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An exploratory case study on the barriers, challenges and benefits of sustainability reporting by small and medium enterprises (SMEs) in South Africa

  • Authors: Mhlope, Veliswa
  • Date: 2021
  • Subjects: Small business -- South Africa -- Case studies , Sustainable development reporting -- South Africa -- Case studies , Social responsibility of business , Environmental responsibility -- South Africa , Environmental reporting -- South Africa
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/172018 , vital:42149
  • Description: SMEs in South Africa and other developing countries have been slow to take up sustainability reporting. This qualitative study is aimed to study the challenges and barriers faced by SMEs, together with the potential benefits for SMEs participating in this type of reporting. It also makes recommendations about how SMEs can participate in and benefit from sustainability reporting. The study shows that indeed there are several challenges in terms of getting involved in sustainability reporting for SMEs. On the other hand, the research finds that the SMEs who are already participating in sustainability reporting can show the benefits of engaging in sustainability reporting and that these benefits far outweigh the challenges. The participating SMEs are also able to show that they have attained a competitive advantage as a result of engaging in sustainability reporting. If, however, sustainability reporting is to become entrenched into SMEs, a few changes need to take place to address challenges such as lack of information about sustainability reporting and its benefits, lack of regulations and more importantly, lack of awareness about sustainable development. As the South African government begins to respond to issues such as climate change, skills development and good governance, it will become necessary for them to introduce regulations to manage this risk. It is also highly possible that in the next few years, reporting will become a regulatory requirement that SMEs will be forced to comply with to continue to do business. The SMEs who are already practising sustainability practices will benefit from being first movers. Those SMEs who start sooner rather than later will already have the internal resources and capabilities to take advantage of the legislative environment. They will have a head start over their rivals in terms of gaining competitive advantage.
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  • Date Issued: 2021

A critical analysis of social enterprise in Slovenia

  • Authors: Malila, Brett
  • Date: 2020
  • Subjects: Social entrepreneurship -- Slovenia , Social entrepreneurship -- Slovenia -- Case studies , Social entrepreneurship -- Law and legilstion-- Slovenia , Business enterprises -- Law and legilstion-- Slovenia
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/166436 , vital:41364
  • Description: This research presents a case study on the nature of social enterprise in Slovenia. From a resource-based view (RBV), the case study has been used to show what some of the intangible resources are that can be used to promote sustainable social enterprise (SE). The purpose of this research study is to analyse social enterprises in Slovenia in order to establish a framework which other social entrepreneurs can use as the basis from which to operate and achieve competitive advantage. It is an important piece of research for both the process of social enterprise development in Slovenia, as well as to provide ideas and thoughts as to the way forward in this sector for other developing societies. Social enterprise is a developing field and it has been be important to develop cases to begin to explore the concept with real life actualities. The goal is to provide a clearer conceptualisation from which other social entrepreneurs can use as the basis to analyse, plan and improve social enterprise in their own specific contexts. The primary purpose of the study is thus to unpack the core elements that identify social enterprise in Slovenia using the resource-based view. The research aims to understand social enterprise within Slovenia in relation to where it occurs, which are the main industries concerned, and what are the unique resources used to promote sustainable growth. To achieve this, the research was guided by the resource-based view for social enterprise as highlighted by Day and Jean-Denis (2016) as well as that proposed by Bacq and Eddleston (2018). A mind map for a possible route towards improved implementation and understanding of social enterprise in Slovenia, was done through accessing registered social enterprises. This database was from the Ministry of Economic Development in Slovenia. An analysis of 2591 social enterprise, a desktop review of the Slovenian legislation on social enterprise and the unpacking of unique resources available to Slovenian social enterprise was done. This provided a perfect test case to show how the provision of legislation, supportive structures; financial targets, a regional vision and government mentoring social enterprise enhance a contested terrain in Slovenia. Findings highlighted that there have been sustainable successes, but not at the levels expected. It is clear that the government has created various unique resources to build and develop the social enterprise (SE) sector. From an RBV analysis of the social enterprise environment in Slovenia, it is essential to have resources such as legislation, mind-set, in migration (labour) and youth skills be created, monitored and supported. However, there is a need for improved monitoring and tighter implementation of the legislation for social enterprise to provide the solution to destructive social ills.
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  • Date Issued: 2020

