Decision analysis to inform invasive alien plant management in the Garden Route Biosphere Reserve
- Authors: Masunungure, Current
- Date: 2020
- Subjects: Invasive plants -- South Africa , Alien plants -- South Africa , Biodiversity -- South Africa -- Management , Ecosystem management -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49159 , vital:41606
- Description: Invasive alien plants (IAP) pose significant threats to global economies and biodiversity and are often considered as wicked problems. With an increasing number of IAP and limited resources, their management and decision-making processes are becoming difficult because of uncertainty, multiple and conflicting objectives, and diverse stakeholder views, facts and values. This is particularly challenging given the complex interactions between economic, ecological, and social elements that exist in invaded areas. Consequently, it is important to incorporate new ways of thinking and novel methodologies to improve our understanding of IAP management and the decision-making processes around them, which are currently inadequate. Decision analysis can help with dealing with these challenges and support decision-making under uncertainty. Drawing on the systems thinking approach and the concepts of leverage points, transition management and transformational change, the aim of this thesis was to explore the effectiveness of IAP management and the decision-making process in the Garden Route Biosphere Reserve (GRBR). This was achieved using a mixed methods approach involving: social-ecological inventory (identifying relevant stakeholders); review of literature on the available decision support tools; key informant interviews (stakeholder perspectives on the current decision-making process); and stakeholder workshop and expert consultation (casual loop modelling). The results of this thesis provide evidence that application of the proposed principles of robust decision-making has the potential to overcome the weaknesses of the current decision-making process and as such, enables decision-makers to efficiently allocate resources towards IAS management. A novel causal loop diagram (CLD) was developed to highlight the interconnections between key variables in IAP management and decision-making. This revealed that to transcend ‘policy resistance’ and ‘quickfixes that fail’ archetypes, and improve IAP management, the stakeholders need to consider deep leverage points, for example, fostering trust and shared understanding among different stakeholder groups. These can be realistically maintained over the long-term and can cause a fundamental change in IAP management, rather than focusing on shallow leverage points that are relatively easy to implement but do not result in significant systemic change. The findings of this thesis are flexible and could guide various stakeholder groups at local, national, and international scales in improving the effectiveness of IAP management and decision-making.
- Full Text:
- Date Issued: 2020
- Authors: Masunungure, Current
- Date: 2020
- Subjects: Invasive plants -- South Africa , Alien plants -- South Africa , Biodiversity -- South Africa -- Management , Ecosystem management -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49159 , vital:41606
- Description: Invasive alien plants (IAP) pose significant threats to global economies and biodiversity and are often considered as wicked problems. With an increasing number of IAP and limited resources, their management and decision-making processes are becoming difficult because of uncertainty, multiple and conflicting objectives, and diverse stakeholder views, facts and values. This is particularly challenging given the complex interactions between economic, ecological, and social elements that exist in invaded areas. Consequently, it is important to incorporate new ways of thinking and novel methodologies to improve our understanding of IAP management and the decision-making processes around them, which are currently inadequate. Decision analysis can help with dealing with these challenges and support decision-making under uncertainty. Drawing on the systems thinking approach and the concepts of leverage points, transition management and transformational change, the aim of this thesis was to explore the effectiveness of IAP management and the decision-making process in the Garden Route Biosphere Reserve (GRBR). This was achieved using a mixed methods approach involving: social-ecological inventory (identifying relevant stakeholders); review of literature on the available decision support tools; key informant interviews (stakeholder perspectives on the current decision-making process); and stakeholder workshop and expert consultation (casual loop modelling). The results of this thesis provide evidence that application of the proposed principles of robust decision-making has the potential to overcome the weaknesses of the current decision-making process and as such, enables decision-makers to efficiently allocate resources towards IAS management. A novel causal loop diagram (CLD) was developed to highlight the interconnections between key variables in IAP management and decision-making. This revealed that to transcend ‘policy resistance’ and ‘quickfixes that fail’ archetypes, and improve IAP management, the stakeholders need to consider deep leverage points, for example, fostering trust and shared understanding among different stakeholder groups. These can be realistically maintained over the long-term and can cause a fundamental change in IAP management, rather than focusing on shallow leverage points that are relatively easy to implement but do not result in significant systemic change. The findings of this thesis are flexible and could guide various stakeholder groups at local, national, and international scales in improving the effectiveness of IAP management and decision-making.
