Despite the fact that wetlands have been understood to be important for a wide range of ecosystem services, wetlands continue to be degraded globally. There has been a growing need to develop biomonitoring tools that reflect the present ecological state of wetlands, but very few attempts have been made in South Africa to achieve this, and those that have attempted this have generally achieved limited success. This study was conducted to develop and test the congruency of four selected biological indicators (dragonflies, frogs, macroinveterbrates and plants) in relation to the assessment of present ecological state using an existing method in South Africa, "WET-Health". WET-Health assessments rely primarily on transformations to a wetland that result from human impacts in both the catchment and the wetland itself. Using the tool, a health score is obtained that is consistent with the Department of Water Affairs (DWA) current "present ecological state” as applied to river health assessment. The study was conducted in agricultural settings of the Midlands of KwaZulu-Natal based on 13 wetlands. The selected wetlands were scored using WET - Health and grouped in four different ecological condition classes (A, B, C and D). Physical characteristics (wetland area, mean depth), biological characteristics (species cover/abundance, presence and species richness), and chemical characteristics (ammonia, pH, sulphate, nitrogen and phosphate) were also recorded in the selected wetlands. Nineteen different species of dragonfly were recorded in this study. The study demonstrated that dragonflies are a promising bioindicator of wetland present ecological state as the dragonfly index was found to be closely correlated with WET- Health scores. Open water bodies within the selected wetlands were the focus of dragonfly sampling, as male dragonflies are territorial and they will patrol or be found around this habitat. Emergent vegetation dominated by sedges formed the focus of macroinvertebrate sampling in this study because greater numbers of macroinvertebrate families were found in this biotope in comparison to open water areas with no emergent vegetation. A total of 47 macroinvertebrate families were recorded in this study, but SASS5 scores based on macroinvetebrates showed no correlation with WET-Health scores. A total of 10 different frog species were recorded in this study. All the species were common frog species found in most parts of the country. Frog species richness and occurrence showed no correlation with WET- Health scores. A total of twenty samples of two meter radius were measured per wetland and sampled for plant species and estimation of cover-abundance of each species per sample. Over 50 different plant species were recorded in this study, and both species accumulation and species richness showed a degree of correlation with WET-Health scores. All the wetlands in class A had generally higher species accumulation rate and species richness compared to the other wetland classes. In addition to testing the congruency of four selected biological indicators with WET- Health, water quality was measured in all the wetlands. Wetlands in class A were associated with improved water quality as the water passes through the wetland. However, wetlands in class C and D did not show consistently improved water quality between the apex and the toe of these wetlands. In some cases the water quality deteriorated as it passed through wetlands in these two classes.

Methanogenesis was studied in soils from two sawgrass wetlands of the Florida Everglades. Marl soils exhibited a significantly higher potential rate of methanogenesis than peat soils. In these wetlands, methanogenesis: (1) decreased rapidly with increasing soil depth, (2) increased at higher temperatures and lower Eh, (3) was stimulated by organic compounds (cellulose, glucose and acetate), and (4) remained unaffected by added ammonium. Lowering the Eh in the peat and marl soils with sulfide or sulfate stimulated methanogenesis. In January 1990, phosphate caused a significant increase in methanogenesis. The potential rates of methanogenesis decreased to undetectable levels when water levels dropped below the surface, and peaked one month after the start of the wet season. Methanogenesis appeared to be a relatively important process in carbon cycling in marl soils and these soils do not accumulate peat. Therefore, one possible explanation for peat accumulation in sawgrass wetlands may be their low rates of methanogenesis.

