| 1. |
- Gullström, Martin, et al.
(författare)
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Blue Carbon Storage in Tropical Seagrass Meadows Relates to Carbonate Stock Dynamics, Plant–Sediment Processes, and Landscape Context : Insights from the Western Indian Ocean
- 2018
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Ingår i: Ecosystems (New York. Print). - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 21:3, s. 551-566
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Tidskriftsartikel (refereegranskat)abstract
- Globally, seagrass ecosystems are considered major blue carbon sinks and thus indirect contributors to climate change mitigation. Quantitative estimates and multi-scale appraisals of sources that underlie long-term storage of sedimentary carbon are vital for understanding coastal carbon dynamics. Across a tropical–subtropical coastal continuum in the Western Indian Ocean, we estimated organic (Corg) and inorganic (Ccarb) carbon stocks in seagrass sediment. Quantified levels and variability of the two carbon stocks were evaluated with regard to the relative importance of environmental attributes in terms of plant–sediment properties and landscape configuration. The explored seagrass habitats encompassed low to moderate levels of sedimentary Corg (ranging from 0.20 to 1.44% on average depending on species- and site-specific variability) but higher than unvegetated areas (ranging from 0.09 to 0.33% depending on site-specific variability), suggesting that some of the seagrass areas (at tropical Zanzibar in particular) are potentially important as carbon sinks. The amount of sedimentary inorganic carbon as carbonate (Ccarb) clearly corresponded to Corg levels, and as carbonates may represent a carbon source, this could diminish the strength of seagrass sediments as carbon sinks in the region. Partial least squares modelling indicated that variations in sedimentary Corg and Ccarb stocks in seagrass habitats were primarily predicted by sediment density (indicating a negative relationship with the content of carbon stocks) and landscape configuration (indicating a positive effect of seagrass meadow area, relative to the area of other major coastal habitats, on carbon stocks), while seagrass structural complexity also contributed, though to a lesser extent, to model performance. The findings suggest that accurate carbon sink assessments require an understanding of plant–sediment processes as well as better knowledge of how sedimentary carbon dynamics are driven by cross-habitat links and sink–source relationships in a scale-dependent landscape context, which should be a priority for carbon sink conservation.
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| 2. |
- Alonso Aller, Elisa, et al.
(författare)
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Single and joint effects of regional- and local-scale variables on tropical seagrass fish assemblages
- 2014
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 161:10, s. 2395-2405
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass beds are highly important for tropical ecosystems by supporting abundant and diverse fish assemblages that form the basis for artisanal fisheries. Although a number of local- and regional-scale variables are known to influence the abundance, diversity and assemblage structure of seagrass-associated fish assemblages, few studies have evaluated the relative and joint (interacting) influences of variables, especially those acting at different scales. Here, we examined the relative importance of local- and regional-scale factors structuring seagrass-associated fish assemblages, using a field survey in six seagrass (Thalassodendron ciliatum) areas around Unguja Island (Zanzibar, Tanzania). Fish density and assemblage structure were mostly affected by two regional-scale variables; distance to coral reefs, which positively affected fish density, and level of human development, which negatively affected fish density. On the local scale, seagrass biomass had a positive (but weaker) influence on fish density. However, the positive effect of seagrass biomass decreased with increasing level of human development. In summary, our results highlight the importance of assessing how multiple local and regional variables, alone and together, influence fish communities, in order to improve management of seagrass ecosystems and their services.
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| 3. |
- Charisiadou, S., et al.
(författare)
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Coastal aquaculture in Zanzibar, Tanzania
- 2022
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Ingår i: Aquaculture. - : Elsevier. - 0044-8486 .- 1873-5622. ; 546
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Tidskriftsartikel (refereegranskat)abstract
- This study provides an overview of the multi-sectoral coastal aquaculture development in Zanzibar (Tanzania) over the last thirty years based on empirical evidence from interviews, field observations, policy reports and literature reviews. Despite the immense potential of aquaculture for food and livelihoods, only seaweed farming has so far established into commercial-scale production. This activity is dominated by women and became widespread in the early 1990s as a small but regular source of income. However, seaweed farming constraints such as frequent seaweed die-offs, as well as economic and institutional constraints inhibit its development. Other types of aquaculture activities such as fish farming, mud crab fattening, half-pearl farming, sea cucumber farming and sponge and coral cultures are under development with limited production or in experimental stages. Common constraints among these activities are economic limitations, lack of technical infrastructure and skills, small and irregular production, and limited trade and market availabilities. At the same time, there is a lack of sufficient management and monitoring systems, while there are no formal regulations or clear strategies to boost aquaculture at the national level. In addition, new aquaculture initiatives are often dominated by donor-driven projects instead of local entrepreneurships. This situation does not encourage engagement in aquaculture and thus such activities are outcompeted by other already established sectors (e.g. agriculture and fisheries). We conclude that aquaculture has great potential to evolve due to high environmental capacity. Nevertheless, achieving profitable production and a stronger commitment within local communities, as well as developing effective mariculture governance through support mechanisms and clear strategies to boost the sector at the national level, are essential for sustainable mariculture development in Zanzibar.
