Vitellogenin in Pimephales promelas was used to assess estrogenicity of a local municipal effluent. Vitellogenin induction in male P. promelas increased in frequency and magnitude with increased exposure duration and was greater ("=0.05) than controls after 2 and 3 weeks of exposure. The level of vitellogenesis induced by effluent exposure was high compared to similar studies. A spring season evaluation followed. Biomarkers in P. promelas were used to assess the efficacy of a treatment wetland to remove toxicity and estrogenicity in final treated wastewater effluent. Comparisons were made with an effluent dominated stream and laboratory controls. Vitellogenin, GSIs (gonado-somatic indices), HSIs (hepato-somatic indices) and secondary sexual characteristics were biomarkers used in P. promelas models to assess aqueous estrogenicity. Biological indicators used to assess general fish health included hematocrit and condition factors. The estrogenic nature of the effluent was screened, concurrent with fish exposure, with GC/MS analysis for target estrogenic compounds including: 17-b estradiol, estrone, ethynylestradiol, Bisphenol A, nonylphenolic compounds, phthalates, and DDT. Plasma vitellogenin measured in P. promelas was significantly elevated (p < 0.0001) at the inflow site of the wetland and stream sites. GSIs for these exposures were less (a=0.001) at the wetland inflow site. At wetland sites closest to the inflow, secondary sexual charateristics, tubercle numbers and fat pad thickness, were less (a=0.0001). Hematocrit and condition factors were less (a=0.001) at sites closer to the wetland inflow. Seasonal variation was examined by repeating the effluent characterization in summer. Additionally, summer testing included exposure to an effluent dilution series. Fish condition heavily influenced interpretation of the results. Pre-acclimation exposure to spawning stresses may have altered many of the biological markers measured. Results are discussed relative to fish health and pre-exposure environment. Toxicity assessed with P. promelas biomarkers was compared with Ceriodaphnia dubia and Vibrio fischeri toxicty tests on this effluent. Biomarkers of fish health were somewhat less sensitive than C. dubia test endpoints, but more sensitive than V. fisheri.

Many herpetofaunal species are imperiled, and the causes of this are often a synergy of multiple factors. In wetlands specifically, two of the possible determinants of species occurrence and faunal community assemblage are fish presence and wetland permanence, which are not always correlated. Twenty wetlands were sampled in Jonathan Dickinson State Park, Florida, USA to observe how wetland herpetofaunal communities vary with fish, wetland permanence and other environmental factors. Herpetofaunal communities with and without fish were significantly different from one another and differences between herpetofaunal communities were primarily due to the contribution of four species of frogs, two generalist ranids and two specialist hylids. Wetland permanence had no observable effect on community structure. Fishless wetlands were significantly more species-rich and possessed higher numbers of individuals even for species that occurred in both fishless and fish wetlands, regardless of their permanence. These findings have implications for wetlands restoration and herpetofaunal conservation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The Menindee Lakes are a series of shallow floodplain depressions on the Lower Darling River, approximately 300 river kilometres upstream from the confluence with the River Murray, in southeastern Australia. The system is the fourth largest water storage in the Murray-Darling Basin (1,680 Gl) and comprises of seven shallow deflation basins: Lakes Malta, Balaka, Bijiji, Tandure, Pamamaroo, Menindee, Cawndilla, and Lake Wetherell. Lake Wetherell was created by the construction of the Menindee Main Weir and subsequent flooding of the main channel of the Darling River and surrounding floodplain. Each deflation lake is individually connected to the Darling River with the exception of Lake Cawndilla, which is connected to Lake Menindee by Morton Boolka Channel. The climate of the Menindee area is arid with a mean annual rainfall of 243.7 mm, average maximum temperature in January of 34.1° C and in July of 16.9° C. Due to the flat topography, local runoff is negligible and the impact of precipitation on the water budget of the lakes is negligible in comparison to evaporation, which exceeds 2.5 m year-1. Prior to regulation, the Menindee Lakes would fill