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Anthropogenic transformation of land globally is threatening water resources in terms of quality and availability. Managing water resources to ensure sustainable utilization is important for a semiarid country such as South Africa. Bayesian networks (BNs) are probabilistic graphical models that have been applied globally to a range of water resources management studies; however, there has been very limited application of BNs to similar studies in South Africa. This article explores the benefits and challenges of BN application in the context of water resources management, specifically in relation to South Africa. A brief overview describes BNs, followed by details of some of the possible opportunities for BNs to benefit water resources management. These include the ability to use quantitative and qualitative information, data, and expert knowledge. BN models can be integrated into geographic information systems and predict impact of ecosystem services and sustainability indicators. With additional data and information, BNs can be updated, allowing for integration into an adaptive management process. Challenges in the application of BNs include oversimplification of complex systems, constraints of BNs with categorical nodes for continuous variables, unclear use of expert knowledge, and treatment of uncertainty. BNs have tremendous potential to guide decision making by providing a holistic approach to water resources management.
Indrani Hazel Govender; Ullrika Sahlin; Gordon C. O'Brien. Bayesian Network Applications for Sustainable Holistic Water Resources Management: Modeling Opportunities for South Africa. Risk Analysis 2021, 1 .
AMA StyleIndrani Hazel Govender, Ullrika Sahlin, Gordon C. O'Brien. Bayesian Network Applications for Sustainable Holistic Water Resources Management: Modeling Opportunities for South Africa. Risk Analysis. 2021; ():1.
Chicago/Turabian StyleIndrani Hazel Govender; Ullrika Sahlin; Gordon C. O'Brien. 2021. "Bayesian Network Applications for Sustainable Holistic Water Resources Management: Modeling Opportunities for South Africa." Risk Analysis , no. : 1.
Overreliance on fishmeal (FM) as an aquafeed ingredient has become economically and ecologically unsustainable because wild stocks of forage fish are declining causing disruptions in aquatic food webs. On the other hand, the crocodile skin business generates substantial quantities of crocodile meat whose demand for human consumption is extremely low. The potential value of crocodile meat meal (CMM) as a FM alternative in fish diets is unknown. Therefore, this short-term, preliminary study investigated the effect of replacing FM with raw or cooked CMM on feed utilization, growth performance, haemato-biochemical parameters, and tissue nutrient composition in juvenile dusky kob (Argyrosomus japonicus, Temminck and Schlegel, 1843). Diets were formulated by replacing FM in a commercial diet (control) with 1. cooked CMM at 50 % (CCR50), 2. raw CMM at 50 % (RCR50), 3. raw CMM at 100 % (RCR100), and 4. cooked CMM at 100 % (CCR100). Fingerlings (7.55 ± 0.87 g) were offered diets at 2.8 % body weight, twice daily, in a recirculating aquaculture system (20 tanks; 110 fish/tank) for 5 weeks. Weight was measured weekly while blood and fillet samples were collected in week 5. Complete replacement of FM with CMM significantly reduced feed intake, weight gain, specific growth rate (SGR), and protein efficiency ratio (PER) while increasing FCR over the 5-week period. The RCR100 and CCR100 diets also resulted in higher levels of urea, alkaline phosphatase, and lower triglycerides in the serum of fish. Complete replacement of FM with CMM increased palmitoleic and oleic acids in fish muscle compared to the control. Regardless of level of FM substitution, CMM had an adverse impact on linoleic acid, linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid concentration of the dusky kob fillet. A supplementation strategy using oils rich in n-3 fatty acids could mitigate the negative impact of dietary CMM on feed utilization, growth performance, and polyunsaturated fatty acid levels in dusky kob fillet without raising economic and ecological costs.
Reginah M. Mdhluvu; Victor Mlambo; Molatelo J. Madibana; Mulunda Mwanza; Gordon O’Brien. Crocodile meat meal as a fishmeal substitute in juvenile dusky kob (Argyrosomus japonicus) diets: Feed utilization, growth performance, blood parameters, and tissue nutrient composition. Aquaculture Reports 2021, 21, 100779 .
AMA StyleReginah M. Mdhluvu, Victor Mlambo, Molatelo J. Madibana, Mulunda Mwanza, Gordon O’Brien. Crocodile meat meal as a fishmeal substitute in juvenile dusky kob (Argyrosomus japonicus) diets: Feed utilization, growth performance, blood parameters, and tissue nutrient composition. Aquaculture Reports. 2021; 21 ():100779.
Chicago/Turabian StyleReginah M. Mdhluvu; Victor Mlambo; Molatelo J. Madibana; Mulunda Mwanza; Gordon O’Brien. 2021. "Crocodile meat meal as a fishmeal substitute in juvenile dusky kob (Argyrosomus japonicus) diets: Feed utilization, growth performance, blood parameters, and tissue nutrient composition." Aquaculture Reports 21, no. : 100779.
Within South Africa, the St. Lucia Basin, comprising the White Mfolozi, Black Mfolozi, Mfolozi Hluhluwe-Mkuze sub-basins, is an ecologically important region. However, the river ecosystems and their inherent biota, especially the ichthyofauna, are inadequately studied. Considering the anthropogenic land-use change currently occurring and the concomitant elevated resource-use, we sought to ascertain the composition of the fish species communities within the basin and the environmental drivers influencing the spatial shifts in these communities to provide baseline information. We collected data from 20 sites in the basin from 2016 to 2018. A total of 4 420 individuals representing 24 fish species, from eight families, were recorded. Using generalised linear modelling, species count data were fitted to sub-catchment factor variables and habitat variables. We observed significant differences in the structure of the ichthyofauna communities between the sub-catchments as well as the environmental drivers to be substrate, mean depth, mean velocity, overhanging vegetation and woody debris. The Hluhluwe sub-catchment was the most diverse, while the White Mfolozi was the least diverse. Continued unsustainable use of the basin's water resources and poor land management practices are likely to shift the ichthyofauna communities into uniform, species-depauperate communities, potentially leading to a loss in ecosystem services and functioning.