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| 4. |
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| 5. |
- Hedberg, Nils, et al.
(författare)
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Habitat preference for seaweed farming - A case study from Zanzibar, Tanzania
- 2018
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Ingår i: Ocean and Coastal Management. - : Elsevier BV. - 0964-5691 .- 1873-524X. ; 154, s. 186-195
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Tidskriftsartikel (refereegranskat)abstract
- Global marine seaweed aquaculture is growing rapidly. In Zanzibar, Tanzania, seaweed farming, primarily conducted by women, is the main coastal aquaculture activity. Many types of aquaculture are linked to a specific ecosystem (e.g. shrimp-mangrove), and understanding if such a coupling exists for seaweed farming important for further development. A prerequisite to understand if farming affects coastal habitats is the need to know where, and on which habitat, the farms are located. In this study, we investigated the habitat preferences of seaweed farmers by interviews, field observations and satellite imagery analysis. We found that the majority of the farms were distributed in a narrow corridor (380-600 m from shore) along the coast where water depth (x) over bar = 2 m) and tidal regime (+/- 2 m) allow for a suitable environment for both the algae and the farmers. Within this corridor, thus defined by depth, the water is deep enough for the algae not to be overexposed to sunlight but also sufficiently shallow for the women to access and work on the farms at low tide. The farmers accordingly expressed depth as the major limiting factor when choosing the site for their farms, and the preferred habitat type was seagrass beds. Most farms (92%) were partly located on seagrass meadows, but also other habitats, such as sand. The total area of the studied seaweed farms was 65.6 ha, with 39% of this being seagrass meadow, which is significantly more than the seagrass cover in the farming corridor. The farms also covered 43% sand; however, the interviews indicate that a substantial part of the sandy areas was, in fact, also recently covered by seagrasses. Our findings are relevant for improved management, conservation, and marine spatial planning, as we show where and on which habitats seaweed farms are preferably located. This information can be used to further investigate the ecological impact on the habitats and their associated fauna and in order to provide more effective management actions. Furthermore, this is much-needed baseline information for investigating the increased production of seaweed, i.e. if the habitat has any effect on the algae growth.
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| 6. |
- Knudby, Anders, et al.
(författare)
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Using multiple Landsat scenes in an ensemble classifier reduces classification error in a stable nearshore environment
- 2014
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Ingår i: International Journal of Applied Earth Observation and Geoinformation. - : Elsevier BV. - 1569-8432 .- 1872-826X. ; 28, s. 90-101
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Tidskriftsartikel (refereegranskat)abstract
- Medium-scale land cover maps are traditionally created on the basis of a single cloud-free satellite scene, leaving information present in other scenes unused. Using 1309 field observations and 20 cloud- and error-affected Landsat scenes covering Zanzibar Island, this study demonstrates that the use of multiple scenes can both allow complete coverage of the study area in the absence of cloud-free scenes and obtain substantially improved classification accuracy. Automated processing of individual scenes includes derivation of spectral features for use in classification, identification of clouds, shadows and the land/water boundary, and random forest-based land cover classification. An ensemble classifier is then created from the single-scene classifications by voting. The accuracy achieved by the ensemble classifier is 70.4%, compared to an average of 62.9% for the individual scenes, and the ensemble classifier achieves complete coverage of the study area while the maximum coverage for a single scene is 1209 of the 1309 field sites. Given the free availability of Landsat data, these results should encourage increased use of multiple scenes in land cover classification and reduced reliance on the traditional single-scene methodology.
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| 7. |
- Mtwana Nordlund, Lina, et al.
