Pulmonary surfactant is a complex mixture of lipids and proteins that lowers surface tension, increases lung compliance, and prevents the adhesion of respiratory surfaces and pulmonary oedema. Pressure can have an enormous impact on respiratory function, by mechanically compressing tissues, increasing gas tension resulting in increased gas absorption and by increasing dissolved gas tensions during diving, resulting in the formation of bubbles in the blood and tissues. The lungs of diving mammals have a huge range of morphological adaptations to enable them to endure the extremely high pressures associated with deep diving. Here, I hypothesise that surfactant will also be modified, to complement the morphological changes and enable more efficient lung function during diving. Molecular adaptations to diving were examined in surfactant protein C (SP-C) using phylogenetic analyses. The composition and function of pulmonary surfactant from several species of diving mammals was examined using biochemical assays, mass spectrometry and captive bubble surfactometry. The development of surfactant in one species of diving mammal (California sea lion), and the control of surfactant secretion using chemical and mechanical stimuli were also determined. Diving mammals showed modifications to SP-C, which are likely to lead to stronger binding to the monolayer, thereby increasing its fluidity. Phospholipid molecular species concentrations were altered to increase the concentration of more fluid species. There was also an increase in the percentage of alkyl molecular species, which may increase the stability of the monolayer during compression and facilitate rapid respreading. Levels of SP-B were much lower in the diving species, and cholesterol was inversely proportional to the maximum dive depth of the three species. Surface activity of surfactant from diving mammals was very poor compared to surfactant from terrestrial mammals. The newborn California sea lion surfactant was similar to terrestrial mammal surfactant, suggesting that these animals develop the diving-type of surfactant after they first enter the water. The isolated cells of California sea lions also showed a similar response to neuro-hormonal stimulation as terrestrial mammals, but were insensitive to pressure. These findings showed diving mammal surfactant to have a primarily anti-adhesive function that develops after the first entry into the water, with a surfactant monolayer, which would be better suited to repeated collapse and respreading. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (pt. 2, leaves 288-304).

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Ching-Sang Chiu, Curtis A. Collins. Includes bibliographical references (p. 43-44). Also available online.

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Pulmonary surfactant is a complex mixture of lipids and proteins that lowers surface tension, increases lung compliance, and prevents the adhesion of respiratory surfaces and pulmonary oedema. Pressure can have an enormous impact on respiratory function, by mechanically compressing tissues, increasing gas tension resulting in increased gas absorption and by increasing dissolved gas tensions during diving, resulting in the formation of bubbles in the blood and tissues. The lungs of diving mammals have a huge range of morphological adaptations to enable them to endure the extremely high pressures associated with deep diving. Here, I hypothesise that surfactant will also be modified, to complement the morphological changes and enable more efficient lung function during diving. Molecular adaptations to diving were examined in surfactant protein C (SP-C) using phylogenetic analyses. The composition and function of pulmonary surfactant from several species of diving mammals was examined using biochemical assays, mass spectrometry and captive bubble surfactometry. The development of surfactant in one species of diving mammal (California sea lion), and the control of surfactant secretion using chemical and mechanical stimuli were also determined. Diving mammals showed modifications to SP-C, which are likely to lead to stronger binding to the monolayer, thereby increasing its fluidity. Phospholipid molecular species concentrations were altered to increase the concentration of more fluid species. There was also an increase in the percentage of alkyl molecular species, which may increase the stability of the monolayer during compression and facilitate rapid respreading. Levels of SP-B were much lower in the diving species, and cholesterol was inversely proportional to the maximum dive depth of the three species. Surface activity of surfactant from diving mammals was very poor compared to surfactant from terrestrial mammals. The newborn California sea lion surfactant was similar to terrestrial mammal surfactant, suggesting that these animals develop the diving-type of surfactant after they first enter the water. The isolated cells of California sea lions also showed a similar response to neuro-hormonal stimulation as terrestrial mammals, but were insensitive to pressure. These findings showed diving mammal surfactant to have a primarily anti-adhesive function that develops after the first entry into the water, with a surfactant monolayer, which would be better suited to repeated collapse and respreading. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Sourcing energy from renewable sources is currently a key theme in modern society. Consequently, the pace of development of these emerging technologies is likely to increase in the near future, particularly in marine renewables. However, the environmental and ecological impact of many of these new developments in the marine environment is largely unknown. My thesis has focused on one unknown area of interaction; the potential effect of tidal-stream devices on marine mammals. Collision risk is often cited as a key concern. Therefore, my premise was - for marine mammals to avoid a collision with a marine renewable device (assuming they are on a collision course) they must first detect the device. It is well understood that marine mammals use sound and hearing as their primary sense for communication, foraging, navigation and predator avoidance, so it is highly likely that the primary cue for device detection will be acoustic. However, it is not known how operational marine renewable devices might modify the acoustic landscape in these areas, or whether they will be audible to marine mammals in time to alert them to the presence of devices. It has been suggested that the high level of natural and anthropogenic background noise in tidal-stream areas may mask (drown out) the signal of the tidal devices. The acoustic characteristics of underwater noise in shallow coastal waters are currently not well known. My thesis adds data to this knowledge gap by measuring and mapping underwater noise levels in tidal-stream areas.