Mahomed Desai; Céline Hanzen; Colleen T. Downs; Gordon C. O’Brien. Environmental drivers of ichthyofauna community composition of the river ecosystems draining the Lake St. Lucia basin, South Africa. Hydrobiologia 2021, 848, 3539 -3554.
AMA StyleMahomed Desai, Céline Hanzen, Colleen T. Downs, Gordon C. O’Brien. Environmental drivers of ichthyofauna community composition of the river ecosystems draining the Lake St. Lucia basin, South Africa. Hydrobiologia. 2021; 848 (15):3539-3554.
Chicago/Turabian StyleMahomed Desai; Céline Hanzen; Colleen T. Downs; Gordon C. O’Brien. 2021. "Environmental drivers of ichthyofauna community composition of the river ecosystems draining the Lake St. Lucia basin, South Africa." Hydrobiologia 848, no. 15: 3539-3554.
Fishmeal is the main source of dietary protein for most commercially farmed fish species. However, fishmeal prices have been raised even further because of competition with domestic animals, shortage in world fishmeal supply, and increased demand. Increased fishmeal prices have contributed to the quest for alternatives necessary to replace fishmeal as a global research priority. A literature search was conducted using these terms on Google Scholar and EBSCOhost; fishmeal replacement in fish feeds, fishmeal alternatives in fish feeds, animal protein sources in aquaculture, insects in fish feeds, terrestrial by-products, and fishery by-products. To calculate the variation between experiments, a random effect model was used. Results indicated that different fish species, sizes, and inclusion levels were used in the various studies and showed that the use of insects, terrestrial by-products, and fishery by-products has some limitations. Despite these drawbacks, the use of animal protein sources as a replacement for fishmeal in fish diets has had a positive impact on the feed conversion ratio, variable growth rate, final weight, and survival rate of different types of fish species of different size groups. Findings also showed that some animal by-products had not been assessed as a protein source in aquaculture or animal feeds, and future studies are recommended.
Rendani Luthada-Raswiswi; Samson Mukaratirwa; Gordon O’Brien. Animal Protein Sources as a Substitute for Fishmeal in Aquaculture Diets: A Systematic Review and Meta-Analysis. Applied Sciences 2021, 11, 3854 .
AMA StyleRendani Luthada-Raswiswi, Samson Mukaratirwa, Gordon O’Brien. Animal Protein Sources as a Substitute for Fishmeal in Aquaculture Diets: A Systematic Review and Meta-Analysis. Applied Sciences. 2021; 11 (9):3854.
Chicago/Turabian StyleRendani Luthada-Raswiswi; Samson Mukaratirwa; Gordon O’Brien. 2021. "Animal Protein Sources as a Substitute for Fishmeal in Aquaculture Diets: A Systematic Review and Meta-Analysis." Applied Sciences 11, no. 9: 3854.
Four freshwater eel species (Anguilla spp.) occur in southern African rivers that are increasingly anthropogenically modified. Information on movements, habitat use and overlap by African eels is needed for their conservation. We carried out a preliminary investigation of the spatial ecology of three eel species in the Thukela River, South Africa, using radio-telemetry. Nineteen yellow-stage eels were surgically implanted with radio-tags, comprising A. mossambica (n = 2), A. bengalensis (n = 9) and A. marmorata (n = 8), and tracked from October 2018 to August 2019. Tagged eels exhibited high individual variability in space use. We recorded very small home ranges in winter for all species. A lack of apparent territoriality at inter- and intra-specific levels was observed. Eel species tended to use similar mesohabitats, especially glides, but habitat preference changed across seasons, and between species, suggesting fine-scale spatial and temporal niche partitioning. Given the breadth of flow typologies used by Thukela eels across the seasons, conservation of these long-lived species indicates that management of river flows needs to be sensitive to their habitat requirements all year round, but in many water-stressed South African rivers, this may be unlikely. Maintaining good habitat connectivity for these migrant species must be prioritised.
Céline Hanzen; Martyn C. Lucas; Gordon O’Brien; Peter Calverley; Colleen T. Downs. Spatial ecology of freshwater eels in South Africa: implications for conservation. Hydrobiologia 2021, 848, 2579 -2593.
AMA StyleCéline Hanzen, Martyn C. Lucas, Gordon O’Brien, Peter Calverley, Colleen T. Downs. Spatial ecology of freshwater eels in South Africa: implications for conservation. Hydrobiologia. 2021; 848 (10):2579-2593.
Chicago/Turabian StyleCéline Hanzen; Martyn C. Lucas; Gordon O’Brien; Peter Calverley; Colleen T. Downs. 2021. "Spatial ecology of freshwater eels in South Africa: implications for conservation." Hydrobiologia 848, no. 10: 2579-2593.
Matthew J. Burnett; Gordon C. O’Brien; Francois J. Jacobs; Graham Jewitt; Colleen T. Downs. Fish telemetry in African inland waters and its use in management: a review. Reviews in Fish Biology and Fisheries 2021, 31, 337 -357.
AMA StyleMatthew J. Burnett, Gordon C. O’Brien, Francois J. Jacobs, Graham Jewitt, Colleen T. Downs. Fish telemetry in African inland waters and its use in management: a review. Reviews in Fish Biology and Fisheries. 2021; 31 (2):337-357.
