https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:4655 Wed 12 May 2021 23:48:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5660 Wed 12 May 2021 23:31:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5120 Wed 12 May 2021 23:30:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4141 Wed 12 May 2021 23:28:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5333 99%) better than presence (60%). Because coelacanths have a unique spot pattern it was possible to quickly and accurately identify specific individuals photographically using computer-aided identification software. Without any manual intervention by an operator the software accurately identified between 56 and 92% of the individuals. Identification success increased to 100% if the operator could also manually select from other potential matching photographs. It was also shown that fish exhibiting a yaw angle not exceeding 60° could be accurately identified in photographs. Each of the sections presented in this thesis represent a possible step towards analysing coelacanth-related habitats, locating and then analysing new habitats. Steps include first locating a population and then performing a habitat analysis. Coelacanth location within the different habitats can then be determined allowing the development of predictive models to potentially identify possible locations of new populations. The final step is to identify individual fish within the population for assessing demographic parameters and population monitoring.]]> Wed 12 May 2021 23:21:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4661 Wed 12 May 2021 23:13:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5272 Wed 12 May 2021 23:00:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4013 Wed 12 May 2021 22:54:42 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4026 Wed 12 May 2021 22:38:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5249 Wed 12 May 2021 20:52:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4371 Wed 12 May 2021 20:52:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5383 3m) coastal shark species, widely distributed in tropical and sub-tropical Indo-Pacific waters. Despite its large size and wide distribution, very little is known about its movement behaviour throughout ontogeny. The primary aim of this thesis was to gain an understanding of the movements of sub-adult N. acutidens, in and around the St. Joseph Atoll, Republic of Seychelles, to facilitate the effective conservation of this vulnerable species. A total of 22 sharks (139 – 202 cm TL) were equipped with coded acoustic transmitters and passively monitored using moored acoustic receivers for a period of 20 month from March 2009 to October 2010. The use of passive acoustic telemetry arrays to study behavioural ecology has increased in popularity in recent years and been successfully applied to study a host of teleost and elasmobranch species in a diversity of habitats, ranging from sheltered estuaries to the offshore pelagic environment. However, the practicalities of designing an effective network of receivers to optimally monitor animal movements can be challenging. In this study the receiver array was optimised through a series of incremental steps to achieve an efficient design that allowed for the specific objectives to be addressed. The specific objectives of this study were to i) gain an understanding of the long term space use patterns and site fidelity of sub-adult N. acutidens within degree of use of the St. Joseph Atoll lagoon and surrounding habitats, and ii) investigate their short term behavioural patterns in response to natural rhythmic cycles. The important role the atoll plays in the sub-adult stage of this species was demonstrated by the very low numbers of detections outside the atoll compared to the very large numbers of detections inside the atoll. Over the course of a year the tagged sharks showed a high degree of site fidelity to the atoll, with 79 – 100% of the individuals detected during each month and 50% being detected on a near daily basis. This result provides testimony of the nursery role of the atoll and importance of these habitats in the early life history for this species. Individual area use was generally found to be restricted to the eastern part of the atoll incorporating a portion of the central deep lagoon and a nearby adjacent area of the sand flats. The movements of sub-adult N. acutidens on and off of the shallow flats surrounding the central lagoon (likely for foraging) were found to be strongly influenced by the tidal height and the diel cycle. Tagged sharks were found to utilise the flats more regularly when the tidal height was greater than 90 cm and particularly more so during the night and early morning than during daylight times. The combined results of this study expose the vulnerability of this species to rapid local depletion. Similarly, the effectiveness of spatial management measures, such as no-take marine protected areas is highlighted as an efficient tool for the future conservation of this species. In the St. Joseph Atoll in particular, the use of a multi-levelled protection approach, where the eastern portion on the atoll is completely restricted while the remaining area is utilized for non-consumptive tourism activities, could be highly effective. Future research should investigate changes in area use throughout the ontogeny of this species as well improve the understanding of the breeding site fidelity and population size of reproductive females using the St. Joseph Atoll.]]> Wed 12 May 2021 20:28:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4670 Wed 12 May 2021 20:21:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4158 Wed 12 May 2021 19:51:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3751 Wed 12 May 2021 19:31:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4825 Wed 12 May 2021 19:22:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5789 Wed 12 May 2021 19:18:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5331 Wed 12 May 2021 19:04:57 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4654 Wed 12 May 2021 19:01:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4752 Wed 12 May 2021 18:49:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5559 Wed 12 May 2021 18:44:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5171 Wed 12 May 2021 18:40:05 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4130 Wed 12 May 2021 18:19:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5788 90% in the last 130 years), the cause(s)of which