Chirema Chine Mazano Chinotamba Chakazendama Madziro

  • Authors: Mapondera, Wallen
  • Date: 2020
  • Subjects: Art, Zimbabwean , Art -- Economic aspects -- Zimbabwe , Artists -- Zimbabwe , Takadiwa, Moffet , Nyandoro, Gareth , Clottey, Serge Attiku , Mapondera, Wallen -- Exhibitions
  • Language: English
  • Type: text , Thesis , Masters , MFA
  • Identifier: http://hdl.handle.net/10962/147457 , vital:38638
  • Description: This mini-thesis has developed as a practice-based supporting document to the exhibition Chirema Chine Mazano Chinotamba Chakazendama Madziro. The exhibition responds to how people become innovative in finding alternative means of survival and staying relevant in an economically depressed country. Zimbabwe is often the first country that comes to mind when people talk about hyperinflation; the situation was and still is intolerable, but somehow its citizens find means to pull through. Unemployment and poverty are the main causes of physical and mental problems for an individual. With this thesis, I highlight the innovations employed by Zimbabweans as a way of keeping themselves busy. I approach this through analysing the Zimbabwean general public’s creative reactions, and by tracing Zimbabwean visual artists’ use of found objects as a reaction to the country’s economic hardships. As people have been pushed to find alternative ways of survival, Zimbabwean artists in particular also shifted from using conventional art materials due to their unavailability. They began to redefine what art material is by employing objects in their artworks that previously had a non-art function. As such, there is a growing need to recognise, classify and document the shifts and establish platforms to generate growth of these innovations. In this minithesis I discuss my own practice, and I analyse the works of Moffat Takadiwa, Gareth Nyandoro and Serge Attiku Clottey.
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  • Date Issued: 2020

Exploring how mobile phones mediate bonding, bridging and linking social capital in a South African rural area

  • Authors: Buthelezi, Stella Mbalenhle Nomfundo
  • Date: 2020
  • Subjects: Social capital (Sociology) -- South Africa -- Eastern Cape , Cell phone users -- South Africa -- Eastern Cape , Cell phones -- Sociological aspects -- South Africa -- Eastern Cape , Cell phones -- Social aspects -- South Africa -- Eastern Cape , Social media -- Influence -- South Africa -- Eastern Cape , WhatsApp (Application software) -- Sociological aspects -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/163419 , vital:41035
  • Description: Many contemporary ICT for development (ICT4D) studies focus on the benefits of mobile phones on the socio-economic development of marginalised communities. For many people in poorly resourced rural areas, one of the significant benefits of mobile phone usage is the expansion of social networks for resources or support. Social capital is one of the concepts that have been found to directly or indirectly influence many aspects of social life, communities and development. In the present study, I explore how mobile phones mediate bonding, bridging and linking social capital in a rural area on the Wild Coast of South Africa, Dwesa. I use individual semi-structured interviews with purposefully selected participants who are mobile phone owners in the area. I employ a thematic analysis to analyse their responses in relation to three dimensions of social capital, i.e. 1) trust and solidarity, 2) social cohesion and inclusion and 3) collective action and empowerment. Like in many South African rural areas, in Dwesa there is endemic poverty, inadequate services and infrastructure and high unemployment. The study found that by increased communication, mobile phones mostly strengthen bonding social capital between close ties who rely on each other for various forms of support. Mobile phones also facilitate the building of bridging social capital among members of various community groups by using WhatsApp group chats and Facebook. The little evidence on the relationship between mobile phone use and linking social capital in the area relates to group networks providing opportunities for interaction between community members and individuals in tertiary institutions and local government positions.
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  • Date Issued: 2020

Observations of diffuse radio emission in the Abell 773 galaxy cluster

  • Authors: Sichone, Gift L
  • Date: 2020
  • Subjects: Galaxies -- Clusters -- Observations , Radio astronomy -- Observations , Astrophysics -- South Africa , Westerbork Radio Telescope , A773 galaxy cluster , Astronomy -- Observations , Radio sources (Astronomy
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/144945 , vital:38394
  • Description: In this thesis, we present 18 and 21 cm observations of the A773 galaxy cluster observed with the Westerbork radio telescope. The final 18 and 21 cm images achieve a noise level of 0.018 mJy beam‾ 1 and 0.025 mJy beam-1 respectively. After subtracting the compact sources, the low resolution images show evidence of a radio halo at 18 cm, whereas its presence is more uncertain in the low resolution 21 cm images due the presence of residual sidelobes from bright sources. In the joint analysis of both frequencies, the radio halo has a 5.37 arcmin2 area with a 6.76 mJy flux density. Further observations and analysis are, however, required to fully characterize its properties.
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  • Date Issued: 2020

