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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Die Saldanhabaai Watergehalte Forum Trust : 'n instrument vir beplande, geintegreerde monitering en bestuur van watergehalte

Van Wyk, Frederick C. (Frederick Christoffel) 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The Saldanha-Langebaan coastal zone is an important natural resource and serves as habitat for several endangered bird and fish species. Development in this coastal zone holds a constant threat for the natural environment and has a negative impact on the water quality of the bay. It is therefore essential to manage the water quality to ensure fitness for use for all the beneficial users in this coastal zone. This study focuses on the utilization and management of the Saldanha-Langebaan coastal zone. The beneficial users have different water quality requirements. It is therefore important to identify all the different water uses and to determine the occurrence of pollution and the dispersion thereof in the bay. The biophysical characteristics of the natural resource are described as part of the objective determining phase of the integrated water quality management process. The thesis also focuses on the inauguration and functioning of an integrated water quality management organization and the development and implementation of a long term monitoring program, with special emphasis on the sediment en health monitoring results. The result of this research study is a functional management instrument for integrated water quality monitoring and management in the Saldanha-Langebaan coastal zone. / AFRIKAANSE OPSOMMING: Die Saldanha-Langebaan kussone is 'n belangrike natuurlike hulpbron en dien as habitat vir verskeie bedreigde voel- en visspesies. Hierdie kussone is egter ook onder konstante ontwikkelingsdruk wat 'n negatiewe impak op die watergehalte van die baai het. Dit is dus noodsaaklik dat die watergehalte so bestuur word dat dit geskik bly vir al die gemeenskaplike watergebruikers in hierdie kussone. In hierdie studie is die benutting en bestuur van die Saldanha-Langebaan kussone ondersoek. Verskillende watergebruikers het uiteenlopende watergehaltebehoeftes en dit is noodsaaklik om die verskillende watergebruikers, sowel as die voorkoms en verspreiding van besoedeling in hierdie gebied te identifiseer. Die biofisiese eienskappe van die natuurlike kusopvanggebied is beskryf as deel van die aanvanklike doelwitbepalingsfase van geïntegreerde watergehaltebestuur. Die tesis fokus ook op die stigting en werkswyse van 'n geïntegreerde watergehaltebestuursliggaam, asook die ontwerp en implementering van 'n langtermyn moniteringsprogram. Daar is veral gelet op die resultate van die . sediment- en bakteriologiese moniteringsprogram. Die resultaat van die navorsingsproses is die totstandkoming van 'n funksionele bestuursliggaam wat as instrument dien vir geïntegreerde monitering en bestuur van die watergehalte in die Saldanha-Langebaan kussone.
12

n Geintegreerde beleidsraamwerk vir doeltreffende kusbestuur en volhoubare kusontwikkeling in die Kaap Agulhas distrik