- Full Text:
- Date Issued: 2020
Stewardship and collaboration in multifunctional landscapes: a transdisciplinary enquiry
- Authors: Cockburn, Jessica Jane
- Date: 2018
- Subjects: Environmental management -- South Africa , Sustainable development -- South Africa , Ecosystem management -- South Africa , Social ecology -- South Africa , Interdisciplinary research
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61267 , vital:27998
- Description: Social-ecological sustainability challenges, from the local to the global level, are of increasing concern. Stewardship has been proposed as a means of dealing with these challenges, but how can it be achieved in practice? In South Africa, the concept is put into practice by practitioners working with local stewards to facilitate more sustainable and equitable management of ecosystem services across landscapes. This landscape approach requires collaboration between multiple stakeholders, as social-ecological processes function beyond the boundaries of individual farms or villages. The aim of this research was to investigate the practice of stewardship and collaboration in multifunctional landscapes in South Africa through a transdisciplinary enquiry. This was achieved using a methodological framework based on critical complexity, transdisciplinarity, and critical realism. This framework was applied through an inductive, mixed methods research design which involved stewardship practitioners, stewards, and other stakeholders in the research. Practitioners' understandings of the stewardship concept vary, yet they coalesce around the idea of responsible use and care of nature. Accordingly, the primary role of stewards is to interact with nature responsibly and carefully, balancing the use of ecosystem services for their own benefit with broader social- ecological interests and needs. Although the biodiversity stewardship tool dominates stewardship practice in South Africa, more integrated social-ecological initiatives are also emerging, often hand-in-hand with this approach. Practitioners working in these initiatives face multiple interacting and mutually reinforcing enablers and barriers that facilitate or hinder collaboration for stewardship. Individual and social-relational enablers are pivotal to long-term sustainability of initiatives, whilst deep-seated inequalities and mistrust are significant barriers to collaboration. Despite such challenges, practitioners are succeeding in fostering collaboration by operating as hubs in the landscape. They are actively building new relationships and networks among diverse stakeholders to address shared sustainability challenges. This results in a patchwork of collaborative stewardship activity across the landscape, suggesting that stewardship and collaboration are fundamentally relational processes and that pluralistic approaches to sustainability are needed in multifunctional landscapes. Moreover, by re-focusing stewardship on stewards, practitioners are finding innovative ways to enable farmers to appreciate and practice stewardship, addressing the conflict between agriculture and conservation. Drawing on these findings, a critical realist analysis revealed underlying generative mechanisms that help to explain the challenges encountered in collaborative efforts toward stewardship. These mechanisms included, amongst others: individual stewards' values, societal constraints on the ability of stewards to express