Thesis (M. Dev.) -- University of Limpopo, 2016 / This mini-dissertation deals with the legal analysis of the prohibition of marine pollution. It is found that the harmful effects of marine pollution on the marine ecosystem, human health and the economy is a problem that needs to be solved immediately. International Conventions and different legislation have been drafted in order to regulate, reduce, mitigate or stop marine pollution. Despite the existence of these conventions and legislation, this problem continues unabated. Large numbers of marine species are known to be harmed and killed as a result of marine pollution. Marine pollution did not receive much attention until many species in the sea and the marine ecosystem faced adverse consequences resulting from marine pollution. Although it has become a global concern, most nations are still producing huge pollution loads. This mini-dissertation analyses the legal framework and the sources of marine pollution, the effects of marine pollution on the marine ecosystem and human health. Furthermore, it makes a comparative analysis between South Africa as developing country and Australia as a developed country in order to determine what South Africa could learn from Australia. The study makes recommendations on how marine pollution can be solved, mitigated or combatted. / National Research Foundation (NRF)

Dans les systèmes d'aide à la décision, sont généralement à disposition des données numériques abondantes et éventuellement certaines connaissances contextuelles qualitatives, disponibles a priori ou fournies a posteriori par retour d'expérience. Les performances des approches de classification, en particulier spectrale, dépendent de l'intégration de ces connaissances dans leur conception. Les algorithmes de classification spectrale permettent de traiter la classification sous l'angle de coupes de graphe. Ils classent les données dans l'espace des vecteurs propres de la matrice Laplacienne du graphe. Cet espace est censé mieux révéler la présence de groupements naturels linéairement séparables. Dans ce travail, nous nous intéressons aux algorithmes intégrant des connaissances type contraintes de comparaison. L'espace spectral doit, dans ce cas, révéler la structuration en classes tout en respectant, autant que possible, les contraintes de comparaison. Nous présentons un état de l'art des approches spectrales semi-supervisées contraintes. Nous proposons un nouvel algorithme qui permet de générer un sous-espace de projection par optimisation d'un critère de multi-coupes normalisé avec ajustement des coefficients de pénalité dus aux contraintes. Les performances de l'algorithme sont mises en évidence sur différentes bases de données par comparaison à d'autres algorithmes de la littérature. Dans le cadre de la surveillance de l'écosystème marin, nous avons développé un système de classification automatique de cellules phytoplanctoniques, analysées par cytométrie en flux. Pour cela, nous avons proposé de mesurer les similarités entre cellules par comparaison élastique entre leurs signaux profils caractéristiques. / In the decision support systems, often, there a huge digital data and possibly some contextual knowledge available a priori or provided a posteriori by feedback. The performances of classification approaches, particularly spectral ones, depend on the integration of the domain knowledge in their design. Spectral classification algorithms address the problem of classification in terms of graph cuts. They classify the data in the eigenspace of the graph Laplacian matrix. The generated eigenspace may better reveal the presence of linearly separable data clusters. In this work, we are particularly interested in algorithms integrating pairwise constraints : constrained spectral clustering. The eigenspace may reveal the data structure while respecting the constraints. We present a state of the art approaches to constrained spectral clustering. We propose a new algorithm, which generates a subspace projection, by optimizing a criterion integrating both normalized multicut and penalties due to the constraints. The performances of the algorithms are demonstrated on different databases in comparison to other algorithms in the literature. As part of monitoring of the marine ecosystem, we developed a phytoplankton classification system, based on flow cytometric analysis. for this purpose, we proposed to characterize the phytoplanktonic cells by similarity measures using elastic comparison between their cytogram signals.

Two sympatric dolphin species, Stenella frontalis and Tursiops truncatus, resident to Little Bahama Bank, Bahamas were found to mostly forage independent of one another, but occasionally foraged in mixed groups. Analysis of over 20 years of data revealed the degree of overlap to be minimal with spatially distinct regions identified for both species, environmental segregation based on depth, bottom type, temperature, and time of day. Results based on observational data indicated significant differences in group size and selected prey. For S. frontalis, lactating females had the most distinct diet, which differed from that of non-reproductively active (NRA) females. Pregnant females had ambiguous prey use results, but diet differences were revealed through nutritional analysis. Lactating females had a higher intake of all nutrients (% moisture, % lipid, % protein, and calories) than pregnant females but lower than NRA females. Mother and calf pairs selected prey for caloric and moisture values. The influence of calves on foraging groups was reflected through discrete differences in all nutrients. Males and females appeared to select the same major prey, but female prey use was much more diverse. / by Christopher R. Malinowski. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