when river levels were higher than the sill level of the feeder creeks. When river levels receded, the lakes drained back to the Darling River leaving a residual pool, which would evaporate. The Darling River is one of the most variable rivers in the world and prior to regulation the Menindee Lakes were often dry for extended periods. The large lakes (Cawndilla, Menindee, Pamamaroo and Tandure) would fill on average every once every one to two years and the longest droughts lasted five years. The small lakes (Bijiji, Balaka and Malta) filled on average every two to three years with the longest droughts lasting eleven years. Construction of the Menindee Lakes Scheme was completed in 1968 and is a series of small dams, regulators, weirs, channels and levees designed to conserve Darling River floodwaters. The main structure is the Menindee Main Weir, which raises the level of the river 12 m above the bed level, creating Lake Wetherell and filling Lakes Tandure, Bijiji, Balaka and Malta. This hydraulic head is used to gravity feed Lakes Pamamaroo, Menindee and Cawndilla. The hydrologic regime is now dictated by the operating procedures developed by the New South Wales Department of Infrastructure, Planning and Natural Resources. The priority of operations is to maximize the potential supply of water for all users and to maximize water quality within the lakes and Lower Darling River for human uses. Now the lakes are inundated for longer periods; rates of drawdown are more rapid and small to medium sized floods downstream of the scheme and in the Darling Anabranch have been eliminated. Despite increased permanency, large water level fluctuations are still common and drying cycles have not been lost entirely. Since the completion of the scheme Lake Malta has dried four times, Lake Balaka three times, Lake Bijiji twice, Lakes Tandure and Pamamaroo once, Lake Menindee five times and Lake Cawndilla four times. Of all of the lakes, Lake Malta is least impacted by regulation. The vegetation dynamics and role of the seed bank have not been extensively investigated in ephemeral systems. The seed bank provides a mechanism for species persistence through unfavourable conditions and colonisation during favourable conditions. In ephemeral lakes, large and aseasonal water level fluctuations are common which may result in long periods of unfavourable conditions. Plants growing in these environments must be able to persist through unfavourable conditions for growth and survival. The main objectives of this study were: - To investigate the seed density, species richness and composition of the seed banks of selected lakes. - To determine if there are any within lake patterns in seed bank density, species richness and composition. - Examine the effect of different water regimes on germination and recruitment from the seed bank. - Determine water regime preferences for germination and recruitment of common species. - Investigate vegetation change during an extended drought. - Determine flood tolerances of Xanthium occidentale, Cyperus gymnocaulos and Ludwigia peploides. - Investigate the interaction between nutrients and water regime on recruitment from the seed bank. No information regarding the seed banks of the Menindee Lakes was available; therefore, a reconnaissance study was undertaken. The aims of this study were to determine the seed density, floristic composition, zonation with respect to elevation, differences between and within lakes and germination strategy (pattern through time) of Lake Malta, Bijiji and Menindee seed banks. Results showed that the seed bank of each lake had a different floristic composition and Lake Menindee had a depauperate seed bank (Lake Malta 27 species and 6,300-43,983 seeds m-2, Lake Bijiji 24 species and 2243-27,417 seeds m-2 and Lake Menindee one species and 117-233 seeds m-2). Within each lake, the seed density, species richness and composition was spatially variable but no zonation with respect to elevation was observed. In Lake Bijiji, the sampling site on the northern shore of the lake had a significantly less dense and less species rich seed bank than the other locations; however, this was not present in Lake Malta. Over 90% of the total germination from the seed bank from all lakes occurred in the first six weeks. This study also provided evidence that the seed bank around the edges of the lakes was concentrated in zones of organic matter deposition (strandlines). The seed bank density and species composition of the strandlines and adjacent sediment was investigated in Lakes Cawndilla, Menindee, Tandure (large highly regulated lakes) and Malta (a small lake minimally impacted by regulation). Three hypotheses were tested in this study: 1. The strandline will have a denser and more species rich seed bank. 2. The strandline provides favourable microsites for germination and recruitment. 