Between blue and light

  • Authors: Campbell, Jennifer
  • Date: 2018
  • Subjects: South African fiction (English) -- 21st century , Short stories, South African (English) -- 21st century
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/63570 , vital:28441
  • Description: My novella follows a narrator observing her life, as she struggles with what it is to live in a world that she finds simultaneously frightening and beautiful. The story touches on the limitations of human connection and with loss in various forms. Set in both Cape Town and small town South Africa, the story explores the inner life of a woman detached and adrift.
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  • Date Issued: 2018

The power of mysticism: understanding political support for President Robert Mugabe in Zimbabwe

  • Authors: Manzira, Rufaro Coucou Annette
  • Date: 2018
  • Subjects: Mysticism -- Psychology , Zimbabwe -- Politics and government -- 1980- , Mugabe, Robert Gabriel, 1924-2019 , Allegiance -- Zimbabwe , Political capital -- Zimbabwe , Political psychology -- Zimbabwe , ZANU-PF (Organization : Zimbabwe) , Apotheosis , Zimbabwe -- Kings and rulers -- Religious aspects
  • Language: English
  • Type: text , Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/63693 , vital:28472
  • Description: Significant debate exists within Zimbabwean studies about the basis for which people support on an ongoing basis the ruling Zimbabweans African National Union- Patriotic Front (ZANU-PF) under the leadership of Robert Mugabe. In academic literature, the party and state president (Mugabe) is typically seen as an oppressor such that any support for Mugabe is understood based on compulsion rather than consent. Genuine support for the ruling party though implies that Mugabe is a liberator. In drawing upon Zimbabwean academic literature which seeks to understand why Mugabe might be understood as a liberator, this thesis seeks to provide an innovative sociological analysis focusing on the mysticism surrounding the person and ruler-ship of Mugabe. The mysticism portrays Mugabe as being blessed by the ancestors and spirits, as having divine and sage-like qualities, as speaking for the bones of the dead heroes, and as acting as a modern day national chief who cares for his national subjects and defends his chiefdom against enemies from within or without. This portrait of Mugabe resonates with many Zimbabweans as it speaks to their everyday experiences and their longings for nation-building and national belonging. Hence, it should not be strictly understood as a ruling party ideology foisted upon citizens as a means of political deception. This is explored through interviews with a small number of ZANU-PF supporters.
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  • Date Issued: 2018

Airline revenue management performance measurement of South African Airways origin-destination revenue management

  • Authors: Githiri, Duncan Wanjau
  • Date: 2017
  • Subjects: Revenue management , Airlines Finance , Performance Measurement , Airlines Rates Mathematical models , South African Airways
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/59188 , vital:27455
  • Description: Revenue Management (RM) in the airline industry is the practise of selling fixed capacity as a service over a finite time horizon. The market is characterised by the customers’ willingness to pay different prices for the service. This creates the opportunity to target different customer segments and use price differential to attain the optimal passenger fare mix to maximise revenue. The aim is to maximise revenue and an airline can expect revenue increase of between 3 to 7 percent with the successful implementation of a Revenue Management system. The question of whether the revenue increase can be attributed to the RMS is crucial in determining its level of success and validating the optimisation strategy applied (Rannou and Melli, 2003). South African Airways (SAA) migration from Leg-based optimisation to Origin-Destination (O&D) network based revenue management optimisation created the opportunity for this study to measure and evaluate the RMS performance. Revenue performance measuring tools using inventory systems data to measure RMS performance, ASK (Available Seat Kilometre), RASK (Revenue per Available Seat Kilometre), CASK (Cost per Available Seat Kilometre), RPK (Revenue Passenger Kilometre) and cabin factor yield. The limitations relating to the performance measuring tools utilising inventory system data, is the inability for continuous measurement and the isolation of the impact to revenue due to the RMS on its own. In seeking to gauge the performance of the O&D optimisation, the Revenue Opportunity Model (ROM) is applied. ROM is a post departure measuring tool utilised to continuously measure and isolate the contribution of the RMS on SAA’s O&D network. The revenue opportunity achieved versus the potential revenue was assessed. A revenue comparison of the airlines 2014 and 2015 financial year is performed. The results of the analysis showed the O&D optimisation yielded positive revenue capture on routes that applied the correct optimisation strategy. Recommendations on the optimisation strategy to be applied on routes having average or low revenues captured are presented. The aim is to provide the SAA revenue management department with tangible solutions that would result in increased revenue for the SAA network.
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  • Date Issued: 2017

