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  • 1.
    Asplund, Maria E.
    et al.
    Department of Biological and Environmental Sciences, University of Gothenburg, Fiskebäckskil, Sweden.
    Bonaglia, Stefano
    Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden.
    Boström, Christoffer
    Faculty of Science and Engineering, Environmental and Marine Biology, Åbo Akademi University, Åbo, Finland.
    Dahl, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Deyanova, Diana
    Department of Biological and Environmental Sciences, University of Gothenburg, Fiskebäckskil, Sweden.
    Gagnon, Karine
    Faculty of Science and Engineering, Environmental and Marine Biology, Åbo Akademi University, Åbo, Finland.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Holmer, Marianne
    Department of Biology, Danish Institute for Advanced Study, University of Southern Denmark, Odense, Denmark.
    Björk, Mats
    Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.
    Methane Emissions From Nordic Seagrass Meadow Sediments2022In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 8, article id 811533Article in journal (Refereed)
    Abstract [en]

    Shallow coastal soft bottoms are important carbon sinks. Submerged vegetation has been shown to sequester carbon, increase sedimentary organic carbon (C-org) and thus suppress greenhouse gas (GHG) emissions. The ongoing regression of seagrass cover in many areas of the world can therefore lead to accelerated emission of GHGs. In Nordic waters, seagrass meadows have a high capacity for carbon storage, with some areas being recognized as blue carbon hotspots. To what extent these carbon stocks lead to emission of methane (CH4) is not yet known. We investigated benthic CH4 emission (i.e., net release from the sediment) in relation to seagrass (i.e. Zostera marina) cover and sedimentary C-org content (%) during the warm summer period (when emissions are likely to be highest). Methane exchange was measured in situ with benthic chambers at nine sites distributed in three regions along a salinity gradient from similar to 6 in the Baltic Sea (Finland) to similar to 20 in Kattegat (Denmark) and similar to 26 in Skagerrak (Sweden). The net release of CH4 from seagrass sediments and adjacent unvegetated areas was generally low compared to other coastal habitats in the region (such as mussel banks and wetlands) and to other seagrass areas worldwide. The lowest net release was found in Finland. We found a positive relationship between CH4 net release and sedimentary C-org content in both seagrass meadows and unvegetated areas, whereas no clear relationship between seagrass cover and CH4 net release was observed. Overall, the data suggest that Nordic Zostera marina meadows release average levels of CH4 ranging from 0.3 to 3.0 mu g CH4 m(-2) h(-1), which is at least 12-78 times lower (CO2 equivalents) than their carbon accumulation rates previously estimated from seagrass meadows in the region, thereby not hampering their role as carbon sinks. Thus, the relatively weak CH4 emissions from Nordic Z. marina meadows will not outweigh their importance as carbon sinks under present environmental conditions.

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  • 2.
    Asplund, Maria E.
    et al.
    University of Gothenburg, Sweden.
    Dahl, Martin
    Stockholm University, Sweden.
    Ismail, Rashid O.
    Stockholm University, Sweden; University of Dar Salaam, Tanzania.
    Arias-Ortiz, Ariane
    Autonomous University of Barcelona, Spain; University of California Berkeley, USA.
    Deyanova, Diana
    University of Gothenburg, Sweden.
    Franco, Joao N.
    Universidade do PortoUniversidade do Porto, Portugal; Polytechnic Institute of Leiria, Portugal.
    Hammar, Linus
    Octopus Ink Research and Analysis, Sweden.
    Hoamby, Arielle, I
    de l’Université de Toliara, Madagascar; Wildlife Conservation Society, Madagascar.
    Linderholm, Hans W.
    University of Gothenburg, Sweden.
    Lyimo, Liberatus D.
    University of Dodoma, Tanzania.
    Perry, Diana
    Swedish University of Agricultural Sciences, Sweden.
    Rasmusson, Lina M.
    University of Gothenburg, Sweden.
    Ridgway, Samantha N.
    Edith Cowan University, Australia.
    Gispert, Gloria Salgado
    Edith Cowan University, Australia.
    D'Agata, Stephanie
    Wildlife Conservation Society, Madagascar; Macquarie University, Australia.
    Glass, Leah
    Blue Ventures Conservat, Madagascar.
    Mahafina, Jamal Angelot
    de l’Université de Toliara, Madagascar.
    Ramahery, Volanirina
    Nexus Madagascar Company, Madagascar.
    Masque, Pere
    Universitat Autònoma de Barcelona, Spain; Edith Cowan University, Australia; International Atomic Energy Agency, Monaco.
    Björk, Mats
    Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dynamics and fate of blue carbon in a mangrove-seagrass seascape: influence of landscape configuration and land-use change2021In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 36, p. 1489-1509Article in journal (Refereed)
    Abstract [en]

    Context Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO2 and through trapping of allochthonous organic material, thereby preserving organic carbon (C-org) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land-sea interface. Objectives We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of C-org in seagrass habitats. Methods Through predictive modelling, we assessed sedimentary C-org content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves. Results The sedimentary C-org content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary C-org levels in seagrass seascapes. There was higher C-org content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of C-org from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary C-org levels in comparison to more diverse and patchy seascapes. Conclusion Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess C-org content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations.

  • 3.
    Björk, Mats
    et al.
    Stockholm University, Sweden.
    Asplund, Maria E
    University of Gothenburg, Sweden.
    Deyanova, Diana
    University of Gothenburg, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    The amount of light reaching the leaves in seagrass (Zostera marina) meadows2021In: PLOS ONE, E-ISSN 1932-6203, Vol. 16, no 9, article id e0257586Article in journal (Refereed)
    Abstract [en]

    Seagrass meadows, and other submerged vegetated habitats, support a wide range of essential ecological services, but the true extents of these services are in many ways still not quantified. One important tool needed to assess and model many of these services is accurate estimations of the systems´ primary productivity. Such productivity estimations require an understanding of the underwater light field, especially regarding the amount of light that actually reaches the plants' photosynthetic tissue. In this study, we tested a simple practical approach to estimate leaf light exposure, relative to incoming light at the canopy, by attaching light sensitive film at different positions on leaves of Zostera marina, eelgrass, in four seagrass meadows composed of different shoot density and at two different depths. We found that the light reaching the leaves decreased linearly down through the canopy. While the upper parts of the leaves received approximately the same level of light (photosynthetic photon flux density, PPFD) as recorded with a PAR meter at the canopy top, the average light that the seagrass leaves were exposed to varied between 40 and 60% of the light on top of the canopy, with an overall average of 48%. We recommend that actual light interception is measured when assessing or modelling light depending processes in submerged vegetation, but if this is not achievable a rough estimation for vegetation similar to Z. marina would be to use a correction factor of 0.5 to compensate for the reduced light due to leaf orientation and internal shading.

