Scuba diving has been around for years and has its origins in history many centuries ago. It has been widely explored and researched as a subject of scientific, medical, and recreational interest. More recently, with the development of sport psychology, it has become the focus of a few social scientists. This research is intended on making a contribution not only to such research in the field of sport psychology and scuba diving, but also that of discursive psychology. This study was executed from a discursive position, using ideas and methods from discursive analysis and applying them to the concept of diving safety. An attempt was made to view discourse as talk, and as such analyze talk as that what is being said. While most research on diving safety focus on how panic and fear are inner entities that drive behaviour leading to accidents, injury and death, this research wanted to look at those inner states as ways of talk and how they are interactionally constructed in talk. The context within which the diving course took place can be divided into three contexts, namely the classroom, the pool and the open water environment. Research was conducted within in the classroom and pool environment, and data consisted of voice recordings of natural conversations in the training context. This research wants to offer alternative explanations in psychology and sport, through explicating what subjects are saying, relating their talk to their situations and actions, and showing how specific situations incite certain types of talk. In conclusion, this was not only a study using naturalistic conversations, but also a study of conversations. / Dissertation (MA (Counselling Psychology))--University of Pretoria, 2004. / Psychology / unrestricted

Photosynthetic activity of three seagrass species, Posidonia sinuosa Cambridge et Kuo, Posidonia australis Hook. f. and Halophila ovalis (R. Br.) Hook., growing in Cockburn Sound, Western Australia, was assessed using an underwater pulse amplitude modulated fluorometer (Diving-PAM). The study aimed to determine possible causes and the extent of stress to seagrasses during transplantation, so that rehabilitation efforts can be improved by reducing stress during the transplant process. Absorptance factors for each species were determined as 0.64 ± 0.04 for P. sinuosa, 0.59 ± 0.02 for P. australis and 0.55 ± 0.02 for H. ovalis, which were substantially lower than previously reported photosynthetic absorption factors. Transmittance, reflectance and non-photosynthetic absorptance of light diverted between 35-45% of irradiance from use in photosynthesis. An investigation of potential errors during measurement of rapid light curves (RLCs) reinforced the importance of ensuring that leaves remained stationary in the Universal Sample Holder. Any movement of seagrass leaves resulted in incorrect measurements of electron transport rates (ETR). A study on seasonal photosynthetic rates of each species found that maximum ETR (ETRmax) varied seasonally and among species. The highest ETRmax for each species occurred during summer, when ambient irradiances were at a maximum, and decreased during autumn. H. ovalis had the highest overall ETRmax in summer, followed by P. australis and P. sinuosa. Effective quantum yield(ΔF/Fm′)of each species varied seasonally, changing inversely with irradiance, which agrees with previously reported studies. ETRmax for each species also showed a diurnal pattern coincident with irradiance throughout the day. The ÄF/Fm for all species demonstrated a diurnal decrease in photosynthetic efficiency coincident with the midday irradiance maximum. Large natural variation in ETR was detected in all species, indicating that the effects of external stress on ETR may be difficult to detect. Two adjacent, physically separated seagrass meadows were examined to determine if apparent visual differences between the sites were reflected by measured physical and photosynthetic characteristics. ETR, leaf area index and sediment grain size differed between sites, but ΔF/Fm, canopy height, shoot density and epiphyte biomass did not, indicating a poor connection between physical and photosynthetic characteristics at these two meadows. Therefore caution should be used when attempting to visually assess the photosynthetic activity of a site based on physical characteristics. Changes in photosynthetic activity were monitored to determine seagrass stress during transplantation, and post-transplantation recovery. Two transplantation methods, sprigs and plugs, were examined, and photosynthetic activity was compared before, during and after transplantation. ETRmax of sprigs took one to two months to increase to the same level recorded at a control meadow, primarily due to desiccation stress suffered during transport. The ΔF/Fm′ decreased below 0.2 after transplantation, but fully recovered after three months. Survival of sprigs was reduced due to strong currents and heavy epiphytic fouling. The ETRmax of transplanted plugs (5, 10 and 15 cm diameter) took up to one week to recover to the same level recorded at a control meadow. Survival of plugs was reduced due to winter swells and storms. Since the leading human-controlled cause of transplant failure was desiccation stress, future transplanting efforts should endeavour to keep seagrasses submerged at all times during the transplanting process.

Many well-studied elasmobranch populations have recently exhibited significant decline. The limited data related to fisheries and sightings for many unstudied or poorly understood populations indicate that these are also suffering. Directed fisheries and more cryptic threats such as entanglement and vessel strike represent significant risk to mobulid rays, arguably one of the most vulnerable elasmobranch groups. Very little information currently exists describing the basic ecology of manta rays or quantifying anthropogenic threats and impacts; however, recent efforts have drastically improved the body of knowledge available for these species, including oceanographic influences on movement, seasonal migration, and mating behaviors. Nevertheless, Red Sea mantas remain completely enigmatic. In this thesis, Chapter 1 details results from tagging 18 reef manta rays Manta alfredi in the eastern Red Sea using satellite and acoustic tag technology and demonstrates that mantas occupy areas with high human traffic. The combined satellite and acoustic techniques define both regional movements and ‘hotspots’ of habitat use where there is significant potential for manta-human interaction. I also present opportunistic sighting data that corroborate anthropogenic impacts on this population. Chapter 2 explores the vertical component of the nine satellite tags that were deployed on Manta alfredi as described in the previous chapter. Seven tags returned adequate data for analysis. Three of the seven were physically recovered yielding full archival datasets of depth, temperature, and light levels every 10-15 seconds for over 2.6 5 million cumulative data points. Mantas frequented the upper 10 m during the day and occupied deeper water through nocturnal periods. Individuals also exhibited deep diving behavior as deep as 432 m, extending the known depth range of the species. An investigation of 76 high-resolution deep dives suggests gliding is a significant behavioral component of these dives and may provide an efficient mechanism for travel compared to continuous horizontal swimming. This study is the first to employ satellite telemetry techniques on Manta alfredi and is the only study directed at mobulids in the Red Sea. A holistic understanding of these behaviors is essential for developing and implementing appropriate management techniques, and this work is particularly timely in light of recent international trade regulation as mantas were listed on Appendix II of the Convention on International Trade in Endangered Species.