3. All species present in the seed bank will bet hedge. The strandline seed banks of Lakes Cawndilla (strandline 25,753 seeds m-2 and adjacent sediment 2,730 seeds m-2), Menindee (strandline 7,427 seeds m-2 and adjacent sediment 646 seeds m-2) and Tandure (strandline 8,006 seeds m-2 and adjacent sediment 2,178 seeds m-2) were significantly denser and more species rich than the adjacent sediment, whereas there was large, species rich seed bank outside the strandline in Lake Malta strandline (70,180 seeds m-2 and adjacent sediment 54,266 seeds m-2). The organic component of the strandline may act to reduce evaporation from the soil and provide a favourable microsite for germination and recruitment. Of the 58 species present in all seed banks 37 bet hedged (had persistent seed banks). The effect of water regime on recruitment from the seed bank and the optimal water regime for germination and recruitment of common species were investigated in a pond experiment. This experiment had three aims: 1. To test the hypothesis that different water regimes will give rise to different plant communities from the same seed bank. 2. Determine optimal water regimes for germination and recruitment of common species. 3. To formulate a testable conceptual model describing recruitment from the seed bank under different, controlled water regimes. Different water regimes did give rise to different plant communities from the same seed bank. Myriophyllum verrucosum was the only species that germinated whilst submerged. All other species required exposed soil with high soil moisture to germinate. All terrestrial and floodplain species died if flooded, however several amphibious species were present that persisted whilst flooded, despite requiring exposed soil for germination. The conceptual model consisted of eight states (dependant on whether the soil was exposed or inundated, soil moisture content, duration of inundation and species present) that predicted which species would be present in each of the states (providing they were present in the seed bank). A series of surveys to investigate recruitment from the seed bank in the field during a period of extended drought was undertaken over 488 days. This study had four aims: 1. To investigate the relationship between the extant vegetation and selected environmental variables. 2. To test a conceptual model that predicts how the environment changes with fluctuating water levels. The model consists of five states (windows of opportunity) that the system switches between; depending water level, elevation and the species present in the seed bank and extant vegetation. The five states are: window of opportunity closed due to inundation, window of opportunity open for germination establishment and reproduction (exposed soil with high moisture content in the top 7.5 cm), window of opportunity closed for germination but open for establishment and reproduction (low soil moisture in the top 7.5 cm), window of opportunity closed for germination and establishment but open for reproduction (top 15 cm low soil moisture) and all windows of opportunity closed because the soil is dry (low soil moisture to 40 cm). 3. To test the part of the conceptual model derived from the pond experiment. 4. To investigate the change in the germinable seed bank as the window of opportunity for germination opens, plants recruit and replenish the seed bank. This aim tests the hypothesis that the species that recruit will reflect the seed bank before the window of opportunity for germination opens, then when the window of opportunity for germination opens the seed bank will become less similar and then recover (reflect the recruited vegetation) after the species present have replenished the seed bank. The floristic composition of Lake Malta was correlated with sediment exposure time and clay content, Lake Balaka with sediment exposure time, soil moisture and clay content, Lake Wetherell with elevation, canopy cover and elevation of the water relative to the quadrat and Lake Menindee with sediment exposure time, soil moisture, elevation and clay content. The floristic composition of Lake Cawndilla was not correlated with any of the measured environmental variables. As water levels fell the window of opportunity for germination opened once the sediment