are unknown. There is a paucity of data on this species in the South Atlantic Ocean, therefore their trophic ecology at Tristan da Cunha was studied, specifically focusing on diet, using stomach content analysis and stable isotope analysis (SIA), in conjunction with an analysis of diving behaviour, assessed using temperature-depth recorders. In order to evaluate the influence of gender on foraging, a morphometric investigation of sexual dimorphism was confirmed using molecular analysis. Additionally, plasma corticosterone levels were measured to examine breeding stage and presence of blood parasites as potential sources of stress during the breeding season. Northern Rockhopper penguins at Tristan da Cunha displayed a high degree of foraging plasticity, and fed opportunistically on a wide variety of prey, probably reflecting local small-scale changes in prey distribution. Zooplankton dominated (by mass) the diet of guard stage females, whereas small meso-pelagic fish (predominantly Photichthyidae)dominated diet of adults of both sexes in the crèche stage, with cephalopods contributing equally in both stages. Adults consistently fed chicks on lower-trophic level prey (assessed using SIA), probably zooplankton, than they consumed themselves indicating that the increasing demands of growing chicks were not met by adults through provisioning of higher- quality prey. SIA also indicated that adults foraged in different oceanic water masses when feeding for self-maintenance and for chick provisioning, thus temporally segregating the prey consumed for different purposes. It is possible that adults ‘selected’ these higher quality prey for themselves, or this may be a reflection of opportunistic behaviour. At Tristan da Cunha sexual dimorphism was observed in culmen dimensions (length, depth, width), with males having larger beaks and feeding on larger individuals of squid and fish than females. No sexual segregation in terms of foraging habitat (i.e. different water masses, based on ð¹³N or trophic level ð¹⁵N) during the breeding season or pre-moult period was revealed through SIA, and stomach content analysis revealed no sexual differences in prey species targeted. The results of SIA of feathers indicate that during the pre-moult period birds foraged in different water masses than during the breeding period. The fact that throughout the breeding season birds foraged in similar habitats suggests no intra-specific competition, despite both sexes feeding on the same prey.Birds were generally diurnal, daily foragers (12 – 16 hr trips), with extended trips (maximum duration 35.5 hours) and nocturnal diving recorded in a few individuals. Birds dived well within their physiological limits, predominantly utilising the upper 20m of the water column, employing two different strategies to target different prey items. Long, deep (30 – 40 m), energetically costly dives were performed when targeting energy-rich prey (fish), and a greater number of shorter, shallower (5 – 20 m), energy-efficient dives were performed when targeting prey with a lower energy content (zooplankton). More than half of the sampled study population were infected with the intra-cellular blood parasite Babesia, but infection showed no relationship to body mass, corticosterone levels or breeding success. Fasting birds showed no signs of elevated corticosterone levels, suggesting they had acquired sufficient fat reserves prior to breeding. Failed breeders did not exhibit elevated corticosterone levels. Tristan skuas, Catharacta antarctica hamiltoni, were observed to be a significant cause of egg and chick mortality. The absence of sex-based differences in foraging, and the absence of any signs of stress in relation to body mass, presence of Babesia or breeding stage, suggest that there are no obvious signs of high levels of stress or food limitations during breeding at Tristan da Cunha.]]> Wed 12 May 2021 17:44:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5432 Wed 12 May 2021 17:38:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4586 Wed 12 May 2021 17:23:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5726 Wed 12 May 2021 17:21:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4769 Wed 12 May 2021 17:15:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5893 Wed 12 May 2021 17:07:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4665 Wed 12 May 2021 17:05:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3866 Wed 12 May 2021 16:33:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5644 Wed 12 May 2021 16:23:44 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5229 0.05) amount of variability (63%) was explained by a predictive model incorporating these variables as investigations were constrained by small sample sizes and aggregated catch information. Scientific survey data provided multi-species information and highlighted the high proportion of non-native fish species in Eastern Cape impoundments. Gillnet catches were influenced primarily by species composition and were less subject to fluctuations induced by environmental factors. Overall standardised gillnet CPUE was influenced by surface area, conductivity and age of impoundment. Although the model fit was not significant at the p<0.05 level, 23% of the variability in the data was explained by a predictive model incorporating these variables. The presence of species which could be effectively targeted by gillnets was hypothesised to represent the most important factor influencing catch rates. Investigation of factors influencing CPUE in impoundments dominated by Clarias gariepinus and native cyprinids indicated that warmer, younger impoundments and smaller, colder impoundments produced higher catches of C. gariepinus and native cyprinids respectively. A predictive model for C. gariepinus abundance explained a significant amount of variability (77%) in CPUE although the small sample size of impoundments suggests that predictions from this model may not be robust. CPUE of native cyprinids was influenced primarily by the presence of Labeo umbratus and constrained by small sample size of impoundments and the model did not adequately explain the variability in the data (r² = 0.31, p>0.05). These results indicate that angling catch- and scientific survey data can be useful in providing predictions of fish abundance that are biologically realistic. However, more data over a greater spatial scale would allow for more robust predictions of catch rates. This could be achieved through increased monitoring of existing resource users, the creation of a centralised database for catch records from angling competitions, and increased scientific surveys of South African impoundments conducted by a dedicated governmental function.]]