care, conflict between agriculture and conservation due to dominant agricultural approaches and neoliberal economic policies, and the divided and unequal nature of South African society. Operationalising transdisciplinary research enabled meaningful engagement with practitioner partners, allowing for novel insights and unexpected findings to emerge from practice-based knowledge. Putting transdisciplinarity into practice revealed the dynamic and multi-faceted role that researchers can play in transdisciplinary research, highlighting the importance of relational knowledge and competencies. Existing support systems and incentives within universities need to be re-configured to enable postgraduate students to conduct engaged science in service of society. , Kuyanda ukuxhalatyiswa yimiceli mngeni yobudlewlane obuhlala buhleli bezentlalo nendalo, ekuhlaleni nakwihlabathi. Kuphakanyiswe umbono wobugosa-bumeli (ubuphathi bendalo, stewardship) ukuze kuhlangatyezwane nale miceli mngeni, kodwa iza kwenziwa njani le nto? EMzantsi Afrika le ngcamango iye yabekwa entsebenzweni ngabo banezakhono no bugcisa besebenza namagosa-bameli asekuhlaleni, benceda ekulawulweni ngendlela ehlala ihleli nelinganayo iinkonzo zobudlelwane nendalo kuyo yonke imihlaba. Le ndlela yokusebenzisa le mihlaba ifuna intsebenziswano phakathi kwabo bonke ababandakanyekayo, njengoko ubudlelwane bentlalo nendalo busebenza ngaphaya kwemida yomfama ngamnye okanye iilali. Injongo yoluhlolisiso ibikukuphanda ngoqheliselo lobugosa-bumeli nentsebenziswano yeemihlaba esebenza ngendlela ezininzi eMzantsi Afrika kubuzwa kumasebe olwazi ohlukeneyo olwazi(transdisciplinarity). Oku kwathi kwaphunyezwa ngenkqubo ehlola izinto ezahlukahlukeneyo kwimigangatho eyahlukeneyo, isekelwe kwingcamango enzulu kunoko kubonakala kuqondakalayo, kumasebe olwazi ohlukeneyo, nakulwazi lwesayensi nentlalo. Le nkqubo yenziwa kusetyenziswa inkqubo yokuqokelela ulwazi luze luhlalutywe, iintlobo ezahlukeneyo zokwenza uhlolisiso, ezazibandakandakanya abanezakhono zobugosa-bumeli, amagosa-bameli nabanye ababandakanyekileyo kolu hlolisiso. Ingcamango zabanezakhono zobubugosa-bumeli ziyohluka, kanti iingcamango zinye ngokuphathelele ukusetyenziswa nokukhathelela indalo yemvelo. Phofu ke, indima esisiseko yamagosa-bameli kukuphembelelana ngokufanelekileyo nangenkathalo nendalo, bethelekisa ukusebenzisa iinkonzo zobudlelwane nendalo ukuze zincede bona, kunye nomdla neemfuno eziphangaleleyo zobudlelwane bendalo nentlalo. Nakubeni isixhobo Sobugosa-Bumeli Bendalo Eyahlukeneyo Yezityalo Nezilwanyana (Biodiversity Stewardship) isesona sitshotsha phambili kuqheliselo lobugosa-bumeli eMzantsi Afrika, zikhona nezinye izixhobo ezivelayo eziqukwayo kwiphulo lobudlelwane bendalo nentlalo, ezisoloko zisebenza kakuhle neli lokuqala. Abanezakhono nabasebenza kula maphulo bajamelene neendidi zokuphembelelana, iingxaki ezahlukeneyo, izisombululo nezithinteli ezinceda okanye zonakalise intebenziswano yobugosa-bumeli. Isisombululo ngasinye nezo zayanyaniswa nentlalo zibaluleke gqitha kumaphulo azakuhlala ehleli, nakubeni ukungalingani okuzinze nzulu nokungathembani iyimiqobo ebelulekileyo kwintsebenziswano. Nangona ikhona le micelimngeni, abanezakhono bayaphumelela ekukhuliseni intsebenziswano ngokuthi basebenze kwiindawo ezithile kwimihlaba. Bakha unxulumano olutsha noqhagamishelwano nababandakanyekileyo ngokwahluka kwabo ukuze kusingathwe nemiceli mngeni yokugcina ubudlelwane bendalo