Movements of sub-adult sicklefin lemon sharks Negaprion acutidens in a remote Indian Ocean atoll
- Authors: Filmalter, John David
- Date: 2012
- Subjects: Silky shark , Silky shark -- Habitat , Sharks -- Amirante Islands (Seychelles)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5383 , http://hdl.handle.net/10962/d1018229
- Description: The sicklefin lemon shark Negaprion acutidens is a large-bodied (> 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.
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- Date Issued: 2012
The effectiveness of internal newsletters: case study of Transnet Freight Rail's platform
- Authors: Matshoba, Thembekile Phillinah
- Date: 2012
- Subjects: Newsletters , Business communication
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8420 , http://hdl.handle.net/10948/d1015672
- Description: The research is based on a case study of an internal newsletter, Platform. The objective was to obtain more information about Transnet Freight Rail employees‘ thoughts on its effectiveness and the effectiveness of internal newsletters by using Platform as an example. The treatise explored the perceptions of employees and Transnet in terms of the effectiveness of the internal newsletter as a communication tool as well as their attitudes towards the newsletter as an information disseminating medium. A mixed methods approach was used for analysis in this study. The first methodological paradigm took an interpretivist approach, focusing primarily on analysing the content of the newsletter. The second methodological design was based on the positivistic theory approach and utilised a survey by questionnaire. One hundred and twenty (120) questionnaires were issued to Transnet Freight Rail employees representing the three regions: Central Region, Eastern Region & Western Region and the Head Office of which 120 (100 percent) were received back by the deadline. Of these respondents 56 (46,66 percent) said that they find Platform very relevant as an internal newsletter. A further finding was that 68,33 percent of the respondents said Platform should stay as it is. About 58,33 percent of the respondents took 30 minutes to an hour to read the newsletter with ratings of 72,5 percent interested in communication from management, 65 percent in financial performance, 60 percent in news about people and 59,16 percent in departmental information. The main types of information required are about updates on business performance and safety news. The content of six editions of the newsletter was analysed. The newsletter editions used were from the latest one published counting backwards. The content of the newsletter varies in each edition and depends on the theme. There are similar themes that come up with every edition such as safety. The style of writing used is simple to ensure maximum understanding.
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- Date Issued: 2012