The objective of this research was to determine how stakeholder engagement impacts on the use and sharing of ecosystem service benefits derived from large lake systems. The Wilderness and Swartvlei lake systems, which form an integral part of the Wilderness Section of the Garden Route National Park (GRNP), were chosen as the study area. The park is juxtaposed with urban and other land uses making it one of the most integrated urban conservation areas in South Africa. The park is an open-access park with only enclosed areas being the camping and chalet areas that borders onto the Touw River Estuary. A major contribution of this research was that it classified stakeholder groups into ten meta-identities (associations, businesses, charity organisations, conservancies, government departments, informal groupings, learning/educational institutions, multiple stakeholder projects, spiritual groupings and sports clubs) and that through an iterative research approach it stimulated dialogue between individuals across the various meta-identities. Engagement is a way of allowing stakeholders to develop a sense of ownership through the decision-making process. This could also lead to a higher level of trust and cooperation. The main insights drawn from this research were that, history is important; engagement is characterised by an on-going blame-game (at least in part as a result of this particular history); meta-identities share some values, but differ in how they see the world; there is a concern over social issues (widespread concern, but few mechanisms to address the issue); management agencies are stewards of the feedbacks between social and ecological systems (responsible for regulating flows of benefits), but in open-access systems cannot do so on their own; all meta-identities are keen to contribute and this can, with appropriate facilitation, be harnessed towards collective action. Stakeholders associated with all ten meta-identities identified provisioning and cultural services as a benefit derived from the lakes. No regulating or supporting services were identified as benefits. This could indicate a gap in awareness of the importance of these services. A category that emerged from this study is the importance of employment opportunities linked to the management of natural resources. The study showed that engagement does not occur around the benefits that can be derived from the lakes, but rather around the issues that have a direct or indirect influence on the ecosystem services and therefore the suite of benefits that would be available for sharing. The issues could be divided into two broad themes; social issues and developmental pressures. The social issues pose an indirect threat to the lakes while the developmental pressures pose a direct threat. As the mandates across agencies differ, with the municipalities concerned with the social issues and SANParks with the pressures, the importance of communication and cooperative governance was highlighted.

Light is the primary source of energy in most of earth's ecosystems . In freshwater ecosystems the major interacting factors that determine the abundance and species composition of planktonic phototrophs, the primary utilizers of light, are nutrients, temperature and light. With increasing eutrophication and declining geographical latitude, nutrient availability becomes in excess of the organisms' requirements, water temperature is more favourable for growth, and community structure depends to a greater extent on light availability. This study focuses on the population dynamics of the bloom-forming cyanobacterium Microcystis aeruginosa Kutz. emend. Elenkin in subtropical Hartbeespoort Dam, South Africa. The objectives of the study were: to investigate the annual cycle, and the factors leading to the dominance and success of the cyanobacterium in this hypertrophic, warm monomictic lake, where light availability is the major factor limiting phytoplankton growth rates; to study the surface blooms and ultimately hyperscums that this species forms; and to assess the ecological significance of hyperscums. A 4. 5-years field study of phytoplankton abundance and species composition in relation to changes in the physical environment, was undertaken. The hypothesis was that M. aeruginosa dominated the phytoplankton population (> 80 % by volume) up to 10 months of every year because it maintained itself within shallow diurnal mixed layers and was thus ensured access to light. It was shown that wind speeds over Hartbeespoort Dam were strong enough to mix the epilimnion (7 - 18 m depth) through Langmuir circulations only 12 % of the time. At other times solar heating led to the formation of shallow ( < 2 m) diurnal mixed layers (Z[1]) that were usually shallower than the euphotic zone (Zeu; x = 3.5 m), while the seasonal mixed layer (zrn) was always deeper than Zeu. From the correspondence between vertical gradients of chlorophyll a concentrations and density gradients, when M. aeruginosa was dominant, it was implied that this species maintained the bulk of its population within Z[1]. Under the same mixing conditions non-buoyant species sank into dark layers. These data point out the importance of distinguishing between Zrn and Z[1], and show the profound effect that the daily pattern of Z[1], as opposed to the seasonal pattern of Zrn can have on phytoplankton species composition Adaptation to strong light intensities at the surface was implicated from low cellular chlorophyll a content (0.132 μg per 10[6] cells) and high I[k ](up to 1230 μE m⁻² S¯¹). Ensured access to light, the postmaximum summer populations persisted throughout autumn and winter, despite suboptimal winter temperatures, by sustaining low losses. Sedimentation caused a sharp decline of the population at the end of winter each year and a short ( 2-3 months) successional episode follCMed, rut by late spring M. aeruginosa. was again dominant. The mixing regime in Hartbeespoort Dam and the buoyancy