  • 4.
    Charisiadou, S.
    et al.
    Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, Anavyssos, Greece; Stockholm University, Sweden.
    Halling, C.
    Stockholm University, Sweden; Swedish University of Agricultural Sciences, Sweden.
    Jiddawi, N.
    Institute of Fisheries Research Zanzibar, Maruhubi, Zanzibar, Tanzania.
    von Schreeb, K.
    Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Larsson, T.
    Stockholm University, Sweden.
    Nordlund, L. M.
    Stockholm University, Sweden; Uppsala University; Sweden.
    Coastal aquaculture in Zanzibar, Tanzania2022In: Aquaculture, ISSN 0044-8486, E-ISSN 1873-5622, Vol. 546, article id 737331Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    Dahl, Martin
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones Científicas (CEAB-CSIC), Blanes, Spain.
    Asplund, Maria E.
    University of Gothenburg, Sweden.
    Bergman, Sanne
    Stockholm University, Sweden.
    Björk, Mats
    Stockholm University, Sweden.
    Braun, Sara
    Stockholm University, Sweden.
    Löfgren, Elin
    Stockholm University, Sweden.
    Martí, Elisa
    University of Cadiz, Spain.
    Masque, Pere
    Edith Cowan University, Australia; IAEA Marine Environment Laboratories, Principality of Monaco, Monaco.
    Svensson, Robin
    University of Gothenburg, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    First assessment of seagrass carbon accumulation rates in Sweden: A field study from a fjord system at the Skagerrak coast2023In: PLOS Climate, E-ISSN 2767-3200, Vol. 2, no 1, article id e0000099Article in journal (Refereed)
    Abstract [en]

    Seagrass meadows are globally important blue carbon sinks. In northern cold-temperate regions, eelgrass (Zostera marina) is the dominant seagrass species, and although their sedimentary carbon stocks have been quantified across regions, information regarding the CO2 withdrawal capacity as carbon sinks remains scarce. Here we assessed the carbon (Corg) accumulation rates (CARs) and stocks as well as the organic matter sources in five seagrass meadows in the Gullmar Fjord area on the Swedish Skagerrak coast. We found that the mean (±SD) CAR was 14 ± 3 g Corg m-2 yr-1 over the last ~120–140 years (corresponding to a yearly uptake of 52.4 ± 12.6 g CO2 m-2). The carbon sink capacity is in line with other Z. marina areas but relatively low compared to other seagrass species and regions globally. About half of the sedimentary carbon accumulation (7.1 ± 3.3 g Corg m-2 yr-1) originated from macroalgae biomass, which highlights the importance of non-seagrass derived material for the carbon sink function of seagrass meadows in the area. The Corg stocks were similar among sites when comparing at a standardized depth of 50 cm (4.6–5.9 kg Corg m-2), but showed large variation when assessed for the total extent of the cores (ranging from 0.7 to 20.6 kg Corg m-2 for sediment depths of 11 to at least 149 cm). The low sediment accretion rates (1.18–1.86 mm yr-1) and the relatively thick sediment deposits (with a maximum of >150 cm of sediment depth) suggests that the carbon stocks have likely been accumulated for an extended period of time, and that the documented loss of seagrass meadows in the Swedish Skagerrak region and associated erosion of the sediment could potentially have offset centuries of carbon sequestration.

  • 6.
    Dahl, Martin
    et al.
    Stockholm University.
    Asplund, Maria E
    University of Gothenburg.
    Björk, Mats
    Stockholm University.
    Deyanova, Diana
    Stockholm University / University of Gothenburg.
    Infantes, Eduardo
    University of Gothenburg / Norwegian Institute for Water Research (NIVA), Oslo, Norway.
    Isaeus, Martin
    AquaBiota Water Research, Stockholm, Sweden.
    Nyström Sandman, Antonia
    AquaBiota Water Research, Stockholm, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Stockholm University / University of Gothenburg.
    The influence of hydrodynamic exposure on carbon storage and nutrient retention in eelgrass (Zostera marina L.) meadows on the Swedish Skagerrak coast2020In: Scientific Reports, E-ISSN 2045-2322, Vol. 10, no 1, article id 13666Article in journal (Refereed)
    Abstract [en]

    Cold-temperate seagrass (Zostera marina) meadows provide several important ecosystem services, including trapping and storage of sedimentary organic carbon and nutrients. However, seagrass meadows are rapidly decreasing worldwide and there is a pressing need for protective management of the meadows and the organic matter sinks they create. Their carbon and nutrient storage potential must be properly evaluated, both at present situation and under future climate change impacts. In this study, we assessed the effect of wave exposure on sedimentary carbon and nitrogen accumulation using existing data from 53 Z. marina meadows at the Swedish west coast. We found that meadows with higher hydrodynamic exposure had larger absolute organic carbon and nitrogen stocks (at 0-25 cm depth). This can be explained by a hydrodynamically induced sediment compaction in more exposed sites, resulting in increased sediment density and higher accumulation (per unit volume) of sedimentary organic carbon and nitrogen. With higher sediment density, the erosion threshold is assumed to increase, and as climate change-induced storms are predicted to be more common, we suggest that wave exposed meadows can be more resilient toward storms and might therefore be even more important as carbon- and nutrient sinks in the future.

