and Middelburg areas, influence the water quality of the river. Point sources of pollution in the upper reaches include mining and industrial activities as well as water care works located at various points along the river. These were addressed in a Water Research Commission Project (No. 608/1/97) titled "Lethal and sublethal effects of metals on the physiology of fish: An experimental approach with monitoring support". Although sixteen localities were chosen for the initial project, this study only focussed around the metal ecotoxicology at two localities (Steenkool Spruit and Witbank Dam) in the upper catchment and the effect of metals (copper and zinc) on fish blood physiology. In aquatic ecosystems water quality is an important variable and full assessment of water quality, of Steenkool Spruit (locality 3) and Witbank Dam (locality 7), included evaluation of the chemical, physical and biological characteristics at each of the localities. Water and sediment samples were collected seasonally during the study period, February 1994 to May 1995, and the chemical and physical water quality variables were measured. During the study period three metal bioaccumulation indicator species, Labeo umbratus, Clarias gariepinus and Labeo capensis, were captured from which tissue (gills, liver, muscle and skin) samples were collected. These samples as well as water and sediment samples, were analysed for aluminium, chromium, copper, iron, manganese, nickel, lead and zinc concentrations, using atomic absorption spectrophotometry. In the past routine monitoring of chemical and physical water quality characteristics left scientists and managers with a sizeable pool of data which is often difficult but not impossible to interpret. To standardise and summarise this collection of data an aquatic toxicity index (ATI), WATER2 was developed by Wepener et at (1992). The present study attempted to expand and refine WATER2, which has resulted in the establishment of a new ATI, RAUWater.

M.Sc. / The Kruger National Park is internationally one of the best known conservation areas. The perennial rivers draining eastward towards and through the park are of great importance in maintaining a healthy ecosystem. The Olifants River catchment is the largest of all the rivers flowing through the Kruger National Park. Although this river has ceased flow for three days in 1968, problems experienced in the Olifants River are of a qualitative rather than a quantitative nature. Several factors contribute to the deteriorating water quality of the Olifants River. Urbanization, agricultural, industrial and mining activities in the Phalaborwa area pose a threat to the lower parts of the Olifants River. Pollution has on several occasions lead to mortalities of populations of fish in these parts...

Due to mining activities, the natural vegetation cover in Gatumba area was removed and replaced either by crops or bare wasteland with reduced available arable land. The main aim of the study was to assess the impact of the mining activities on the plant mineral uptake and the dynamics of the vegetation. The vegetation in this area under investigation was diversified and heterogeneous. Trace element concentrations in soils were similar to those in plant parts but some elements were highly concentrated in soils than in plants. According to the bioaccumulation factors of the analyzed trace elements in plant parts, two categories of plants were identified, and these are excluders and accumulators. No toxic levels of the evaluated trace elements were found in the analyzed plant samples. As a recommendation for the adaptation of plants to Gatumba mining environment, the most useful plant species for the revegetation/restitution of the technosols should be Sesbania sesban, Crotalaria dewildemaniana and Tithonia diversifolia subject to further experiments on trace elements bioaccumulation and organic matter production / Environmental Sciences / M.A. Science (Environmental Sciences)