Dispute resolution

  • Authors: Arendse, Jacqueline A , Clegg, David , Williams, Robert C
  • Date: 2016
  • Subjects: To be catalogued
  • Language: English
  • Type: text , book chapter
  • Identifier: http://hdl.handle.net/10962/131084 , vital:36522 , https://store.lexisnexis.co.za/products/silke-on-tax-administration-skuZASKUPG1440
  • Description: Chapter 9 of the Tax Administration Act 2011, deals with the objection and appeals processes of the tax Acts administered by SARS in terms of s 4 of the SARS Act, 1997. A taxpayer who is aggrieved by an assessment or a decision in which he has an interest, has the right to object against the assessment or decision.
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  • Date Issued: 2016

Visit the exotic birthplaces of transdisciplinarity

  • Authors: Burt, Jane C , Cockburn, Jessica J , Fox, Helen E , Copteros, Athina
  • Date: 2016
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/68442 , vital:29256 , https://doi.org/10.13140/RG.2.1.1511.7048
  • Description: Publisher version , Preface: Why a new approach to science? The world we live in is very different to the world of one hundred years ago. The world has never been so populated by humans and never before have the spe-cies ‘human’ influenced and manipulated the natural world in the way in which we do now. Academics are calling it the age of the Anthropocene. In the age of the Anthropocene we face different challenges to what hu- mans faced centuries ago. As we find ourselves in this new age we have had to not only question ‘what we know’ but also ‘how we know’ and whether the ‘how we know’ is the right kind of ‘how’ for the problems that we face today. This has led to a questioning of the way in which we generate knowledge and the way in which this knowledge is used. This critique is not aimed at all knowledge generation it is mostly a frustration that has arisen out of the physical and biological sciences with the realisation that doing good science is just not enough to bring about meaningful change in the world. Trans-disciplinary scientists and practitioners have begun this journey in search of a new kind of science - A science in service of society! This tourist trip will re- trace the few first steps of these emerging ideas so that we can understand where these new ideas have come from and how they may influence our own research. , This document was developed for a postgraduate course on Transdisciplinary research held at Rhodes University. It explores three key theoretical approaches to transdisciplinarity in relation to the question 'Why TD?'.
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  • Date Issued: 2016

The New Unity Movement Bulletin

COSATU Gender Conference

  • Authors: COSATU
  • Date: Mar 2012
  • Subjects: COSATU
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/135258 , vital:37252
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  • Date Issued: Mar 2012

Domestic workers: discussion document 27-29 March 2012

  • Authors: Congress of South African Trade Unions (COSATU)
  • Date: 2012
  • Subjects: Labor unions South Africa , Household employees South Africa , Cosatu
  • Language: English
  • Type: book , text
  • Identifier: http://hdl.handle.net/10962/68711 , vital:29307
  • Description: The 5th Cosatu Congress resolved that a research be commissioned by the CEC and conducted by Naledi on the need for establishment of advice centres for servicing and assisting domestic workers. Again, part of the resolution indicated that we should consider finding a viable home for domestic workers. As we move towards the 11th Cosatu Gender Conference, we need to reflect and take stock of the previous resolutions passed on domestic workers, assess the strategies/ steps taken for implementation and make a way forward. This paper has arisen as a follow-up of the afore-mentioned resolution including the commitment made by Cosatu on the Summit held between 27-28 August 2011 which the federation hosted in partnership with the South African Domestic Services and Allied Workers Union (SADSAWU) and the South African Office of the ILO. The aim is to stimulate and resuscitate discussions on domestic work acknowledging the positive steps taken at international level of adoption of ILO Convention 189 (C189) on Decent Work for Domestic Workers and its Recommendation 201 (R201).
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  • Date Issued: 2012

Participation in Integrated Resource Management (IWRM) in South Africa Quick Reference Guide