Lourens, J. C. (Jan Christoffel) 12 1900 (has links)
Study project (MS en S)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The purpose of this study is to determine a framework for integrated and sustainable development in the Cape Agulhas area. The researcher focussed on the policy context and the opportunities and constraints for development in the study area. The relevant policy documents concerning development activities in the study area, were analysed. These policies contain key concepts for development. This includes concepts such as sustainable development, equity, public participation, Co-operative Governance and integrated coastal management. Development must aim to realise these concepts and the policies prescribe processes and procedures accordingly. Firstly, coastal management and control is necessary because coastal areas are multidimensional and vulnerable to development activities. Secondly, the inequalities in society as a result of Apartheid must be demolished. Legislation must prescribe active measures to promote equality. Lastly, coastal management and control is necessary to promote cooperation between the different participants for development and to enforce it, if necessary. The main participants for the study areas are Co-operative Governance, the private sector and the local community. The Overberg Distriiet Municipality and the Cape Agulhas Municipality are of utmost importance. Municipalities have been identified as the facilitators for development at local level. They must bring together the different participants for development to co-operative and integrate development actions. Legislation prescribes Integrated Development Planning (IDP) to promote co-operation and integration between participants. It is a strategic planning process and integration is the essence of the process. The IDP process for Cape Agulhas Municipality contains a number of mechanisms for public participation. Opportunities and constrains for development in study area also determine which development activities will be possible or not possible. The unique vegetation presents opportunities for tourism but constrains development because it must be conserved as well. The wildflower industry also offers economic opportunities. Marine resources present opportunities for example fishing and abalone farming. Tourism however is the industry with the greatest development potential for the study area. It can serve as catalyst for the development of the region as a whole. The socio-economic reality of communities in the area and the insufficient physical infrastructure are the main constraining factors for development. The case study focuses on the development priorities for Struisbay/L' Agulhas according to the IDP and the Agulhas CoastCare Project. It is an example of the projects in the study area with the aim to realise the development priorities mentioned above. / AFRIKAANSE OPSOMMING: Die doel van die studie is om 'n raamwerk vas te stel vir geïntegreerde en volhoubare ontwikkeling in die Kaap Agulhas gebied. Die navorser het gefokus op die beleidskonteks en die geleenthede en beperkinge vir ontwikkeling in die studiegebied. Die relevante beleidsdokumente rakende ontwikkelingsaktiwiteite in die studiegebied, is ontleed. Hierdie beleide bevat sleutelkonsepte vir ontwikkeling. Dit sluit konsepte in soos volhoubare ontwikkeling, gelykheid, publieke deelname, Regering van Samewerking en geïntegreerde kusbestuur. Hierdie konsepte moet nagestreef word en die beleide skryf prosesse en prosedures voor in die verband. Kusbestuur en kontrole is eerstens nodig omdat kusgebiede multi-dimensioneel is en kwesbaar is vir ontwikkelingsaktiwiteite. Tweedens salongelykhede in die samelewing as gevolg van Apartheid nie vanself uitgewis word nie. Wetgewing moet aktiewe stappe voorskryf om gelykheid te bevorder. Laastens is kusbestuur en kontrole nodig om samewerking tussen die verskillende rolspelers in ontwikkeling aan te moedig en af te dwing indien nodig. Die hoof rolspelers vir die studiegebied is die Regering van Samewerking, privaatsektor en die plaaslike gemeenskap. Die Overberg Distriksmunisipaliteit en die Kaap Agulhas Munisipaliteit is veral belangrik. Munisipaliteite is geïdentifiseer as fasiliteerders vir ontwikkeling op plaaslike vlak. Hulle moet die verskillende rolspelers vir ontwikkeling bymekaar bring om samewerking en integrasie van ontwikkelingsaksies te bevorder. Geïntegreerde Ontwikkelingsbeplanning (GOP) word deur wetgewing voorgeskryf om samewerking en integrasie tussen rolspelers te bevorder. Dit is 'n strategiese beplanningsproses met integrasie wat die kern van die proses vorm. In die GOP proses vir Kaap Agulhas Munisipaliteit is 'n aantal meganismes vir publieke deelname vasgestel. Geleenthede en beperkinge vir ontwikkeling in die studiegebied bepaalook in 'n groot mate watter ontwikkelingsaktiwiteite moontlik sal wees en watter nie. Die unieke plantegroei hou geleenthede in vir toerisme, maar beperk ook ontwikkeling deurdat ditbewaar moet word. Die Veldblomindustrie bied ekonomiese geleenthede. Mariene hulpbronne bied ook geleenthede byvoorbeeld visindustrie en perlemoenboerdery. Toerisme is egter die industrie wat die grootste ontwikkelingspotensiaal inhou vir die studiegebied. Dit kan dien as katalisator vir die ontwikkeling van die gebied as geheel. Die sosio-ekonomiese realiteite van gemeenskappe in die gebied en die gebrekkige fisiese infrastruktuur is die hoofbeperkende faktore vir ontwikkeling. Die gevallestudie fokus op StruisbaaiIL'Agulhas se ontwikkelingsprioriteite uit die GOP, asook die Agulhas CoastCare Projek. Dit is 'n voorbeeld van die projekte in die studiegebied met die doelom die bogenoemde ontwikkelingsprioriteite te realiseer.
13

A GIS assessment of development and land use change in the coastal zone of the Ndlambe and Ngqushwa local municipalities, Eastern Cape, South Africa