Mitochondrial and supernatant glutamate-oxalacetate transaminases (EC 2.6.1.1) and supernatant glutamate-pyruvate transaminase (EC 2.6.1.2) were purified 89, 204 and 240-fold respectively, from dolphin muscle. Starch gel electrophoresis of crude and purified perparations revealed that all three enzymes exist as single forms. Km values of a-ketoglutarate, alanine, pyruvate and glutamate for the glutamate-pyruvate transaminase were 0.45, 8.2, 0.87 and 15 mM, respectively. For the glutamate-oxalacetate transaminases, the Km values of a-ketoglutarate, aspartate, oxalacetate and glutamate were 0.76, 0.50, 0.10 and 9.4 mM, respectively, for the mitochondrial form and 0.13, 2.4, 0.06 and 3.2 mM, respectively, for the supernatant form. In all cases, as the assay pH was decreased from pH 7.3, the Km values of the a-keto acids decreased while those of the amino acids increased. This caused the apparent equilibrium constants for the glutamate-oxalacetate transaminases to remain independent of pH. These values were 9.2 and 6.8 for the mitochondrial and supernatant forms, respectively where K'eq = [asPartate][α-ketoglutarate]/[glutamate][oxalacetate]. Studies of the inhibition of the glutamate-oxalacetate transaminases by dicarboxylic acids indicated that these enzymes may be controlled by pools of metabolic intermediates. Three key roles are suggested for the transminases in the energy metabolism of the diving mammal. First, it is believed that a combined action of the transaminases could enhance energy production during hypoxia by providing (1) fumarate from aspartate for the ATP producing reversal of succinate dehydrogenase and (2) α-ketoglutarate from glutamate for the GTP producing succinyl thiokinase reaction. Next, diving mammals probably accumulate more NADH than other mammals during hypoxia. The glutamate-oxalacetate transaminases seem particularly well suited for restoring redox balance via the malate-aspartate cycle after aerobic metabolism is resumed. Finally, since migrating divers oxidize large amounts of stored fats, the combined reactions of the transaminases could be instrumental in providing increased supplies of oxalacetate to condense with the fat derived acetyl CoA in the citrate synthase reaction. / Science, Faculty of / Zoology, Department of / Graduate

This thesis investigated the use of a static acoustic data logger known as a Cetacean and Porpoise Detection (C-POD) device for monitoring two species of dolphins that occur in Mossel Bay, South Africa: the Indo-Pacific bottlenose dolphin, Tursiops aduncus, and the Indian Ocean humpback dolphin, Sousa plumbea. These two species have a near shore distribution which brings them into frequent contact with human activities such as boating, fishing, desalination plants and the onshore component of gas extraction facilities which can potentially affect their behaviour and populations dynamics. Although both species are relatively well studied within South Africa in terms of biology and abundance, this has been limited to the KwaZulu-Natal coast and Algoa Bay with little information available for areas west of Algoa Bay, and almost no information available locally on their acoustic behaviour. This study aimed to: 1) calculate the detection range and effective detection radius (EDR) of C-PODs for T. aduncus and S. plumbea taking into account environmental and group parameters that may affect these and 2) distinguish T. aduncus from S. plumbea based on temporal variation in specific echolocation click parameters. Field work took place in Mossel Bay from a land-based platform during the period May 2013 to August 2014. A surveyor‟s theodolite was used to collect positional data on dolphins and behavioural information was collected through visual observations. A C-POD was deployed near the land based site and serviced and downloaded on a monthly basis for the same survey period. Visual detections were matched to acoustic detections (echolocation clicks) made within a 60 sec and 30 sec time window. Data were analysed using the software programme R. General Estimating Equations (GEE) were used to 1) model the detection probability and EDR of a C-POD for both species during both time windows; 2) model differences