  • 7.
    Dahl, Martin
    et al.
    Stockholms universitet, Sweden.
    Bergman, Sanne
    Stockholms universitet, Sweden.
    Björk, Mats
    Stockholms universitet, Sweden.
    Diaz-Almela, Elena
    Centro de Estudios Avanzados de Blanes, Spanien.
    Granberg, Maria
    IVL Svenska Miljöinstitutet, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Leiva-Dueñas, Carmen
    Centro de Estudios Avanzados de Blanes, Spanien.
    Magnusson, Kerstin
    IVL Svenska Miljöinstitutet, Sweden.
    Marco-Méndez, Candela
    Centro de Estudios Avanzados de Blanes, Spanien.
    Piñeiro-Juncal, Nerea
    Centro de Estudios Avanzados de Blanes, Spanien; Universidade de 5 Santiago de Compostela, Spanien.
    Mateo, Miguel Ángel
    Centro de Estudios Avanzados de Blanes, Spanien; Edith Cowan University, Australien.
    A temporal record of microplastic pollution in Mediterranean seagrass soils2021In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 273, article id 116451Article in journal (Refereed)
    Abstract [en]

    Plastic pollution is emerging as a potential threat to the marine environment. In the current study, we selected seagrass meadows, known to efficiently trap organic and inorganic particles, to investigate the concentrations and dynamics of microplastics in their soil. We assessed microplastic contamination and accumulation in 210Pb dated soil cores collected in Posidonia oceanica meadows at three locations along the Spanish Mediterranean coast, with two sites located in the Almería region (Agua Amarga and Roquetas) and one at Cabrera Island (Santa Maria). Almería is known for its intense agricultural industry with 30 000 ha of plastic-covered greenhouses, while the Cabrera Island is situated far from urban areas. Microplastics were extracted using enzymatic digestion and density separation. The particles were characterized by visual identification and with Fourier-transformed infrared (FTIR) spectroscopy, and related to soil age-depth chronologies. Our findings showed that the microplastic contamination and accumulation was negligible until the mid-1970s, after which plastic particles increased dramatically, with the highest concentrations of microplastic particles (MPP) found in the recent (since 2012) surface soil of Agua Amarga (3819 MPP kg-1), followed by the top-most layers of the soil of the meadows in Roquetas (2173 kg-1) and Santa Maria (68-362 kg-1). The highest accumulation rate was seen in the Roquetas site (8832 MPP m-2 yr-1). The increase in microplastics in the seagrass soil was associated to land-use change following the intensification of the agricultural industry in the area, with a clear relationship between the development of the greenhouse industry in Almería and the concentration of microplastics in the historical soil record. This study shows a direct linkage between intense anthropogenic activity, an extensive use of plastics and high plastic contamination in coastal marine ecosystems such as seagrass meadows. We highlight the need of proper waste management to protect the coastal environment from continuous pollution.

  • 8.
    Dahl, Martin
    et al.
    Department of Ecology, Environment and Plant Sciences, Stockholm University, Sweden.
    Björk, Mats
    Department of Ecology, Environment and Plant Sciences, Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Effects of seagrass overgrazing on sediment erosion and carbon sink capacity: Current Understanding And Future Priorities2021In: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 6, no 6, p. 309-319Article in journal (Refereed)
    Abstract [en]

    We searched the literature for experimental and observational studies assessing the effects of seagrass overgrazing on erosion of sediment and sedimentary organic carbon (SOC) and found that most studies reported a significant impact, likely caused by a cascading effect (i.e., seagrass shoot loss -> belowground biomass degradation -> sediment destabilization or SOC erosion). However, there appears to be a clear lack of knowledge on the extent and mechanisms behind SOC erosion in seagrass meadows and we highlight the need for research to (1) define spatial and temporal scales of occurrence; (2) assess the influence of belowground biomass degradation, sediment characteristics, and hydrodynamic exposure on sediment stabilization; and (3) estimate the greenhouse gas emission after a disturbance. Such information would help coastal resource managers to address the causes and effects of SOC loss and sediment erosion when evaluating impacts of global change on coastal ecosystems.

  • 9.
    Dahl, Martin
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Bernabeu, I.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC), Spain.
    Serrano, O.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC),Spain, Edith Cowan University, Australia.
    Leiva-Dueñas, C.
    Aarhus University, Denmark.
    Linderholm, H. W.
    University of Gothenburg, Sweden.
    Asplund, M. E.
    University of Gothenburg, Sweden.
    Björk, M.
    Stockholm University, Sweden.
    Ou, T.
    University of Gothenburg, Sweden.
    Svensson, J. R.
    University of Gothenburg, Sweden.
    Andrén, Elinor
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Andrén, Thomas
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Bergman, S.
    UiT—The Arctic University of Norway, Norway.
    Braun, Sara
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Eklöf, A.
    Stockholm University, Sweden.
    Ežerinskis, Z.
    Center for Physical Sciences and Technology, Lithuania.
    Garbaras, A.
    Center for Physical Sciences and Technology, Lithuania.
    Hällberg, P.
    Stockholm University, Sweden.
    Löfgren, E.
    Stockholm University, Sweden.
    Kylander, M. E.
    Stockholm University, Sweden.
    Masqué, P.
    Edith Cowan University, Australia, PrincipalityofMonaco,Monaco.
    Šapolaitė, J.
    Center for Physical Sciences and Technology, Lithuania.
    Smittenberg, R.
    Stockholm University, Sweden, Principality of Monaco, Monaco.
    Mateo, M. A.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC), Spain, Edith Cowan University, Australia.
    A 2,000-Year Record of Eelgrass (Zostera marina L.): Colonization Shows Substantial Gains in Blue Carbon Storage and Nutrient Retention2024In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 38, no 3, article id e2023GB008039Article in journal (Refereed)
    Abstract [en]

    Assessing historical environmental conditions linked to habitat colonization is important for understanding long-term resilience and improving conservation and restoration efforts. Such information is lacking for the seagrass Zostera marina, an important foundation species across cold-temperate coastal areas of the Northern Hemisphere. Here, we reconstructed environmental conditions during the last 14,000 years from sediment cores in two eelgrass (Z. marina) meadows along the Swedish west coast, with the main aims to identify the time frame of seagrass colonization and describe subsequent biogeochemical changes following establishment. Based on vegetation proxies (lipid biomarkers), eelgrass colonization occurred about 2,000 years ago after geomorphological changes that resulted in a shallow, sheltered environment favoring seagrass growth. Seagrass establishment led to up to 20- and 24-fold increases in sedimentary carbon and nitrogen accumulation rates, respectively. This demonstrates the capacity of seagrasses as efficient ecosystem engineers and their role in global change mitigation and adaptation through CO2 removal, and nutrient and sediment retention. By combining regional climate projections and landscape models, we assessed potential climate change effects on seagrass growth, productivity and distribution until 2100. These predictions showed that seagrass meadows are mostly at risk from increased sedimentation and hydrodynamic changes, while the impact from sea level rise alone might be of less importance in the studied area. This study showcases the positive feedback between seagrass colonization and environmental conditions, which holds promise for successful conservation and restoration efforts aimed at supporting climate change mitigation and adaptation, and the provision of several other crucial ecosystem services. © 2024. The Authors.