Palmer, Bronwyn Jane January 2009 (has links)
The coastal zone accommodates some of the most diverse ecosystems in the world and offers a wide range of ecosystem goods and services; consequently it has become a focal point of human development. People are attracted to the coast because of access to resources, favourable climate, aesthetic appeal and potential for recreational activities. As pressure for utilisation and development increases, so does the need to manage the coastal system more effectively. This research focuses on the coastal zone of the Ndlambe and Ngqushwa local municipalities in the Eastern Cape, South Africa, which are physically and environmentally similar, yet have distinct demographic and socio-economic differences. The research integrates information using GIS, from three time epochs, to determine where development and land use change is occurring. The Ndlambe Local Municipality displays high levels of formal development, while the Ngqushwa Local Municipality exhibits little formal development. These differences in development and land use are related to economic, social and legislative ‘drivers’ based on an adapted Driver-Pressure-State- Impact-Response model. The model identifies that development and land use changes lead to increased pressure on the natural system, which in turn leads to shifts in the natural state of the coastal zone, resulting in adverse impacts on the coastal zone. Changes in the natural functioning of the coastal zone highlight the need for a response in terms of changes in legislation governing coastal management and spatial planning. This research concludes that pressure for development in the coastal zone within the research site is beginning to increase and will adversely affect the coastal zone if not managed effectively. These two local municipalities have the opportunity to move forward and develop in such a way that allows for conservation and sound management of the coastal zone, which will ensure long-term sustainability within the coastal zones of the Ndlambe and Ngqushwa local municipalities
14

Towards a cost-efficient & standardised monitoring protocol for subtidal reef fish in the Agulhas ecoregion of South Africa / Towards a cost-efficient & standardised monitoring protocol for sub-tidal reef fish in the Agulhas eco-region of South Africa

Bernard, Anthony Thomas Firth January 2013 (has links)
Under the growing demand for marine fish resources, and the apparent and expected impacts of global climate change, there is a need to conduct long-term monitoring (LTM) to ensure effective management of resources and conservation of biodiversity. However LTM programmes often suffer from design deficiencies and fail to achieve their objectives. These deficiencies stem from the fact that insufficient consideration is afforded to the design phase, with programmes selecting methods that are not suitable to address the objectives, or are not cost-efficient, compromising the sustainability of the LTM. To facilitate the establishment of LTM programmes along the southern coast of South Africa, background research needed to be conducted to identify which methods were most appropriate for LTM of reef fish. This study presents a detailed field-based assessment of the suitability and cost-efficiency of monitoring methods for long-term monitoring of reef fish in the Agulhas Ecoregion of South Africa. The approach adopted to identify the method, or suite of methods most suited for LTM, involved (i) the selection of methods considered suitable for LTM, (ii) the individual assessment and optimisation of method performance, and (iii) the comparative assessment of the fish community sampled by the different methods. The most suited method(s) were then identified as those that provide the most comprehensive assessment of the fish community and had the highest cost-efficiency. The research was conducted between January 2008 and 2011 in the Tsitsikamma and Table Mountain National Park (TNP and TMNP, respectively) marine protected areas (MPAs) within the Agulhas Ecoregion. The methods selected included fish traps (FT), controlled angling (CA), underwater visual census (UVC), remote underwater video (RUV), baited RUV (BRUV) and remotely operated vehicles (ROV). The individual assessment and optimisation was conducted with the FT, UVC, RUV and BRUV methods. The assessment of the FT method aimed to identify the optimal soak time, and whether or not the size of the funnel entrance to the trap affected the catch. The results identified that larger funnel entrances caught more fish and soak times of 80 minutes produced the highest catches per unit effort. However the data were highly variable and the method detected few of the species typical of the region. Fish traps were also associated with high levels of mortality of fish post-release. The assessment of UVC strip transect method involved directly comparing the precision of data collected by researchers and volunteers using a novel double-observer technique (paired-transects). The results showed considerable error in both the volunteers and researchers data, however the researchers produced significantly higher precision data, compared to the volunteers. The distinction between researchers and volunteers was not evident in the data for the dominant species of fish. For all observers, the abundance of a species in the sample had a significant influence on its detectability, with locally scarce or rare species poorly detected. UVC was able to sample the majority of species typical of reefs in the region, however it appeared plagued by observer and detectability biases. The assessments of RUV and BRUV were conducted simultaneously which enabled the assessment of the effect of bait on the observed fish community. In addition the optimal deployment time for both methods to maximise species richness and abundance was determined. The results showed that BRUV, and to a lesser degree RUV, were able to effectively survey the reef fish community for the region with a 50 minute and 35 minute deployment time, respectively. Baited remote underwater video was especially good at detecting the invertebrate and generalist carnivores, and cartilaginous species. On the other hand, RUV was more effective at surveying the microinvertebrate carnivores. Remote underwater video was characterised by higher data variability, compared to BRUV, and was ultimately considered a less cost-efficient monitoring method. Comparative methods assessments were conducted during two field experiments with the FT, UVC and BRUV methods in the TMNP MPA, and the FT, CA, UVC, RUV, BRUV and ROV methods compared in the TNP MPA. The objectives of the comparison were to investigate differences in the fish communities observed with the different methods, and to determine the power of the data to detect an annual 10% growth in the fish populations over a period of five years. The results from the method comparison were in turn used to conduct the cost-benefit analysis to determine the efficiency of the different methods at achieving monitoring objectives requiring population data from multiple trophic and functional groups with the community, and from species of fisheries importance. The results indicated that FT, CA and ROV were ineffective at monitoring the reef fish community, although CA appeared to provide valuable data for the dominant fisheries species. Both CA and FT required minimal initial investment however, the variability in the data translated into high annual monitoring costs, as the required sampling effort was great. The ROV required the highest initial investment and was identified as the least cost-efficient method. Underwater visual census was able to adequately survey the bony fish within the community, however it did not detect the cartilaginous species. Underwater visual census required a large initial investment and was not cost-efficient, as a many samples were required to account for the variability in the data. Remote underwater video provided a comprehensive assessment of the reef fish community, however it too was associated with high levels of variability in the data, compared to BRUV, reducing its cost-efficiency. BRUV provided the most comprehensive assessment of the reef fish community and was associated with the highest cost-efficiency to address the community and fisheries species monitoring objectives. During the course of this research stereo-BRUV has gained considerable support as an effective reef fish monitoring method. Although not tested during this research, stereo-BRUV is preferred to BRUV as it provides accurate data on the size of fish. However, the initial investment of stereo-BRUV is over three times that required for the BRUV. Although it is recommended that a baited video technique be used for LTM in the Agulhas Ecoregion, the choice between BRUV and stereo-BRUV will depend on the specific objectives of the programme and the available budget at the implementing agency.
15