> Wed 12 May 2021 16:19:14 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5766 1700m) sites within the Sneeuberg Mountain Complex (SMC) from June 2009 to May 2010. I also tested the effectiveness of five different bait types for measuring small mammal diversity (i.e. number of individuals caught, species richness, Shannon diversity index and Simpson index of diversity). Out of a total of 423 captures, 292 individuals of 12 small mammal species (one shrew, one elephant shrew and 10 rodents) were recorded over 5280 trap nights. The species richness and diversity of small mammals captured at the three sites were similar and this homogeneity was probably related to the regional processes (e.g. climate and latitude) that govern species richness and diversity. The most effective bait type in terms of capture success, species richness and diversity measurements was peanut butter and oats. In addition, the use of richness estimators revealed that peanut butter and oats was the most effective bait for sampling the species richness of small mammals. The effectiveness of peanut butter and oats was related to this bait having a more attractive scent, when compared to the other bait types. Future studies should focus on researching the range of local and regional processes that drive small mammal diversity at high altitudes in South Africa. I also recommend the use of more than one bait type when planning to survey small mammal communities.]]> Wed 12 May 2021 16:13:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5493 Wed 12 May 2021 15:59:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5288 Thu 13 May 2021 07:30:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4021 Thu 13 May 2021 07:22:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5335 Thu 13 May 2021 07:17:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5693 Thu 13 May 2021 07:16:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5767 Thu 13 May 2021 07:13:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4024 Thu 13 May 2021 07:08:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3867 Thu 13 May 2021 07:08:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4129 Thu 13 May 2021 06:49:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5296 Thu 13 May 2021 06:49:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5170 Thu 13 May 2021 06:36:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5476 Thu 13 May 2021 06:18:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5573 Thu 13 May 2021 05:44:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5104 Thu 13 May 2021 05:24:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4664 Thu 13 May 2021 05:18:30 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4663 Thu 13 May 2021 04:41:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5916 2.5 % TFA) and exhibited intermediate omnivory (intermediate levels of 20:1n-11 and 20:1n-9, intermediate 18:1n-9/18:1n-7 ratios at ~1.3, less enriched δ¹⁵N values at ~7.9 ‰; zooplankton contribution of 10-15 % of the diet). The more depleted nitrogen signatures in the mussels relative to the barnacles and polychaetes possibly illustrated a stronger preference for autotrophic food. Polychaetes mainly consumed plant food sources (i.e. microalgae, macroalgae and detritus; high levels of i-18:0, 18:1n-9, 18:4n-3 and 20:5n-3) and displayed little omnivory (low levels of 20:1n-11 and 20:1n-9, low 18:1n-9/18:1n-7 ratios at ~0.4, intermediate δ¹⁵N values at ~9.1 ‰; zooplankton contribution of <10 % of the diet). The barnacles, mussels and polychaetes are all suspension-feeders, originally presumed to consume the same food sources. The variations observed among the species, therefore, may result from differences in the proportional contributions of the various food sources to their diets as well as distinctions in metabolism. The distinct changes in the fatty acid and stable isotope signatures in all three filter-feeders in the Kariega and Great Fish regions are likely influenced by the diversity in regional vegetation and hydrology in the different systems, combined with interspecific differences in resource partitioning among the species.]]> Thu 13 May 2021 04:32:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4748 Thu 13 May 2021 04:27:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5124 0.05) differences for muscle activity between conditions, except for the semitendinosus muscle, which was significantly (p< 0.05) higher during the control condition while running at high speeds. Players‘ heart rates, core temperatures and perceptual responses were significantly (p< 0.05) higher during the experimental condition, compared to the control condition. Performance responses were significantly (p< 0.05) lower during the experimental condition. Conclusion: The main driver of physiological and perceptual responses was the exercise itself. However, the additional clothing and protective gear exacerbated the responses, particularly towards the end stages of the protocol. This negatively impacted players‘ performance. Muscle activity appeared to be unaffected by increased body temperatures. However, core temperatures never reached critically high levels during either condition.]]> Thu 13 May 2021 04:19:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5636 Thu 13 May 2021 03:50:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3870 Thu 13 May 2021 03:35:30 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3871 Thu 13 May 2021 03:06:22 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5724 Thu 13 May 2021 03:05:16 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5141 Thu 13 May 2021 02:50:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5297 Thu 13 May 2021 02:27:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4005 Thu 13 May 2021 02:15:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5308 Thu 13 May 2021 02:15:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5661 Thu 13 May 2021 02:02:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4851 Thu 13 May 2021 01:25:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4334 Thu 13 May 2021 01:17:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5956 Thu 13 May 2021 01:08:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4025 Thu 13 May 2021 00:34:02 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4057 Thu 13 May 2021 00:06:54 SAST ]]>