  • 10.
    Dahl, Martin
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Stockholm University, Sweden.
    Ismail, Rashid
    Stockholm University, Sweden; University of Dar es Salaam, Tanzania.
    Braun, Sara
    Stockholm University, Sweden.
    Masqué, Pere
    Edith Cowan University, Australia; International Atomic Energy, Monaco.
    Lavery, Paul S
    Edith Cowan University, Australia.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Arias-Ortiz, Ariane
    University of California, USA.
    Asplund, Maria E
    University of Gothenburg, Sweden.
    Garbaras, Andrius
    Center for Physical Sciences and Technology, Lithuania.
    Lyimo, Liberatus D
    Sokoine University of Agriculture, Tanzania.
    Mtolera, Matern S P
    University of Dar es Salaam, Tanzania.
    Serrano, Oscar
    Edith Cowan University, Australia; Centro de Estudios Avanzados de Blanes, Consejo Superior de Investigaciones Científicas (CEAB-CSIC), Blanes, Spain.
    Webster, Chanelle
    Edith Cowan University, Australia.
    Björk, Mats
    Stockholm University, Sweden.
    Impacts of land-use change and urban development on carbon sequestration in tropical seagrass meadow sediments2022In: Marine Environmental Research, ISSN 0141-1136, E-ISSN 1879-0291, Vol. 176, article id 105608Article in journal (Refereed)
    Abstract [en]

    Seagrass meadows store significant carbon stocks at a global scale, but land-use change and other anthropogenic activities can alter the natural process of organic carbon (Corg) accumulation. Here, we assessed the carbon accumulation history of two seagrass meadows in Zanzibar (Tanzania) that have experienced different degrees of disturbance. The meadow at Stone Town has been highly exposed to urban development during the 20th century, while the Mbweni meadow is located in an area with relatively low impacts but historical clearing of adjacent mangroves. The results showed that the two sites had similar sedimentary Corg accumulation rates (22-25 g m-2 yr-1) since the 1940s, while during the last two decades (∼1998 until 2018) they exhibited 24-30% higher accumulation of Corg, which was linked to shifts in Corg sources. The increase in the δ13C isotopic signature of sedimentary Corg (towards a higher seagrass contribution) at the Stone Town site since 1998 points to improved seagrass meadow conditions and Corg accumulation capacity of the meadow after the relocation of a major sewage outlet in the mid-1990s. In contrast, the decrease in the δ13C signatures of sedimentary Corg in the Mbweni meadow since the early 2010s was likely linked to increased Corg run-off of mangrove/terrestrial material following mangrove deforestation. This study exemplifies two different pathways by which land-based human activities can alter the carbon storage capacity of seagrass meadows (i.e. sewage waste management and mangrove deforestation) and showcases opportunities for management of vegetated coastal Corg sinks.

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  • 11.
    Eggertsen, Linda
    et al.
    Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden; Uppsala University, Department of Earth Sciences, Visby, Sweden; Reef Systems Ecology and Conservation Lab, Department of Marine Biology, Fluminense Federal University, Niterói, Brazil.
    Goodell, Whitney
    Fisheries Ecology Research Lab, University of Hawaii, Honolulu, HI, United States; Pristine Seas, National Geographic Society, Washington DC, United States.
    Cordeiro, Cesar A. M. M.
    Reef Systems Ecology and Conservation Lab, Department of Marine Biology, Fluminense Federal University, Niterói, Brazil; Ecology Post Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
    Cossa, Damboia
    Department of Biological Sciences, Eduardo Mondlane University, Maputo, Mozambique.
    de Lucena, Marcos
    Reef Systems Ecology and Conservation Lab, Department of Marine Biology, Fluminense Federal University, Niterói, Brazil; Ecology Post Graduation Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
    Berkström, Charlotte
    Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden; Department of Aquatic Resources, Institute of Coastal Research, Swedish University of Agricultural Sciences, Öregrund, Sweden.
    Franco, João N.
    MARE - Marine and Environmental Sciences Centre, ESTM, Politécnico de Leiria, Peniche, 2520-620, Portugal; CIIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Matosinhos, 4450-208, Portugal.
    Ferreira, Carlos E. L.
    Reef Systems Ecology and Conservation Lab, Department of Marine Biology, Fluminense Federal University, Niterói, Brazil.
    Bandeira, Salomão
    Department of Biological Sciences, Eduardo Mondlane University, Maputo, Mozambique.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Where the grass is greenest in seagrass seascapes depends on life history and simple species traits of fish2022In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 266, article id 107738Article in journal (Refereed)
    Abstract [en]

    Tropical seagrass meadows are critical habitats for many fish species, yet few studies have investigated the influence of multiple scale-dependent factors and marine protected areas on seagrass fish species of differing life histories. We assessed the influence of fine-scale seagrass meadow characteristics and seascape-scale variables on the abundance of fish in a seagrass-dominated seascape in the Bazaruto Archipelago, Mozambique, particularly examining patterns of nursery- vs. resident species as well as mobile- vs. sedentary species. We found that fish distribution patterns in this seagrass-dominated seascape were dependent on species’ life history characteristics; nursery taxa showed lower abundance in seagrass meadows further from adult reef habitats, while resident species within seagrass meadows occurred in higher abundances far from reefs. For taxa utilizing both mangroves and seagrass meadows as nursery habitat, proximity to mangroves was an important factor. Fish abundances were generally influenced by variables at the seascape scale (km), while sedentary species were predominantly influenced by area variables, and smaller seascapes (<500 m in radius) better explained distribution patterns. The influence of marine protected areas was taxon-specific, with the strongest effects of protection on resident species. Our results indicate that protection efforts in seagrass-dominated seascapes can have varying impacts on fish distribution, depending on the life history of the species present, and the geographical placement of the reserve within the seascape. Further, we suggest that simple species attributes can be utilised to describe generalized abundance patterns of fish in seagrass seascapes.

