2021 |
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Osuka, Kennedy E; McClean, Colin; Stewart, Bryce D; Bett, Brian J; Bas, Tim Le; Howe, John; Abernerthy, Colin; Yahya, Saleh; Obura, David; Samoilys, Melita Characteristics of shallow and mesophotic environments of the Pemba Channel, Tanzania: Implications for management and conservation Journal Article Ocean & Coastal Management, 200 , pp. 105463, 2021, ISSN: 0964-5691. Abstract | Links | BibTeX | Tags: Acoustic backscatter, Autonomous underwater vehicle, Bathymetry, Mesophotic coral ecosystems, Western Indian Ocean @article{OSUKA2021105463, title = {Characteristics of shallow and mesophotic environments of the Pemba Channel, Tanzania: Implications for management and conservation}, author = {Kennedy E Osuka and Colin McClean and Bryce D Stewart and Brian J Bett and Tim Le Bas and John Howe and Colin Abernerthy and Saleh Yahya and David Obura and Melita Samoilys}, url = {http://www.sciencedirect.com/science/article/pii/S0964569120303707}, doi = {https://doi.org/10.1016/j.ocecoaman.2020.105463}, issn = {0964-5691}, year = {2021}, date = {2021-01-01}, journal = {Ocean & Coastal Management}, volume = {200}, pages = {105463}, abstract = {Information on the spatial distribution of habitats and vulnerable species is important for conservation planning. In particular, detailed knowledge on connectivity of marine ecosystems in relation to depth and seafloor characteristics is crucial for any proposed conservation and management actions. Yet, the bulk of the seafloor remains under-sampled, unstudied and unmapped, thereby limiting our understanding of connections between shallow and deep-water communities. Recent studies on mesophotic coral ecosystems (MCEs) have highlighted the Western Indian Ocean as a particularly understudied marine region. Here we utilise an autonomous underwater vehicle (AUV) to collect in-situ temperature, oxygen concentration, bathymetry, acoustic backscatter and photographic data on benthic communities from shallow (<30 m) and mesophotic (30–150 m) depths at selected sites in the Greater Pemba Channel, Tanzania. Further, we use generalised additive models (GAMs) to determine useful predictors of substratum (hard and sand) and benthic community type (coral, turf algae, fleshy algae, fish). Our results revealed the presence of a complex seafloor characterised by pockmarks, steep slopes, submarine walls, and large boulders. Photographs confirmed the presence of MCE composed of corals, algae and fishes on the eastern margins of the Pemba Channel. The GAMs on the presence and absence of benthic community explained 35%–91% of the deviance in fish and fleshy algae assemblages, respectively. Key predictors of the distribution of hard substrata and the coral reef communities were depth, showing the upper boundary of MCEs present at 30–40 m, and seafloor slope that showed more occurrences on steep slopes. The upper 100 m of water column had stable temperatures (25–26 °C) and oxygen concentrations (220–235 μmol/l). We noted the presence of submarine walls, steeply inclined bedrock, which appeared to support a highly bio-diverse community that may be worthy of particular conservation measures. Our results also highlight the capability of using marine robotics, particularly autonomous vehicles, to fill the knowledge gap for areas not readily accessible by divers or with surface vessels, and their potential application for the initial survey and subsequent monitoring of Marine Protected Areas.}, keywords = {Acoustic backscatter, Autonomous underwater vehicle, Bathymetry, Mesophotic coral ecosystems, Western Indian Ocean}, pubstate = {published}, tppubtype = {article} } Information on the spatial distribution of habitats and vulnerable species is important for conservation planning. In particular, detailed knowledge on connectivity of marine ecosystems in relation to depth and seafloor characteristics is crucial for any proposed conservation and management actions. Yet, the bulk of the seafloor remains under-sampled, unstudied and unmapped, thereby limiting our understanding of connections between shallow and deep-water communities. Recent studies on mesophotic coral ecosystems (MCEs) have highlighted the Western Indian Ocean as a particularly understudied marine region. Here we utilise an autonomous underwater vehicle (AUV) to collect in-situ temperature, oxygen concentration, bathymetry, acoustic backscatter and photographic data on benthic communities from shallow (<30 m) and mesophotic (30–150 m) depths at selected sites in the Greater Pemba Channel, Tanzania. Further, we use generalised additive models (GAMs) to determine useful predictors of substratum (hard and sand) and benthic community type (coral, turf algae, fleshy algae, fish). Our results revealed the presence of a complex seafloor characterised by pockmarks, steep slopes, submarine walls, and large boulders. Photographs confirmed the presence of MCE composed of corals, algae and fishes on the eastern margins of the Pemba Channel. The GAMs on the presence and absence of benthic community explained 35%–91% of the deviance in fish and fleshy algae assemblages, respectively. Key predictors of the distribution of hard substrata and the coral reef communities were depth, showing the upper boundary of MCEs present at 30–40 m, and seafloor slope that showed more occurrences on steep slopes. The upper 100 m of water column had stable temperatures (25–26 °C) and oxygen concentrations (220–235 μmol/l). We noted the presence of submarine walls, steeply inclined bedrock, which appeared to support a highly bio-diverse community that may be worthy of particular conservation measures. Our results also highlight the capability of using marine robotics, particularly autonomous vehicles, to fill the knowledge gap for areas not readily accessible by divers or with surface vessels, and their potential application for the initial survey and subsequent monitoring of Marine Protected Areas. | |
2020 |
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Alati, Victor Mwakha; Olunga, Jibril; Olendo, Mike; Daudi, Lillian Nduku; Osuka, Kennedy; Odoli, Cyprian; Tuda, Paul; Nordlund, Lina Mtwana Mollusc shell fisheries in coastal Kenya: Local ecological knowledge reveals overfishing Journal Article Ocean & Coastal Management, 195 , pp. 105285, 2020, ISSN: 0964-5691. Abstract | Links | BibTeX | Tags: Gleaning, Local ecological knowledge, Marine shelled molluscs, Seagrass meadows, Shifting baselines @article{Alati2020b, title = {Mollusc shell fisheries in coastal Kenya: Local ecological knowledge reveals overfishing}, author = {Victor Mwakha Alati and Jibril Olunga and Mike Olendo and Lillian Nduku Daudi and Kennedy Osuka and Cyprian Odoli and Paul Tuda and Lina Mtwana Nordlund}, url = {http://www.sciencedirect.com/science/article/pii/S0964569120301952}, doi = {https://doi.org/10.1016/j.ocecoaman.2020.105285}, issn = {0964-5691}, year = {2020}, date = {2020-07-07}, journal = {Ocean & Coastal Management}, volume = {195}, pages = {105285}, abstract = {There is limited documentation on the status and dynamics of fished marine shelled mollusc species in many countries. Some of the challenges are due to obscure documentation of species, extensive unregulated and unrecorded fishing and unawareness of drivers behind declining stocks. The lack of understanding makes it difficult to formulate effective management plans. Here, we assess the fishers’ perceptions on changes in abundance of targeted marine shelled mollusc species and status of associated fished habitats. We interviewed 132 marine shelled mollusc gleaners (fishing by walking) at five sites in coastal Kenya. We established that a multispecies marine shelled mollusc fishery is present in Kenya and that this fishery is conducted by both women and men. We distinguished 158 different shelled mollusc species being targeted. The gleaners perceived a temporal decline of gleaned species. The main causes for the decline were perceived to be overfishing of shells, elevated sea-surface temperature and habitat destruction. The more experienced gleaners perceived a greater decline indicating a baseline shift in perceptions. Our findings suggest that local ecological knowledge is useful to understand historic changes in fisheries lacking long-term scientific data. Furthermore, it highlights the potential benefits of a collaboration between ecologists and gleaners to improve our understanding of the status and dynamics of fishing of marine shelled molluscs as well as other types of fishing.