Dynamics of larval fish and zooplankton in selected south and west coast estuaries of South Africa

Montoya-Maya, Phanor Hernando January 2009 (has links)
Larval fish and zooplankton assemblages were studied in nine south and west coast estuaries in the cool-temperate and the cool/warm-temperate boundary region between June 2003 and March 2004. This study served to provide new information on previously unstudied estuaries and expand on existing knowledge of larval fish and zooplankton assemblages associated with various estuary types. The south and west coast estuaries sampled in this study showed lower salinities (12.2 - 13.7), lower water temperatures (14.5 - 16.9 °C) and higher turbidities (k = 0.02 - 0.04) in winter and spring while higher salinities (21.7 - 21.8), higher water temperatures (21.7 - 23.1°C) and lower turbidities (k <0.02) were observed in summer and autumn. Mean winter and summer water temperatures in estuaries were lower than those observed in warm-temperate and subtropical systems by other researchers. A total of 49274 larval fishes were caught, comprising 9 orders, 20 families, 29 genera and 47 taxa. The clupeid Gilchristella aestuaria (78.8 %) dominated the larval fish assemblages and occurred in all estuaries. The majority (70 %) of identified species are endemic to southern Africa and 96.4 % of larval fishes caught were estuary-resident species. The zooplankton study yielded a total of 44 taxa, comprising 7 phyla, >20 orders and >35 families. The copepod Pseudodiaptomus hessei dominated (59 %) the zooplankton and occurred in similar densities to those observed in other South African estuaries. Larval fish and zooplankton varied across seasons, peaking simultaneously in summer although zooplankton showed additional density peaks during the closed phase of some estuaries. Both plankton components were more abundant in the oligohaline and mesohaline zones within the estuaries. Freshwater input, estuary type and the biogeography of the area influenced the composition and structure of larval fish and zooplankton assemblages in these estuaries. The findings suggest that the estuaries are functioning as successful breeding areas for the larvae of endemic estuary-resident fish species and that these estuaries have to be managed to ensure an adequate freshwater supply to maintain the biological integrity of the ecosystem, specially the maintenance of the highly productive River-Estuary Interface (REI) regions.
16