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  • 12.
    Elma, Eylem
    et al.
    Newcastle University, UK; Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Yahya, Saleh A.S.
    University of Dar es Salaam, Tanzania.
    Jouffray, Jean-Baptiste
    Stockholm University, Sweden.
    East, Holly K.
    Northumbria University, UK.
    Nyström, Magnus
    Stockholm University, Sweden.
    Post-bleaching alterations in coral reef communities2023In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 186, article id 114479Article in journal (Refereed)
    Abstract [en]

    We explored the extent of post-bleaching impacts, caused by the 2014–2016 El Niño Southern Oscillation (ENSO) event, on benthic community structure (BCS) and herbivores (fish and sea urchins) on seven fringing reefs, with differing protection levels, in Zanzibar, Tanzania. Results showed post-bleaching alterations in BCS, with up to 68 % coral mortality and up to 48 % increase in turf algae cover in all reef sites. Herbivorous fish biomass increased after bleaching and was correlated with turf algae increase in some reefs, while the opposite was found for sea urchin densities, with significant declines and complete absence. The severity of the impact varied across individual reefs, with larger impact on the protected reefs, compared to the unprotected reefs. Our study provides a highly relevant reference point to guide future research and contributes to our understanding of post-bleaching impacts, trends, and evaluation of coral reef health and resilience in the region.

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  • 13.
    Gerhardt, Karin
    et al.
    Sveriges lantbruksuniversitet, Sverige.
    Wolrath Söderberg, Maria
    Södertörn University, School of Culture and Education, Rhetoric.
    Lindblad, Inger
    Södertörn University, School of Social Sciences, Social Work.
    Diderichsen, Öjvind
    Södertörn University, Teacher Education, Teacher Education and Aesthetic Learning Processes.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dahlin, Maria
    Södertörn University, School of Culture and Education, Rhetoric.
    Köping Olsson, Ann-Sofie
    Södertörn University, School of Social Sciences, Business Studies.
    Lehtilä, Kari
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Rasoal, Chato
    Södertörn University, School of Police Studies.
    Dobers, Peter
    Södertörn University, School of Social Sciences, Business Studies.
    Johansson, Johanna
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Berndt, Kurt D.
    Södertörn University, Teacher Education, Mathematics Education.
    Karlholm, Dan
    Södertörn University, School of Culture and Education, History and Theory of Art.
    Kjellqvist, Tomas
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Lalander, Rickard
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Vallström, Maria
    Södertörn University, School of Historical and Contemporary Studies, Ethnology.
    Alvarsson-Hjort, Jesper
    Södertörn University, School of Social Sciences, Psychology.
    Sjöholm, Cecilia
    Södertörn University, School of Culture and Education, Aesthetics.
    Lönngren, Ann-Sofie
    Södertörn University, School of Culture and Education, Comparative Literature.
    Bydler, Charlotte
    Södertörn University, School of Culture and Education, History and Theory of Art.
    Färjsjö, Eva
    Södertörn University, Teacher Education, Mathematics Education.
    Porseryd, Tove
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Sio, Miriam
    Södertörn University, Teacher Education, Teacher Education and Aesthetic Learning Processes.
    Yazdanpanah, Soheyla
    Södertörn University, School of Culture and Education, Gender Studies.
    Pihl Skoog, Emma
    Södertörn University, School of Historical and Contemporary Studies, Archive Studies.
    Sörbom, Adrienne
    Södertörn University, School of Social Sciences, Sociology.
    Gallardo Fernández, Gloria L.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Wadstein MacLeod, Katarina
    Södertörn University, School of Culture and Education, History and Theory of Art.
    Garrison, Julie
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Andrén, Elinor
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Svärd, Veronica
    Södertörn University, School of Social Sciences, Social Work.
    Hajighasemi, Ali
    Södertörn University, School of Social Sciences, Social Work.
    Spånberger Weitz, Ylva
    Södertörn University, School of Social Sciences, Social Work.
    Elmersjö, Magdalena
    Södertörn University, School of Social Sciences, Social Work.
    Persson, Sara
    Södertörn University, School of Social Sciences, Business Studies.
    Borevi, Karin
    Södertörn University, School of Social Sciences, Political Science.
    Carlsson, Nina
    Södertörn University, School of Social Sciences, Political Science.
    Löfgren, Isabel
    Södertörn University, School of Culture and Education, Media and Communication Studies.
    Ghose, Sheila
    Södertörn University, School of Culture and Education, English language.
    Bonow, Madeleine
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Bornemark, Jonna
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Podolian, Olena
    Södertörn University, School of Social Sciences, Political Science.
    Grahn, Mats
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Gunnarsson Payne, Jenny
    Södertörn University, School of Historical and Contemporary Studies, Ethnology.
    Kaun, Anne
    Södertörn University, School of Culture and Education, Media and Communication Studies.
    Faber, Hugo
    Södertörn University, School of Social Sciences, Political Science.
    Cederberg, Carl
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Gradén, Mattias
    Högskolan Dalarna, Sverige.
    Nog nu, politiker – ta klimatkrisen på allvar2022In: Aftonbladet, no 2022-08-25Article in journal (Other (popular science, discussion, etc.))
  • 14.
    Gullström, Martin
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dahl, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Lindén, Olof
    Vorhies, Francis
    Forsberg, Sara
    Stockholm University, Sweden .
    Ismail, Rashid O.
    Stockholm University, Sweden; University of Dar es Salaam, Tanzania.
    Björk, Mats
    Stockholm University, Sweden.
    Coastal blue carbon stocks in Tanzania and Mozambique: Support for climate adaptation and mitigation actions2021Report (Other academic)
  • 15.
    Henriksson, Oskar
    et al.
    Södertörn University, School of Life Sciences, Biology.
    Mwandya, Augustine
    Sokoine University of Agriculture.
    Gullström, Martin
    Stockholm University.
    Thorberg, Marika
    Södertörn University, School of Life Sciences.
    Grahn, Mats
    Södertörn University, School of Life Sciences, Biology.
    Genetic Identification and Population Structure of Juvenile Mullet (Mugilidae) Collected for Aquaculture in East Africa2012In: Western Indian Ocean Journal of Marine Science, ISSN 0856-860X, E-ISSN 2683-6416, Vol. 11, no 1, p. 41-54Article in journal (Refereed)
    Abstract [en]