}, keywords = {Gleaning, Local ecological knowledge, Marine shelled molluscs, Seagrass meadows, Shifting baselines}, pubstate = {published}, tppubtype = {article} } There is limited documentation on the status and dynamics of fished marine shelled mollusc species in many countries. Some of the challenges are due to obscure documentation of species, extensive unregulated and unrecorded fishing and unawareness of drivers behind declining stocks. The lack of understanding makes it difficult to formulate effective management plans. Here, we assess the fishers’ perceptions on changes in abundance of targeted marine shelled mollusc species and status of associated fished habitats. We interviewed 132 marine shelled mollusc gleaners (fishing by walking) at five sites in coastal Kenya. We established that a multispecies marine shelled mollusc fishery is present in Kenya and that this fishery is conducted by both women and men. We distinguished 158 different shelled mollusc species being targeted. The gleaners perceived a temporal decline of gleaned species. The main causes for the decline were perceived to be overfishing of shells, elevated sea-surface temperature and habitat destruction. The more experienced gleaners perceived a greater decline indicating a baseline shift in perceptions. Our findings suggest that local ecological knowledge is useful to understand historic changes in fisheries lacking long-term scientific data. Furthermore, it highlights the potential benefits of a collaboration between ecologists and gleaners to improve our understanding of the status and dynamics of fishing of marine shelled molluscs as well as other types of fishing. | |
Yvonne J. Sadovy de Mitcheson; Christi Linardich; Joao Pedro Barreiros; Gina M. Ralph; Alfonso Aguilar-Perera; Pedro Afonso; Brad E. Erisman; David A. Pollard; Sean T. Fennessy; Athila A. Bertoncini; Rekha J. Nair; Kevin L. Rhodes; Patrice Francour; Thierry Brul; Melita A. Samoilys; Beatrice P. Ferreira; Matthew T. Craig, Valuable but vulnerable: Over-fishing and under-management continue to threaten groupers so what now? Journal Article Marine Policy, 116 , pp. 103909, 2020, ISSN: 0308-597X. Abstract | Links | BibTeX | Tags: Epinephelidae, Extinction risk, IUCN, Overfishing, Sustainability @article{deMitcheson2020, title = {Valuable but vulnerable: Over-fishing and under-management continue to threaten groupers so what now?}, author = {Yvonne J. Sadovy de Mitcheson; Christi Linardich; Joao Pedro Barreiros; Gina M. Ralph; Alfonso Aguilar-Perera; Pedro Afonso; Brad E. Erisman; David A. Pollard; Sean T. Fennessy; Athila A. Bertoncini; Rekha J. Nair; Kevin L. Rhodes; Patrice Francour; Thierry Brul; Melita A. Samoilys; Beatrice P. Ferreira; Matthew T. Craig,}, url = {http://www.sciencedirect.com/science/article/pii/S0308597X19306116}, doi = {https://doi.org/10.1016/j.marpol.2020.103909}, issn = {0308-597X}, year = {2020}, date = {2020-03-14}, journal = {Marine Policy}, volume = {116}, pages = {103909}, abstract = {Among threats to marine species, overfishing has often been highlighted as a major contributor to population declines and yet fishing effort has increased globally over the past decade. This paper discusses the decadal reassessment of groupers (family Epinephelidae), an important and valuable group of marine fishes subjected to high market demand and intense fishing effort, based on IUCN criteria. Allowing for uncertainty in the status of species listed as Data Deficient, 19 species (11.4%) are currently assigned to a “threatened” category. This first reassessment for a large marine fish taxon permits an evaluation of changes following the original assessments, provides a profile of the current conservation condition of species, identifies the challenges of assessing conservation status, and highlights current and emerging threats. Measures needed to reduce threats and lessons learned from conservation efforts are highlighted. Present threats include intensifying fishing effort in the face of absent or insufficient fishery management or monitoring, growing pressures from international trade, and an inadequate coverage in effectively managed, sized, or located protected areas. Emerging threats involve expansion of fishing effort into deeper waters and more remote locations, shifts to previously non-targeted species, increases in the capture, marketing and use of juveniles, growing demands for domestic and international trade, and, potentially, climate change. Those species most threatened are larger-bodied, longer-lived groupers, most of which reproduce in spawning aggregations. }, keywords = {Epinephelidae, Extinction risk, IUCN, Overfishing, Sustainability}, pubstate = {published}, tppubtype = {article} } Among threats to marine species, overfishing has often been highlighted as a major contributor to population declines and yet fishing effort has increased globally over the past decade. This paper discusses the decadal reassessment of groupers (family Epinephelidae), an important and valuable group of marine fishes subjected to high market demand and intense fishing effort, based on IUCN criteria. Allowing for uncertainty in the status of species listed as Data Deficient, 19 species (11.4%) are currently assigned to a “threatened” category. This first reassessment for a large marine fish taxon permits an evaluation of changes following the original assessments, provides a profile of the current conservation condition of species, identifies the challenges of assessing conservation status, and highlights current and emerging threats. Measures needed to reduce threats and lessons learned from conservation efforts are highlighted. Present threats include intensifying fishing effort in the face of absent or insufficient fishery management or monitoring, growing pressures from international trade, and an inadequate coverage in effectively managed, sized, or located protected areas. Emerging threats involve expansion of fishing effort into deeper waters and more remote locations, shifts to previously non-targeted species, increases in the capture, marketing and use of juveniles, growing demands for domestic and international trade, and, potentially, climate change. Those species most threatened are larger-bodied, longer-lived groupers, most of which reproduce in spawning aggregations. | |
Gudka, Mishal; Obura, David; Mbugua, James; Ahamada, Said; Kloiber, Ulli; Holter, Tammy Participatory reporting of the 2016 bleaching event in the Western Indian Ocean Journal Article Coral Reefs, 39 (1), pp. 1-11, 2020, ISSN: 1432-0975. Abstract | Links | BibTeX | Tags: Climate change, Coral bleaching, Coral reefs, El Niño, Western Indian Ocean @article{Gudka2020, title = {Participatory reporting of the 2016 bleaching event in the Western Indian Ocean}, author = {Mishal Gudka and David Obura and James Mbugua and Said Ahamada and Ulli Kloiber and Tammy Holter}, url = {https://doi.org/10.1007/s00338-019-01851-3}, doi = {10.1007/s00338-019-01851-3}, issn = {1432-0975}, year = {2020}, date = {2020-02-01}, journal = {Coral Reefs}, volume = {39}, number = {1}, pages = {1-11}, abstract = {Climate change, coupled with an El Niño, caused a devastating bleaching event in the Western Indian Ocean (WIO) in 1998. Similar extreme conditions at the end of 2015 meant that there was a very high risk of widespread bleaching in the WIO at the start of 2016. In anticipation of a regional bleaching event, a citizen-science online reporting tool was developed to collect data in broad categories of bleaching and mortality from various stakeholders across the region, e.g. general public, scientists, reef managers, divers. The main objectives were to (i) document in real-time the impacts of the 2016 coral bleaching event at a regional scale and (ii) demonstrate the value of basic data to illustrate and understand important trends. A total of 698 records from 55 organisations and over 80 observers were collected through the online reporting form and via email. Thermal stress across the WIO during the bleaching season (January--May) was high enough to cause widespread bleaching and significant mortality, with reef sites on average, experiencing a maximum of 5.4 Degree-Heating-Weeks (DHW), with some sites experiencing up to 15 DHW. During the peak-bleaching months, 37% of sites were affected by high or extreme bleaching, while 8.5% of sites showed no evidence of bleaching. Seychelles was the most affected by bleaching with 90% of reported sites showing high or extreme bleaching, followed by Tanzania, Comoros, Reunion and Mauritius. Sites in the Mozambique Channel (south and north) were the least affected by bleaching. Over 60% of sites experienced some level of bleaching-induced coral mortality from April onwards, but the impact was heterogeneous, with reefs in some areas showing substantial recovery from bleaching and others showing almost no recovery. As the first effort in the WIO to gather bleaching data at this scale during a major bleaching event, this study has shown that participatory data collection from various stakeholders, even at a basic level, can reveal important regional-scale, real-time trends and information about coral bleaching.