Chicago/Turabian StyleMatthew J. Burnett; Gordon C. O’Brien; Francois J. Jacobs; Graham Jewitt; Colleen T. Downs. 2021. "Fish telemetry in African inland waters and its use in management: a review." Reviews in Fish Biology and Fisheries 31, no. 2: 337-357.
The Phongolo floodplain is one of southern Africa's most important systems. In this study, we carried out a regional scale ecological risk assessment to evaluate the risk of multiple stressors associated with the use of the aquatic resources in the floodplain to selected social and ecological endpoints representing its sustainability. The floodplain has undergone significant changes as a result of the impacts of multiple stressors. This includes high risk of impact and threatened sustainability between the Pongolapoort Dam and the Ndumo Game Reserve (NGR). This compares to relatively low risk to the maintenance of the endpoints within the NGR. The reserve provides a protection and refuge function for regional biodiversity maintenance and ecosystem sustainability processes. In the study a range of scenarios were considered and demonstrate that the system will respond to protection measures and or increased resource use options. Should flood reductions in the or water quality pollution drivers continue on increasing trajectories, the condition of the Phongolo River and floodplain will probably deteriorate into an unacceptable, unsustainable state. Removal of the protection services of the NGR would result in an unsustainable ecosystem and loss of ecosystem services for regional vulnerable African communities. Additional evidence should be obtained from monitoring and research to refine, validate, and update the assessment in an adaptive management context. The risk assessment framework approach implemented in the Phongolo floodplain can contribute to the management of other floodplains ecosystems and the sustainability management of social and ecological attributes and processes of these important ecosystems.
Gordon O'Brien; Nico J Smit; Victor Wepener. Regional Scale Risk to the Ecological Sustainability and Ecosystem Services of an African Floodplain System. Risk Analysis 2021, 1 .
AMA StyleGordon O'Brien, Nico J Smit, Victor Wepener. Regional Scale Risk to the Ecological Sustainability and Ecosystem Services of an African Floodplain System. Risk Analysis. 2021; ():1.
Chicago/Turabian StyleGordon O'Brien; Nico J Smit; Victor Wepener. 2021. "Regional Scale Risk to the Ecological Sustainability and Ecosystem Services of an African Floodplain System." Risk Analysis , no. : 1.
Floodplains are particularly important in the semi-arid region of the Sub-Sahelian Africa. In this region, water governance is still being developed, often without adequate information and technical capacity for good, sustainable water resource management. However, water resources are being allocated for use with minimal sustainability considerations. Environmental flows (e-flows) include the quantity and timing of flows or water levels needed to meet the sustainable requirements of freshwater and estuarine ecosystems. Holistic regional scale e-flows linked to floodplain management can make a noticeable contribution to sustainable floodplain management. The Inner Niger Delta (IND) in Mali is an example of a vulnerable, socio-ecologically important floodplain in the Sahel region of North Africa that is being developed with little understanding of sustainability requirements. Although integrally linked to the Upper Niger River catchment, the IND sustains a million and half people within the region and exports food to surrounding areas. The flooding of the Delta is the engine of the socio-economic development as well as its ecological integrity. This paper aims to demonstrate the contribution that holistic regional e-flow assessment using the PROBFLO approach has to achieving floodplain sustainability. This can be achieved through the determining the e-flow requirements to maintain critical requirements of the ecosystems and associated services used by local vulnerable human communities for subsistence and describing the socio-ecological consequences of altered flows. These outcomes can contribute to the management of the IND. In this study, the socio-ecological consequences of altered flows have been evaluated by assessing the risk of alterations in the volume, duration, and timing of flows, to a number of ecological and social endpoints. Based on the risk posed to these endpoints by each scenario of change, an e-flow of 58% (26,685 million cubic meters (MCM) of water annually) was determined that would protect the ecosystem and maintain indicator components at a sustainable level. These e-flows also provide sustainable services to local communities including products for subsistence and limit any abnormal increases in diseases to the vulnerable African communities who live in the basin. Relative risk outputs for the development scenarios result in low-to-high-risk probabilities for most endpoints. The future development scenarios include insufficient flows to maintain sustainability during dry or low-flow periods with an increase in zero flow possibilities. Although unsuitable during the low-flow or dry periods, sufficient water is available through storage in the basin to meet the e-flows if these scenarios were considered for implementation. The IND is more vulnerable to changes in flows compared to the rivers upstream of the IND. The e-flow outcomes and consequences of altered flow scenarios has contributed to the management of vulnerable IND floodplains and the requirements and trade-off considerations to achieve sustainability.
Gordon O’Brien; Chris Dickens; Chris Baker; Retha Stassen; Frank Van Weert. Sustainable Floodplains: Linking E-Flows to Floodplain Management, Ecosystems, and Livelihoods in the Sahel of North Africa. Sustainability 2020, 12, 10578 .
AMA StyleGordon O’Brien, Chris Dickens, Chris Baker, Retha Stassen, Frank Van Weert. Sustainable Floodplains: Linking E-Flows to Floodplain Management, Ecosystems, and Livelihoods in the Sahel of North Africa. Sustainability. 2020; 12 (24):10578.
Chicago/Turabian StyleGordon O’Brien; Chris Dickens; Chris Baker; Retha Stassen; Frank Van Weert. 2020. "Sustainable Floodplains: Linking E-Flows to Floodplain Management, Ecosystems, and Livelihoods in the Sahel of North Africa." Sustainability 12, no. 24: 10578.