(författare)
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Global significance of seagrass fishery activity
- 2018
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Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 19:3, s. 399-412
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows support fisheries through provision of nursery areas and trophic subsidies to adjacent habitats. As shallow coastal habitats, they also provide key fishing grounds; however, the nature and extent of such exploitation are poorly understood. These productive meadows are being degraded globally at rapid rates. For degradation to cease, there needs to be better appreciation for the value of these habitats in supporting global fisheries. Here, we provide the first global scale study demonstrating the extent, importance and nature of fisheries exploitation of seagrass meadows. Due to a paucity of available data, the study used a global expert survey to demonstrate the widespread significance of seagrass-based fishing activity. Our study finds that seagrass-based fisheries are globally important and present virtually wherever seagrass exists, supporting subsistence, commercial and recreational activity. A wide range of fishing methods and gear is used reflecting the spatial distribution patterns of seagrass meadows, and their depth ranges from intertidal (accessible by foot) to relatively deep water (where commercial trawls can operate). Seagrass meadows are multispecies fishing grounds targeted by fishers for any fish or invertebrate species that can be eaten, sold or used as bait. In the coastal communities of developing countries, the importance of the nearshore seagrass fishery for livelihoods and well-being is irrefutable. In developed countries, the seagrass fishery is often recreational and/or more target species specific. Regardless of location, this study is the first to highlight collectively the indiscriminate nature and global scale of seagrass fisheries and the diversity of exploitative methods employed to extract seagrass-associated resources. Evidence presented emphasizes the need for targeted management to support continued viability of seagrass meadows as a global ecosystem service provider.
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| 8. |
- Mtwana Nordlund, Lina, et al.
(författare)
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Intertidal Zone Management in the Western Indian Ocean : Assessing Current Status and Future Possibilities Using Expert Opinions
- 2014
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 43:8, s. 1006-1019
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Tidskriftsartikel (refereegranskat)abstract
- This expert opinion study examined the current status of the intertidal zone in the Western Indian Ocean (WIO) and ranked and discussed future management approaches. Information was gathered from scientists, practitioners, and managers active in the WIO region through a questionnaire and a workshop. The experts stated that the productive intertidal environment is highly valuable for reasons such as recreation, erosion protection, and provision of edible invertebrates and fish. Several anthropogenic pressures were identified, including pollution, harbor activities, overexploitation, and climate change. The experts considered the WIO intertidal zone as generally understudied, undermanaged, and with poor or no monitoring. The most important management strategies according to the expert opinions are to develop and involve local people in integrated coastal zone management (ICZM), to increase knowledge on species-environment relationships, and to develop awareness campaigns and education programs. To improve coastal environmental management and conservation, we argue that the intertidal zone should be treated as one organizational management unit within the larger framework of ICZM.
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| 9. |
- Mtwana Nordlund, Lina, et al.
(författare)
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Seagrass ecosystem services - What's next?
- 2018
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X .- 1879-3363. ; 134, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- Seagrasses, marine flowering plants, provide a wide range of ecosystem services, defined here as natural processes and components that directly or indirectly benefit human needs. Recent research has shown that there are still many gaps in our comprehension of seagrass ecosystem service provision. Furthermore, there seems to be little public knowledge of seagrasses in general and the benefits they provide. This begs the questions: how do we move forward with the information we have? What other information do we need and what actions do we need to take in order to improve the situation and appreciation for seagrass? Based on the outcomes from an international expert knowledge eliciting workshop, three key areas to advance seagrass ecosystem service research were identified: 1) Variability of ecosystem services within seagrass meadows and among different meadows; 2) Seagrass ecosystem services in relation to, and their connection with, other coastal habitats; and 3) Improvement in the communication of seagrass ecosystem services to the public. Here we present ways forward to advance seagrass ecosystem service research in order to raise the profile of seagrass globally, as a means to establish more effective conservation and restoration of these important coastal habitats around the world.
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| 10. |
- Mtwana Nordlund, Lina, 1979-
(författare)
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Teaching ecology at university—Inspiration for change
- 2016
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Ingår i: Global Ecology and Conservation. - : Elsevier BV. - 2351-9894. ; 7, s. 174-182
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Forskningsöversikt (refereegranskat)abstract
- How do you, as a university lecturer, change from teacher-centered teaching to a more student-centered, active teaching? This paper aims to inspire you to make a change, big or small, to increase your students’ engagement and learning, by presenting suggestions on what you can do. The ideas and suggestions synthesized here are based on several different teaching philosophies and methods, which are well tested and shown to be effective in the right setting. The selection of suggestions is believed to be specifically suitable for ecology.The paper includes suggestions on how to plan a course or a lecture by setting a good learning environment. Both pre-lecture activities and during lecture activities are included, with a focus on activities to engage students and encourage increased discussion and reflections, as well as what to think about when choosing learning activities and how and why it is important to teach students to think and act like professionals in ecology. While changing teaching methods takes investment of time, time that is limited for many researchers, even small changes in your teaching can make big differences in learning, and the investment will hopefully pay back by making teaching more fun and rewarding. The suggestions presented are understandable without being be conversant in the ‘education literature’, but will provide you with a vocabulary of teaching activities that will be useful if you are inspired to find more information and learn more about teaching.