nentlalo buhlale buhleli. Oku kuye kwaphumela kwintsebenziswano yobugosa-bumeli ethe yakho pha na pha kule mihlaba, nto leyo ebonisa ukuba ubugosa- bumeli nentsebenziswano ngokusisiseko yinkqubo enxulumeneyo, kwaye iindlela ezininzi zokwenza ubudlelwane bendalo nentlalo buhlale buhleli ziyimfuneko kwimihlaba ekwenziwa izinto ezininzi kuyo. Ngapha koko, ngokuthi kuphindwe kunikelwe ingqalelo kubugosa-bumeli isiya kumagosa bameli, abanezakhono bafumana iindlela ezintsha zokunceda amafama axabise aze aqhelisele ubugosa-bumeli, ngolu hlobo kusingathwa ingxabano phakathi kwezolimo nolondolozo lwendalo. Xa sifunda koku, ukucamngca nzulu ngako kutyhile enye indlela eye yanceda ekucaciseni imiceli mngeni ekuhlangatyezwane nayo kwimigudu yentsebenziswano yobugosa-bumeli. Ezi ndlela zibandakanya, phakathi kwezinye: indlela aziphatha ngayo amagosa-bameli, iingcinezelo yabahlali ekubeni amagosa-bameli abonakalise inkathalo, ukungavisisani phakathi kwezolimo nolondolozo lwendalo ngenxa yendlela ezongamelayo nezisetyenziswayo zolimo, nemigaqo-nkqubo yezoqoqosho elawulwa bucala, nokwahlukana, ukungalingani kwabantu baseMzantsi Afrika. Ukusebenzisa uhlolisiso lwamasebe olwazi ohlukeneyo kubangele ukufuthelana okunentsingiselo namaqabane abo banezakhono, oku kuvulele iingcamango ezinzulu nokufumana izinto ebezingalindelekanga kulwazi olusekelwe kuqheliselo. Ukubeka ulwazi lwamasebe ahlukeneyo entsebenzweni kutyhile iindima ezahlukeneyo okanye ezininzi ezidlalwa ngabahlolisisi kuhlolisiso lolwazi lwamasebe ohlukeneyo, kubalaseliswa ukubaluleka kolwazi olunxulunyaniswayo nozimiselo. Iinkqubo zenkxaso nezinye izinto ezincedayo ezikhoyo kwiyunivesiti kufuneka ziphinde zakhiwe ukuze zincede abafundi abenza uhlolisiso balwenze benomfutho wesayensi enceda abahlali.
- Full Text:
- Date Issued: 2018
- Authors: Cockburn, Jessica Jane
- Date: 2018
- Subjects: Environmental management -- South Africa , Sustainable development -- South Africa , Ecosystem management -- South Africa , Social ecology -- South Africa , Interdisciplinary research
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61267 , vital:27998
- Description: Social-ecological sustainability challenges, from the local to the global level, are of increasing concern. Stewardship has been proposed as a means of dealing with these challenges, but how can it be achieved in practice? In South Africa, the concept is put into practice by practitioners working with local stewards to facilitate more sustainable and equitable management of ecosystem services across landscapes. This landscape approach requires collaboration between multiple stakeholders, as social-ecological processes function beyond the boundaries of individual farms or villages. The aim of this research was to investigate the practice of stewardship and collaboration in multifunctional landscapes in South Africa through a transdisciplinary enquiry. This was achieved using a methodological framework based on critical complexity, transdisciplinarity, and critical realism. This framework was applied through an inductive, mixed methods research design which involved stewardship practitioners, stewards, and other stakeholders in the research. Practitioners' understandings of the stewardship concept vary, yet they coalesce around the idea of responsible use and care of nature. Accordingly, the primary role of stewards is to interact with nature responsibly and carefully, balancing the use of ecosystem