Studies have reported poor survival of surgically‐tagged freshwater fishes in warm African waters. This study aimed to assess the applicability of using radio telemetry (and surgical implantation of tags) for Anguilla spp. Nineteen yellow eels (Anguilla bengalensis, A. marmorata and A. mossambica) were surgically implanted with radio tags between October 2018 and January 2019 in the Thukela River, South Africa. Most eels were alive 6 months after tagging, and recaptured eels displayed advanced or complete healing at the incision site. Therefore, this method appears suitable for African freshwater eels. This article is protected by copyright. All rights reserved.
Céline Hanzen; Martyn C. Lucas; Gordon O'Brien; Peter Calverley; Colleen T. Downs. Surgical implantation of radio tags in three eel species ( Anguilla spp.) in South Africa. Journal of Fish Biology 2020, 96, 847 -852.
AMA StyleCéline Hanzen, Martyn C. Lucas, Gordon O'Brien, Peter Calverley, Colleen T. Downs. Surgical implantation of radio tags in three eel species ( Anguilla spp.) in South Africa. Journal of Fish Biology. 2020; 96 (3):847-852.
Chicago/Turabian StyleCéline Hanzen; Martyn C. Lucas; Gordon O'Brien; Peter Calverley; Colleen T. Downs. 2020. "Surgical implantation of radio tags in three eel species ( Anguilla spp.) in South Africa." Journal of Fish Biology 96, no. 3: 847-852.
Fishes are indicators of aquatic ecosystem wellbeing globally and used when understanding impacts from water resources. The behavioural ecology of fishes as a Line of Evidence (LoE) is between 10 and 100 times more responsive to changes in environmental variables, compared with traditional LoEs including standard mortality bioassay LoEs. Fish telemetry methods are available to monitor fish behaviour and the response of tagged fish to altered water quality, flow and instream habitat variability exist globally. Developing regions have relatively poor use of fish telemetry as a methodology to gather behavioural information, compared with developed regions for various reasons. Fish telemetry methods can assist in answering water resource management questions faced in developing regions. For this purpose, we describe the development of the southern African inland fish tracking (FISHTRAC) programme and its use for collecting fish behaviour, and water quality and quantity data in real-time and remotely. We also detail eight case studies that contributed to FISHTRAC over the past decade. The FISHTRAC programme was initially based on internationally recognised radio telemetry methods that were then adapted for application in southern Africa. Developments within the FISHTRAC programme have seen radio telemetry methods expand beyond manual monitoring techniques to incorporate a real-time and remote monitoring feature. The case studies demonstrated the development of FISHTRAC’s functionality; data management systems, real-time communications and data evaluations. This included its implementation in five economically important freshwater ecosystems across southern Africa and using eight large charismatic fish species. Following the description of the FISHTRAC programme, we provide a four-phase guideline to successfully implement radio telemetry methods to obtain behavioural information of fishes and contribute to the essential management and monitoring of fisheries and water resources within the southern Africa context, applicable globally with continued anthropogenic stressors.
Matthew J. Burnett; Gordon C. O'Brien; Francois J. Jacobs; Francois Botha; Graham Jewitt; Colleen T. Downs. The southern African inland fish tracking programme (FISHTRAC): An evaluation of the approach for monitoring ecological consequences of multiple water resource stressors, remotely and in real-time. Ecological Indicators 2020, 111, 106001 .
AMA StyleMatthew J. Burnett, Gordon C. O'Brien, Francois J. Jacobs, Francois Botha, Graham Jewitt, Colleen T. Downs. The southern African inland fish tracking programme (FISHTRAC): An evaluation of the approach for monitoring ecological consequences of multiple water resource stressors, remotely and in real-time. Ecological Indicators. 2020; 111 ():106001.
Chicago/Turabian StyleMatthew J. Burnett; Gordon C. O'Brien; Francois J. Jacobs; Francois Botha; Graham Jewitt; Colleen T. Downs. 2020. "The southern African inland fish tracking programme (FISHTRAC): An evaluation of the approach for monitoring ecological consequences of multiple water resource stressors, remotely and in real-time." Ecological Indicators 111, no. : 106001.
Freshwater eels (Anguilla spp.) have a long and complex catadromous life cycle. This unique feature, coupled with difficulty in separating species based on morphology, makes them complex targets for conservation. In this study we evaluated the utility of DNA barcoding using cytochrome oxidase I (COI) to delimit the four species of African eels found in the western Indian Ocean region. We collected 76 individual fin clips from the four eel species (A. mossambica, n=51; A. marmorata, n=17; A. bengalensis, n=6; A. bicolor, n=2) in the rivers of KwaZulu–Natal, South Africa, in 2016–18. Phylogenetic analysis of the COI sequences recovered all four species as monophyletic. Barcoding gap analyses were performed and there was no found overlap in inter- and intraspecific genetic distances. Consequently, the use of COI barcoding as an identification tool was found to be reliable for identifying African eels to the species level, which suggests that this marker should be included in future environmental DNA or metabarcoding studies.
Céline Hanzen; Martyn C. Lucas; Gordon O'brien; Colleen T. Downs; Sandi Willows-Munro. African freshwater eel species (Anguilla spp.) identification through DNA barcoding. Marine and Freshwater Research 2020, 71, 1543 .
AMA StyleCéline Hanzen, Martyn C. Lucas, Gordon O'brien, Colleen T. Downs, Sandi Willows-Munro. African freshwater eel species (Anguilla spp.) identification through DNA barcoding. Marine and Freshwater Research. 2020; 71 (11):1543.