mechanism of M. aeruginosa led to frequent formation of surface bloons and ultimately hyperscums. Hyperscums were defined as thick (decimeters), crusted, buoyant cyanobacterial mats, in which the organisms are so densely packed that free water is not evident. In Hartbeespoort Dam in winter M. aeruginosa formed hyperscums that measured up to 0.75 m in thickness, covered more than a hectare, contained up to 2 tonnes of chlorophyll a, and persisted for 2 - 3 monnths. Hyperscum formation was shown to depend upon the coincidence of the following preconditions: a large, pre-existing standing crop of positively buoyant cyanobacteria; turbulent mixing that is too weak to overcome the tendency of the cells to float, over prolonged periods (weeks); lake morphometry with wind-protected sites on lee shores; and high incident solar radiation. The infrequent occurrence of hyperscums can be attributed to the rare co-occurrence of these conditions. Colonies in the hyperscum were arranged in a steep vertical gradient, where colony compaction increased exponentially with decreasing distance form the surface. This structure was caused by evaporative dehydration at the surface, and by the buoyancy regulation mechanism of M. aeruginosa., which results with cells being unable to lose boyancy when deprived access to light from above. The mean chlorophyll a concentration and water content were 3.0 g 1¯¹ and 14 % at the surface crust, 1.0 g 1¯¹ and 77 % at a few mm depth, and 0.3 g 1¯¹ and 94 % at 10 cm depth, where M. aeruginosa cell concentration exceeded 109 ml¯¹. A consequence of the high cell and pigment concentrations was that light penetrated only 3 mm or less, below which anaerobic, highly reduced conditions developed. Nutrient concentrations in hyperscum interstitial water, collected by dialysis, increased dramatically with time (phosphate: 30-fold over 3 months; ammonia: 260-fold). Volatile fatty acids, intermediate metabolites in anaerobic decomposition processes, were present. Gas bubbles trapped within the hyperscum contained methane (28 %) , and CO[2] (19 %), the major end products of anaerobic decomposition, and no oxygen. The structure and function of M. aeruginosa in hyperscum was examined in relation to the vertical position of colonies and the duration of exposure to hyperscum condition. Colonies and cells collected from 10 em depth in the hyperscum were similar in their morphology (light and fluorescent microscopy) and ultrastructure (transmission and scanning electron microscopy) to those of colonies from surface blooms in the main basin of the lake. With declining depth over the uppermost 10 mm of the hyperscum cells appeared increasingly dehydrated, decomposed and' colonized by bacteria. studies employing microelectrode techniques demonstrated that photosynthetic activity of colonies at the surface of a newly accumulated hyperscum rapidly photoinhibited, substrate-limited, and then ceased within hours of exposure to light intensities > 625 μE m⁻² S¯¹. Photooxidative death followed. The dead cells dehydrated to form the dry crust, from underneath. and space was thus created for colonies rising Cells collected from 10 cm depth retained their photosynthetic capacity ([14]C-uptake experiments) throughout the hyperscum season, although a considerable decline in this capacity was noted over the last (third) month. Altogether the data indicated that spatial separation developed within the hyperscum, between a zone at the surface of lethal physical conditions, a zone beneath the surface of stressful and probably lethal chemical conditions, and a deeper zone of more moderate conditions, which nevertheless, deteriorated after 2 - 3 months. A conceptual model describing the fate of a colony entering a hyperscum was then proposed. According to this model, a colony that arrives below a hyperscum and is not carried away by currents, becomes over-buoyant in the dark and floats into the bottom of the hyperscum. With time it migrates towards, due to its own positive buoyancy, the buoyancy of colonies rising from underneath, and the collapse of cells at the top. It survives in the dark, anaerobic environment by maintaining low levels of basal metabolism while utilizing stored reserves. Depending on weather conditions, the colony mayor may not remain within the hyperscum long enough to reach the zone of decomposition near the surface, where it would die. With the aging of the hyperscum and the accumulation of trapped decomposition products, the zone of decomposition expands. Thus, a hyperscum is essentially a site of a continuous cycle of death and dehydration at the surface and upward migration of colonies from below to replace those that died, although not all colonies entering the hyperscum necessarily reach the lethal zone. The formation of hyperscums was shown to have no major influence on the annual cycle of M. aeruginosa in Hartbeespoort Dam. The seasonality of increase and decline of the planktonic population was similar from year to year, irrespective of whether or not hyperscums formed. The phenomenon of hyperscums demonnstrated that, as Reynolds and Walsby (1975) claimed, thick cyanobacterial water-blooms do form incidentally and have no vital function in the biology of the organism. water temperature did have a major effect on the annual cycle of this species in Hartbeespoort Dam. In temperate lakes the low water temperatures in autumn and winter (<10° C) cause M. aeruginosa to lose its ability to regain buoyancy in the dark, and consequently it sinks to bottom sediments. The higher ( > l2°C) minimum winter temperature in Hartbeespoort Dam leads to the maintenance of a relatively large residual planktonic population throughout the winter. Unlike the case in temperate lakes, the long-term survival of M. aeruginosa in warm-water lakes probably does not depend on winter benthic stocks for the provision of an inoculum for the following growth season. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1987.