services for their own benefit with broader social- ecological interests and needs. Although the biodiversity stewardship tool dominates stewardship practice in South Africa, more integrated social-ecological initiatives are also emerging, often hand-in-hand with this approach. Practitioners working in these initiatives face multiple interacting and mutually reinforcing enablers and barriers that facilitate or hinder collaboration for stewardship. Individual and social-relational enablers are pivotal to long-term sustainability of initiatives, whilst deep-seated inequalities and mistrust are significant barriers to collaboration. Despite such challenges, practitioners are succeeding in fostering collaboration by operating as hubs in the landscape. They are actively building new relationships and networks among diverse stakeholders to address shared sustainability challenges. This results in a patchwork of collaborative stewardship activity across the landscape, suggesting that stewardship and collaboration are fundamentally relational processes and that pluralistic approaches to sustainability are needed in multifunctional landscapes. Moreover, by re-focusing stewardship on stewards, practitioners are finding innovative ways to enable farmers to appreciate and practice stewardship, addressing the conflict between agriculture and conservation. Drawing on these findings, a critical realist analysis revealed underlying generative mechanisms that help to explain the challenges encountered in collaborative efforts toward stewardship. These mechanisms included, amongst others: individual stewards' values, societal constraints on the ability of stewards to express care, conflict between agriculture and conservation due to dominant agricultural approaches and neoliberal economic policies, and the divided and unequal nature of South African society. Operationalising transdisciplinary research enabled meaningful engagement with practitioner partners, allowing for novel insights and unexpected findings to emerge from practice-based knowledge. Putting transdisciplinarity into practice revealed the dynamic and multi-faceted role that researchers can play in transdisciplinary research, highlighting the importance of relational knowledge and competencies. Existing support systems and incentives within universities need to be re-configured to enable postgraduate students to conduct engaged science in service of society. , Kuyanda ukuxhalatyiswa yimiceli mngeni yobudlewlane obuhlala buhleli bezentlalo nendalo, ekuhlaleni nakwihlabathi. Kuphakanyiswe umbono wobugosa-bumeli (ubuphathi bendalo, stewardship) ukuze kuhlangatyezwane nale miceli mngeni, kodwa iza kwenziwa njani le nto? EMzantsi Afrika le ngcamango iye yabekwa entsebenzweni ngabo banezakhono no bugcisa besebenza namagosa-bameli asekuhlaleni, benceda ekulawulweni ngendlela ehlala ihleli nelinganayo iinkonzo zobudlelwane nendalo kuyo yonke imihlaba. Le ndlela yokusebenzisa le mihlaba ifuna intsebenziswano phakathi kwabo bonke ababandakanyekayo, njengoko ubudlelwane bentlalo nendalo busebenza ngaphaya kwemida yomfama ngamnye okanye iilali. Injongo yoluhlolisiso ibikukuphanda ngoqheliselo lobugosa-bumeli nentsebenziswano yeemihlaba esebenza ngendlela ezininzi eMzantsi Afrika kubuzwa kumasebe olwazi ohlukeneyo olwazi(transdisciplinarity). Oku kwathi kwaphunyezwa ngenkqubo ehlola izinto ezahlukahlukeneyo kwimigangatho eyahlukeneyo, isekelwe kwingcamango