Chicago/Turabian StyleCéline Hanzen; Martyn C. Lucas; Gordon O'brien; Colleen T. Downs; Sandi Willows-Munro. 2020. "African freshwater eel species (Anguilla spp.) identification through DNA barcoding." Marine and Freshwater Research 71, no. 11: 1543.
Effective environmental management and restoration of impacted estuaries in South Africa necessitates a holistic understanding of the contribution of various stressor-related impacts throughout the catchment. Ecological risk assessment for aquatic ecosystems is an important tool for water resource management. In this study, we describe results of a preliminary assessment that was conducted to evaluate the relative risks of multiple anthropogenic stressors currently acting within the catchments of uMvoti, Thukela and aMatikulu/Nyoni estuaries using Bayesian Network Relative Risk Model (BN-RRM) framework. Four socio-ecological endpoints selected for the present study included biodiversity habitat, safe environment, fisheries and productivity. We constructed a conceptual model which depicted potential and effect pathways from the source, to the stressor, to the habitat and to the endpoint. We also developed five scenarios (including historical and future scenarios) to predict the potential risk distributions in different proposed scenarios. Results revealed that productivity was the endpoint at the lower risk in all the estuaries and all scenarios except for scenario 5. Results also showed that scenario 3 which is a scenario before major resource development had the lowest risk scores for all the endpoints. Scenario 4 (year 2025 if no laws and management measures are implemented) had the highest risk scores for all the endpoints. Overall endpoints generally displayed low to medium risk throughout all scenarios (except scenario 3) and different flows. All endpoints generally displayed zero risk in scenario 3. All endpoints were at a highest risk in the uMvoti Estuary followed by aMatikulu/Nyoni and then Thukela Estuary. Results highlighted that in the uMvoti and Thukela estuaries, people were at a higher risk when compared with the ecological components of these systems as social endpoints displayed higher risk scores than the ecological endpoints, however the opposite was observed in the aMatikulu/Nyoni Estuary. This study provided the foundation for evaluating the risks of multiple stressors in the catchments of these estuaries to a variety of endpoints. Management options and research should focus on collecting necessary data and information to refine the developed RRM. By establishing such framework, we believe that stakeholders within the catchments of these systems together with government organisations will be able to make more informed and risk-based management decisions pertaining restoration and rehabilitation options for these three estuaries.
Madonna Vezi; Colleen Downs; Victor Wepener; Gordon O'Brien. Application of the relative risk model for evaluation of ecological risk in selected river dominated estuaries in KwaZulu-Natal, South Africa. Ocean & Coastal Management 2019, 185, 105035 .
AMA StyleMadonna Vezi, Colleen Downs, Victor Wepener, Gordon O'Brien. Application of the relative risk model for evaluation of ecological risk in selected river dominated estuaries in KwaZulu-Natal, South Africa. Ocean & Coastal Management. 2019; 185 ():105035.
Chicago/Turabian StyleMadonna Vezi; Colleen Downs; Victor Wepener; Gordon O'Brien. 2019. "Application of the relative risk model for evaluation of ecological risk in selected river dominated estuaries in KwaZulu-Natal, South Africa." Ocean & Coastal Management 185, no. : 105035.
African tigerfish Hydrocynus vittatus (n = 35) were tagged with external radio-transmitters in the Kavango River, Namibia, to determine whether freshwater protected areas could be an effective tool for the management and conservation of this species. They were manually tracked in the core study area of 33 km every c. 12 days from July-October 2016 to May 2017 for between 123 to 246 days. In addition, 14 extended surveys were carried out for up to 680 km to determine the total area use of the tagged individuals. Tigerfish displayed at least two behavioural patterns either having high site fidelity with shorter movements or using larger areas with longer movements. Twenty-three (66%) of the triggerfish had high site fidelity using an area of less than 33 km of river, whereas 12 tigerfish (34%) undertook long distance movements of up to 397 km upstream and 116 km downstream from their tagging locations. During the long-distance movements tigerfish crossed the territorial boundaries of Angola, Namibia and Botswana. Of the 35 fish that were monitored, 14 (40%) spent more than 80% of the monitored time in the 33 km study area and 18 (51%) stayed within the study area for at least 50% of the monitored time. These findings suggest that freshwater protected areas may be a useful management tool and we predict that a protected river area of 2-5 km river length could protect 25.9-34.6% of the population for at least 75% of the time whereas protection of 10 km river length could protect at least 50% of tigerfish for at least 75% of the time. This article is protected by copyright. All rights reserved.
Francois J. Jacobs; Tor F. Næsje; Eva M. Ulvan; Olaf Weyl; Deon Tiyeho; Clinton J. Hay; Gordon O'Brien; Colleen T. Downs; T. F. Naesje. Implications of the movement behaviour of African tigerfish Hydrocynus vittatus for the design of freshwater protected areas. Journal of Fish Biology 2019, 96, 1260 -1268.
AMA StyleFrancois J. Jacobs, Tor F. Næsje, Eva M. Ulvan, Olaf Weyl, Deon Tiyeho, Clinton J. Hay, Gordon O'Brien, Colleen T. Downs, T. F. Naesje. Implications of the movement behaviour of African tigerfish Hydrocynus vittatus for the design of freshwater protected areas. Journal of Fish Biology. 2019; 96 (5):1260-1268.
Chicago/Turabian StyleFrancois J. Jacobs; Tor F. Næsje; Eva M. Ulvan; Olaf Weyl; Deon Tiyeho; Clinton J. Hay; Gordon O'Brien; Colleen T. Downs; T. F. Naesje. 2019. "Implications of the movement behaviour of African tigerfish Hydrocynus vittatus for the design of freshwater protected areas." Journal of Fish Biology 96, no. 5: 1260-1268.