Dans les domaines de la modélisation et de la simulation numérique, les simulateurs développés prennent parfois en compte de nombreux paramètres dont l'impact sur les sorties n'est pas toujours bien connu. L'objectif principal de l'analyse de sensibilité est d'aider à mieux comprendre comment les sorties d'un modèle sont sensibles aux variations de ces paramètres. L'approche la mieux adaptée pour appréhender ce problème dans le cas de modèles potentiellement complexes et fortement non linéaires repose sur la décomposition ANOVA et les indices de Sobol'. En particulier, ces derniers permettent de quantifier l'influence de chacun des paramètres sur la réponse du modèle. Dans cette thèse, nous nous intéressons au problème de l'estimation des indices de Sobol'. Dans une première partie, nous réintroduisons de manière rigoureuse des méthodes existantes au regard de l'analyse harmonique discrète sur des groupes cycliques et des tableaux orthogonaux randomisés. Cela nous permet d'étudier les propriétés théoriques de ces méthodes et de les généraliser. Dans un second temps, nous considérons la méthode de Monte Carlo spécifique à l'estimation des indices de Sobol' et nous introduisons une nouvelle approche permettant de l'améliorer. Cette amélioration est construite autour des hypercubes latins et permet de réduire le nombre de simulations nécessaires pour estimer les indices de Sobol' par cette méthode. En parallèle, nous mettons en pratique ces différentes méthodes sur un modèle d'écosystème marin. / In the fields of modelization and numerical simulation, simulators generally depend on several input parameters whose impact on the model outputs are not always well known. The main goal of sensitivity analysis is to better understand how the model outputs are sensisitive to the parameters variations. One of the most competitive method to handle this problem when complex and potentially highly non linear models are considered is based on the ANOVA decomposition and the Sobol' indices. More specifically the latter allow to quantify the impact of each parameters on the model response. In this thesis, we are interested in the issue of the estimation of the Sobol' indices. In the first part, we revisit in a rigorous way existing methods in light of discrete harmonic analysis on cyclic groups and randomized orthogonal arrays. It allows to study theoretical properties of this method and to intriduce generalizations. In a second part, we study the Monte Carlo method for the Sobol' indices and we introduce a new approach to reduce the number of simulations of this method. In parallel with this theoretical work, we apply these methods on a marine ecosystem model.

Coral reefs are suffering unprecedented declines in coral cover and species diversity. These changes are often associated with  substantial shifts in community structure to new dominant organisms. Ultimately, these “phase shifts” can be persistent and very difficult to return from. Building insurance against degradation and decreasing the likelihood of reefs undergoing shifts to undesirable states will require sustainable management practices that uphold coral reef resilience. This thesis consists of five papers that contribute new knowledge useful for managing the resilience of coral reefs, and other marine ecosystems. Paper I shows how the morphology of natural substrate (dead coral colonies) can significantly influence coral recruitment patterns. Paper II focuses on larval lipid levels, a key determinant of coral dispersal potential, in a common Caribbean coral (Favia fragum). It shows that i) lipid levels exhibit a significant, non-linear reduction throughout the larval release period of F. fragum and ii) exposure to a common pollutant (copper) could potentially lead to a more rapid lipid consumption in the larvae. Paper III presents a broader analysis of the different undesirable states a coral reef can shift to as a consequence of reef degradation. It concludes that different states are caused by different driving factors and that management must explicitly acknowledge this. Paper IV proposes a suite of resilience indicators that can help managers assess when a coral-dominated reef might be moving towards a shift to an undesirable state. These indicators capture key-processes occuring on different temporal and spatial scales and signal resilience loss early enough for managers to take appropriate measures. Finally, Paper V reviews the feedback loops that reinforce the undesirable states of five important marine ecosystems and suggests certain strategies that can ease the restoration back to healthier conditions. Managing these critical feedbacks will recquire monitoring the processes underpinning these feedbacks, breaking already established feedbacks loops through large-scale management trials and acknowledging transdisciplinary solutions that move management beyond the discipline of ecology / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 5: In progress.

<p>No corner of the world's oceans is untouched by humans. Yet in marine science, management, and conservation, oceans are consistently treated as 'unpeopled', that is, human systems are divorced systematically from ecological systems, and assumptions of human/environmental relationships are oversimplified. This dissertation aims to contribute to interdisciplinary, or 'peopled', approaches to marine sciences and management by integrating biophysical and social sciences, specifically historical ecology and resilience thinking on social-ecological systems. Herein, I examine this theoretically (Chapter 2) and empirically by investigating the coral reefs of Hawaii Island's Kona Coast historically, through the oral histories of 'ocean experts', diverse locally-living people from diverse knowledge systems. I investigate human, biophysical, and social-ecological aspects of 'ecological change.' </p><p>Chapter 3 demonstrates that currently there are six expert ocean knowledge systems surrounding Kona's reefs: Native Hawaiians, dive shop operators, tropical aquarium collectors, shoreline fishers, scientists, and conservationists. These are distinct in what experts know about Kona's reefs, and how they know it. The giving and taking of authority between ocean experts, and among people and marine management, influences the condition of the biophysical, social, and management dimensions of Kona's reef systems. </p><p>Chapter 4 examines the biophysical dimensions of change, specifically the historic abundance and distribution of 271 coral reef species. Ocean expert's observations of ecological change are surprisingly consistent, regardless of perspective. Historically, species tend to follow one of eight trends in abundance and distribution, grouping into what I term 'social-ecological guilds'. Analyzing these data with Western scientific frameworks (e.g., trends in apex predators, herbivores, corallivores) proved inappropriate, compared to qualitative approaches. Engaging a multiplicity of perspectives reveals historical ecology broader and richer than from any one knowledge system alone. </p><p>Chapter 5 identifies coupled aspects of marine social-ecological systems, or what I call 'keystone social-ecological features'. I examine 8 features in detail and show how they are central to understanding 'sea change' through such diverse perspectives. Comparing expert's perceptions and responses to ecological through keystone features, I show that 'change' differs based on sociopolitical, economic, etc. perspective. Understanding relationships between and among people, the ecosystem, and marine management institutions is critical for improved ocean management.</p> / Dissertation