    There is a growing demand for wild caught juvenile fish to supply the market for aquaculture. However, little is known about the genetic effects of juvenile collection from wild populations. There are a number of imminent threats to both aquaculture systems and wild fish populations. Juvenile collection from a single population can for example reduce population’s evolutionary potential as well as the disease resistance within an aquaculture pond. In this study, we investigated the local genetic structure of juvenile mullets collected from five sites around Bagamoyo (Tanzanian mainland) and Zanzibar Island, East Africa. Fish were caught in low tide using a seine net. The fish were morphologically identified, and then genetically identified using direct sequencing of the CO1 gene with cross referencing with the Barcode of Life Database (BOLD) systems.  Molecular variance analyses were used to infer genetic subdivision based on geographic sampling site as well as inferring population structure through the Bayesian assignment test implemented in STRUCTURE 2.3. Our results showed that samples morphologically identified as Mugil cephalus where in fact Valamugil buchanani and we also found evidence of an introgression genome event, where the gene flow from one species may have affected the general gene pool. The Bayesian analysis revealed a clear genetic population structure among the sampled fish; the main difference was the presence of a unique mainland cluster. Our findings may have important implications for management and conservation of mullet fishes in the region and elsewhere.

  • 16.
    Ismail, R. O.
    et al.
    Stockholm University, Sweden; University of Dar es Salaam, Tanzania.
    Asplund, M. E.
    University of Gothenburg, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    George, R.
    Stockholm University, Sweden; Tanzania Fisheries Research Institute (TAFIRI), Tanzania.
    Dahl, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Buriyo, A. S.
    University of Dar es Salaam, Tanzania.
    Mtolera, M. S. P.
    University of Dar es Salaam, Tanzania.
    Björk, M.
    Stockholm University, Sweden.
    Effects of calcification on air-water CO2 fluxes in tropical seagrass meadows: A mesocosm experiment2023In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 561, article id 151864Article in journal (Refereed)
    Abstract [en]

    Seagrass meadows deliver a range of ecosystem services, where one of the more important is the capacity to store carbon and serve as sinks for atmospheric carbon dioxide. The capacity of seagrass meadows for carbon storage might, however, be modified and complicated by several factors; one important factor is the possible effects of calcification within the meadows. In tropical areas, seagrass meadows can contain high proportions of calcareous organisms, which through their calcification may cause release of CO2. To study this aspect of the CO2 balance within tropical seagrass systems, we investigated the air-water CO2 flux in seagrass mesocosms with different plant community compositions, i.e. mixtures of seagrass and calcifying macroalgae, having similar overall photosynthetic oxygen evolution rates. The measured CO2 fluxes changed both in rate and direction over the day and were significantly related to plant community composition. Downward fluxes of CO2 were found only over vegetation with high proportion of seagrass and in the afternoon, whereas occurrence of calcifying algae appeared to reverse the flow. A partial least squares (PLS) regression model indicated that pH, pCO2 and dissolved inorganic carbon (DIC) were the primary environmental variables predicting the CO2 fluxes. Our findings show that algal calcification might partly counteract the carbon sequestration in seagrass meadows.

  • 17.
    Jahnke, Marlene
    et al.
    University of Gothenburg / University of Groningen, Groningen, Netherlands.
    Gullström, Martin
    Stockholm University / University of Gothenburg.
    Larsson, Josefine
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Asplund, Maria E.
    Stockholm University / University of Gothenburg.
    Mgeleka, Said
    Stockholm University / Tanzania Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania.
    Silas, Mathew Ogalo
    Stockholm University / Tanzania Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania.
    Hoamby, Arielle
    Institut Halieutique et des Science Marine Toliara (IH.SM), Toliara, Madagascar.
    Mahafina, Jamal
    Institut Halieutique et des Science Marine Toliara (IH.SM), Toliara, Madagascar.
    Nordlund, Lina Mtwana
    Stockholm University / Uppsala University.
    Population genetic structure and connectivity of the seagrass Thalassia hemprichii in the Western Indian Ocean is influenced by predominant ocean currents2019In: Ecology and Evolution, E-ISSN 2045-7758, Vol. 9, no 16, p. 8953-8964Article in journal (Refereed)
    Abstract [en]

    This study is the first large-scale genetic population study of a widespread climax species of seagrass, Thalassia hemprichii, in the Western Indian Ocean (WIO). The aim was to understand genetic population structure and connectivity of T. hemprichii in relation to hydrodynamic features. We genotyped 205 individual seagrass shoots from 11 sites across the WIO, spanning over a distance of similar to 2,700 km, with twelve microsatellite markers. Seagrass shoots were sampled in Kenya, Tanzania (mainland and Zanzibar), Mozambique, and Madagascar: 4-26 degrees S and 33-48 degrees E. We assessed clonality and visualized genetic diversity and genetic population differentiation. We used Bayesian clustering approaches (TESS) to trace spatial ancestry of populations and used directional migration rates (DivMigrate) to identify sources of gene flow. We identified four genetically differentiated groups: (a) samples from the Zanzibar channel; (b) Mozambique; (c) Madagascar; and (d) the east coast of Zanzibar and Kenya. Significant pairwise population genetic differentiation was found among many sites. Isolation by distance was detected for the estimated magnitude of divergence (D-EST), but the three predominant ocean current systems (i.e., East African Coastal Current, North East Madagascar Current, and the South Equatorial Current) also determine genetic connectivity and genetic structure. Directional migration rates indicate that Madagascar acts as an important source population. Overall, clonality was moderate to high with large differences among sampling sites, indicating relatively low, but spatially variable sexual reproduction rates. The strongest genetic break was identified for three sites in the Zanzibar channel. Although isolation by distance is present, this study suggests that the three regionally predominant ocean current systems (i.e., East African Coastal Current, North East Madagascar Current, and the South Equatorial Current) rather than distance determine genetic connectivity and structure of T. hemprichii in the WIO. If the goal is to maintain genetic connectivity of T. hemprichii within the WIO, conservation planning and implementation of marine protection should be considered at the regional scale-across national borders.