Examining the feasibility of introducing environmental surcharges to finance local coastal management initiatives in South Africa : a case study in Plettenberg Bay

Mollatt, David G R January 2004 (has links)
The management of coastal resources in South Africa has come under review as a result of the degradation of environmental resources along the coast. The challenge being faced by resource managers is to achieve economic growth while sustaining South Africa’s coastal resource base (Nobel, 2000). The South African government (RSA, 2000) has developed a coastal management strategy to meet this challenge: The strategy involves the inclusion of all stakeholders in the formation of policy regarding the management of coastal resources, in a more integrated approach to coastal management. To effectively achieve this stakeholder inclusion, it has become necessary to decentralize the political, administrative and fiscal authority to conduct coastal management functions. With regard to the need for fiscal decentralisation this thesis considers the possibility of implementing localised environmental surcharges to finance coastal management initiatives. The ability of the White Paper for Sustainable Coastal Development (RSA, 2000) to provide theformal institutional structure necessary for the introduction of environmental surcharges is firstconsidered. It is shown that the decentralised management strategy has the potential to create a management style that is transparent and accountability orientated. In addition to this the style is capable of adapting to dynamic local coastal conditions and is therefore an appropriate direction in which to steer coastal management in South Africa. The effectiveness of coastal co-management as an informal institutional arrangement is then examined. Provided that local Coastal Management Fora are created to include all relevant stakeholders and that a source of long term financing is secured co-management has the potential to create the conditions necessary for effective coastal management. With regard to a source of long term financing, local environmental surcharges to finance coastal management initiatives are considered. The public’s willingness to contribute to such a surcharge is analysed in the context of Plettenberg Bay by probing their willingness to pay (WTP) for a Bay Management Plan. A survey instrument is developed to measure the public’s WTP. The design of the instrument is based on the Contingent Valuation (CV) method that is used to analyse the nonmarket benefits that environmental resources (such as Plettenberg Bay) provide the public. It is found that the resident population is willing to pay R15 per month toward a Bay Management Plan whilst domestic and foreign tourists respectively are willing to pay R6 and R22 daily. The aggregation of these WTP estimates yields a total passive use value of between R15 397 900 – R20330 500 annually. This nuclear value of the Bay should be included in the formation of local coastal management policy and provides guidance for the introduction of a local environmental surcharge. A budget for a Bay Management Plan is proposed and a progressive surcharge based on municipal property value is set. To finance the local residents’ share of the budget, a monthly surcharge of R1 would be required of the average valued property. To calculate the domestic and foreign tourist contribution to the budget a schedule of accommodation offering property will be required. However, to finance the entire budget a residential surcharge of approximately R10 would be required of the average valued property. This figure is well below the average resident population WTP of R15, highlighting the fact that an environmental surcharge in Plettenberg Bay is indeed feasible. The difference in reported WTP and the contribution required to finance the Bay Management Plan also highlights that there is scope for experimentation in the introduction of such a surcharge.
17

The dynamics of Larval fish and Zooplankton assemblages in the Sundays Estuary, South Africa

Sutherland, Kate January 2010 (has links)
The larval fish and zooplankton assemblages were studied in the permanently open Sundays Estuary on the south-east coast of South Africa, using standard boat-based plankton towing methods. A total of 8174 larval and early juvenile fishes were caught, representing 12 families and 23 taxa. The Clupeidae, Gobiidae and Blenniidae were the dominant fish families. Common species included Gilchristella aestuaria, Caffrogobius gilchristi, Omobranchus woodi, Liza dumerilii, Glossogobius callidus and Myxus capensis. Estuarine resident species (Category I) predominantly in the preflexion developmental stage, dominated the system. A total of 19 zooplankton taxa were recorded. Copepoda dominated the zooplankton community. Dominant species included Pseudodiaptomus hessei, Acartia longipatella, Halicyclops sp., Mesopodopsis wooldridgei, and the larvae of Paratylodiplax edwardsii and Hymenosoma orbiculare. Mean larval fish density showed similar trends seasonally, spatially and across salinity zones, with mean zooplankton density in the Sundays Estuary. Gut content analysis of five larval fish species: Gilchristella aestuaria, Pomadasys commersonnii, Monodactylus falciformis, Myxus capensis and Rhabdosargus holubi, revealed species specific diet and prey selection. Although larval fish diet contained a variety of prey items, guts were dominated by P. hessei, chironomid larvae, Corophium triaenonyx, copepod eggs and insect larvae. Physico-chemical drivers and the interactions between these two plankton communities provide information that enables a more holistic view of the dynamics occurring in the Sundays Estuary planktonic ecosystem.
18