}, keywords = {Climate change, Coral bleaching, Coral reefs, El Niño, Western Indian Ocean}, pubstate = {published}, tppubtype = {article} } Climate change, coupled with an El Niño, caused a devastating bleaching event in the Western Indian Ocean (WIO) in 1998. Similar extreme conditions at the end of 2015 meant that there was a very high risk of widespread bleaching in the WIO at the start of 2016. In anticipation of a regional bleaching event, a citizen-science online reporting tool was developed to collect data in broad categories of bleaching and mortality from various stakeholders across the region, e.g. general public, scientists, reef managers, divers. The main objectives were to (i) document in real-time the impacts of the 2016 coral bleaching event at a regional scale and (ii) demonstrate the value of basic data to illustrate and understand important trends. A total of 698 records from 55 organisations and over 80 observers were collected through the online reporting form and via email. Thermal stress across the WIO during the bleaching season (January--May) was high enough to cause widespread bleaching and significant mortality, with reef sites on average, experiencing a maximum of 5.4 Degree-Heating-Weeks (DHW), with some sites experiencing up to 15 DHW. During the peak-bleaching months, 37% of sites were affected by high or extreme bleaching, while 8.5% of sites showed no evidence of bleaching. Seychelles was the most affected by bleaching with 90% of reported sites showing high or extreme bleaching, followed by Tanzania, Comoros, Reunion and Mauritius. Sites in the Mozambique Channel (south and north) were the least affected by bleaching. Over 60% of sites experienced some level of bleaching-induced coral mortality from April onwards, but the impact was heterogeneous, with reefs in some areas showing substantial recovery from bleaching and others showing almost no recovery. As the first effort in the WIO to gather bleaching data at this scale during a major bleaching event, this study has shown that participatory data collection from various stakeholders, even at a basic level, can reveal important regional-scale, real-time trends and information about coral bleaching. | |
Osuka, Kennedy; Rosendo, Sérgio; Riddell, Michael; Huet, Jeremy; Daide, Mario; Chauque, Ercilio; Samoilys, Melita Applying a Social–Ecological Systems Approach to Understanding Local Marine Management Trajectories in Northern Mozambique Journal Article Sustainability, 12 (9), 2020, ISSN: 2071-1050. Abstract | Links | BibTeX | Tags: @article{su12093904, title = {Applying a Social–Ecological Systems Approach to Understanding Local Marine Management Trajectories in Northern Mozambique}, author = {Kennedy Osuka and Sérgio Rosendo and Michael Riddell and Jeremy Huet and Mario Daide and Ercilio Chauque and Melita Samoilys}, url = {https://www.mdpi.com/2071-1050/12/9/3904}, doi = {10.3390/su12093904}, issn = {2071-1050}, year = {2020}, date = {2020-01-01}, journal = {Sustainability}, volume = {12}, number = {9}, abstract = {This study applied the social–ecological systems framework (SESF) to six fishing communities in northern Mozambique where marine resource management is being implemented through the Our Sea Our Life project. Data on 11 variables and 27 indicators were organised using the SESF to represent the key system dimensions (Governance system, Actors, Resource units and Resource system). Variables within each dimension were weighed to a cumulative score of one. High scores (> 0.50) for Governance system occurred where communities had fisheries management rules and good knowledge of fishing gear regulations. High scores for Actors were evident in communities with few migrant fishers and high participation in village savings and loans associations. Elevated scores of the Resource units occurred where fishers targeted a variety of fish taxa. A healthy Resource system was found in communities neighbouring highly productive and resilient reefs, characterised by high fish biomass and diversity. The status of social and ecological conditions coupled with initial levels of project support and quality of technical support were linked with project achievements. Application of the SESF is therefore valuable in understanding interdependent linkages between social and environmental conditions to inform the design of localised management interventions for social–ecological sustainability.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This study applied the social–ecological systems framework (SESF) to six fishing communities in northern Mozambique where marine resource management is being implemented through the Our Sea Our Life project. Data on 11 variables and 27 indicators were organised using the SESF to represent the key system dimensions (Governance system, Actors, Resource units and Resource system). Variables within each dimension were weighed to a cumulative score of one. High scores (> 0.50) for Governance system occurred where communities had fisheries management rules and good knowledge of fishing gear regulations. High scores for Actors were evident in communities with few migrant fishers and high participation in village savings and loans associations. Elevated scores of the Resource units occurred where fishers targeted a variety of fish taxa. A healthy Resource system was found in communities neighbouring highly productive and resilient reefs, characterised by high fish biomass and diversity. The status of social and ecological conditions coupled with initial levels of project support and quality of technical support were linked with project achievements. Application of the SESF is therefore valuable in understanding interdependent linkages between social and environmental conditions to inform the design of localised management interventions for social–ecological sustainability. | |
Obura, David O Getting to 2030 - Scaling effort to ambition through a narrative model of the SDGs Journal Article Marine Policy, 117 , pp. 103973, 2020, ISSN: 0308-597X. Abstract | Links | BibTeX | Tags: Blue economy, Convention on biological diversity, Ecosystem-based approach, Nature's contributions to people, Sustainability, Sustainable development goals @article{OBURA2020103973, title = {Getting to 2030 - Scaling effort to ambition through a narrative model of the SDGs}, author = {David O Obura}, url = {http://www.sciencedirect.com/science/article/pii/S0308597X19309340}, doi = {https://doi.org/10.1016/j.marpol.2020.103973}, issn = {0308-597X}, year = {2020}, date = {2020-01-01}, journal = {Marine Policy}, volume = {117}, pages = {103973}, abstract = {The Sustainable Development Goals express a narrative about the relationships between people and nature. This paper builds a narrative from an ocean perspective – through the lens of a coral reef seascape, and the blue economy. The ocean, intimately connected with the land, freshwater flows and climate provides a vast array of benefits to humanity. These benefits are valued at trillions of dollars per year globally, supporting hundreds of millions of jobs, and contributing to all countries both coastal and inland, through living and non-living resources, transport infrastructure and natural products, and sustainable energy solutions; the coastal zone is home to half the world's population. Through these direct benefits, the ocean contributes to reduced hunger and poverty, improved health, and all these benefits may be shared across gender, social and national boundaries. However accessing ocean benefits results in pressures that may drive decline in ocean health. Managing this complex system for a sustainable blue economy requires developing and using the right knowledge, new governance mechanisms and investment by stakeholders from global to local levels. This ‘blue economy’ narrative builds on the links between ocean health (SDG14) and economy (SDG8), but the general model can be expressed from the perspective of any goal(s) towards the others. The model also applies across scales from local to global, the relationships defined in the model enabling monitoring and assessment. The model can thus help align global instruments such as the post-2020 Global Biodiversity Framework with Agenda 2030, and linking from national to grassroots levels.