was exposed and closed when the sediment surface dried. The window of opportunity for establishment and reproduction did not close until the sediment dried further. For the most desiccation tolerant species the window of opportunity for growth and reproduction remained open. If the species composition of the seed bank was known, the pond model predicted the potential floristic composition. However, it did not take into account sediment exposure time. Extended drought in the Darling catchment meant that the lakes did not fill during the study period and the effect of flooding could not be investigated in the field. Therefore, a pond experiment to test the effect of flooding on Xanthium occidentale, Cyperus gymnocaulos and Ludwigia peploides was undertaken. Three hypotheses were tested: 1. Xanthium occidentale when top flooded for more than two weeks will die. Plants partially flooded will survive, increase above ground to below ground biomass ratio and grow when water levels fall. 2. Cyperus gymnocaulos when top flooded for two weeks will show no adverse effects and grow when water levels fall. When top flooded for more than two weeks the above ground biomass will senesce and resprout when water levels fall. Plants partially flooded will show no adverse effects. 3. Ludwigia peploides when top flooded will rapidly increase above ground biomass in order to reach the water surface. Each species generally responded as hypothesised. Xanthium occidentale also produced adventitious roots and lost stem rigidity when partially flooded. Cyperus gymnocaulos showed reduced growth rates when partially flooded compared to plants that were not flooded. Water regime is only one factor that may influence the floristic composition derived from the seed bank. A pond experiment was undertaken to test the hypothesis that the combination of different soil nutrient concentrations and water regime will give rise to different plant communities from the same seed bank. The effect of different nutrient loadings however, had no effect on floristic composition and the differences could be explained by differences in water regime. The sediment seed banks of the Menindee Lakes provide a mechanism for survival through droughts and floods. They are spatially variable and the strandline accounted for the majority of seed around the edges of the large regulated lakes. All but one species present in the seed banks of all lakes sampled required exposed sediment with high soil moisture to germinate and many species were very desiccation tolerant (especially terrestrial and floodplain species). Most species were intolerant to flooding as juvenile or adults; however, there were a few amphibious species present. Water regime influences the floristic composition derived from the seed bank but soil texture is also an important factor, whereas nutrients appeared to have no effect. / Thesis (Ph.D.)--School of Earth and Environmental Studies, 2004.

Transitional areas between upland and aquatic habitats, commonly known as wetland, were once viewed as unproductive areas and were drained for farming or pasture. Wetlands are now accepted as significant ecological resources, and their protection is a mandate of federal, state, and local land managers. Due to the diversity of wetland areas, the appropriate assessment of wetland resources cannot be accomplished without long term monitoring of wetland functions. Knowledge of the duration of saturation and associated anaerobic conditions of soils in wetlands is critical to correctly classify and assess wetland areas. Soil, hydrological, and biogeochemical characteristics of the soils of the Jackson-Frazier wetland were observed from October 1992 through March 1994. Weekly observations of water levels and redox potential at depths of 25, 50, and 100 cm were made in order to characterize the degree and duration of saturation and the anaerobic conditions in the soil over time. Permanently installed piezometers measured free water in the soil and indicated the presence of two separated water tables from the onset of the rainy season in October until February when the entire soil profile became saturated with free water. Platinum electrodes measured redox potential in the soil and indicated anaerobic conditions for ten months during the first season of observation and through March of the second season. Anaerobic conditions were considered to be achieved when Fe����� was reduced to Fe����� at a potential of 200 millivolts. The highly reducing conditions correspond to periods of soil saturation indicated by piezometers. Concentrations