A retrospective assessment of the Port Alfred linefishery with respect to the changes in the South African fisheries management environment

Donovan, Bruce 18 July 2013 (has links)
Since the study on the Port Alfred/Kenton-on-Sea/Boknes linefishery by Hecht and Tilney (1989) there have been substantive changes to the linefish management environment in South Africa. Using the Port Alfred linefishery as a model, the aim of this study was to evaluate the effectiveness of the linefish management regulations that were implemented by Marine and Coastal Management (MCM) since 1992, and to assess the behaviour and 'status' of the fishery in response to these changes. Changes to both the licensing structure and catch regulations have had a significant effect on the functioning of many aspects of the Port Alfred linefishery (fishing effort, catch composition, cpue) as well as on the structure of the fishery and its socio-economic profile. Overall commercial cpue decreased from 1985 to 1998. Since 1998 there has been a significant increase in cpue (from 2.3 Kg.fisher⁻¹ hour⁻¹ to a peak of 4.8 Kg.fisher⁻¹.hour⁻¹ in 2005. This was attributed to good catches of geelbek, particularly in 2005, 2007 and 2008 (during these years geelbek contributed an average of 35% to the total landings in comparison to a mean contribution of II % between 1985 and 2004). However, size spectra analysis suggests that the increase in overall cpue since 1998 misrepresents the actual status of the fishery. If geelbek is excluded from the analysis on the grounds that it is the only species in the fishery that is highly migratory, susceptible to recruitment fluctuations and it does not contribute to the catches on a year round basis, then the results suggest that the fishery is still in a declining phase despite the 80% reduction in commercial effort and numerous stricter catch regulations (e.g. size/bag limits). Furthermore, the cpue of silver kob, which has been the "mainstay" species of the fishery, has consistently declined over the last 23 year period (from 1.69 Kg.fisher⁻1 .hour1 in 1986 to 0.86 Kg.fisher⁻1.hour⁻1in 2007). The substantial reduction in commercial effort in the fishery from 33 vessels in 2001 to 13 in 2002 resulted in a shift from commercial to recreational fishing. The number of active commercial vessels in Port Alfred alone decreased from 29 in 1989 (Hecht 1993) to four in 2008. During the same timeframe, the number of regularly active recreational vessels had almost doubled (16 in 1989 to 26 in 2008). Despite the greater number of recreational boats in the fishery they only landed approximately half the average yearly tonnage of the commercial vessels (21,5 and 44,7 tonnes,annum-I , respectively) between 2006 and 2008, This was ascribed to the differences in catch regulations for the two sectors, Furthermore, it was speculated that increasing operating costs and narrowing profit margins have contributed to lower levels of compliance in both the commercial and recreational sectors since 2006, For example, 16% of silver kob landed during 2006-08 were under the minimum size, Despite the changes made to the regulations since 1998 and the 60,6% reduction In legislated commercial effort in the fishery between 2001 and 2002 it was concluded that the fishery has continued to decline, Except for the good recruitment of geelbek (which may be due to regulatory changes made in 1992) the changes in the management environment have had no measurable positive effect on this fishery, It is recommended that commercial effort should not be allowed to increase beyond the current number of active boats, that there should be an area restriction on all commerciallinefish vessels, that the current recreational bag limit for silver kob should be re-assessed, there should also be a concerted and nationally funded effort to educate recreational anglers about the merits of catch and release, and the frequency of catch inspections of both sectors should be increased, / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in
19