}, keywords = {Blue economy, Convention on biological diversity, Ecosystem-based approach, Nature's contributions to people, Sustainability, Sustainable development goals}, pubstate = {published}, tppubtype = {article} } The Sustainable Development Goals express a narrative about the relationships between people and nature. This paper builds a narrative from an ocean perspective – through the lens of a coral reef seascape, and the blue economy. The ocean, intimately connected with the land, freshwater flows and climate provides a vast array of benefits to humanity. These benefits are valued at trillions of dollars per year globally, supporting hundreds of millions of jobs, and contributing to all countries both coastal and inland, through living and non-living resources, transport infrastructure and natural products, and sustainable energy solutions; the coastal zone is home to half the world's population. Through these direct benefits, the ocean contributes to reduced hunger and poverty, improved health, and all these benefits may be shared across gender, social and national boundaries. However accessing ocean benefits results in pressures that may drive decline in ocean health. Managing this complex system for a sustainable blue economy requires developing and using the right knowledge, new governance mechanisms and investment by stakeholders from global to local levels. This ‘blue economy’ narrative builds on the links between ocean health (SDG14) and economy (SDG8), but the general model can be expressed from the perspective of any goal(s) towards the others. The model also applies across scales from local to global, the relationships defined in the model enabling monitoring and assessment. The model can thus help align global instruments such as the post-2020 Global Biodiversity Framework with Agenda 2030, and linking from national to grassroots levels. | |
2019 |
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David O. Obura; Greta Aeby; Natchanon Amornthammarong; Ward Appeltans; Nicholas Bax, Joe Bishop; Russell Brainard; Samuel Chan; Pamela Fletcher; Timothy Gordon; Lew Gramer; Mishal Gudka; John Halas; James Hendee; Gregor Hodgson; Danwei Huang; Mike Jankulak; Albert Jones; Tadashi Kimura; Joshua Levy; Patricia Miloslavich; Loke Ming Chou; Frank Muller-Karger; Kennedy Osuka; Melita Samoilys; Stephen Simpson; Karenne Tun; Supin Wongbusarakum E A C D Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management Journal Article Frontiers in Marine Science, 6 , pp. 580, 2019, ISSN: 2296-7745. Abstract | Links | BibTeX | Tags: Coral reefs @article{Obura2019c, title = {Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management}, author = {David O. Obura; Greta Aeby; Natchanon Amornthammarong; Ward Appeltans; Nicholas Bax, Joe Bishop; Russell E. Brainard; Samuel Chan; Pamela Fletcher; Timothy A. C. Gordon; Lew Gramer; Mishal Gudka; John Halas; James Hendee; Gregor Hodgson; Danwei Huang; Mike Jankulak; Albert Jones; Tadashi Kimura; Joshua Levy; Patricia Miloslavich; Loke Ming Chou; Frank Muller-Karger; Kennedy Osuka; Melita Samoilys; Stephen D. Simpson; Karenne Tun; Supin Wongbusarakum}, url = {https://www.frontiersin.org/article/10.3389/fmars.2019.00580}, doi = {https://doi.org/10.3389/fmars.2019.00580}, issn = {2296-7745}, year = {2019}, date = {2019-09-19}, journal = {Frontiers in Marine Science}, volume = {6}, pages = {580}, abstract = {Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems.}, keywords = {Coral reefs}, pubstate = {published}, tppubtype = {article} } Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems. | |
Chassot, Emmanuel; Bodin, Nathalie; Sardenne, Fany; Obura, David The key role of the Northern Mozambique Channel for Indian Ocean tropical tuna fisheries Journal Article Reviews in Fish Biology and Fisheries, 29 (3), pp. 613-638, 2019, ISSN: 1573-5184. Abstract | Links | BibTeX | Tags: @article{Chassot2019, title = {The key role of the Northern Mozambique Channel for Indian Ocean tropical tuna fisheries}, author = {Emmanuel Chassot and Nathalie Bodin and Fany Sardenne and David Obura}, url = {https://doi.org/10.1007/s11160-019-09569-9}, doi = {10.1007/s11160-019-09569-9}, issn = {1573-5184}, year = {2019}, date = {2019-09-01}, journal = {Reviews in Fish Biology and Fisheries}, volume = {29}, number = {3}, pages = {613-638}, abstract = {The Northern Mozambique Channel (NMC) is a tropical area of textasciitildethinspace1 million km2 where pelagic fisheries supply proteins to more than 9 million people living in Comoros, Mayotte, and along the coasts of Mozambique, Tanzania and Madagascar. Although uncertain, statistics suggest that about 20,000 mt of tropical tuna and other pelagic fish are annually caught by artisanal fisheries in the area. The NMC is also a major seasonal fishing ground for high-seas fleets that export an annual average catch of more than 20,000 mt to tuna can and sashimi markets of high-income countries for a value estimated to be more than 100 million USD. The fisheries productivity of the NMC appears to be highly variable in relation to strong annual and seasonal variability in oceanographic conditions. Our review shows that the NMC is a key feeding area for tropical tunas and a major spawning area for skipjack tuna thanks to warm waters and strong mesoscale activity that results in the enrichment of surface waters and efficient energy transfers enabled by short food chains. Projections of climate models under future warming scenarios predict some strong changes in the oceanographic conditions of the NMC which has already experienced substantial warming over the last decades. Changes in the pelagic ecosystem of the NMC could have dramatic consequences on the coastal populations that are expected to increase towards 100 million people by 2100. Improving monitoring systems and collecting information on the socio-economics of coastal fisheries is crucial to assess the dependence of NMC populations on tuna resources and empower the countries to more involvement in the management of tuna stocks.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The Northern Mozambique Channel (NMC) is a tropical area of textasciitildethinspace1 million km2 where pelagic fisheries supply proteins to more than 9 million people living in Comoros, Mayotte, and along the coasts of Mozambique, Tanzania and Madagascar. Although uncertain, statistics suggest that about 20,000 mt of tropical tuna and other pelagic fish are annually caught by artisanal fisheries in the area. The NMC is also a major seasonal fishing ground for high-seas fleets that export an annual average catch of more than 20,000 mt to tuna can and sashimi markets of high-income countries for a value estimated to be more than 100 million USD. The fisheries productivity of the NMC appears to be highly variable in relation to strong annual and seasonal variability in oceanographic conditions. Our review shows that the NMC is a key feeding area for tropical tunas and a major spawning area for skipjack tuna thanks to warm waters and strong mesoscale activity that results in the enrichment of surface waters and efficient energy transfers enabled by short food chains. Projections of climate models under future warming scenarios predict some strong changes in the oceanographic conditions of the NMC which has already experienced substantial warming over the last decades. Changes in the pelagic ecosystem of the NMC could have dramatic consequences on the coastal populations that are expected to increase towards 100 million people by 2100. Improving monitoring systems and collecting information on the socio-economics of coastal fisheries is crucial to assess the dependence of NMC populations on tuna resources and empower the countries to more involvement in the management of tuna stocks. | |