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| 11. |
- Nordlund, Lina Mtwana, et al.
(författare)
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Biodiversity loss in seagrass meadows due to local invertebrate fisheries and harbour activities
- 2013
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Ingår i: Estuarine, Coastal and Shelf Science. - : Elsevier BV. - 0272-7714 .- 1096-0015. ; 135, s. 231-240
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Tidskriftsartikel (refereegranskat)abstract
- Seagrass meadows provide a wide variety of ecosystem services, but their distribution and health are adversely affected by man. In the present study, we examined the influence of coastal exploitation in terms of invertebrate harvesting and harbour activity on invertebrate community composition in subtropical seagrass meadows at Inhaca Island, Mozambique, in the Western Indian Ocean. There was a fivefold higher invertebrate density and biomass, and clearly higher invertebrate species richness, in the protected (control) site compared to the two exploited sites. The causes for the clear differences between protected and exploited sites were probably a result of (1) the directional outtake of large edible or saleable invertebrates (mostly molluscs) and the absence of boat traffic in the harvested site, and (2) harbour activities. Invertebrate community composition in the two exploited sites also differed (although less clear), which was likely due to inherent distinction in type of disturbance. Our findings revealed that protection of seagrass habitat is necessary and that disturbances of different origin might require different forms of management and conservation. Designing protected areas is however a complex process due to competition for use and space with activities such as invertebrate harvesting and harbours.
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| 12. |
- Nordlund, Lina Mtwana, et al.
(författare)
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One hundred priority questions for advancing seagrass conservation in Europe
- 2024
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Ingår i: PLANTS PEOPLE PLANET. - 2572-2611.
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Tidskriftsartikel (refereegranskat)abstract
- Societal Impact StatementSeagrass ecosystems are of fundamental importance to our planet and wellbeing. Seagrasses are marine flowering plants, which engineer ecosystems that provide a multitude of ecosystem services, for example, blue foods and carbon sequestration. Seagrass ecosystems have largely been degraded across much of their global range. There is now increasing interest in the conservation and restoration of these systems, particularly in the context of the climate emergency and the biodiversity crisis. The collation of 100 questions from experts across Europe could, if answered, improve our ability to conserve and restore these systems by facilitating a fundamental shift in the success of such work.SummarySeagrass meadows provide numerous ecosystem services including biodiversity, coastal protection, and carbon sequestration. In Europe, seagrasses can be found in shallow sheltered waters along coastlines, in estuaries & lagoons, and around islands, but their distribution has declined. Factors such as poor water quality, coastal modification, mechanical damage, overfishing, land-sea interactions, climate change and disease have reduced the coverage of Europe's seagrasses necessitating their recovery. Research, monitoring and conservation efforts on seagrass ecosystems in Europe are mostly uncoordinated and biased towards certain species and regions, resulting in inadequate delivery of critical information for their management. Here, we aim to identify the 100 priority questions, that if addressed would strongly advance seagrass monitoring, research and conservation in Europe. Using a Delphi method, researchers, practitioners, and policymakers with seagrass experience from across Europe and with diverse seagrass expertise participated in the process that involved the formulation of research questions, a voting process and an online workshop to identify the final list of the 100 questions. The final list of questions covers areas across nine themes: Biodiversity & Ecology; Ecosystem services; Blue carbon; Fishery support; Drivers, Threats, Resilience & Response; Monitoring & Assessment; Conservation & Restoration; Governance, Policy & Management; and Communication. Answering these questions will fill current knowledge gaps and place European seagrass onto a positive trajectory of recovery. Seagrass ecosystems are of fundamental importance to our planet and wellbeing. Seagrasses are marine flowering plants which engineer ecosystems that provide a multitude of ecosystem services, for example, blue foods and carbon sequestration. Seagrass ecosystems have largely been degraded across much of their global range. There is now increasing interest in the conservation and restoration of these systems, particularly in the context of the climate emergency and the biodiversity crisis. The collation of 100 questions from experts across Europe could, if answered, improve our ability to conserve and restore these systems by facilitating a fundamental shift in the success of such work. image
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| 13. |
- Nordlund, Lina Mtwana, et al.