of iron and manganese observed in soil profiles correspond to conditions of prolonged saturation and reduction confirmed by monitoring. A soil stratigraphic study done with auger holes revealed a recent alluvial deposit of montmorrillonitic clay overlying lacustrine silts identified as the Irish Bend Member of the Willamette Formation. The clay deposit overlying the surface of the wetland acts as an aquitard and creates extensive surface ponding, which maintains the saturated habitat required for wetland vegetation. The subsurface hydrology is controlled by water flowing through the Irish Bend silts which results in saturation of the soils from below. Biogeochemical transformations of iron and manganese due to suboxic and anaerobic conditions are controlled by this type of soil saturation in the Jackson-Frazier wetland. / Graduation date: 1995

Hlatikulu Vlei, situated in the foothills of the Natal Drakensberg, is one of the priority wetlands in KwaZulu-Natal, occupying an area of 733 Hectares. The importance of Hlatikulu Vlei lies in its functions to store water, regulate stream flow and attenuate floods, as well as to provide suitable habitat for wildlife and grazing for livestock. Hlatikulu Vlei is a threatened system and has suffered the effects of human mismanagement. Forty-nine percent of the vlei has been classified as disturbed or destroyed, mainly due to the construction of two large dams and past drainage of vlei to facilitate pasture planting. The effects of grazing and fire on the plant communities has been considerably less. Vegetation communities at Hlatikulu Vlei have similarities with those at Ntabamhlope Vlei. The main plant communities present at Hlatikulu Vlei are: vlei grassland, sege-meadows, bulrushes and reedswamp. Species compositions of the mixed sedge and grass sedge-meadow community have a notably higher species diversity than similar communities sampled at Ntabamhlope Vlei and the mires at Highmoor. Soil type and moisture content are shown to be the most significant environmental factors determining the distribution of plant communities and species within the vlei. A wetland re-establishment and rehabilitation programme in the Hlatikulu Crane and Wetland Sanctuary has been effective in allowing many wetland plants to become reestablished. The sanctuary communities bear greater similarity to the sedge and rush sedge-meadow community, than the mixed sedge and grass sedge-meadow communities that were originally present. This is also reflected in the seed bank. All three Southern African crane species (Blue, Wattled and Crowned Crane) and fourteen species of waterfowl have been recorded in the Hlatikulu Crane and Wetland Sanctuary since the wetland rehabilitation programme. The waterfowl play a role in the dispersal of seeds into the sanctuary, particularly those of Schoenoplectus decipiens and Eleocharis dregeana and are in part responsible for the return of certain wetland plants to the sanctuary. The flooding of soils, the fluctuating water level and the soil type related to hummocks and to channels are shown to be responsible for the location of Cyperus denudatus, Arundinella nepalensis and Aristida junciformis in differing positions in the channels and on the hummocks and are also responsible for the maintenance and functioning of the hummocks and channels. Seed banks on the hummocks are similar to seed banks in the channels, however the extant vegetation on the hummocks is distinctly different to that in the channels. Certain species represented in the channel seed bank are being excluded from surviving to maturity. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.

This study examines the relationship between nutrient additions and algae and invertebrate productivity in a nutrient-poor wetland of the Interlake Region of Manitoba, Canada. Alfalfa hay was added to experimental enclosures in May 1992. Alfalfa additions were made in unprocessed and ground forms and consisted of three treatments: ground low, whole low, and whole high. Dissolved oxygen, surface water nutrients, algae standing crop, and invertebrate production were monitored at open marsh sites and in treatment and control enclosures during 1992 and 1993. Stable $ sp{13}$C, $ sp{15}$N and $ sp{34}$S isotope ratios were determined for the alfalfa additions, and for surface water, algae, macrophytes, sediments and invertebrates. / In general, the effects of nutrient additions were confined to 1992. Treatment enclosure dissolved oxygen levels decreased immediately following fertilization, recovering in the low treatments by early