Musembi, Peter; Fulanda, Bernerd; Kairo, James; Githaiga, Michael Species composition, abundance and fishing methods of small-scale fisheries in the seagrass meadows of Gazi Bay, Kenya Journal Article Journal of the Indian Ocean Region, 15 (2), pp. 139-156, 2019, ISSN: 1948-0881. @article{Musembi2019, title = {Species composition, abundance and fishing methods of small-scale fisheries in the seagrass meadows of Gazi Bay, Kenya}, author = {Peter Musembi and Bernerd Fulanda and James Kairo and Michael Githaiga}, url = {https://doi.org/10.1080/19480881.2019.1603608}, doi = {10.1080/19480881.2019.1603608}, issn = {1948-0881}, year = {2019}, date = {2019-05-04}, journal = {Journal of the Indian Ocean Region}, volume = {15}, number = {2}, pages = {139-156}, publisher = {Routledge}, keywords = {}, pubstate = {published}, tppubtype = {article} } | |
Samoilys, Melita Anne; Osuka, Kennedy; Mussa, Jamen; Rosendo, Sergio; Riddell, Michael; Diade, Mario; Mbugua, James; Kawaka, Joan; Hill, Nicholas; Koldewey, Heather An integrated assessment of coastal fisheries in Mozambique for conservation planning Journal Article Ocean & Coastal Management, 182 , pp. 104924, 2019, ISSN: 0964-5691. Abstract | Links | BibTeX | Tags: Conservation, Coral reefs, Gender, Management, Small scale fisheries @article{SAMOILYS2019104924, title = {An integrated assessment of coastal fisheries in Mozambique for conservation planning}, author = {Melita Anne Samoilys and Kennedy Osuka and Jamen Mussa and Sergio Rosendo and Michael Riddell and Mario Diade and James Mbugua and Joan Kawaka and Nicholas Hill and Heather Koldewey}, url = {http://www.sciencedirect.com/science/article/pii/S0964569119302091}, doi = {https://doi.org/10.1016/j.ocecoaman.2019.104924}, issn = {0964-5691}, year = {2019}, date = {2019-01-01}, journal = {Ocean & Coastal Management}, volume = {182}, pages = {104924}, abstract = {Conservation planning of coastal ecosystems is improved by quantitative data on human activities and marine habitats, though is challenging in artisanal fisheries due to their characteristics of multiple species, gears and landing sites. Small-scale coastal fisheries in northern Mozambique were quantified using a multi-faceted approach, to inform area-based conservation and fisheries management. Fishers captured 153 taxa using eleven different fishing gears with a high proportion of gleaning. The most prevalent gear was the mosquito net (27%), largely used by women, followed by gleaning, handline and spear (12–15%), but with high inter-fishing ground variability. Median (interquatile range) catch rates ranged from 7.0 (3.4, 15.1) kg fisher−1 trip−1 (handlines) to 2.3 (1.6, 4.5) kg fisher−1 trip−1 (mosquito nets), which represent relatively high catch rates for eastern Africa. Knowledge of the complex spatial variability in these fisheries can contribute to conservation planning by minimizing opportunity costs while maximizing conservation benefits.}, keywords = {Conservation, Coral reefs, Gender, Management, Small scale fisheries}, pubstate = {published}, tppubtype = {article} } Conservation planning of coastal ecosystems is improved by quantitative data on human activities and marine habitats, though is challenging in artisanal fisheries due to their characteristics of multiple species, gears and landing sites. Small-scale coastal fisheries in northern Mozambique were quantified using a multi-faceted approach, to inform area-based conservation and fisheries management. Fishers captured 153 taxa using eleven different fishing gears with a high proportion of gleaning. The most prevalent gear was the mosquito net (27%), largely used by women, followed by gleaning, handline and spear (12–15%), but with high inter-fishing ground variability. Median (interquatile range) catch rates ranged from 7.0 (3.4, 15.1) kg fisher−1 trip−1 (handlines) to 2.3 (1.6, 4.5) kg fisher−1 trip−1 (mosquito nets), which represent relatively high catch rates for eastern Africa. Knowledge of the complex spatial variability in these fisheries can contribute to conservation planning by minimizing opportunity costs while maximizing conservation benefits. | |
Barkley, A N; Gollock, M; Samoilys, M; Llewellyn, F; Shivji, M; Wetherbee, B; Hussey, N E Complex transboundary movements of marine megafauna in the Western Indian Ocean Journal Article Animal Conservation, 22 (5), pp. 420-431, 2019. Abstract | Links | BibTeX | Tags: exclusive economic zones, migration, satellite tags, spatial management, tiger sharks, tracking, transboundary, Western Indian Ocean @article{doi:10.1111/acv.12493, title = {Complex transboundary movements of marine megafauna in the Western Indian Ocean}, author = {A N Barkley and M Gollock and M Samoilys and F Llewellyn and M Shivji and B Wetherbee and N E Hussey}, url = {https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/acv.12493}, doi = {10.1111/acv.12493}, year = {2019}, date = {2019-01-01}, journal = {Animal Conservation}, volume = {22}, number = {5}, pages = {420-431}, abstract = {Abstract Transboundary marine species have an increased risk of overexploitation as management regimes and enforcement can vary among states. The complex geopolitical layout of exclusive economic zones (EEZs) in the Western Indian Ocean (WIO) introduces the potential for migratory species to cross multiple boundaries, consequently a lack of scientific data could complicate regional management. In the current study, we highlight both the relative lack of spatial data available in the WIO, and the prevalence of transboundary movements in species that have previously been studied in the region. Five tiger sharks Galeocerdo cuvier were tracked with near real-time positioning (SPOT) satellite tags to determine individual shark movements relative to EEZs within the WIO. Concurrently, a literature search was performed to identify all satellite telemetry studies conducted to date in the WIO for marine megafaunal species, and the results compared to global satellite telemetry effort. Finally, the satellite tracks of all marine species monitored in the WIO were extracted and digitized to examine the scale of transboundary movements that occur in the region. Tiger sharks exhibited both coastal and oceanic movements, with one individual crossing a total of eight EEZs. Satellite telemetry effort in the WIO has not matched the global increase, with only 4.7% of global studies occurring in the region. Species in the WIO remained within the EEZ in which they were tagged in only three studies, while all other species demonstrated some level of transboundary movement. This study demonstrates the lack of spatial data available for informed regional management in an area where transboundary movements by marine megafauna are highly prevalent. Without more dedicated funding and research, the rich biodiversity of the WIO is at risk of overexploitation from the diverse threats present within the various political regions.}, keywords = {exclusive economic zones, migration, satellite tags, spatial management, tiger sharks, tracking, transboundary, Western Indian Ocean}, pubstate = {published}, tppubtype = {article} } Abstract Transboundary marine species have an increased risk of overexploitation as management regimes and enforcement can vary among states. The complex geopolitical layout of exclusive economic zones (EEZs) in the Western Indian Ocean (WIO) introduces the potential for migratory species to cross multiple boundaries, consequently a lack of scientific data could complicate regional management. In the current study, we highlight both the relative lack of spatial data available in the WIO, and the prevalence of transboundary movements in species that have previously been studied in the region. Five tiger sharks Galeocerdo cuvier were tracked with near real-time positioning (SPOT) satellite tags to determine individual shark movements relative to EEZs within the WIO. Concurrently, a literature search was performed to identify all satellite telemetry studies conducted to date in the WIO for marine megafaunal species, and the results compared to global satellite telemetry effort. Finally, the satellite tracks of all marine species monitored in the WIO were extracted and digitized to examine the scale of transboundary movements that occur in the region. Tiger sharks exhibited both coastal and oceanic movements, with one individual crossing a total of eight EEZs. Satellite telemetry effort in the WIO has not matched the global increase, with only 4.7% of global studies occurring in the region. Species in the WIO remained within the EEZ in which they were tagged in only three studies, while all other species demonstrated some level of transboundary movement. This study demonstrates the lack of spatial data available for informed regional management in an area where transboundary movements by marine megafauna are highly prevalent. Without more dedicated funding and research, the rich biodiversity of the WIO is at risk of overexploitation from the diverse threats present within the various political regions. | |