Thesis (PhD) -- Stellenbosch University, 1995. / ENGLISH ABSTRACT: Graling in the Kruger National Park. south of Phalaborwa Gate, is contaminated with copper, probably from a nearby copper refinery. Cattle in the neighbourhood have died from copper poisoning while the average copper concentration in the livers of impala in the Krgler National Park, was found to be abnormally high. The possibility exists that the ultrastructure of spermatozoa may serve as an indicator of environmental conditions. To examine this statement further, the purpose of this study includes the following: - To describe the ultrastructure of normal impala sperm as well as their abnormalities. - To quantify the sperm abnormalities of each experimental animal and to relate the abnormalities with the copper concentration in the impala liver, in order to determine whether any correlation exists between these two variables. Impala have been terminated monthly, from 1992.06.09 to 1993.05.15. in the vicinity of Phalaborwa Gate and in the Skukuza area for other research projects. Their sperm were made available for this study. The control group consisted of 20 animals which comprised 14 animals from an area, not contaminated with copper, along the Nwaswitshaka spruit near Skukula and 6 animals originally from the same area but which had been kept in captivity at Skukuza on a diet, not contaminated with copper. The experimental group consisted of 44 animals which comprised 32 animals from copper contaminated grazing along the Tshutshi spruit south of Phalaborwa Gate and 12 animals captured along the Nwaswitshaka spruit which were kept on a copper contaminated diet in captivity at Skukuza. Sperm from the epididymis of each animal were collected and fixed in a temporary laboratory. The sperm were processed at the Electron Microscopy Unit of the Faculty of Veterinary Science of the University of Pretoria and studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The copper concentration in the liver was analyzed and bone marrow collected of each animal in order to determine the condition of the animal. The external morphology of a normal impala sperm was documented by means of SEM and the dimensions of the sperm determined. SEM micrographs of observed sperm abnormalities were taken. Percentages for normal sperm and the percentages of some abnormalities of a control group (Average liver copper concentration - ALCC = 37.9 ppm WB) were calculated. The same percentages were also calculated for an experimental group (ALCC = 104 ppm WB). The control group and the experimental group exhibited 91.6% and 93.6% normal sperm respectively. The difference in percentage sperm abnormalities of the two groups was of the same order. The increased copper in the livers of the experimental group has thus not lead to an increase of the percentage macro-abnormalities observed with SEM. The ultrastructure of normal impala sperm were described and documented with micrographs by means of TEM. The deviations of the normal sperm ultrastructure were also recorded on micrographs. Percentages were calculated for the normal sperm sections, as well as the abnormalities of some sperm sections of a contrl group (ALCC = 33.86 ppm WB). The same percentages were also calculated for an experimental group (ALCC = 122.5 ppm WB). For the control group the average percentage sperm neck sections with vacuoles was : 31.5% and for the experimental group this percentage was : 57.9%. The increased copper concentrations in the livers of the experimental group thus led to an increase of the percentage of sperm necks with vacuoles. There is also reason to believe that the difference of the percentages of sections of the sperm head, in the control and experimental group, should be remarkably greater. A graphic analysis of the TEM-data has also shown that a statistically significant correlation exists between the percentage of sperm with vacuoles in the neck and the copper concentrations in the livers of impalas. The conclusion is that high level copper concentrations exert a detrimental effect on the ultrastructure of the sperm neck. The possibility also exists that copper concentrations in impala liver > 500 ppm WB. will show a correlation with the percentages of some of the other abnormalities observed. / AFRIKAANSE OPSOMMING: Die weiding suid van Phalaborwahek in die Krugerwildtuin word waarskynlik vanaf 'n nabygeleë kopersmeltery met koper besoedel. Van die plaasdiere in die omgewing het reeds van kopervergiftiging gevrek en die gemiddeIde koperkonsentrasie in die lewers van rooibokke is abnormaal hoog. Die moontlikheid bestaan dat die ultrastruktuur van spermatozoa as 'n indikator van omgewingstoestande kan dien. Om bogenoemde moontlikheid verder te ondersoek was die doelwit van hierdie studie die volgende: Om die ultrastruktuur van normaIe rooiboksperme en hulle abnormaliteite te beskryf en die spermabnormaliteite van elke proefdier te kwantifiseer en met die koperkonsentrasie in die lewer in verband te bring om sodoende te bepaal of daar 'n korrelasie tussen die twee veranderlikes bestaan. Rooibokke wat maandeliks vanaf 1992.06.09 tot 1993.05.15 vir ander navorsingsprojekte in die omgewing van Phalaborwahek en Skukuza getermineer is, se sperme is vir die studie beskikbaar gestel. Die kontrolegroep het bestaan uit 20 diere wat saamgestel is uit 14 diere afkomstig van die Nwaswitshakaspruit naby Skukuza, uit 'n gebied wat nie met koper besoedel is nie en 6 diere uit 'n groep wat oorspronklik uit dieselfde gebied gekom het, maar wat te Skukuza in aanhouding geleef het op voedsel wat nie met koper besoedel was nie. Die eksperimentele groep het bestaan uit 44 diere waarvan 32 in die omgewing van die Tshutshispruit suid van Phalaborwahek versamel is en die ander 12 diere is langs die Nwaswitshakaspruit gevang en op 'n koperbesoedelde dieet te Skukuza aangehou. Sperme uit die epididymis van elke dier is in 'n tydelike laboratorium versamel en gefikseer. By die Elektronmikroskopie Eenheid van die Fakutreit van Veeartsenykunde van die Universiteit van Pretoria is die sperme voorberei en met behulp van skandeerelektronmikroskopie (SEM) en transmissie-elektronmikroskopie (TEM) bestudeer. Die koperkonsentrasie in die lewer is bepaal en murgvet is versamel om die kondisie van die diere te bepaaI. Met SEM is die uitwendige morfologie van 'n normale rooiboksperm met mikrograwe gedokumenteer en die mates van die sperm bepaal. Mikrograwe van waargeneemde spermabnormaliteite is met SEM geneem. Persentasies is vir normale sperme en die abnormaliteite van sommige sperme van 'n kontrolegroep (Gemiddelde lewerkoperkonsentrasie - GLKK =37.9 dpm NB) bereken. Dieselfde persentasies is ook vir 'n eksperimentele groep (GLKK = 104 dpm NB) bereken. Van die kontrolegroep het 91.6% en van die eksperimentele groep 93.6% sperme normaal vertoon. Die verskil in persentasies spermafwykings van die twee groepe was ook van dieselfde orde. Die verhoogde koperkonsentrasie in die lewers van die eksperimentele groep het dus nie gelei tot 'n verhoging van die persentasie makro-abnormaliteite wat met SEM waargeneem is nie. Die ultrastruktuur van 'n normale rooiboksperm is met behulp van TEM beskryf en met mikrograwe gedokumenteer. Die afwykings van die spermultrastruktuur is ook op mikrograwe vasgelê. Persentasies is vir die normale spermsneë en die abnormaliteite van sommige spermsneë van 'n kontrolegroep (GLKK = 33.86 dpm NB) bereken. Dieselfde persentasies is ook vir 'n eksperimentele groep (GLKK = 122.5 dpm NB) bereken. Vir die kontrolegroep was die persentasie neksneë met vakuoles = 31.5% en vir die eksperimentele groep was die persentasie = 57.9%. Die verhoogde koperkonsentrasie in die lewer van die eksperimentele groep het dus gelei tot 'n verhoging van die persentasie neksneë met vakuoles. Rede bestaan om te glo dat die verskil van die persentasies kopsneë van die kontrole- en eksperimentele groep ook aansienlik hoër behoort te wees. 'n Grafiese analise van die TEM-data het ook getoon dat daar 'n statisties betekenisvolle korrelasie tussen die persentasie spermnekke met vakuoles en die koperkonsentrasie in die lewer van rooibokke bestaan. Die bevinding is dat hoë lewerkoperkonsentrasies 'n nadelige invloed op die ultrastruktuur van die spermnek uitoefen. Die moontlikheid bestaan ook dat koperkonsentrasies in die lewer > 500 dpm NB ook 'n korrelasie met sommige van die ander abnormaliteite sal toon.