(författare)
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Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e. g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional-and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e. g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e. g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide.
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| 14. |
- Pike, Felicity, 1993-, et al.
(författare)
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Intertidal gleaning fisheries : Recognising local-scale contributions and management scenarios
- 2024
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Ingår i: Marine Policy. - : Elsevier. - 0308-597X .- 1872-9460. ; 162
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Tidskriftsartikel (refereegranskat)abstract
- Intertidal gleaning is a widespread means through which women participate in the fishery harvest sector. However, the fishery is often under recognised in management and policy-making. Accordingly, there is a need to further our understanding of the fishery, and how local factors may help or hinder effective management. This study focuses on Zanzibar, Tanzania, using focus group discussions (FGDs) and interviews to investigate local-scale contributions from gleaning in seagrass dominated areas – which are particularly frequented gleaning grounds locally, and more widely in the Indo-Pacific region. The study also gathered insight into how gleaners perceived different management scenarios used elsewhere within the small-scale fishery sector. Despite being typically viewed as a sustenance means, gleaning was found to be primarily an economic activity, mainly through catching the bivalve, Anadara antiquata, and commercial gastropod species (Chicoreus ramosus and Pleuroploca spp). FGD respondents held positive pre-conceived ideas about rotating no-take zone scenarios as a management strategy, as well as indicating preferences for community-based measures. In order for no-take zones to have a higher chance of success, further investigation is needed to understand the life histories of commonly gleaned species in order to inform rotation periods, as well as developing means of cross-community cooperation due to the shared, open access nature of intertidal zones. These results demonstrate the economic importance of gleaning for coastal women in Zanzibar, who have invaluable insights, built on lived experience and local knowledge, which could enable and benefit a more inclusive management system.
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| 15. |
- Stiepani, Johann, et al.
(författare)
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Social-ecological system analysis of an invertebrate gleaning fishery on the island of Unguja, Zanzibar
- 2023
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Ingår i: Ambio. - : Springer Nature. - 0044-7447 .- 1654-7209. ; 52:1, s. 140-154
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Tidskriftsartikel (refereegranskat)abstract
- Invertebrate gleaning is a small-scale fishery that commonly occurs in the intertidal zone across the tropical Indo-Pacific. In this study, we investigated and analyzed several components of this fishery on the island of Unguja, Zanzibar by employing the social-ecological systems framework from Ostrom 2009. In doing so, we conducted ecological surveys, catch assessments, interviews with gleaners, household surveys, focus group interviews and analyzed the governance structure. This social-ecological systems analysis showed that gleaning is important for food security, local culture and livelihood. Yet, the multiple approaches in our study revealed that the local intertidal zone is degrading and that the gleaned catch is changing. Local narratives indicate that economically important bivalves (Modiolus spp.) and gastropods (Strombus spp.) are in decline, which was paralleled with low abundances of both genera within the ecological survey of the intertidal and catch landing assessment. We recommend that invertebrate gleaning, a fishery mainly comprised of women should be included in fisheries management.
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| 16. |
- Unsworth, Richard K. F., et al.
(författare)
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Seagrass meadows support global fisheries production
- 2019
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Ingår i: Conservation Letters. - : Wiley. - 1755-263X. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- The significant role seagrass meadows play in supporting fisheries productivity and food security across the globe is not adequately reflected in the decisions made by authorities with statutory responsibility for their management. We provide a unique global analysis of three data sources to present the case for why seagrass meadows need targeted policy to recognize and protect their role in supporting fisheries production and food security. (1) Seagrass meadows provide valuable nursery habitat to over 1/5th of the world's largest 25 fisheries, including Walleye Pollock, the most landed species on the planet. (2) In complex small-scale fisheries from around the world (poorly represented in fisheries statistics), we present evidence that many of those in proximity to seagrass are supported to a large degree by these habitats. (3) We reveal how intertidal fishing activity in seagrass is a global phenomenon, often directly supporting human livelihoods. Our study demonstrates that seagrasses should be recognized and managed to maintain and maximize their role in global fisheries production. The chasm that exists between coastal habitat conservation and fisheries management needs to be filled to maximize the chances of seagrass meadows supporting fisheries, so that they can continue to support human wellbeing.
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| 17. |
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