June. Low oxygen conditions persisted in whole high enclosures throughout most of 1992. Dissolved and suspended nutrient concentrations, and phytoplankton chlorophyll a increased but, with the exception of dissolved N, were soon lost from the water column. Treatment enclosure epiphytic algae increased while epipelon did not respond to fertilization. The primary effect of fertilization on invertebrate production was an increase in treatment enclosure chironomid larvae during 1992. As with productivity measures, stable isotope ratio values suggested a temporary presence of alfalfa nutrients in the enclosed food webs. Only the isotope ratios of metaphytic algae and snails collected during August 1992 indicated an incorporation of alfalfa nutrients.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Wetlands are key to providing important ecosystem goods and services yet they are under threat from a number of anthropogenic activities. In particular, in this study area, agriculture in the form of sugarcane farming is a threat to wetlands as sugarcane is reliant on a good water supply. The impacts of sugarcane farming emanates from the fact that sugarcane is a mono crop that requires wetland resources and uses a lot of pesticides and fertilisers. Despite the assumed contribution of sugarcane farming to wetland loss and degradation, few studies have quantitatively assessed the spatio-temporal changes in wetland extent as well as changes in water quality because of this activity. This study assesses the impacts of sugarcane farming on wetland extent and water quality in two coastal wetlands of KwaDukuza, North coast of Zululand, South Africa. Specifically this study sought to (i) assess the impacts of sugarcane farming on the spatial extent of wetlands between 1959 and 2012, (ii) determine if sugarcane farming negatively affect water quality within the wetlands and (iii) evaluate the perceptions of local farmers regarding impacts of sugarcane farming on wetlands. Results of the study indicated an increase in the extent of Zinkwazi sugarcane fields from 62.3% to 67% between 1959 and 1989 and Nonoti sugarcane fields’ extent increased from 50.5 % to 56.4% between 1959 and 2000. The last decade from the year 2000 showed gradual decrease in the area of wetland farmed by sugarcane due to the global sugar price remaining static while the cost of farming inputs increased and due to conversion of some farms to urban developments. Unfortunately, this has not lead to an increase in wetland area as the waterfront type developments, as well as a formal settlement have replace the sugarcane in the wetlands. Water was analysed for nitrogen (N), phosphorus (P) and potassium (K) and results for both Zinkwazi and Nonoti indicated an increasing trend of N and P from upstream to the middle region of the rivers and a decreasing trend of the N and P from the middle region to downstream. Sugarcane farming does not take place below the middle region and so does not provide fresh sources of these nutrients. The downstream area where the N and P decrease also coincides with the area of the river under tidal influence such that the N and P are being diluted by the incoming tidal seawater. K showed an increasing trend from upstream to downstream and its values were higher than N and P. Concentrations of N and P above the South African water quality guidelines for aquatic ecosystem were recorded in the middle region. Furthermore, farmers’ perceived wetlands to have been transformed to agricultural land and related these changes to their sugarcane farming activities. It can thus, be concluded that sugarcane farming has resulted in wetland loss as well as deterioration of water quality within the Zinkwazi and Nonoti wetlands in KwaDukuza. In that regard, there isneed to engage farmers in wetland management programs in order to reduce the negative environmental impacts associated with sugarcane farming in wetlands. / AFRIKAANSE OPSOMMING: Vleilande is die sleutel tot die verskaffing van ‘n belangrike ekosisteem dienste, maar hulle is onder ‘n bedreiging deur 'n aantal menslike aktiwiteite. In besonder in hierdie studie area, is Argriculture in die vorm van suikerriet boerdery is bedraging vir vleilande, en suikerriet is afhanklik van 'n goeie watervoorraad. Ten spyte van die veronderstelde bydraes van suikerriet boerdery, is die vleiland aan die agteruitgang, 'n Paar studies het kwantitatief die tydruimtelike veranderinge in die vleiland, sowel as veranderinge in die gehalte van water as gevolg van hierdie aktiwiteit waargeneem. Spesifiek is hierdie studie