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  • 18.
    Kalokora, Olivia J
    et al.
    Dar es Salaam University College of Education (DUCE), Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Buriyo, Amelia S
    University of Dar es Salaam, Tanzania.
    Mtolera, Matern S P
    University of Dar es Salaam, Tanzania.
    Björk, Mats
    Stockholm University, Sweden.
    Seagrass meadows mixed with calcareous algae have higher plant productivity and sedimentary blue carbon storage2022In: Ecology and Evolution, E-ISSN 2045-7758, Vol. 12, no 2, article id e8579Article in journal (Refereed)
    Abstract [en]

    Seagrass meadows capture and store large amounts of carbon in the sediment beneath, thereby serving as efficient sinks of atmospheric CO2. Carbon sequestration levels may however differ greatly among meadows depending on, among other factors, the plant community composition. Tropical seagrass meadows are often intermixed with macroalgae, many of which are calcareous, which may compete with seagrass for nutrients, light, and space. While the photosynthetic CO2 uptake by both seagrasses and calcareous algae may increase the overall calcification in the system (by increasing the calcium carbonate saturation state, Ω), the calcification process of calcareous algae may lead to a release of CO2, thereby affecting both productivity and calcification, and eventually also the meadows' carbon storage. This study estimated how plant productivity, CaCO3 production, and sediment carbon levels were affected by plant community composition (seagrass and calcareous algae) in a tropical seagrass-dominated embayment (Zanzibar, Tanzania). Overall, the patterns of variability in productivity differed between the plant types, with net areal biomass productivity being highest in meadows containing both seagrass and calcareous algae. Low and moderate densities of calcareous algae enhanced seagrass biomass growth, while the presence of seagrass reduced the productivity of calcareous algae but increased their CaCO3 content. Sedimentary carbon levels were highest when seagrasses were mixed with low or moderate cover of calcareous algae. The findings show that plant community composition can be an important driver for ecosystem productivity and blue carbon sequestration.

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  • 19.
    Krause-Jensen, Dorte
    et al.
    Aarhus University, Denmark.
    Gundersen, Hege
    Norwegian Institute for Water Research (NIVA), Norway.
    Björk, Mats
    Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dahl, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Asplund, Maria E.
    University of Gothenburg, Sweden.
    Boström, Christoffer
    Åbo Akademi University, Finland.
    Holmer, Marianne
    University of Southern Denmark, Denmark.
    Banta, Gary T.
    University of Southern Denmark, Denmark.
    Graversen, Anna Elizabeth Lovgren
    Aarhus University, Denmark.
    Pedersen, Morten Foldager
    Roskilde University, Denmark.
    Bekkby, Trine
    Norwegian Institute for Water Research (NIVA), Norway.
    Frigstad, Helene
    Norwegian Institute for Water Research (NIVA), Norway.
    Skjellum, Solrun Figenschau
    Norwegian Institute for Water Research (NIVA), Norway.
    Thormar, Jonas
    Institute of Marine Research, Norway.
    Gyldenkærne, Steen
    Aarhus University, Denmark.
    Howard, Jennifer
    Conservation International, Arlington, USA.
    Pidgeon, Emily
    Conservation International, Arlington, USA.
    Ragnarsdottir, Sunna Björk
    Icelandic Institute of Natural History, Iceland.
    Mols-Mortensen, Agnes
    TARI Faroe Seaweed, Faroe Islands; Fiskaaling, Faroe Islands.
    Hancke, Kasper
    Norwegian Institute for Water Research (NIVA), Norway.
    Nordic Blue Carbon Ecosystems: Status and Outlook2022In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 9, article id 847544Article, review/survey (Refereed)
    Abstract [en]

    Vegetated coastal and marine habitats in the Nordic region include salt marshes, eelgrass meadows and, in particular, brown macroalgae (kelp forests and rockweed beds). Such habitats contribute to storage of organic carbon (Blue Carbon - BC) and support coastal protection, biodiversity and water quality. Protection and restoration of these habitats therefore have the potential to deliver climate change mitigation and co-benefits. Here we present the existing knowledge on Nordic BC habitats in terms of habitat area, C-stocks and sequestration rates, co-benefits, policies and management status to inspire a coherent Nordic BC roadmap. The area extent of BC habitats in the region is incompletely assessed, but available information sums up to 1,440 km(2) salt marshes, 1,861 (potentially 2,735) km(2) seagrass meadows, and 16,532 km(2) (potentially 130,735 km(2), including coarse Greenland estimates) brown macroalgae, yielding a total of 19,833 (potentially 134,910) km(2). Saltmarshes and seagrass meadows have experienced major declines over the past century, while macroalgal trends are more diverse. Based on limited salt marsh data, sediment C-stocks average 3,311 g C-org m(-2) (top 40-100 cm) and sequestration rates average 142 g C-org m(-2) yr(-1). Eelgrass C-stocks average 2,414 g C-org m(-2) (top 25 cm) and initial data for sequestration rates range 5-33 g C-org m(-2), quantified for one Greenland site and one short term restoration. For Nordic brown macroalgae, peer-reviewed estimates of sediment C-stock and sequestration are lacking. Overall, the review reveals substantial Nordic BC-stocks, but highlights that evidence is still insufficient to provide a robust estimate of all Nordic BC-stocks and sequestration rates. Needed are better quantification of habitat area, C-stocks and fluxes, particularly for macroalgae, as well as identification of target areas for BC management. The review also points to directives and regulations protecting Nordic marine vegetation, and local restoration initiatives with potential to increase C-sequestration but underlines that increased coordination at national and Nordic scales and across sectors is needed. We propose a Nordic BC roadmap for science and management to maximize the potential of BC habitats to mitigate climate change and support coastal protection, biodiversity and additional ecosystem functions.

