Published as the author's thesis (doctor, Wageningen University, 2009). / Vita. Includes bibliographical references (p. 125-138). Includes list of author's publications (p. 147-149).

Published as the author's thesis (doctor, Wageningen University, 2009). / Includes bibliographical references (p. 125-138). Includes list of author's publications (p. 147-149).

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)

Harmful algal blooms, commonly referred to as red tides, occur yearly with dramatic impacts on marine ecology, coastal economies, and human health. As a consequence, research into the zooplankton grazers that consume HABs is highly important. However, changes in ocean temperature may increase the range of many HABs, exposing historically naive copepods to new species and their associated chemicals. Little research into the impact of allopatric verses sympatric species, particularly on the immediate behavioral impact, has been performed, leaving the indirect fitness effects of HAB exposure and consumption relatively unknown. We measured alterations in the swimming behavior of the calanoid copepod Temora longicornis following exposure to sympatric Alexandrium fundyense and allopatric Karenia brevis treatments. After a 15-16 hours depuration period postA. fundyense exposure, T. longicornis exhibited increased average swimming speed and an elevated net to gross displacement ratio (NGDR). During exposure toK. brevis, copepods exhibited an immediate decrease in swimming speed and NGDR, as well as an increased frequency of jump behavior. However, these effects faded after an one-hour depuration period, and disappeared after a 15-16 hour depuration period. The alterations in swimming behavior demonstrated by the copepods treated A. fundyense may increase encounter rate with predators, while copepods treated with K. brevis remain in bloom conditions for longer periods of time, negatively affecting survivorship. Temora longicornis individuals also may be made more visible to predators due to the increase in jumps seen during treatment with K. brevis. These behavioral changes suggest how HABs escape from zooplankton grazer control by altering copepod swimming behavior, and the pattern of predator-prey evolution that occurs over time.

I investigated effects of environmental change on disease, and effects of disease on ecosystems, using a freshwater zooplankton host and its fungal parasite. This research involved lake surveys, manipulative experiments, and mathematical models. My results indicate that ecosystem characteristics such as habitat structure, nutrient availability, and quality of a host’s resources (here, phytoplankton) can affect the spread of disease. For example, a survey of epidemics in lakes revealed direct and indirect links between habitat structure and epidemic size, where indirect connections were mediated by non-host species. Then, in a mesocosm experiment in a lake, manipulations of habitat structure and nutrient availability interactively affected the spread of disease, and nutrient enrichment increased densities of infected hosts. In a separate laboratory experiment, poor quality resources were shown to decrease parasite transmission rate by altering host foraging behavior. My experimental results also suggest that disease can affect ecosystems through effects on host densities and host traits. In the mesocosm experiment, the parasite indirectly increased abundance of algal resources by decreasing densities of the zooplankton host. Disease in the experimental zooplankton populations also impacted nutrient stoichiometry of algae, which could entail a parasite-mediated shift in food quality for grazers such as the host. Additionally, I showed that infection dramatically reduces host feeding rate, and used a dynamic epidemiological model to illustrate how this parasite-mediated trait change could affect densities of resources and hosts, as well as the spread of disease. I discuss the implications of these ecosystem–disease interactions in light of ongoing changes to habitat and nutrient regimes in freshwater ecosystems.

Thesis (LLD.) -- University of Limpopo, 2021 / This thesis, “Regulation, control and prevention of marine pollution in South Africa: A Comparative analysis between national and international legal framework” focuses on the existing laws, conventions, treaties and policies on the control and prevention of marine pollution. Various laws have been enacted in South Africa to prevent and control marine pollution. However, marine pollution continues to increase at a rapid rate. This study aims to establish a basic approach that is aimed at combating marine pollution through examining the regulation, prevention and control of marine pollution in South Africa, with a specific focus on the comparative analysis of national and international framework. To this end, a comparison is made between South Africa and other jurisdictions in Africa, Europe, Asia and Latin America. The reason for employing a comparative approach is to learn best practices and finding solutions to the problem of marine pollution. Thus, the international legal framework, regional framework and operations of intergovernmental bodies and non-governmental bodies on the effort of combatting marine pollution were analysed. The objectives of this study were to examine how marine pollution is prevented through the existing legal framework; to identify the reason for the increasing rate of marine pollution despite the existing legal framework promulgated to curb marine pollution; to determine the effectiveness of the newly created IMOrg, juxtaposing it with similar organisations in other jurisdictions and to propose amendments to legislation that prevent and control marine pollution to ensure effective protection of the marine environment. This study was guided by questions such as the following: Do the existing legal frameworks adequately protect and control marine pollution? What is the reason for the increase in marine pollution despite the existing legal framework regulating marine pollution? How effective is the IMOrg in ensuring that South Africa address marine pollution? Is there a need to promulgate more effective legislation preventing and controlling marine pollution? x The study adopted a non-empirical qualitative research design that does not include data collection, questionnaire, systematic data analysis, observations and/or interviews. The study relied on the library materials that include but are not limited to textbooks, reports, legislations, regulations, charters, policies, amendments to the legislation, journals or academic journals, government gazette, constitution, national and international journals. From the materials consulted, the study revealed the existence of a relationship between the national and international legal framework. However, such an existing relationship is not good enough to effectively prevent the marine environment from harm. This is because a plethora of national legislations that regulate the marine environment comprise less stringent measures to deter future contravention. The study recommends amendments to legislations that regulate marine pollution to impose penalties that have a deterrent value on parties. The study advises against the repealing of these legislations.