Due to mining activities, the natural vegetation cover in Gatumba area was removed and replaced either by crops or bare wasteland with reduced available arable land. The main aim of the study was to assess the impact of the mining activities on the plant mineral uptake and the dynamics of the vegetation. The vegetation in this area under investigation was diversified and heterogeneous. Trace element concentrations in soils were similar to those in plant parts but some elements were highly concentrated in soils than in plants. According to the bioaccumulation factors of the analyzed trace elements in plant parts, two categories of plants were identified, and these are excluders and accumulators. No toxic levels of the evaluated trace elements were found in the analyzed plant samples. As a recommendation for the adaptation of plants to Gatumba mining environment, the most useful plant species for the revegetation/restitution of the technosols should be Sesbania sesban, Crotalaria dewildemaniana and Tithonia diversifolia subject to further experiments on trace elements bioaccumulation and organic matter production / Environmental Sciences / M.A. Science (Environmental Sciences)

Ph.D. / The Crocodile River catchment, in Mpumalanga, is one the most intensively used catchments in South Africa. The large number of intensively cultivated crops grown in the middle and lower subcatchments; industrial discharges; highly intensive irrigation; and extensive areas of exotic afforestation in the upper and middle sub-catchments has dramatically changed land use patterns within the catchment. The Middle Crocodile River sub-catchment is also impacted by intensive urbanisation; around Nelspruit, KaNyamazane and Matsulu. The Kaap River sub-catchment has been intensively mined for minerals and the impacts of these mining operations are still reflected in the water quality of streams and rivers in this sub-catchment. The downstream uses of the Crocodile River's water quality are the aquatic ecosystem, the Kruger National Park (as the river is the southern boundary of the park) and Mozambique (international obligations). The Crocodile River catchment supports one of the richest fish species diversities in South Africa. It is therefore important to determine the impacts of these land use activities on the fish populations and the potential human health risks if fish are consumed. In the present study data from five gauging stations for each of the main tributaries draining the five sub-catchments (the Upper, Middle and Lower Crocodile River, Kaap and Elands Rivers) were used. The water quality and quantity was determined from Department of Water Affairs and Forestry's (DWAF) National Hydrological Chemical Data Bank. Assessments of water quality (chemical, physical), sediment characteristics, and fish biological characteristics were undertaken at each of the chosen sampling sites. Water and fish samples were collected seasonally on ten sampling trips during the study period, June 1989 to September 1992. Eleven species of fish were collected, by means of gill and seine nets, at eight sites. The biological characteristics of the larger fish captured were measured and tissue (gills, liver, muscle, intestine, ovaries, testes and abdominal fat) samples were collected. These samples were analysed for eleven metals and Pyrethroid, Carbamate, Organochlorine, Organophosphate and Triazine pesticides. Sediment core samples were collected and determinations made of particle size, percentage organics, metals and pesticides. Standard methods were used for the determination of .the metal and pesticide concentrations in the water, sediment and fish tissues. The pesticide use per crop for South Africa was determined from a data-base. This data was used to determine the potential pesticide runoff from the different crops in the sub-catchments and to compare with the sediment and fish tissue levels recorded. The water quality status of the Crocodile River catchment is impacted by a variety of diffuse and point sources of pollution. The water quality indicated that diffuse sources of pollution originated from afforestation in the Upper, Middle and Kaap River sub-catchments; current and abandoned mining activities in the Kaap River sub-catchment; runoff from irrigated lands in the Middle, Lower and Kaap River sub-catchments; and wastes from industrial activities in the Elands and Middle sub-catchments. Point sources of pollution in the Crocodile River include ndustrial and waste water treatment works discharges mainly in the Middle sub-catchment.