The depth of constructed wetlands (CWs) significantly affects the construction investment that influences the efficiency of the CW and is an important design consideration for optimal performance. The aim of the study was to examine the influence of depth on nitrogen retention in 12 pilot scale free surface water CWs in Plönninge (56◦43 45 N, 12◦43 33 E): 6 shallow wetlands with a maximum depth of 0.5 m and 6 deeper wetlands with a maximum depth of 0.8 m. The outlet N concentration in shallow and deep wetlands were found to be significantly different (p<0.05, p= 0.017). Outlet N concentration over the months June to December in deep and shallow wetlands, was found to be significantly different (F (6,60 = 20.594, p< 0.05). and the N concentration in deep and shallow wetlands was significantly different (F (1,10) = 8.087, p<0.05). The N concentration in September was found to be significantly different from those in all other months. The first order rate constant k was calculated for shallow and deep wetlands; higher k value indicates higher nitrogen retention. The deeper wetlands had higher k values than shallow wetlands and was statistically different (p<0.05, p= 0.002) from the k values for shallow wetlands. This implies that the N retention was higher in deeper wetlands than in shallow and was the highest in September. This was most likely due to the effect of temperature and vegetation in the wetlands.

In order to combat the loss of valuable wetland functions and services, federal, state and tribal governments must have the tools to accurately assess and monitor the condition of wetland ecosystems. One particular method of wetland assessment is Floristic Quality Assessment (FQA), which has been growing in popularity throughout the United States since its creation in the 1970s. FQA relies on vegetative indicators of human disturbance to assess the integrity of an ecosystem. FQA calculations are based on Coefficients of Conservatism (C-scores), professionally-assigned scores ranging from 0-10 that denote a local species' tolerance to anthropogenic disturbance. Despite increasing interest in the use of FQA, few studies have thoroughly tested the performance of FQA, especially in New England. We used the Conservation Assessment and Prioritization System (CAPS), a landscape-based, coarse-scale assessment method, as a basis for evaluating FQA's performance in Massachusetts's forested wetlands. Our objective was to use CAPS Index of Ecological Integrity (IEI) scores (a form of generalized stressor gradient) to evaluate the performance of a variety of FQA indices (biological condition gradients), using C-scores from 7 states in the Northeast, and 2 ecoregions in Massachusetts. Based on our calculations of r-squared, and Spearman's rank analysis, we determined that FQA and C-scores have a moderate to weak relationship with the CAPS index of ecological integrity. Of the 12 indices and metrics we tested, the index with the strongest relationship to the IEI stressor gradient was mean Coefficient of Conservatism. Based on this research a number of suggestions are proposed for improving FQA as it applies to wetland assessment.

The lack of cultural and economic recognition of the significance of wetlands arguably led to theirdevastating and rapid loss compared to other ecosystems. To reverse this trend and establish a reasonablevaluation of wetlands, the foundations of socio-ecological concepts were laid in late 20th century thatsuggested the acknowledgement of the functions, values, and services of ecosystems. Subsequently, inthe 21st century the scientific interest in wetland functionality is driven beyond mere conservationalefforts and includes the appropriation of their values for sustainable development, and the utilization oftheir functions as nature-based solutions to humanity’s growing environmental problems. In light of thistrend, this literature review outlines the most critical functions of Swedish wetlands and places them intheir contexts of significance. A meta-analysis of the scientific literature on Swedish wetlandswas conducted with the assessment of wetland functions, wetland types, and the drivers that motivatedeach study. To identify the most critical functions and their contexts, patterns and trends wereinvestigated among these categories. Results show that the most recognised functions of Swedishwetlands are their nutrient-pollutant retention, ecosystem maintenance, and carbon sink functions.Their connections to distinct drivers suggest that their values mainly lie in their potential tomitigate negative impacts of anthropogenic activities, such as eutrophication and global warming,and to support local and regional biodiversity. Synergies among these functions are alsodiscussed, as exemplified by dual-purpose constructed wetlands. Moreover, understudiedhydrological functions are thought to reflect their undervaluation and indicate possible risksattached to associated knowledge gaps. By summarising and contextualising the most importantfunctions, this literature review sheds light on the contemporary understanding and valuation ofwetland functions in Sweden. It is suggested that these novel perceptions effectively drive wetlandconstruction and restoration, the ever-more popular strategies to mitigate climate- and industryrelated risks. Consequently, the recognition, interpretation, and application of wetland functionswill all contribute to the future landscape composition of Sweden.