between the two species for seven click parameters produced by the C-POD. The impact of background noise on C-POD detections was also assessed. As cetaceans are not the only form of sound in a marine environment distinguishing dolphin clicks from all other noise sources can be a challenge. Sources of background noise include clicking shrimp, movement of sediment, boat traffic and chorusing by reef fish and crustaceans during reproductive or territorial displays and storms which can either mask the clicks produced by dolphins or fill up the memory card. Data collected from two different deployment locations at different depths were subsequently compared after significant ix interference from other noise source was detected at the first deployment location. Mean number of detected dolphin clicks after filtering increased from 6463.33 to 97820 clicks per deployment and mean number of minutes in which detections were recorded increased from 0.23 min to 2.79 min per deployment. Average detection probability for bottlenose dolphins was 0.357 (95% CI: 0.352 - 0.363) for the 60 sec window and 0.257 (95% CI: 0.253 - 0.262) for the 30 second window. For humpback dolphins the average detection probability was 0.084 (95% CI: 0.082 - 0.087) for the 60 sec window, and 0.043 (95% CI: 0.042 - 0.044) for the 30 sec window. EDR for bottlenose dolphins was 1161.38 mm (95% CI: 1150.14m – 1172.62 m) for the 60 sec window and 1035.761 m (95% CI: 1024.89 m – 1046. 64 m) for the 30 sec window. EDR for humpback dolphins was 765.25m (95% CI: 755.64 m – 774.85 m) for the 60 sec window and 751.00 m (95% CI: 741. 40 m – 760. 60 m) for the 30 sec window. Detection probability and EDR were higher for bottlenose dolphins than humpback dolphins over both time windows. For both species, during both windows, detection probability was significantly influenced by group size (p < 0.05). Four out of the seven parameters produced by the C-POD yielded significant pairwise differences (p < 0.05) between the species. Average inter-click interval was the only co-variable that was significant in the GEE model. The average ICI for bottlenose dolphins was 55.91 ms (95% CI: 51.23 – 60.60) whilst the average ICI for humpback dolphins was longer at 119.76 ms (95% CI: 119.76 – 174.00). The interaction between average ICI and modal frequency was also significant (p < 0.05) indicating that a combination of co-variables might be required in order to differentiate between the two species. Despite the small sample size and the challenges associated with acoustic studies in a noisy marine environment this study provided valuable information regarding the use of static acoustic data loggers such as C-POD in South Africa. As newer versions of C-POD are frequently introduced many of the challenges encountered in this study will be minimized. / Dissertation (MSc)--University of Pretoria, 2016. / Zoology and Entomology / Unrestricted

Marine mammals breeding in sympatry use resources differently depending on their time-activity budgets and prey distribution. We measured isotopic values and patterns of δ15N and δ13C in keratinous whiskers of satellite-tagged adult female Antarctic (Arctocephalus gazella) - and Subantarctic (Arctocephalus tropicalis) fur seals from three colonies at Marion Island in the Southern Indian Ocean. The three sympatric colonies were Mixed Pickle (HD_MP), Rockhopper Bay (LD_RhB), and Watertunnel (HD_WT). A comparison between two colonies of differing A. tropicalis densities will also be investigated. We investigated resource use in breeding mature females over varying time and spatial scales during summer and winter. The aim was to understand the variation in resource and habitat use at population and individual levels. The whiskers of A. gazella and A. tropicalis grow constantly at a rate of 0.16 ± 0.05 day-1 and 0.12 ± 0.05 day-1, respectively. To compare and relate behaviours, the stable isotope data and satellite tracks were grouped into winter and summer (pooled for 2010 - 2014). In summer, A. gazella from HD_WT had a larger isotopic niche width (0.85 ± 0.67‰2) compared to A. tropicalis from both HD_MP (0.18 ± 0.19‰2) and LD_RhB (0.21 ± 0.15‰2). However, the isotopic niche width of A. gazella reduced