This study examined the effectiveness of macroinvertebrate community-based multimetrics to assess the ecological health of 38 rivers in KwaZulu-Natal (KZN) Province, South Africa. The study area comprised of headwater to lowland rivers determined by their hydro-morphology. Of the 40 tested metrics, only 11 core metrics were finally selected because of their ability to distinguish between reference and impaired sites, correlation strength with environmental variables and their reliability. Nine out of the selected metrics had strong correlations with environmental variables and these were total number of taxa, total number of Diptera taxa, total number of Plecoptera individuals, percentage of Ephemeroptera Plecoptera and Trichoptera taxa, percentage of Odonata taxa, total number of Trichoptera individuals, total number of Gastropoda individuals, total number of Oligochaeta individuals and total number of Coleoptera individuals. This study showed increasing chemical deterioration along longitudinal gradients of the rivers in KZN. We found that macroinvertebrate community metrics could detect nutrient pollution, organic pollution and physical habitat degradation in the rivers of KZN. We recommend more studies and validation of macroinvertebrate community-based metrics in the assessment of rivers in KZN, because they are relatively cheap and easy to use. The use of macroinvertebrate community metrics could be an effective alternative assessment method in the case of the lowland rivers where the lack of quality data often has negative impacts on the use of the biotic indices (South African Scoring System (SASS), Average Score Per Taxon (ASPT) and Macroinvertebrate Response Assessment Index (MIRAI)).
Olalekan A. Agboola; Colleen T. Downs; Gordon O'Brien. Macroinvertebrates as indicators of ecological conditions in the rivers of KwaZulu-Natal, South Africa. Ecological Indicators 2019, 106, 105465 .
AMA StyleOlalekan A. Agboola, Colleen T. Downs, Gordon O'Brien. Macroinvertebrates as indicators of ecological conditions in the rivers of KwaZulu-Natal, South Africa. Ecological Indicators. 2019; 106 ():105465.
Chicago/Turabian StyleOlalekan A. Agboola; Colleen T. Downs; Gordon O'Brien. 2019. "Macroinvertebrates as indicators of ecological conditions in the rivers of KwaZulu-Natal, South Africa." Ecological Indicators 106, no. : 105465.
Globally, estuaries are among the most productive ecosystems with many threatened by anthropogenic activities. Zooplankton is a bioindicator of ecosystem integrity. The spatial and temporal composition of zooplankton communities were quantified and compared within and between three estuaries (uMvoti, Thukela and aMatikulu/Nyoni estuaries) with different levels of human pressure in KwaZulu-Natal, South Africa. Additional effects of some physico-chemical variables and seasonal flow patterns to zooplankton community structuring were analyzed. The aMatikulu/Nyoni Estuary was selected as a reference site due to its good ecological state. Sampling dates represented high flow (March and April) and low flow (August and September) from 2014 to 2016. Following aMatikulu/Nyoni, highest abundance was recorded in Thukela and then uMvoti Estuary with copepod Pseudodiaptomus hessei and Acartia natalensis dominating the three estuaries. Highest abundance was recorded during low flow in the uMvoti and Thukela estuaries. Redundancy analysis revealed higher salinity and oxygen as environmental determinants of zooplankton community structure in the aMatikulu/Nyoni while turbidity and pH were the determinants of zooplankton community structures in uMvoti and Thukela estuaries. Elevated concentrations of DIN in the Thukela Estuary during high flow identifies the Thukela River as an important source of nitrogen to this estuary. Our findings suggest that these estuaries be managed to ensure sufficient freshwater supply which controls primary production. Although the three estuaries were from the same biogeographical region with a similar river dominated function, high variability in their zooplankton communities could be explained by differing water quality due to differing human pressure in their catchments.
Madonna Vezi; Colleen T. Downs; Victor Wepener; Gordon O'Brien. Response of zooplankton communities to altered water quality and seasonal flow changes in selected river dominated estuaries in KwaZulu-Natal, South Africa. Ecohydrology & Hydrobiology 2019, 19, 393 -406.
AMA StyleMadonna Vezi, Colleen T. Downs, Victor Wepener, Gordon O'Brien. Response of zooplankton communities to altered water quality and seasonal flow changes in selected river dominated estuaries in KwaZulu-Natal, South Africa. Ecohydrology & Hydrobiology. 2019; 19 (3):393-406.
Chicago/Turabian StyleMadonna Vezi; Colleen T. Downs; Victor Wepener; Gordon O'Brien. 2019. "Response of zooplankton communities to altered water quality and seasonal flow changes in selected river dominated estuaries in KwaZulu-Natal, South Africa." Ecohydrology & Hydrobiology 19, no. 3: 393-406.
