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Gram-positive bacteria are increasingly becoming more prevalent especially Staphylococcus epidermidis in association with indwelling devices. Lipopolysaccaride (LPS) is the key Gram-negative component involved in this process, but it is not clear which components of Gram-positive bacteria are responsible for progression of this often fatal disease. The aim of this thesis was to investigate the effect of bacterial components on the immune systems. Lipid S, a short chain form of lipoteichoic acid (LTA) found to be excreted from bacteria during growth in culture medium was examined along with other Gram-positive cell wall components: LTA, peptidoglycan (PG) and wall teichoic acids (WTA) and LPS from Gram-negative bacteria. Lipid S, LTA, PG and LPS but not WTA all stimulated murine macrophages and cell lines to produce significant amounts of NO, TNF-a, IL-6 and IL-1 and would induce fever and tissue damage seen in inflammatory diseases. Lipid S proved to be the most potent out of the Gram-positive samples tested. IgG antibodies in patients serum were found to bind to and cross react with lipid S and LTA. Anti-inflammatory antibiotics, platelet activating factor (PAF), PAF receptor antagonists and monoclonal antibodies (mAbs) directed to LTA, CD14 and toll-like receptors were utilised to modulate cytokine and NO production. In cell culture the anti-LTA and the anti-CD14 mAbs failed to markedly attenuate the production of NO, TNF-a, IL-6 or IL-1, the anti-TLR4 antibody did greatly inhibit the ability of LPS to stimulate cytokine production but not lipid S. The tetracyclines proved to be the most effective compounds, many were active at low concentrations and showed efficacy to inhibit both lipid S and LPS stimulated macrophages to produce NO.

In this thesis I assess the efficacy of large no-take marine protected areas (MPAs), known as marine reserves, in safeguarding mobile pelagic predators. The creation of reserves excludes fisheries, so while removing a pressure, it also removes a key source of data on pelagic predators. Therefore, I also evaluate two fisheries-independent monitoring techniques: telemetry and camera trapping. I use the British Indian Ocean Territory (BIOT) marine reserve as a case study. In Chapter 2 I assess trends in tuna populations, showing that yellowfin tuna (Thunnus albacares) were declining in BIOT prior to the reserve’s creation. While there is no discernible signal of overall species recovery four years after reserve establishment, BIOT may house resident tuna populations. In Chapter 3 I evaluate environmental correlates of tuna distribution, identifying sea surface temperature and depth as drivers, and show that yellowfin and bigeye tuna (Thunnus obesus) occupy different spatial and thermal habitats. In Chapter 4 I investigate the reserve’s role in conserving silky sharks (Carcharhinus falciformis). From fisheries records I infer that BIOT may be an important nursery ground, and telemetry data show they have clear habitat preferences within BIOT. In Chapter 5 I examine the potential of using remote camera-traps to monitor populations of pelagic sharks and demonstrate that significant investment would be required to develop an effective array. Overall, I conclude that BIOT may have more conservation value to species like the silky shark than it does to pelagic tunas. I show that spatial-temporal distributions of pelagic predators are predictable, meaning that enforcement could be better directed in order to improve efficiency. I suggest actively removing drifting fish aggregation devices (FADs) in BIOT to improve its conservation value for silky sharks. Lastly, I recommend that managers wishing to monitor pelagic populations undertake full cost-benefit analyses of camera-trap techniques prior to implementation.