M.Sc. (Zoology) / The world’s ever increasing human population has lead to an almost unimaginable amount of waste being released in to the aquatic environment every day. Aquatic systems are faced with the greatest risk due to the fact that water is an indispensable resource required for industrial and agricultural processes. In recent years there has been a dire need for the monitoring and rehabilitation of aquatic systems. As a result many biological monitoring programmes were set into place in an attempt to manage this problem. The use of aquatic organisms as sentinels for biomonitoring studies has been wildly accepted with the majority of biomonitoring research focusing on the use of various fish and invertebrate species as aquatic sentinel organisms. However, the use of parasites as sentinel organisms is a relatively new field and as a result there has been little published work on the use of monogenean ectoparasites parasites as such sentinels. The bioaccumulation and subsequent biomagnification of metals by certain parasite species is well known, with bulk of the published work focusing on endoparasites (cestodes, acanthocephalans & nematodes), these published studies indicate that some species of endoparasites exhibit a remarkable ability to biomagnify metals in concentrations that far exceed that of their respective hosts as well as the ambient environment. Thus this project aims to assess the bioaccumulation and biomagnification of metals by the ectoparasitic diplozoon. The study site that was chosen for this project was the Vaal Dam; this site was deemed appropriate due to its near pristine condition and major economic importance. This meant that this particular site is ideal for the testing of a new biomonitoring system. All field sampling was performed around UJ Island (26°52.249’S; 20°10.249’E) from February 2011 to April 2011. A total of 29 Labeo umbratus (Smith, 1841) were collected with the aid of gill nets and three sediment samples were also taken using a grab sampler. Water quality data was obtained from the Rand Water Analytical Facility in Vereeniging as this organisation routinely monitors of the water quality parameters and the metal concentrations within the surface waters of the Vaal Dam, this information was obtained with the aid of data loggers situated in the dam...

Concentrations of selenium (Se), manganese (Mn), zinc (Zn), cadmium (Cd), lead (Pb) and arsenic (As) were measured in the water column, sediment and biota, in conjunction with selected physicochemical data, from representative wetland types at a mining site within Salt Lake County, Utah, USA. The selected field sites included Oolitic Pond (lentic) and Lee Creek (lotic), which are moderately contaminated brackish, alkaline aquatic wetlands managed by a copper mining industry. These fishless wetlands are located in a geographic region that poses risk to migratory shorebird populations from dietary Se. A spatial sampling study demonstrated the extent of variation in total Se concentration within the wetlands. With the exception of the sediment compartment, Se concentration did not differ significantly along the 2-mile length of Lee Creek or within the Pond. The differences in sediment total Se concentrations between the Creek East and West segments characterize lower Lee Creek as having two segments distinguished by unique processes that influence the sediment Se accumulation profiles. Se accumulation trends were observed temporally over 3-years (2000 to 2002) and over two seasons (spring and autumn). Total Se body burden in benthic invertebrates was more clearly associated with sediment/detritus Se concentrations than with surface water concentrations. Three invertebrate groups dominated the aquatic invertebrates assemblage in the lotic and lentic benthos; primary consumers (Chironomidae, Diptera), generalist feeders (Hemiptera) and predators (Odonata). The chironomid larvae accumulated 1.3 to 39 times the trace metal concentrations of the Hemiptera or odonate taxa, independent of trace metal type (essential or non-essential) or wetland occupation. Organism-specific factors, such as habitat selection and preferential feeding habits, were proposed to influence benthic invertebrate accumulation profiles by modifying trace metal exposure. Mixed diets, trophic omnivory and the complexity of wetland biogeochemistry limit the power of stable nitrogen fractionation signatures to define benthic food web relationships. Wetland site-specific processes impacted Se accumulating efficiency, with trace metal concentrations from 4 to 7 times greater within the lentic benthic system than the lotic. The fractionation of the natural abundant stable carbon isotopes revealed the importance of sedimentary and detrital organic carbon as dietary sources for the benthic food web. Sediment organic content was not significantly associated with sediment, or invertebrate, Se accumulation profiles. Ecological risk assessments based on sound understanding of metal chemistry and the interactions between the sediment matrix and benthic organisms are necessary to provide tools for environmental management. / Graduation date: 2005