  • Authors: Motteux, Nicole , Rowntree, Kate , Fargher, John , Berold, Robert , Stanford, Mindy
  • Date: 2006
  • Subjects: To be catalogued
  • Language: English
  • Type: text , report
  • Identifier: http://hdl.handle.net/10962/437585 , vital:73395 , ISBN 1-77005-065-5 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT%20258-06%20for%20printers.pdf
  • Description: South Africa’s National Water Act of 1998 makes the management of any water resource a partnership between local water users, regional catchment managers, and the Department of Water Affairs and Forestry. The Act encourages communities to become actively involved in developing and managing their water resources. The three volumes of guidelines summarised here are aimed at social practitioners who work with stakeholder communities. The guidelines help practitioners make partici-patory water resource management a reality. They introduce the necessary social tools and scientific knowledge to enable communities to participate as envisioned by the legislative framework.
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  • Date Issued: 2006

Regionalism and conflict resolution in the Horn of Africa : the role of inter-governmental authority on development in the Sudanese civil war

  • Authors: Onyango, Moses
  • Date: 2003
  • Subjects: Africa, Northeast -- Politics and government -- 1900-1974 , Africa, Northeast -- Politics and government -- 1974- , Africa, Northeast -- Foreign relations -- 1974- , Federal government -- Africa, Northeast , Sudan -- History -- Civil War, 1955-1972 , Mediation, International , Culture conflict Sudan
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2869 , http://hdl.handle.net/10962/d1007715 , Africa, Northeast -- Politics and government -- 1900-1974 , Africa, Northeast -- Politics and government -- 1974- , Africa, Northeast -- Foreign relations -- 1974- , Federal government -- Africa, Northeast , Sudan -- History -- Civil War, 1955-1972 , Mediation, International , Culture conflict Sudan
  • Description: This thesis expounds the theoretical underpinnings of problem-solving approach to conflict resolution. It also criticizes the traditional state-centric approach to conflict resolution being followed by the Inter Governmental Authority on Development (IGAD) in the Sudanese civil war. IGAD was initially known as Inter Governmental Authority on Drought and Desertification (IGADD), but was renamed IGAD in 1996. Its objectives were reformulated to give priority to conflict prevention, resolution, and management, and humanitarian affairs. It is stipulated in the thesis that IGAD faces problems that need attention if the Sudanese civil war is to be resolved. A key problem is that while IGAD's objectives were reformulated to give priority to conflict resolution, IGAD's management structure has remained the same. The management structure is state-centric and lacks neutrality, which is a very important ingredient in deep-rooted social conflict resolution. The management structure, which was initially based on combating drought and desertification, was not restructured to conform to the realities of a problem solving approach to conflict resolution. The committee that was formed to look into the Sudanese conflict is composed of states in dispute with Sudan. The other structural problem cited in the thesis is that the IGAD peace process is cumbersome and does not include all aggrieved parties. The meetings involve heads of state, ministers, ambassadors and other government representatives. The peace process is not inclusive of other important players such as other rebel movements. This thesis concludes that: 1. there is a need for peace keeping forces from neutral African Union (AU) member states; 2. conflict resolution specialists are deployed in the region whose main task would be to assist the belligerent groups to reach a common understanding of their problems; 3. the United Nations (UN) acts proactively to create international awareness to the Sudanese problem.
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  • Date Issued: 2003

Child prostitution in Southern Africa: a search for legal protection

  • Authors: Network Against Child Labour
  • Date: 1996-03-26/28
  • Subjects: Child prostitution -- Law and legislation -- Africa, Southern -- Congresses , Child prostitutes -- Legal status, laws, etc. -- Africa, Southern -- Congresses
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/66314 , vital:28932
  • Description: In October 1995 representatives from ECPAT (End Child Prostitution in Asian Tourism) visited several Eastern and Southern African countries. The purpose of the visit was to collect information on child prostitution and the impact of tourism on child prostitution and to assess whether to expand the ECPAT campaign to Africa. Although child prostitution in tourism did not presently appear to be a problem, child prostitution was found to be widespread. One common problem identified by ECPAT in all these countries visited was a lack of legislation to protect children from prostitution and a general helplessness in how best to address the issue. So the idea of a workshop, focusing on legal aspects, was bom with the aim to bring together stakeholders from the various countries to learn from each other’s experiences and begin to formulate responses to child prostitution and prevent child prostitution in tourism. The Network Against Child Labour (NACL) South Africa was able to organise a workshop with the financial support from Bread for the World. Participants from NGO’s and governments from Kenya, Mozambique, Zambia, Zimbabwe and South Africa attended this first workshop on child prostitution in the region. Two international legal experts and advisers to ECPAT were present and partly facilitated the workshop, enriching our work with their expertise and world wide experience. The aim of the workshop extended beyond a focus on the legal aspects of child prostitution. Other specific purposes were networking, exchanging each other’s experience and achievements in order to develop strategies to combat child prostitution and finding a common ground for co-ordinated action. The Human Science Research Council (HSRC) provided a venue for the workshop and catered for the event. Dr. Willem Schurink from the HSRC organised, together with the Child Protection Unit from the South African Police, a tour to Johannesburg in areas were child prostitution is considered rife. This gave the participants an insight into the situation in South Africa’s largest city and “economic capital”. The two days of our workshop were intense and enriching. We all learned from each other’s experience and realised that there are many common problems that could be tackled with mutual support and advice in order to change legislation, policies and attitudes in the respective countries in the Eastern and Southern African region to ensure that the problem of child prostitution is declining and eventually eradicated. Continued networking and intensifying contacts will be part of our future efforts to combat child prostitution. The NACL wants to take this occasion to thank all participants for their efforts and contributions that made the workshop a success: Muireann OBrian and Denise Ritchie, who helped us in organising and facilitating. Thanks to our two volunteers, Rakgadi Masetlha and Tilman Rapp for the organisation of the workshop and especially to Dr. Willem Schurink of the HSRC, as well as to the funder - Bread for the World. With this publication we hope not only to reach stakeholders in South Africa and the region but to contribute our experience to world wide efforts to eradicate the degrading and often lethal practice of child prostitution by encouraging organisations and individuals to join a network in order to fight the problem.
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  • Date Issued: 1996-03-26/28