The 2030 Agenda for Sustainable Development, the Sustainable Development Goals (SDGs), are high on the agenda for most countries of the world. In its publication of the SDGs, the UN has provided the goals and target descriptions that, if implemented at a country level, would lead towards a sustainable future. The IAEG (InterAgency Expert Group of the SDGs) was tasked with disseminating indicators and methods to countries that can be used to gather data describing the global progress towards sustainability. However, 2030 Agenda leaves it to countries to adopt the targets with each government setting its own national targets guided by the global level of ambition but taking into account national circumstances. At present, guidance on how to go about this is scant but it is clear that the responsibility is with countries to implement and that it is actions at a country level that will determine the success of the SDGs. Reporting on SDGs by country takes on two forms: i) global reporting using prescribed indicator methods and data; ii) National Voluntary Reviews where a country reports on its own progress in more detail but is also able to present data that are more appropriate for the country. For the latter, countries need to be able to adapt the global indicators to fit national priorities and context, thus the global description of an indicator could be reduced to describe only what is relevant to the country. Countries may also, for the National Voluntary Review, use indicators that are unique to the country but nevertheless contribute to measurement of progress towards the global SDG target. Importantly, for those indicators that relate to the security of natural resources security (e.g., water) indicators, there are no prescribed numerical targets/standards or benchmarks. Rather countries will need to set their own benchmarks or standards against which performance can be evaluated. This paper presents a procedure that would enable a country to describe national targets with associated benchmarks that are appropriate for the country. The procedure builds on precedent set in other countries but in particular on a procedure developed for the setting of Resource Quality Objectives in South Africa. The procedure focusses on those SDG targets that are natural resource-security focused, for example, extent of water-related ecosystems (6.6), desertification (15.3) and so forth, because the selection of indicator methods and benchmarks is based on the location of natural resources, their use and present state and how they fit into national strategies.
Chris Dickens; Vladimir Smakhtin; Matthew McCartney; Gordon O’Brien; Lula Dahir. Defining and Quantifying National-Level Targets, Indicators and Benchmarks for Management of Natural Resources to Achieve the Sustainable Development Goals. Sustainability 2019, 11, 462 .
AMA StyleChris Dickens, Vladimir Smakhtin, Matthew McCartney, Gordon O’Brien, Lula Dahir. Defining and Quantifying National-Level Targets, Indicators and Benchmarks for Management of Natural Resources to Achieve the Sustainable Development Goals. Sustainability. 2019; 11 (2):462.
Chicago/Turabian StyleChris Dickens; Vladimir Smakhtin; Matthew McCartney; Gordon O’Brien; Lula Dahir. 2019. "Defining and Quantifying National-Level Targets, Indicators and Benchmarks for Management of Natural Resources to Achieve the Sustainable Development Goals." Sustainability 11, no. 2: 462.
People throughout the world depend on the services we derive from freshwater ecosystems. Human land-use activities often affect the quality, quantity and habitat of freshwater ecosystem, which need to be carefully managed to ensure their integrity and provision of services is sustainable. In South Africa, legislation has established resource-directed measures to attain a sustainable balance between the use and protection of water resources. These procedures have been implemented in most of South Africa’s nine water-management areas, resulting in new legislation to protect these resources. Unfortunately, very little protection has been afforded to river connectivity maintenance and fish migrations. For water storage and flow regulation for agriculture and other resource use activities, >610 formal dams and ~1430 gauging weirs have been constructed that act a partial or complete barriers to fish migration on river ecosystems. Only ~60 fish passage structures have been built, but many are not functional. River connectivity and fish migration management appears to be a shortcoming of the existing management approach for multiple stressors.
Gordon C. O'brien; Mathew Ross; Céline Hanzen; Vuyisile Dlamini; Robin Petersen; Gerhard J. Diedericks; Matthew J. Burnett. River connectivity and fish migration considerations in the management of multiple stressors in South Africa. Marine and Freshwater Research 2019, 70, 1254 .
AMA StyleGordon C. O'brien, Mathew Ross, Céline Hanzen, Vuyisile Dlamini, Robin Petersen, Gerhard J. Diedericks, Matthew J. Burnett. River connectivity and fish migration considerations in the management of multiple stressors in South Africa. Marine and Freshwater Research. 2019; 70 (9):1254.
Chicago/Turabian StyleGordon C. O'brien; Mathew Ross; Céline Hanzen; Vuyisile Dlamini; Robin Petersen; Gerhard J. Diedericks; Matthew J. Burnett. 2019. "River connectivity and fish migration considerations in the management of multiple stressors in South Africa." Marine and Freshwater Research 70, no. 9: 1254.
Irrigated agriculture and inland fisheries both make important contributions to food security, nutrition, livelihoods and wellbeing. Typically, in modern irrigation systems, these components operate independently. Some practices, commonly associated with water use and intensification of crop production can be in direct conflict with and have adverse effects on fisheries. Food security objectives may be compromised if fish are not considered in the design phases of irrigation systems. The 2030 Agenda for Sustainable Development provides a framework that can serve as a backdrop to help integrate both sectors in policy discussions and optimise their contributions to achieving the Sustainable Development Goals (SDGs). Inland fisheries systems do play an important role in supporting many SDG objectives, but these contributions can sometimes be at odds with irrigated agriculture. Using case studies of two globally important river catchments, namely the Lower Mekong and Murray–Darling basins, we highlight the conflicts and opportunities for improved outcomes between irrigated agriculture and inland fisheries. We explore SDG 2 (Zero Hunger) as a path to advance our irrigation systems as a means to benefit both agriculture and inland fisheries, preserving biodiversity and enhancing the economic, environmental and social benefits they both provide to people.2
Abigail J. Lynch; Lee Baumgartner; Craig A. Boys; John Conallin; Ian G. Cowx; C. Max Finlayson; Paul Franklin; Zeb Hogan; John D. Koehn; Matthew P. McCartney; Gordon O'Brien; Kaviphone Phouthavong; Luiz G. M. Silva; Chann Aun Tob; John Valbo-Jørgensen; An Vi Vu; Louise Whiting; Arif Wibowo; Phil Duncan. Speaking the same language: can the sustainable development goals translate the needs of inland fisheries into irrigation decisions? Marine and Freshwater Research 2019, 70, 1211 .