enzulu kunoko kubonakala kuqondakalayo, kumasebe olwazi ohlukeneyo, nakulwazi lwesayensi nentlalo. Le nkqubo yenziwa kusetyenziswa inkqubo yokuqokelela ulwazi luze luhlalutywe, iintlobo ezahlukeneyo zokwenza uhlolisiso, ezazibandakandakanya abanezakhono zobugosa-bumeli, amagosa-bameli nabanye ababandakanyekileyo kolu hlolisiso. Ingcamango zabanezakhono zobubugosa-bumeli ziyohluka, kanti iingcamango zinye ngokuphathelele ukusetyenziswa nokukhathelela indalo yemvelo. Phofu ke, indima esisiseko yamagosa-bameli kukuphembelelana ngokufanelekileyo nangenkathalo nendalo, bethelekisa ukusebenzisa iinkonzo zobudlelwane nendalo ukuze zincede bona, kunye nomdla neemfuno eziphangaleleyo zobudlelwane bendalo nentlalo. Nakubeni isixhobo Sobugosa-Bumeli Bendalo Eyahlukeneyo Yezityalo Nezilwanyana (Biodiversity Stewardship) isesona sitshotsha phambili kuqheliselo lobugosa-bumeli eMzantsi Afrika, zikhona nezinye izixhobo ezivelayo eziqukwayo kwiphulo lobudlelwane bendalo nentlalo, ezisoloko zisebenza kakuhle neli lokuqala. Abanezakhono nabasebenza kula maphulo bajamelene neendidi zokuphembelelana, iingxaki ezahlukeneyo, izisombululo nezithinteli ezinceda okanye zonakalise intebenziswano yobugosa-bumeli. Isisombululo ngasinye nezo zayanyaniswa nentlalo zibaluleke gqitha kumaphulo azakuhlala ehleli, nakubeni ukungalingani okuzinze nzulu nokungathembani iyimiqobo ebelulekileyo kwintsebenziswano. Nangona ikhona le micelimngeni, abanezakhono bayaphumelela ekukhuliseni intsebenziswano ngokuthi basebenze kwiindawo ezithile kwimihlaba. Bakha unxulumano olutsha noqhagamishelwano nababandakanyekileyo ngokwahluka kwabo ukuze kusingathwe nemiceli mngeni yokugcina ubudlelwane bendalo nentlalo buhlale buhleli. Oku kuye kwaphumela kwintsebenziswano yobugosa-bumeli ethe yakho pha na pha kule mihlaba, nto leyo ebonisa ukuba ubugosa- bumeli nentsebenziswano ngokusisiseko yinkqubo enxulumeneyo, kwaye iindlela ezininzi zokwenza ubudlelwane bendalo nentlalo buhlale buhleli ziyimfuneko kwimihlaba ekwenziwa izinto ezininzi kuyo. Ngapha koko, ngokuthi kuphindwe kunikelwe ingqalelo kubugosa-bumeli isiya kumagosa bameli, abanezakhono bafumana iindlela ezintsha zokunceda amafama axabise aze aqhelisele ubugosa-bumeli, ngolu hlobo kusingathwa ingxabano phakathi kwezolimo nolondolozo lwendalo. Xa sifunda koku, ukucamngca nzulu ngako kutyhile enye indlela eye yanceda ekucaciseni imiceli mngeni ekuhlangatyezwane nayo kwimigudu yentsebenziswano yobugosa-bumeli. Ezi ndlela zibandakanya, phakathi kwezinye: indlela aziphatha ngayo amagosa-bameli, iingcinezelo yabahlali ekubeni amagosa-bameli abonakalise inkathalo, ukungavisisani phakathi kwezolimo nolondolozo lwendalo ngenxa yendlela ezongamelayo nezisetyenziswayo zolimo, nemigaqo-nkqubo yezoqoqosho elawulwa bucala, nokwahlukana, ukungalingani kwabantu baseMzantsi Afrika. Ukusebenzisa uhlolisiso lwamasebe olwazi ohlukeneyo kubangele ukufuthelana okunentsingiselo namaqabane abo banezakhono, oku kuvulele iingcamango ezinzulu nokufumana izinto ebezingalindelekanga kulwazi olusekelwe kuqheliselo. Ukubeka ulwazi lwamasebe ahlukeneyo entsebenzweni kutyhile iindima ezahlukeneyo okanye ezininzi ezidlalwa ngabahlolisisi kuhlolisiso lolwazi lwamasebe ohlukeneyo, kubalaseliswa ukubaluleka kolwazi olunxulunyaniswayo nozimiselo. Iinkqubo zenkxaso nezinye izinto ezincedayo ezikhoyo kwiyunivesiti kufuneka ziphinde zakhiwe ukuze zincede abafundi abenza uhlolisiso balwenze benomfutho wesayensi enceda abahlali.