>Magister Scientiae - MSc / This work aimed at assessing the response of wetland vegetation productivity to the 2014-2017 climate-induced drought at the Soetendalsvlei wetland system in the Western Cape province of South Africa. To achieve this objective, firstly a literature review on the progress of remotely sensed data applications in assessing and monitoring wetland vegetation productivity was conducted. The review elaborates on the role of remote sensing in monitoring and assessing wetland vegetation productivity, with a detailed discussion of the climate change and variability impacts on wetland vegetation productivity. Accurate assessment results are produced when suitable processing techniques are selected as well as appropriate spatial and spectral resolution for extracting spectral information of wetland vegetation productivity. Secondly, wetland vegetation changes and productivity status was assessed using multi-temporal resolution Landsat series imagery and Normalized Difference Vegetation Index (NDVI) during the wet and dry seasons for the period between 2014 and 2018.

Wetlands in densely urbanized landscapes display altered physical, chemical, and biological features; however, long term trends in these are poorly known. The purpose of this study was to determine if biological, physical, and chemical changes in isolated cypress domes are related to time since incorporation within an urban landscape. Sixteen cypress domes in Tampa, Florida were placed into four decadal age groups based on construction date of residential homes within 200 m of wetland edge, with multiples in each age group: 1970s, 1980s, 1990s, 2000s, and rural sites as regional controls. Each site was visited monthly from July 2008 until July 2009. Hylid treefrogs were monitored using PVC refugia and mating calls. Non-hylid anuran species were monitored using mating call surveys and pitfall traps. Hydrology, pH, and conductivity were recorded, transects were made once at each site from wetland center to terrestrial edge in all four cardinal directions, and all trees greater than 8cm DBH were identified and measured for basal area. The dominant treefrog captured was the exotic O. septentrionalis, which was significantly more abundant in 1990s urban cypress domes than either rural sites or other urban decadal groups. The number of both the exotic O. septentrionalis and the native H. cinerea were positively correlated to more recent decades of development surrounding wetlands. H. squirella was detected at sites where O. septentrionalis was rare, and H. femoralis was found almost exclusively at rural sites. Hydroperiods of all urban cypress domes were three times longer on average than rural sites, and conductivity was significantly elevated at all urban sites. In cypress domes within the 1970s decade group, the relative abundance of Florida "facultative wet" tree species was greater than "obligate wet" tree species suggesting encroachment of Acer rubrum into cypress domes possibly due to decades of fire exclusion. At these long isolated sites exotic plants such as Sapium sebiferum were most abundant. Results indicate rapid changes in both physico-chemical characteristics and anuran composition, and long term effects of decreased treefrog abundance and altered tree community structure following incorporation within the urban landscape.

Please read the abstract in the thesis. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Paraclinical Sciences / Unrestricted

>Magister Scientiae - MSc / Wetlands have been recognised as one of the most intrinsically valuable and threatened ecosystems in the world. Global estimates indicate that wetlands are being lost or transformed at a rapid rate, exacerbated by projected climate change impacts. This has prompted the need to improve wetland mapping to address the conservation and management of these ecosystems effectively. However, this remains a challenge. Current mapping approaches estimates of wetland extent vastly underestimate the true extent. Ancillary data has been acknowledged to improve the accuracy of mapping the distribution of wetlands.

Philosophiae Doctor - PhD / Enhancing our understanding of wetland properties and the ecosystem services provided by wetlands within a dynamic landscape, is fundamental to ensuring appropriate management strategies for enhanced biodiversity and ecosystem benefits. With increased anthropogenic activities and the impacts of climatic variability, a better understanding of the factors influencing the water balance dynamics of wetlands can provide insight into how wetlands respond to change. The main aim of the research was to improve the understanding of the spatial and temporal availability of water and storage of a depression wetland in a semi-arid climate, and to relate these to ecosystem functions. As ecosystems are intricately connected to society, a secondary aim of the research was to gain insight to how wetland ecosystems, within a changing climate and landscape, provide benefits to society, and add value to human-wellbeing. Soetendalsvlei, a shallow freshwater depression, and one of the few coastal freshwater lakes of South Africa, was the focus of the research.