Samoilys, Melita A; Halford, Andrew; Osuka, Kennedy Disentangling drivers of the abundance of coral reef fishes in the Western Indian Ocean Journal Article Ecology and Evolution, 9 (7), pp. 4149-4167, 2019. Abstract | Links | BibTeX | Tags: biogeography, biomass, climate, coral reef, fish, geomorphology @article{doi:10.1002/ece3.5044, title = {Disentangling drivers of the abundance of coral reef fishes in the Western Indian Ocean}, author = {Melita A Samoilys and Andrew Halford and Kennedy Osuka}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ece3.5044}, doi = {10.1002/ece3.5044}, year = {2019}, date = {2019-01-01}, journal = {Ecology and Evolution}, volume = {9}, number = {7}, pages = {4149-4167}, abstract = {Abstract Aim Understanding the drivers of the structure of coral reef fish assemblages is vital for their future conservation. Quantifying the separate roles of natural drivers from the increasing influence of anthropogenic factors, such as fishing and climate change, is a key component of this understanding. It follows that the intrinsic role of historical biogeographical and geomorphological factors must be accounted for when trying to understand the effects of contemporary disturbances such as fishing. Location Comoros, Madagascar, Mozambique and Tanzania, Western Indian Ocean (WIO). Methods We modeled patterns in the density and biomass of an assemblage of reef-associated fish species from 11 families, and their association with 16 biophysical variables. Results Canonical analysis of principal coordinates revealed strong country affiliations of reef fish assemblages and distance-based linear modeling confirmed geographic location and reef geomorphology were the most significant correlates, explaining 32% of the observed variation in fish assemblage structure. Another 6%–8% of variation was explained by productivity gradients (chl_a), and reef exposure or slope. Where spatial effects were not significant between mainland continental locations, fishing effects became evident explaining 6% of the variation in data. No correlation with live coral was detected. Only 37 species, predominantly lower trophic level taxa, were significant in explaining differences in assemblages between sites. Main Conclusions Spatial and geomorphological histories remain a major influence on the structure of reef fish assemblages in the WIO. Reef geomorphology was closely linked to standing biomass, with “ocean-exposed” fringing reefs supporting high average biomass of ~1,000 kg/ha, while “lagoon-exposed fringing” reefs and “inner seas patch complex” reefs yielded substantially less at ~500kg/ha. Further, the results indicate the influence of benthic communities on fish assemblages is scale dependent. Such insights will be pivotal for managers seeking to balance long-term sustainability of artisanal reef fisheries with conservation of coral reef systems.}, keywords = {biogeography, biomass, climate, coral reef, fish, geomorphology}, pubstate = {published}, tppubtype = {article} } Abstract Aim Understanding the drivers of the structure of coral reef fish assemblages is vital for their future conservation. Quantifying the separate roles of natural drivers from the increasing influence of anthropogenic factors, such as fishing and climate change, is a key component of this understanding. It follows that the intrinsic role of historical biogeographical and geomorphological factors must be accounted for when trying to understand the effects of contemporary disturbances such as fishing. Location Comoros, Madagascar, Mozambique and Tanzania, Western Indian Ocean (WIO). Methods We modeled patterns in the density and biomass of an assemblage of reef-associated fish species from 11 families, and their association with 16 biophysical variables. Results Canonical analysis of principal coordinates revealed strong country affiliations of reef fish assemblages and distance-based linear modeling confirmed geographic location and reef geomorphology were the most significant correlates, explaining 32% of the observed variation in fish assemblage structure. Another 6%–8% of variation was explained by productivity gradients (chl_a), and reef exposure or slope. Where spatial effects were not significant between mainland continental locations, fishing effects became evident explaining 6% of the variation in data. No correlation with live coral was detected. Only 37 species, predominantly lower trophic level taxa, were significant in explaining differences in assemblages between sites. Main Conclusions Spatial and geomorphological histories remain a major influence on the structure of reef fish assemblages in the WIO. Reef geomorphology was closely linked to standing biomass, with “ocean-exposed” fringing reefs supporting high average biomass of ~1,000 kg/ha, while “lagoon-exposed fringing” reefs and “inner seas patch complex” reefs yielded substantially less at ~500kg/ha. Further, the results indicate the influence of benthic communities on fish assemblages is scale dependent. Such insights will be pivotal for managers seeking to balance long-term sustainability of artisanal reef fisheries with conservation of coral reef systems. | |
Popova, Ekaterina; Vousden, David; Sauer, Warwick H H; Mohammed, Essam Y; Allain, Valerie; Downey-Breedt, Nicola; Fletcher, Ruth; Gjerde, Kristina M; Halpin, Patrick N; Kelly, Stephen; Obura, David; Pecl, Gretta; Roberts, Michael; Raitsos, Dionysios E; Rogers, Alex; Samoilys, Melita; Sumaila, Ussif Rashid; Tracey, Sean; Yool, Andrew Marine Policy, 104 , pp. 90 - 102, 2019, ISSN: 0308-597X. Abstract | Links | BibTeX | Tags: Areas beyond national jurisdiction, Coastal zone, Ecological connectivity, Marine ecosystems, Ocean governance @article{POPOVA201990, title = {Ecological connectivity between the areas beyond national jurisdiction and coastal waters: Safeguarding interests of coastal communities in developing countries}, author = {Ekaterina Popova and David Vousden and Warwick H H Sauer and Essam Y Mohammed and Valerie Allain and Nicola Downey-Breedt and Ruth Fletcher and Kristina M Gjerde and Patrick N Halpin and Stephen Kelly and David Obura and Gretta Pecl and Michael Roberts and Dionysios E Raitsos and Alex Rogers and Melita Samoilys and Ussif Rashid Sumaila and Sean Tracey and Andrew Yool}, url = {http://www.sciencedirect.com/science/article/pii/S0308597X19300764}, doi = {https://doi.org/10.1016/j.marpol.2019.02.050}, issn = {0308-597X}, year = {2019}, date = {2019-01-01}, journal = {Marine Policy}, volume = {104}, pages = {90 - 102}, abstract = {The UN General Assembly has made a unanimous decision to start negotiations to establish an international, legally-binding instrument for the conservation and sustainable use of marine biological diversity within Areas Beyond National Jurisdiction (ABNJ). However, there has of yet been little discussion on the importance of this move to the ecosystem services provided by coastal zones in their downstream zone of influence. Here, we identify the ecological connectivity between ABNJ and coastal zones as critically important in the negotiation process and apply several approaches to identify some priority areas for protection from the perspective of coastal populations of Least Developed Countries (LDCs). Initially, we review the scientific evidence that demonstrates ecological connectivity between ABNJ and the coastal zones with a focus on the LDCs. We then use ocean modelling to develop a number of metrics and spatial maps that serve to quantify the connectivity of the ABNJ to the coastal zone. We find that the level of exposure to the ABNJ influences varies strongly between countries. Similarly, not all areas of the ABNJ are equal in their impacts on the coastline. Using this method, we identify the areas of the ABNJ that are in the most urgent need of protection on the grounds of the strength of their potential downstream impacts on the coastal populations of LDCs. We argue that indirect negative impacts of the ABNJ fishing, industrialisation and pollution, communicated via oceanographic, cultural and ecological connectivity to the coastal waters of the developing countries should be of concern.