in size by more than half (0.40 ± 0.40‰2) during winter when the mature females were no longer constrained by the lactation mandate. The mean δ15N values in whiskers of both A. tropicalis and A. gazella in summer were similar (11.3 ± 0.4‰ and 11.0 ± 0.9‰, respectively). The A. gazella broadens its’ isotopic niche feeding at different trophic levels in summer (lactation period). We used a Repeatability index (R) to assess levels of intra- and inter-individual consistency. Repeatability indicated that the bigger isotopic niche width for A. gazella is attributed to high inter- and intra-individual variability in their resource use. The A. gazella individuals ranging closer to the colony consistently consumed myctophid fish. Other individuals foraged on low 15N content euphausiids (i.e., Euphausia spp. and Thysanoessa spp.) south of Marion Island in both winter and summer. The A. tropicalis from LD_RhB were repeatable in their δ15N values (trophic level) (Rglobal = 0.63; [95% CI: 0.29 – 0.80]) and δ13C values (habitat) (Rglobal = 0.69; [95% CI: 0.35 – 0.84]). At HD_MP, the A. tropicalis colony, diet was moderately repeatable (Rglobal = 0.33; [95% CI: 0.11 – 0.51]) while habitat was repeatable (Rglobal = 0.58; [95% CI: 0.33 – 0.73]). Consistency in diet (Rglobal = 0.27; [95% CI: 0.08 – 0.44] and foraging habitat (Rglobal = 0.45; [95% CI: 0.21 – 0.63] was moderate at HD_WT, the A. gazella colony. The diet varied with habitat at the individual level, across seasons. Segregation in diet and foraging habitat minimises resource-use overlap between sympatric fur seals. The behaviour of A. gazella from HD_WT (a high-density colony) might have a direct or indirect impact on the A. tropicalis from LD_RhB (a low-density colony) (i.e., competitive exclusion). Seasonality, at-sea movement, and intrinsic factors shaped the foraging behaviour and diet of adult female fur seals breeding at Marion Island. Some breeding mature females changed diets between seasons and depending on foraging habitat. / Dissertation (MSc (Zoology))--University of Pretoria, 2021. / NRF, Grantholder linked / Zoology and Entomology / MSc (Zoology) / Unrestricted

Understanding what psycho-physiological and behavioural factors influence aversiveness of sound in marine mammals is important for conservation and practical applications. The aim of this study was to determine predictors for impact of anthropogenic noise and to develop a target-specific predator deterrence system for use on fish farms. Three classes of stimuli were tested: 1.) grey seal underwater communication calls expected to be used in territorial defence, 2.) high duty-cycle moderately loud artificial sounds (some of which were based on models of unpleasantness for humans), 3.) brief, intense pulses designed to elicit the acoustic startle reflex. Communication calls had no deterrence effect but instead caused attraction responses. Tests with high duty-cycle artificial sounds showed that food-motivated animals habituate quickly, although sound exposure caused subtle changes in diving patterns over a longer time. Field trials using the same stimuli were used to determine avoidance thresholds but also indicated that sound features like ‘roughness’ play a role. The startle eliciting stimuli, however, had the most dramatic effects. To this stimulus most seals exhibited rapid flight responses, hauled out, sensitised and showed signs of fear conditioning. Startle thresholds were found to be 80-85 dB above the assumed hearing threshold. The data showed that startle thresholds are a crucial predictor for the occurrence of strong avoidance behaviour and suggests that the startle response evolved to increase an animal’s propensity for flight. Finally, a prototype predator deterrence system based on the startle sounds was developed to repel seals whilst not affecting toothed whales. In fish farm trials, seals were deterred at close ranges but local abundance of cetaceans did not change showing that it is possible to cause differential responses between species based on differences in their audiograms. The results are used to develop noise exposure criteria and to elucidate acoustic parameters that can be used to predict responses to anthropogenic noise.