gepoog om (i) te bepaal wat die impak van suikerriet boerdery op die ruimtelike omvang van die vleiland tussen 1959 en 2012 is, (ii) bepaal of suikerriet boerdery negatief beïnvloed is deur die gehalte van water in die vleilande en (iii) die persepsies van plaaslike boere rakende die evalueering en impak van suikerriet boerdery op die vleilande. Resultate van die studie het aangedui 'n toename in die omvang van Zinkwazi suikerriet velde van 62,3% tot 67% tussen 1959 en 1989, en die Nonoti suikerriet velde toegeneem het met 50,5% tot 56,4% tussen 1959 en 2000. Die laaste dekade van die jaar 2000 het geleidelike afname in die area van die vleilande getoon, omdat suikerriet as gevolg van die globale suiker prys die koste van boerdery-insette verhoog het, en dit het gelei tot die omskakeling van 'n paar plase na stedelike ontwikkelings. Ongelukkig het dit nie gelei tot 'n toename in die vleiland gebiede nie, met die gevolg die waterfront tipe ontwikkelings, asook 'n formele nedersetting, vervang die suikerriet in die vleilande. Water is ontleed vir N, P en K en resultate vir beide Zinkwazi en Nonoti, het aangedui 'n toenemende tendens van stikstof en Fosfor. Dit gaan stroomop na die middel-streek van die riviere en 'n dalende neiging van die N en P uit die middel streek stroomaf. Suikerriet boerdery vind nie plaas onder die middel streek nie, en so is daar nie vars bronne, wat van hierdie voedingstowwe verskaf nie. Die stroomaf gebied waar die N en P ‘n afname het, val ook saam met die gebied van die rivier onder die gety , en dit beinvloed sodanig dat die N en P se water verdun word deur die inkomende gety se seewater. K het 'n toenemende neiging van stroomop en stroomaf en sy waardes is hoër as van die N en P. Konsentrasies van N en P bo die Suid-Afrikaanse water standaard riglyne is in die middel streek aangeteken. Verder, beskou boere dat die vleilande behoort te verander om die landbougrond en verwante veranderinge aan hul suikerriet boerdery en aktiwiteite. Ons kan dus aflei dat suikerriet boerdery het gelei tot die vleiland se verlies asook die verandering in die watergehalte in die Zinkwazi en die Nonoti vleilande in KwaDukuza. In dié verband is dit nodig dat die boere in die vleiland by programme betrek word ten einde die negatiewe omgewingsimpakte wat met suikerriet boerdery gepaard gaan in vleilande te verminder.

Macrophytes are an integral component of lake littoral zones and play an irreplaceable role in maintaining the ecological balance of wetlands. Recent research has highlighted the role of lake-scale environmental factors (or “filters”) and catchment- and/or landscape-scale processes in explaining variation in macrophyte communities across different scales. In this work, the effects of land-use and connectivity on macrophyte communities were explored at two contrasting spatial scales (i.e. local catchment scale and topographic catchment scale). At the local catchment scale, the results revealed strong scale-dependency. The effects of land use on macrophyte richness were most apparent at fine spatial scales (within 0.5 to 1 km) and significantly outweighed the importance of hydrology. In terms of growth form composition, the effects of hydrological connectivity were stronger than those of land use, with the greatest effect observed at an intermediate distance (~ 5 km) from the lake. The study on the hydrologically-connected lake pairs indicated that environmental filters were more influential in explaining species turnover than lake connectivity. Interestingly, geographical connectivity explained more of the variability in species turnover than hydrological connectivity. Moreover, the relative importance of environmental filters and lake connectivity to species turnover was very sensitive to the degree of human disturbance. The multi-scale interaction analyses indicated the effect of lake alkalinity on macrophyte composition is strongly influenced by catchment scale variables including hydrological features and land use intensity. The turnover in macrophyte composition in response to variability in alkalinity was stronger in catchments with low lake and stream density and weaker in catchments with a more highly developed hydrological network. Lake abiotic variables were found to have more influence on macrophyte composition in lowland catchments with a higher intensity of human disturbance. Moreover, the catchment-scale factors promoting the establishment of different communities were found to vary between catchments depending on lake type, the degree of environmental heterogeneity and hydrological connectivity.