}, keywords = {Areas beyond national jurisdiction, Coastal zone, Ecological connectivity, Marine ecosystems, Ocean governance}, pubstate = {published}, tppubtype = {article} } The UN General Assembly has made a unanimous decision to start negotiations to establish an international, legally-binding instrument for the conservation and sustainable use of marine biological diversity within Areas Beyond National Jurisdiction (ABNJ). However, there has of yet been little discussion on the importance of this move to the ecosystem services provided by coastal zones in their downstream zone of influence. Here, we identify the ecological connectivity between ABNJ and coastal zones as critically important in the negotiation process and apply several approaches to identify some priority areas for protection from the perspective of coastal populations of Least Developed Countries (LDCs). Initially, we review the scientific evidence that demonstrates ecological connectivity between ABNJ and the coastal zones with a focus on the LDCs. We then use ocean modelling to develop a number of metrics and spatial maps that serve to quantify the connectivity of the ABNJ to the coastal zone. We find that the level of exposure to the ABNJ influences varies strongly between countries. Similarly, not all areas of the ABNJ are equal in their impacts on the coastline. Using this method, we identify the areas of the ABNJ that are in the most urgent need of protection on the grounds of the strength of their potential downstream impacts on the coastal populations of LDCs. We argue that indirect negative impacts of the ABNJ fishing, industrialisation and pollution, communicated via oceanographic, cultural and ecological connectivity to the coastal waters of the developing countries should be of concern. | |
Gamoyo, Majambo; Obura, David; Reason, Chris J C Estimating Connectivity Through Larval Dispersal in the Western Indian Ocean Journal Article Journal of Geophysical Research: Biogeosciences, 124 (8), pp. 2446-2459, 2019. Abstract | Links | BibTeX | Tags: biophysical model, connectivity, coral reef larvae, dispersal, graph theory analysis @article{doi:10.1029/2019JG005128, title = {Estimating Connectivity Through Larval Dispersal in the Western Indian Ocean}, author = {Majambo Gamoyo and David Obura and Chris J C Reason}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005128}, doi = {10.1029/2019JG005128}, year = {2019}, date = {2019-01-01}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {124}, number = {8}, pages = {2446-2459}, abstract = {Abstract The health and functioning of coral reef ecosystems in the Western Indian Ocean are in decline due to anthropogenic stress, and the rate of decline is set to accelerate. Marine reserves have become important tools in mitigating these pressures, and one of the most critical factors in determining their spatial design is the degree of connectivity among populations. However, the spatial scale and strength at which populations are potentially connected by dispersal remain uncertain. In this paper, the potential connectivity of corals was assessed through a Lagrangian particle-tracking algorithm coupled offline with an ocean circulation numerical model. Connectivity metrics and graph theory were used to analyze the networks and highlight those reefs that are critical for maintaining the connectivity of corals across the region. Western Indian Ocean coral reefs formed about 13 clusters for larvae with short pelagic larval duration (PLD; 5 days) but grouped into stable larger clusters at 15, 30, and 60 days PLDs, with strong westward dispersal from the northern tip of Madagascar and Comoro Islands toward the East African coast. Reefs at Mafia-Latham Island (Tanzania), Angoche-Nacala and Pemba-Mucufi (Mozambique), Anjouan and Ngazidja (Comoros), and Glorieuses (France) were the most significant for multigenerational connectivity, as measured by betweenness centrality. The small islands Agalega and Tromelin were completely disconnected from other sites at all PLDs. These findings identify priority conservation areas and actions to help support coral reef resilience through a connected network of marine protected areas.}, keywords = {biophysical model, connectivity, coral reef larvae, dispersal, graph theory analysis}, pubstate = {published}, tppubtype = {article} } Abstract The health and functioning of coral reef ecosystems in the Western Indian Ocean are in decline due to anthropogenic stress, and the rate of decline is set to accelerate. Marine reserves have become important tools in mitigating these pressures, and one of the most critical factors in determining their spatial design is the degree of connectivity among populations. However, the spatial scale and strength at which populations are potentially connected by dispersal remain uncertain. In this paper, the potential connectivity of corals was assessed through a Lagrangian particle-tracking algorithm coupled offline with an ocean circulation numerical model. Connectivity metrics and graph theory were used to analyze the networks and highlight those reefs that are critical for maintaining the connectivity of corals across the region. Western Indian Ocean coral reefs formed about 13 clusters for larvae with short pelagic larval duration (PLD; 5 days) but grouped into stable larger clusters at 15, 30, and 60 days PLDs, with strong westward dispersal from the northern tip of Madagascar and Comoro Islands toward the East African coast. Reefs at Mafia-Latham Island (Tanzania), Angoche-Nacala and Pemba-Mucufi (Mozambique), Anjouan and Ngazidja (Comoros), and Glorieuses (France) were the most significant for multigenerational connectivity, as measured by betweenness centrality. The small islands Agalega and Tromelin were completely disconnected from other sites at all PLDs. These findings identify priority conservation areas and actions to help support coral reef resilience through a connected network of marine protected areas. | |
Cowburn, B; Samoilys, M A; Osuka, K; Klaus, R; Newman, C; Gudka, M; Obura, D Healthy and diverse coral reefs in Djibouti – A resilient reef system or few anthropogenic threats? Journal Article Marine Pollution Bulletin, 148 , pp. 182 - 193, 2019, ISSN: 0025-326X. Abstract | Links | BibTeX | Tags: Coral bleaching, coral reef, Ecosystem health, fisheries, Red Sea, Resilience @article{COWBURN2019182, title = {Healthy and diverse coral reefs in Djibouti – A resilient reef system or few anthropogenic threats?}, author = {B Cowburn and M A Samoilys and K Osuka and R Klaus and C Newman and M Gudka and D Obura}, url = {http://www.sciencedirect.com/science/article/pii/S0025326X19305788}, doi = {https://doi.org/10.1016/j.marpolbul.2019.07.040}, issn = {0025-326X}, year = {2019}, date = {2019-01-01}, journal = {Marine Pollution Bulletin}, volume = {148}, pages = {182 - 193}, abstract = {Djiboutian coral reefs are poorly studied, but are of critical importance to tourism and artisanal fishing in this small developing nation. In 2014 and 2016 we carried out the most comprehensive survey of Djiboutian reefs to date, and present data on their ecology, health and estimate their vulnerability to future coral bleaching and anthropogenic impacts. Reef type varied from complex reef formations exposed to wind and waves along the Gulf of Aden, to narrow fringing reefs adjacent to the deep sheltered waters of the Gulf of Tadjoura. Evidence suggests that in the past 35 years the reefs have not previously experienced severe coral bleaching or significant human impacts, with many reefs having healthy and diverse coral and fish populations. Mean coral cover was high (52%) and fish assemblages were dominated by fishery target species and herbivores. However, rising sea surface temperatures (SSTs) and rapid recent coastal development activities in Djibouti are likely future threats to these relatively untouched reefs.}, keywords = {Coral bleaching, coral reef, Ecosystem health, fisheries, Red Sea, Resilience}, pubstate = {published}, tppubtype = {article} } Djiboutian coral reefs are poorly studied, but are of critical importance to tourism and artisanal fishing in this small developing nation. In 2014 and 2016 we carried out the most comprehensive survey of Djiboutian reefs to date, and present data on their ecology, health and estimate their vulnerability to future coral bleaching and anthropogenic impacts. Reef type varied from complex reef formations exposed to wind and waves along the Gulf of Aden, to narrow fringing reefs adjacent to the deep sheltered waters of the Gulf of Tadjoura. Evidence suggests that in the past 35 years the reefs have not previously experienced severe coral bleaching or significant human impacts, with many reefs having healthy and diverse coral and fish populations. Mean coral cover was high (52%) and fish assemblages were dominated by fishery target species and herbivores. However, rising sea surface temperatures (SSTs) and rapid recent coastal development activities in Djibouti are likely future threats to these relatively untouched reefs. | |