AMA StyleAbigail J. Lynch, Lee Baumgartner, Craig A. Boys, John Conallin, Ian G. Cowx, C. Max Finlayson, Paul Franklin, Zeb Hogan, John D. Koehn, Matthew P. McCartney, Gordon O'Brien, Kaviphone Phouthavong, Luiz G. M. Silva, Chann Aun Tob, John Valbo-Jørgensen, An Vi Vu, Louise Whiting, Arif Wibowo, Phil Duncan. Speaking the same language: can the sustainable development goals translate the needs of inland fisheries into irrigation decisions? Marine and Freshwater Research. 2019; 70 (9):1211.
Chicago/Turabian StyleAbigail J. Lynch; Lee Baumgartner; Craig A. Boys; John Conallin; Ian G. Cowx; C. Max Finlayson; Paul Franklin; Zeb Hogan; John D. Koehn; Matthew P. McCartney; Gordon O'Brien; Kaviphone Phouthavong; Luiz G. M. Silva; Chann Aun Tob; John Valbo-Jørgensen; An Vi Vu; Louise Whiting; Arif Wibowo; Phil Duncan. 2019. "Speaking the same language: can the sustainable development goals translate the needs of inland fisheries into irrigation decisions?" Marine and Freshwater Research 70, no. 9: 1211.
Environmental flow (E-flow) frameworks advocate holistic, regional-scale, probabilistic E-flow assessments that consider flow and non-flow drivers of change in a socio-ecological context as best practice. Regional-scale ecological risk assessments of multiple stressors to social and ecological endpoints, which address ecosystem dynamism, have been undertaken internationally at different spatial scales using the relative-risk model since the mid-1990s. With the recent incorporation of Bayesian belief networks into the relative-risk model, a robust regional-scale ecological risk assessment approach is available that can contribute to achieving the best practice recommendations of E-flow frameworks. PROBFLO is a holistic E-flow assessment method that incorporates the relative-risk model and Bayesian belief networks (BN-RRM) into a transparent probabilistic modelling tool that addresses uncertainty explicitly. PROBFLO has been developed to evaluate the socio-ecological consequences of historical, current and future water resource use scenarios and generate E-flow requirements on regional spatial scales. The approach has been implemented in two regional-scale case studies in Africa where its flexibility and functionality has been demonstrated. In both case studies the evidence-based outcomes facilitated informed environmental management decision making, with trade-off considerations in the context of social and ecological aspirations. This paper presents the PROBFLO approach as applied to the Senqu River catchment in Lesotho and further developments and application in the Mara River catchment in Kenya and Tanzania. The 10 BN-RRM procedural steps incorporated in PROBFLO are demonstrated with examples from both case studies. PROBFLO can contribute to the adaptive management of water resources and contribute to the allocation of resources for sustainable use of resources and address protection requirements.
Gordon C. O'Brien; Chris Dickens; Eleanor Hines; Victor Wepener; Retha Stassen; Leo Quayle; Kelly Fouchy; James MacKenzie; P. Mark Graham; Wayne G. Landis. A regional-scale ecological risk framework for environmental flow evaluations. Hydrology and Earth System Sciences 2018, 22, 957 -975.
AMA StyleGordon C. O'Brien, Chris Dickens, Eleanor Hines, Victor Wepener, Retha Stassen, Leo Quayle, Kelly Fouchy, James MacKenzie, P. Mark Graham, Wayne G. Landis. A regional-scale ecological risk framework for environmental flow evaluations. Hydrology and Earth System Sciences. 2018; 22 (2):957-975.
Chicago/Turabian StyleGordon C. O'Brien; Chris Dickens; Eleanor Hines; Victor Wepener; Retha Stassen; Leo Quayle; Kelly Fouchy; James MacKenzie; P. Mark Graham; Wayne G. Landis. 2018. "A regional-scale ecological risk framework for environmental flow evaluations." Hydrology and Earth System Sciences 22, no. 2: 957-975.
Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering‐focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South‐East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post‐passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed.
Ana T. Silva; Martyn C. Lucas; Theodore Castro-Santos; Christos Katopodis; Lee Baumgartner; Jason Thiem; Kim Aarestrup; Paulo Santos Pompeu; Gordon O'Brien; Douglas C. Braun; Nicholas J. Burnett; David Z. Zhu; Hans-Petter Fjeldstad; Torbjørn Forseth; Nallamuthu Rajaratnam; John G. Williams; Steven Cooke. The future of fish passage science, engineering, and practice. Fish and Fisheries 2017, 19, 340 -362.
AMA StyleAna T. Silva, Martyn C. Lucas, Theodore Castro-Santos, Christos Katopodis, Lee Baumgartner, Jason Thiem, Kim Aarestrup, Paulo Santos Pompeu, Gordon O'Brien, Douglas C. Braun, Nicholas J. Burnett, David Z. Zhu, Hans-Petter Fjeldstad, Torbjørn Forseth, Nallamuthu Rajaratnam, John G. Williams, Steven Cooke. The future of fish passage science, engineering, and practice. Fish and Fisheries. 2017; 19 (2):340-362.
Chicago/Turabian StyleAna T. Silva; Martyn C. Lucas; Theodore Castro-Santos; Christos Katopodis; Lee Baumgartner; Jason Thiem; Kim Aarestrup; Paulo Santos Pompeu; Gordon O'Brien; Douglas C. Braun; Nicholas J. Burnett; David Z. Zhu; Hans-Petter Fjeldstad; Torbjørn Forseth; Nallamuthu Rajaratnam; John G. Williams; Steven Cooke. 2017. "The future of fish passage science, engineering, and practice." Fish and Fisheries 19, no. 2: 340-362.