Ecosystem modelling allows for an understanding of the structure and functioning of ecosystems. During this study, the oligotrophic KwaZulu-Natal (KZN) Bight, a data-limited system on the east coast of South Africa, was modelled. A framework for modelling data-poor systems, incorporating the construction of multiple models, sensitivity analyses and comparative analyses was applied to the Bight using literature data. Models converged on general trends of ecosystem functioning showing 99% of flows originated from detritus, primarily imported from rivers. The largest source of riverine detritus is the Thukela River which flows into the central Bight. This area supports a shallow-water prawn trawl fishery which targets penaeid prawns. Fisheries time series‘ were incorporated into the model framework to study the effects of prawn trawling and the decrease in prawn recruitment, caused by estuarine nursery loss, on the central Bight ecosystem. Dynamic simulations suggest the biomass of biotic groups were more affected by prawn recruitment level than trawling effort level. To understand the importance of nutrients in more detail, nutrient content, biomass and stoichiometric ratios were documented for various pelagic and demersal functional groups, and compared between areas in this oligotrophic system. Results showed the central Bight had the highest carbon, nitrogen and phosphorus biomasses, due to riverine nutrient sources, and the southern Bight had the lowest. In addition, the demersal community had higher biomasses than the pelagic community for all nutrients. Nutrient dynamics and limitations within the Bight were explored through the construction and analysis of trophic flow networks of carbon, nitrogen and phosphorus for the southern, central and northern Bight. Network analyses suggest nutrient cycling was lowest in the central Bight, and highest in the southern Bight. Cycling of nitrogen was highest in all areas due to the dominance of benthos, in terms of biomass, which was nitrogen-limited. Higher trophic levels were found to be phosphorus-limited. However many pelagic groups were co-limited by nitrogen and phosphorus, probably due to the oligotrophic nature of the bight. This suite of ecosystem models provides the first holistic view of the KZN Bight and an understanding of ecosystem functioning in the southern, central and northern Bight. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.

The KwaZulu‒Natal Bight is formed from a narrow indentation in the SE coast of South Africa with the waters within considered to be oligotrophic. These waters therefore depend on both allochthonous sources of nutrients such as intermittent upwelling of deeper water and nutrients supplied by riverine inputs, as well as the autochthonous nutrients supplied by phytoplankton production, microbial fixation and recycling of nutrients by the microbial loop. Two African Coelacanth Ecosystem Programme cruises were undertaken during 2010, during the wet summer, and dry winter months. During each cruise, the waters of the KZN‒B were sampled rapidly to provide spatial scales (synoptic) of bacterial abundance and biomass, as well as at four predetermined locations to determine temporal scales (focus) of bacterial abundance, biomass and productivity. During the synoptic section, samples were taken in surface waters, close to F‒max (the depth at which phytoplankton were at their most dense as determined by in situ fluorometry), below the F‒max (where depths exceeded 50 m), and near the bottom. These samples were fixed with formaldehyde, stained with DAPI and cells were visualised by epifluorescent microscopy. During the focus section, samples were taken in surface waters, close to F‒max and below F‒max and incubated with 3H‒Thymidine to determine bacterial productivity. Bacterioplankton dynamics (numbers, biomass and productivity) for both cruises, synoptic section, were higher within the photic zone and near riverine influenced waters, with summer showing higher dynamics than winter. Irrespective of season, bacterioplankton dynamics decreased with increasing distance from the coast as well as with increasing depth, potentially via bottom‒up control mechanisms. Results obtained from the focus section of both cruises showed a significant difference between seasons for the Thukela Mouth and Richards Bay North, while no difference at the Durban Eddy. These results from the focus section suggest that bacterioplankton temporal dynamics were more top‒down controlled, rather than environmentally influenced, resulting in fluctuating dynamics over time. Overall, it is proposed that the degree of inorganic nutrient supply to the phytoplankton, resulted in the formation of DOM for use by the heterotrophic bacteria, resulting in a bottom‒up control mechanism, where Chl‒a concentrations within the euphotic zone induces either top‒down or bottom‒up control mechanisms on the heterotrophic bacteria directly affecting their numbers, biomass and productivity. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2013.

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)