 | Mcleod, Elizabeth; Anthony, Kenneth R N; Mumby, Peter J; Maynard, Jeffrey; Beeden, Roger; Graham, Nicholas A J; Heron, Scott F; Hoegh-Guldberg, Ove; Jupiter, Stacy; MacGowan, Petra; Mangubhai, Sangeeta; Marshall, Nadine; Marshall, Paul A; McClanahan, Tim R; Mcleod, Karen; Nyström, Magnus; Obura, David; Parker, Britt; Possingham, Hugh P; Salm, Rodney V; Tamelander, Jerker The future of resilience-based management in coral reef ecosystems Journal Article Journal of Environmental Management, 233 , pp. 291 - 301, 2019, ISSN: 0301-4797. Abstract | Links | BibTeX | Tags: @article{Mcleod2019b, title = {The future of resilience-based management in coral reef ecosystems}, author = {Elizabeth Mcleod and Kenneth R N Anthony and Peter J Mumby and Jeffrey Maynard and Roger Beeden and Nicholas A J Graham and Scott F Heron and Ove Hoegh-Guldberg and Stacy Jupiter and Petra MacGowan and Sangeeta Mangubhai and Nadine Marshall and Paul A Marshall and Tim R McClanahan and Karen Mcleod and Magnus Nyström and David Obura and Britt Parker and Hugh P Possingham and Rodney V Salm and Jerker Tamelander}, url = {http://www.sciencedirect.com/science/article/pii/S0301479718312994}, doi = {https://doi.org/10.1016/j.jenvman.2018.11.034}, issn = {0301-4797}, year = {2019}, date = {2019-01-01}, journal = {Journal of Environmental Management}, volume = {233}, pages = {291 - 301}, abstract = {Resilience underpins the sustainability of both ecological and social systems. Extensive loss of reef corals following recent mass bleaching events have challenged the notion that support of system resilience is a viable reef management strategy. While resilience-based management (RBM) cannot prevent the damaging effects of major disturbances, such as mass bleaching events, it can support natural processes that promote resistance and recovery. Here, we review the potential of RBM to help sustain coral reefs in the 21st century. We explore the scope for supporting resilience through existing management approaches and emerging technologies and discuss their opportunities and limitations in a changing climate. We argue that for RBM to be effective in a changing world, reef management strategies need to involve both existing and new interventions that together reduce stress, support the fitness of populations and species, and help people and economies to adapt to a highly altered ecosystem.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Resilience underpins the sustainability of both ecological and social systems. Extensive loss of reef corals following recent mass bleaching events have challenged the notion that support of system resilience is a viable reef management strategy. While resilience-based management (RBM) cannot prevent the damaging effects of major disturbances, such as mass bleaching events, it can support natural processes that promote resistance and recovery. Here, we review the potential of RBM to help sustain coral reefs in the 21st century. We explore the scope for supporting resilience through existing management approaches and emerging technologies and discuss their opportunities and limitations in a changing climate. We argue that for RBM to be effective in a changing world, reef management strategies need to involve both existing and new interventions that together reduce stress, support the fitness of populations and species, and help people and economies to adapt to a highly altered ecosystem. |
 | Obura, David; Salomao, Bandeira; Bodin, Nathalie; V, Burgener; Braulik, Gill; Chassot, Emmanuel; Gullström, Martin; Kochzius, Marc; Nicoll, Martin; Osuka, Kennedy; Ralison, Harifidy The Northern Mozambique Channel Book Chapter Chapter 4, 2019, ISBN: 9780081008539. Abstract | Links | BibTeX | Tags: @inbook{Obura2019b, title = {The Northern Mozambique Channel}, author = {David Obura and Bandeira Salomao and Nathalie Bodin and Burgener V and Gill Braulik and Emmanuel Chassot and Martin Gullström and Marc Kochzius and Martin Nicoll and Kennedy Osuka and Harifidy Ralison}, doi = {10.1016/B978-0-08-100853-9.00003-8}, isbn = {9780081008539}, year = {2019}, date = {2019-01-01}, chapter = {4}, abstract = {The northern half of the Northern Mozambique Channel (NMC) extends northwards from the narrowest part of the channel between Madagascar and Mozambique, at about 17°S (Fig. 4.1). The Aldabra group of islands lies just to the north, at about 9°S, but the precise northern limit is not clear and is operationally set to include Mafia Island in central Tanzania at about 7°S. It is bounded by northwest Madagascar, northern Mozambique, and southern Tanzania, with the Comoro archipelago at its heart. The NMC is entirely covered by the exclusive economic zones of the countries in the region—Mozambique, Madagascar, Tanzania, Comoros, Seychelles, and France. The total marine area is estimated at about 700,000 km2. To date a relatively poorly known part of the world ocean, the NMC is relatively unimpacted (Halpern, Walbridge, Selkoe, & Kappel, 2008), and is designated as an ecologically or biologically significant area (CBD, 2012). This chapter presents the current status and trends of the principal marine habitats and resources of the NMC, and outlines pressures and management challenges faced in the region. It concludes with key opportunities and approaches to improve management of ocean resource use. It complements other articles on management and governance in the NMC (Obura, 2018; Obura et al., 2017), and with them addresses broader policy approaches in the Western Indian Ocean focused on supporting sustainable ocean-based development (ASCLME/UNDP, 2012; Obura et al., 2017; UNEP/Nairobi Convention Secretariat, 2009; UNEP-Nairobi Convention and WIOMSA, 2015; Unger et al., 2017). Overall, the goal is to foster the development of Integrated Ocean Governance approaches to development (Stojanovic & Farmer, 2013; Van Tatenhove, 2011) in the NMC, as a foundation for future prosperity.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } The northern half of the Northern Mozambique Channel (NMC) extends northwards from the narrowest part of the channel between Madagascar and Mozambique, at about 17°S (Fig. 4.1). The Aldabra group of islands lies just to the north, at about 9°S, but the precise northern limit is not clear and is operationally set to include Mafia Island in central Tanzania at about 7°S. It is bounded by northwest Madagascar, northern Mozambique, and southern Tanzania, with the Comoro archipelago at its heart. The NMC is entirely covered by the exclusive economic zones of the countries in the region—Mozambique, Madagascar, Tanzania, Comoros, Seychelles, and France. The total marine area is estimated at about 700,000 km2. To date a relatively poorly known part of the world ocean, the NMC is relatively unimpacted (Halpern, Walbridge, Selkoe, & Kappel, 2008), and is designated as an ecologically or biologically significant area (CBD, 2012). This chapter presents the current status and trends of the principal marine habitats and resources of the NMC, and outlines pressures and management challenges faced in the region. It concludes with key opportunities and approaches to improve management of ocean resource use. It complements other articles on management and governance in the NMC (Obura, 2018; Obura et al., 2017), and with them addresses broader policy approaches in the Western Indian Ocean focused on supporting sustainable ocean-based development (ASCLME/UNDP, 2012; Obura et al., 2017; UNEP/Nairobi Convention Secretariat, 2009; UNEP-Nairobi Convention and WIOMSA, 2015; Unger et al., 2017). Overall, the goal is to foster the development of Integrated Ocean Governance approaches to development (Stojanovic & Farmer, 2013; Van Tatenhove, 2011) in the NMC, as a foundation for future prosperity. |