- Full Text:
- Date Issued: 2018
The role of acute toxicity data for South African freshwater macroinvertebrates in the derivation of water quality guidelines for salinity
- Authors: Browne, Samantha
- Date: 2005
- Subjects: Water-supply -- South Africa , Water quality management -- South Africa , Aquatic ecology -- South Africa , Ecosystem management -- South Africa , Freshwater invertebrates -- South Africa -- Ecology , Water -- Toxicology -- South Africa , Water quality biological assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4742 , http://hdl.handle.net/10962/d1006173 , Water-supply -- South Africa , Water quality management -- South Africa , Aquatic ecology -- South Africa , Ecosystem management -- South Africa , Freshwater invertebrates -- South Africa -- Ecology , Water -- Toxicology -- South Africa , Water quality biological assessment
- Description: Water resources are under ever-increasing pressure to meet the demands of various water users both nationally and internationally. The process of anthropogenically-induced salinisation serves to exacerbate this pressure by limiting the quantity and quality of water available for future use. Water quality guidelines provide the numerical goals which water resource managers can use to adequately manage and protect aquatic ecosystems. Various methods which have been developed and used internationally to derive such guidelines are discussed. Acute toxicity tests were conducted using two inorganic salts, NaCl and Na₂SO₄. Field collected, indigenous, freshwater macroinvertebrates were used as tests organisms. Data generated from these tests contributed to the expansion of the currently limited toxicological database of response data for indigenous organisms and the suitability of using such organisms for future testing was discussed. Salt sensitivities of indigenous freshwater invertebrates were compared those of species sourced from an international toxicological database and were found to have similar ranges of tolerances to NaCl and Na₂SO₄. Species sensitivity distributions (SSDs), a method of data extrapolation, were derived using different types of toxicological data, and hence different guideline values or protective concentrations were derived. These concentrations were equated to boundary values for South Africa’s ecological Reserve categories, which are used to describe degrees of health for aquatic ecosystems. Provisional results suggest that using only acute toxicity data in guideline derivation provides ecosystem protection that is under-protective. Chronic toxicity data, which include endpoints other than mortality, provide the most realistic environmental protection but lack data confidence due to small sample sizes (acute tests are more readily conducted than chronic tests). The potential contribution of sub-chronic data to guideline derivation is highlighted as these data are more readily extrapolated to chronic endpoints than acute data and sub-chronic tests are not as complex and demanding to conduct as chronic tests.
- Full Text:
- Date Issued: 2005
- Authors: Browne, Samantha
- Date: 2005
- Subjects: Water-supply -- South Africa , Water quality management -- South Africa , Aquatic ecology -- South Africa , Ecosystem management -- South Africa , Freshwater invertebrates -- South Africa -- Ecology , Water -- Toxicology -- South Africa , Water quality biological assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4742 , http://hdl.handle.net/10962/d1006173 , Water-supply -- South Africa , Water quality management -- South Africa , Aquatic ecology -- South Africa , Ecosystem management -- South Africa , Freshwater invertebrates -- South Africa -- Ecology , Water -- Toxicology -- South Africa , Water quality biological assessment
- Description: Water resources are under ever-increasing pressure to meet the demands of various water users both nationally and internationally. The process of anthropogenically-induced salinisation serves to exacerbate this pressure by limiting the quantity and quality of water available for future use. Water quality guidelines provide the numerical goals which water resource managers can use to adequately manage and protect aquatic ecosystems. Various methods which have been developed and used internationally to derive such guidelines are discussed. Acute toxicity tests were conducted using two inorganic salts, NaCl and Na₂SO₄. Field collected, indigenous, freshwater macroinvertebrates were used as tests organisms. Data generated from these tests contributed to the expansion of the currently limited toxicological database of response data for indigenous organisms and the suitability of using such organisms for future testing was discussed. Salt sensitivities of indigenous freshwater invertebrates were compared those of species sourced from an international toxicological database and were found to have similar ranges of tolerances to NaCl and Na₂SO₄. Species sensitivity distributions (SSDs), a method of data extrapolation, were derived using different types of toxicological data, and hence different guideline values or protective concentrations were derived. These concentrations were equated to boundary values for South Africa’s ecological Reserve categories, which are used to describe degrees of health for aquatic ecosystems. Provisional results suggest that using only acute toxicity data in guideline derivation provides ecosystem protection that is under-protective. Chronic toxicity data, which include endpoints other than mortality, provide the most realistic environmental protection but lack data confidence due to small sample sizes (acute tests are more readily conducted than chronic tests). The potential contribution of sub-chronic data to guideline derivation is highlighted as these data are more readily extrapolated to chronic endpoints than acute data and sub-chronic tests are not as complex and demanding to conduct as chronic tests.
- Full Text:
- Date Issued: 2005
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