A preliminary investigation into the use of biomarkers and a fish community index to assess estuarine health in selected Eastern Cape estuaries

Richardson, Naomi January 2008 (has links)
The aims of this study were to determine the potential use of biomarkers at multiple levels of biological organisation together with a fish community bioindicator to assess the estuarine health status of three temporarily open/closed estuaries. The estuaries investigated were the East Kleinemonde (EK), Old Woman's (OW) and Mtana (MTN), all of which are situated in the Eastern Cape Province. Three biomarkers, the acetylcholinesterase (AChE) assay, lipid peroxidation (LPx) assay, liver histopathology and a condition factor were used to determine sub-organism health and one bioindicator, the Estuarine Fish Community Index (EFCI), was used as a bioindicator of community health. The estuarine-dependent marine species Rhabdosargus holubi was selected as an indicator species for the sub-organism level analyses. The results from the community analyses indicated that the EK and OW estuaries were in 'good' condition, while the MTN was found to be in 'moderate' condition. Histological analyses revealed that R. holubi from all three estuaries showed signs of pathological changes to the liver, with the fish from the MTN eliciting the highest occurrence of these changes. The LPx assay found that R. holubi from both the OW and MTN showed signs of oxidative damage in the liver tissue, but those from the EK did not appear to be affected. The AChE assay showed that only the fish from the OW had been affected by anticholinesterase compounds. A laboratory study was undertaken using R. holubi as a positive control for the AChE and LPx assay. The fish were exposed to 3 μg/L chlorpyrifos, a known cholinesterase inhibitor, for six hours and their tissues were examined for changes to LPx levels and AChE activities. AChE activity was significantly inhibited (Mann Whitney U test, Z = 3.65, n = 38, P < 0.001) by the exposure, but LPx levels were not significantly affected. A composite index incorporating the biomarkers at different biological levels of organisation was developed. The index was designed to assist managers and scientists to determine whether the ichthyofauna of a system was being affected by environmental stressors and what management interventions could be undertaken to ameliorate the water quality in an estuary. The index was applied to the three estuaries investigated during the present study and both the OW and MTN were assessed to be in need of immediate management intervention. The fish in the OW were found to be stressed at all the sub-organism levels measured and the reason for this was hypothesised to be as a result of golf course activities in this adjacent estuary. A number of management actions are proposed to reduce the sub-organism stress observed in the fish from the OW. The livers of fish from the MTN were shown to be under stress; however the causative agent of this stress was unknown because there is no formal development in the MTN catchment. However, a possible contaminant source is proposed and management interventions to alleviate the stress on the biota of the MTN are suggested. The EK does not require immediate management intervention, however, continuous routine monitoring is recommended to ensure that conditions do not deteriorate. Shortcomings of the index were outlined and a number of suggestions were made in terms of other measures of biological health which could be incorporated into the index.
20

Morphology, patterns and processes in the Oyster Bay headland bypass dunefield, South Africa / Investigation of the relationship between morphology, patterns and processes in a headland bypass dunefield, in the Eastern Cape, South Africa

McConnachie, Lauren Bernyse January 2013 (has links)
Studies of the dunefield systems crossing the Cape St. Francis headland in the Eastern Cape have focused on the role that wind plays in sediment transfer in coastal dunefield systems, with limited consideration of the role of water. The aim of this study was to improve understanding of the morphology, processes and patterns within the Oyster Bay HBD system, focussing particularly on surface water and groundwater interactions and the role of surface water in sediment transfer across the dunefield system. An extensive field survey was conducted, to collect related data, complimented by spatial and temporal analysis of the study area using GIS. The key findings from this research were the apparent differences between the western and eastern regions of the dunefield with regard to specific drivers and the respective processes and responses. Wind is the major driver of change up to and across the crest of the dunefield. In the eastern region water (ground water, surface water and the Sand River System) is the primary agent of sediment flux through processes of aggregation and slumping as well as episodic events including debris flows. This study has highlighted a need for further quantitative studies that investigate the movement of sediment through dunefield systems such as this (where water is at or near the land surface). The paradigm that sediment flux is entirely due to wind is almost certainly simplistic, and deeper understanding of these systems is needed / Maiden name: Elkington, Lauren

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