Lake St Lucia in northern KwaZulu-Natal, South Africa, experiences severe ecological stress during dry periods largely as a result of diminishing freshwater supplies and conditions of hypersalinity. Possible intervention involves diverting the Mfolozi River to the St Lucia Lake system. However, due to high sediment loading, water from the Mfolozi river requires considerable filtration before a link can be established. A suggested option considered in this study is to restore the existing sugarcane farmlands on the Mfolozi Floodplain (~20 800 ha) to previous wetland conditions to reinstate a sediment removal function amongst other benefits. Proposed restoration will have a direct impact on the industries currently supported by the iSimangaliso Wetland Park and the Mfolozi Floodplain (tourism, sugar, conservation). to understand a measure of such impacts, ecosystem services for both Lake St Lucia and the Mfolozi Floodplain were analysed (flood alleviation, water provision, water purification, sediment regulation, tourism, fisheries, vegetation for harvest, existence, cultural and research). Annual economic values for each ecosystem service were determined by means of valuation methods that included benefit transfer and replacement cost. Results showed a current annual minimum value of the Mfolozi Floodplain and Lake St Lucia as greater than R21 million and R1.1 billion respectively. Partial restoration of the floodplain (~6 000 ha) is expected to increase the sum of all ecosystem services values by approximately 26% for the Mfolozi Floodplain and by 23% for the St Lucia System. Full restoration (~20 800 ha) increases the total ecosystem services value by 88% and 50% for the Mfolozi Floodplain and St Lucia System respectively. Results showed that economic values for existence, fisheries, tourism and water provision increase by the greatest percentage for the St Lucia System under both restoration scenarios. Partial and full restoration of the floodplain will result in the greatest increases in economic value for the services existence, tourism, fisheries and the harvesting of vegetation on the Mfolozi Floodplain.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The Swartvlei estuary and lake system is situated on the southern coast of the Western Cape Province of South Africa and forms part of the core conservation area of the Wilderness National Park. The Swartvlei system comprises two interlinked water bodies, namely Swartvlei Lake and Swartvlei estuary. SANParks have been monitoring this estuary closely over the past two decades, due to its importance to the ecology and to tourism. There are also low-lying properties on the perimeter of the Swartvlei estuary which run the risk of occasional flooding. Two of the major monitoring issues in this estuary system are the water level required for successful mouth breaching, and the influence of the water level on the low-lying properties. This study presents a preliminary analysis of the sediment budget across the Swartvlei estuary mouth. The objective of this study was to identify the various sediment contributory factors and to estimate the quantities that each individually contributed towards the defined sediment budget. / AFRIKAANSE OPSOMMING: Die Swartvlei meer en see monding is geleë aan die kaapse suidkus van Suid- Afrika. Dit vorm deel van die kern bewarings area van die Wilderness Nationale Park. Die Swartvlei sisteem bestaan uit twee verbinde, kern dele nl: Swartvlei meer en estuarium. Vir die afgelope twee dekades is hierdie area onder die noue toesig van SANParke as gevolg van die belangrikheid van die area met betrekking tot toerisme en ekologie. Daar is ook menigde laag liggende eiendomme aan die oewers, wat baie sensitief is vir watervlak stygings. Die optimum water vlakke benodig vir die uitskuring van die gety monding het ook implikasies vir die laag liggende eiendome en vereis noukeurige monitering. ‘n Voorlopige analise van die sediment begroting rondom die gety monding word deur hierdie studie voorgelê.