Status report on the Kruger National Park Rivers Research Programme: A synthesis of results and assessment of progress to January 1996

  • Authors: O'Keeffe, Jay H , Coetzee, Yvette
  • Date: 1996
  • Subjects: To be catalogued
  • Language: English
  • Type: text , report
  • Identifier: http://hdl.handle.net/10962/437715 , vital:73404 , ISBN 1 86845 242 5 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/711-1-96.pdf
  • Description: In August 1995, the Programme Development and Management Committee of the Kruger National Park Rivers Research Programme (KNPRRP) recommended to the Water Research Commission (WRC) that an information synthesis and status report of the Programme be undertaken. The main purpose of the report is to inform all the interested parties (including researchers, managers, and funding agencies) of the achievements and capabilities of the Programme; to assess these in relation to the stated goals and tasks of the "Second Phase: Programme description"; and to identify gaps and priorities for further work.
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  • Date Issued: 1996

The ability of four species of Southern African cichlid fishes to enter deep water

  • Authors: Caulton, Mark S
  • Date: 1973
  • Subjects: Cichlids -- Africa, Southern , Tilapia
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5840 , http://hdl.handle.net/10962/d1010429 , Cichlids -- Africa, Southern , Tilapia
  • Description: Using an experimental pressure chamber the rates of descent and the maximum depths of buoyancy equilibrium of some cichlid fishes were tested. Tilapia mossambica juveniles could descend to depths greater than 30 metres very rapidly. At 22°C small sub adult male fish (length ± 160 mm) could descend to a maximum buoyancy depth of 20 metres, small sub adult females to 13 metres while large adults (length ± 200 mm) of both sexes could descend to 11 metres. The fish generally take 4 to 5 days to reach their maximum equilibration depth. At 30°C mature adult male and female T.mossambica increased their maximum equilibration depth to 20 metres and at 15°C showed a decrease to a maximum depth of 6.7 metres. Temperature affects the rates of descent in a similar manner. T.rendalli can descend to 7.5 metres at 22°C. T.sparmanii can descend to 15 metres at 22°C. Hemihaplochromis philander fry and young juveniles are not affected by pressure. Adult males can descend to 16 metres at 22°C and 20 metres at 30°C. Adult females can descend to 26 metres at 22°C and 27 metres at 30°C. In T.mossambica oxygen appears to be the only gas secreted into the swimbladder to compensate for buoyancy loss. The haemoglobin of T.mossambica showed a marked Bohr and Root effect. Increased rates of descent with increased temperature are believed to be due to increased O₂ uptake, heart output etc. rather than as a direct effect of blood chemistry. The swimbladder wall of T.mossambica is extremely thin (2.8 ∕∪ m) and consequently a large amount of gas is lost through passive diffusion. Diffusion is not affected by temperature, consequently the increased secretory rates at higher temperatures are not balanced by a proportionately higher diffusion loss, thus enabling the fish to maintain a deeper buoyancy equilibrium at higher temperatures. Summary, p. 62-63.
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  • Date Issued: 1973
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