M.Sc. (Environmental Management) / Wetlands play a significant role in our environment as they provide a variety of goods, services and benefits to living species ranging from humans, animals and plants to microorganisms. Despite their importance, wetlands have somewhat been neglected over the past few years which has led to a rapid deterioration of wetland conditions and functions. Wetlands provide unique functions that cannot be provided by any other ecosystem; their value was recognised in the 1960s. Prior to this realisation the value of wetlands had been seriously underestimated to the extent where they were even previously labelled as “wastelands”. The reality is that to date minimal measures have been put in place to assist in the rehabilitation and future conservation of wetlands. The lack of wetland management and monitoring can be attributed to the fact that very little is known about the functioning of some of the wetland systems. Endorheic wetlands have recently been emerging as ecosystems of importance. Very little is known about endorheic wetlands and their ecological functioning. To date a fair amount of studies have been conducted on the pans in Mpumalanga and in the Free State but minimal information exists on the pans in the North West Province. The objectives of this study were therefore to compare the abiotic and biotic composition of pans in Mpumalanga and North West Provinces, in order to contribute to the knowledge which will eventually assist in devising rehabilitation measures and future conservation of pans in the area. Three different water ecosystem components were studied; these included aquatic invertebrate communities, water quality and sediment characteristics. The collected water samples were taken to an accredited laboratory to be analysed. When compared between the two provinces, the water-quality results indicated differences between provinces as well as among individual pans. However, most of the pans in both provinces show characteristics of being dystrophic alkaline systems. The invertebrates were collected using sweep nets and stored in jars containing 5% neutrally buffered formalin and a staining agent (Rose Bengal). The sediment characteristics were determined by using standard techniques and results showed that there were no obvious similarities between the different pans in the different provinces. Water-quality analyses were performed on samples taken during both winter- and summer-sampling surveys and these samples were analysed by a reputable laboratory. Based on the analyses of the invertebrate community samples, 25 taxa were identified; results show similarities in the structure of communities in both provinces with the exception of one or two different species. Sampling was conducted over a period of two seasons at all sampling points and several species were found belonging to different families. Invertebrates sampled in Mpumalanga pans were similar to those reported in previous studies done in the area and most of the invertebrates sampled in Mpumalanga and the North West are known to be commonly found in temporary habitats. Spatial and temporal variations in invertebrate assemblages were determined; this analysis displayed differences in the different variables (biotic, physical and chemical) tested over the two seasons. The pans in Mpumalanga were dominated by coarse sand. Large amounts of coarse sand accompanied by poor water quality were observed in MP Pan A in Mpumalanga Province; this could be an indication of somewhat poor catchment management. The results of the abiotic and biotic comparison show that there are minor similarities and differences among the selected pans studied in each province. The knowledge acquired can now be utilised to enhance the available literature on these pans. Long-term studies have to be done to better understand the ecological functioning of the pans in the North West Province in order to devise mitigation measures as well as appropriate rehabilitation strategies and conservation measures.

M.Sc. (Aquatic Health) / Wetlands play an extremely important role in the hydrological cycle as well as biodiversity. Until recently, however, wetlands in South Africa have been neglected both in terms of research and monitoring. The lack of knowledge is even greater for the inward draining wetlands, which is better known as pans. Pans are isolated aquatic systems, which are quite shallow and do not have an outlet. Pans receive water from precipitation and surface runoff, and lose water mainly through evaporation. Some pans can be ephemeral (dry up often) and other perennial (dry up only during drought). The little ecological knowledge available is mainly focused on these ephemeral pans. In this present study conducted in the Western Free-State province, study was only focused on the perennial pans in this area. Due to the fact that this province are one of the biggest areas for gold mining in the country, the pans suffer under the impacts, and this results in the alteration of community structures in and around the pan, simplifying food chains which can lead to the collapse of an ecosystem. The aim of the study was to assess the water quality, bioaccumulation of toxicants (metals and pesticides) in sediment and aquatic invertebrate community of perennial pans in the Western Free State Province, mainly because of the lack of literature on pans in these areas. Seventeen pans were selected for the study of which eight were classified as saline eutrophic and nine as alkaline dystrophic. Various physico-chemical and sediment characteristics were assessed in addition to the characterization of the aquatic invertebrate communities. It became clear that there is great difference in the physical-chemical characteristics of the selected pans. The difference in the trophic state was the most clear, with differences in water colour, nutrient concentration and vegetation growth, classifying pans as either saline eutrophic or alkaline dystrophic. These trophic states influence the distribution and richness of aquatic invertebrates in certain pans. Mining activity, urbanization, agricultural activities and sewage runoff into the pan, all affects the pans negatively, there is sighs of water quality degradation as well as changes in the community structure of invertebrates when compared to the reference pans.