  • 20.
    Mgeleka, Said S. S.
    et al.
    Stockholm University, Sweden; Tanzania Fisheries Research Institute, Tanzania.
    Silas, Mathew Ogalo
    Tanzania Fisheries Research Institute, Tanzania.
    Mtonga, Cretus
    The Nelson Mandela African Institution of Science and Technology, Tanzania; The Leibniz Centre for Tropical Marine Research (ZMT), Germany.
    Rumisha, Cyrus
    Sokoine University of Agriculture, Tanzania.
    Viinamaki, Elina
    Stockholm University, Sweden.
    Polte, Patrick
    Institute of Baltic Sea Fisheries, Rostock, Germany.
    Sköld, Mattias
    Swedish University of Agricultural Sciences, Sweden.
    Winder, Monika
    Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Population genetics of the hound needlefish Tylosurus crocodilus (Belonidae) indicate high connectivity in Tanzanian coastal waters2023In: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 19, no 4-5, p. 261-270Article in journal (Refereed)
    Abstract [en]

    The hound needlefish Tylosurus crocodilus (Belonidae) is a highly demanded fish in the local markets of Tanzania, but the growing coastal population threatens its sustainability. As belonids are highly migratory fishes utilising various parts of the seascape, increased fishing pressure may disrupt connectivity patterns on different spatiotemporal scales and disaggregate populations. Using the COI gene, this study assessed the genetic population structure, connectivity patterns, and historical demography of T. crocodilus collected in seven sites spread along Tanzanian coastal waters. Results showed fourteen haplotypes with low overall nucleotide and haplotype diversity. Pairwise F-ST comparisons revealed no significant differences among the sampled sites, except for the northernmost site (Tanga) and an island in the south (Songosongo). Analysis of molecular variance (AMOVA) revealed a non-significant genetic structure among populations (F-ST = 0.01782), suggesting the fishery across Tanzanian waters exploits the same population. Moreover, there was no correlative relationship between genetic and pairwise geographic distances, rejecting the isolation by distance hypothesis. However, neutrality tests and mismatch distribution analysis revealed that recent demographic expansion might exist. Empirical evidence of panmixia suggests high genetic connectivity. In combination with low genetic diversity, management should be directed to actions that prevent genetic diversity loss and the effect of genetic drift on populations.

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  • 21.
    Moberg, Christina
    et al.
    EASAC; KTH, Sverige.
    Wolrath Söderberg, Maria
    Södertörn University, School of Culture and Education, Rhetoric.
    Sandberg, Linn
    Södertörn University, School of Culture and Education, Gender Studies.
    Lindblad, Inger
    Södertörn University, School of Social Sciences, Social Work.
    Sjöholm, Cecilia
    Södertörn University, School of Culture and Education, Aesthetics.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Lalander, Rickard
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Andrén, Elinor
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Vallström, Maria
    Södertörn University, School of Historical and Contemporary Studies, Ethnology.
    Bonow, Madeleine
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Andrén, Thomas
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Porseryd, Tove
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Grahn, Mats
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Karlholm, Dan
    Södertörn University, School of Culture and Education, History and Theory of Art.
    Smith, Nicholas
    Södertörn University, School of Culture and Education, Philosophy.
    Lehtilä, Kari
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Cederberg, Carl
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Svärd, Veronica
    Södertörn University, School of Social Sciences, Social Work.
    Gunnarsson Payne, Jenny
    Södertörn University, School of Historical and Contemporary Studies, Ethnology.
    Bornemark, Jonna
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Kaun, Anne
    Södertörn University, School of Culture and Education, Media and Communication Studies.
    Bergkvist, Anna-Mia
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Gunnarson, Martin
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Persson, Sara
    Södertörn University, School of Social Sciences, Business Studies.
    Jacobsson, Ellen
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Spånberger Weitz, Ylva
    Södertörn University, School of Social Sciences, Social Work.
    Diderichsen, Öjvind
    Södertörn University, Teacher Education, Teacher Education and Aesthetic Learning Processes.
    Gilek, Michael
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Garrison, Julie
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Pröckl, Maria
    Södertörn University, School of Culture and Education, Centre for Studies in Practical Knowledge.
    Janzén, Therese
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dobers, Peter
    Södertörn University, School of Social Sciences, Business Studies.
    Dinnétz, Patrik
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Bydler, Charlotte
    Södertörn University, School of Culture and Education, History and Theory of Art.
    Westerberg, Charles
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Elmersjö, Magdalena
    Södertörn University, School of Social Sciences, Social Work.
    Bisander, Thea
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Oreskovic, Nikolina
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Fröhlig, Florence
    Södertörn University, School of Historical and Contemporary Studies, Ethnology.
    Stedt, Kristoffer
    Göteborgs universitet, Sverige.
    De unga gör helt rätt när de stämmer staten: 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav2022In: Aftonbladet, no 2022-12-07, p. 2Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Vi, 1 620 forskare samt lärare vid universitet och högskolor, är eniga med de unga bakom Auroramålet: De drabbas och riskerar att drabbas allvarligt av klimatkrisen under sin livstid. De klimatåtgärder vi vidtar i närtid avgör deras framtid. Sverige måste ta ansvar och göra sin rättvisa andel av det globala klimatarbetet. 

    I strid med Parisavtalet ökar utsläppen av växthusgaser i en takt som gör att 1,5-gradersmålet kan överskridas om några år. De globala effekterna blir allt mer synliga med ständiga temperaturrekord, smältande isar, havshöjning och extremväder som torka, förödande bränder och skyfall med enorma översvämningar, som i Pakistan nyligen. Försörjningen av befolkningen utsätts för allvarliga hot i många länder.

    Minskningen av den biologiska mångfalden är extrem. Klimatkrisen är enligt WHO det största hotet mot människors hälsa i hela världen och barn utgör en särskilt sårbar grupp. Med Sveriges nordliga läge sker uppvärmningen här dubbelt så fort som det globala genomsnittet. Det förskjuter utbredningsområden för växtlighet och sjukdomsbärande insekter och ökar förekomsten av extremväder såsom värmeböljor, skogsbränder och översvämningar samt av många olika sorters infektioner och allergier. När extremväder ökar, ökar även stressen och risken för mental ohälsa. Värmeböljor ökar risken för sjukdom och död hos sårbara grupper som äldre, små barn och personer med kroniska sjukdomar. De negativa effekterna på hälsan kommer att öka i takt med klimatkrisen och barn riskerar att drabbas av ackumulerade negativa hälsoeffekter under hela sina liv. Redan i dag är mer än hälften av unga mellan 12 och 18 år i Sverige ganska eller mycket oroliga för klimat och miljö. Detta är förståeligt när våra beslutsfattare inte gör vad som krävs.

    Den juridiska och moraliska grunden för arbetet mot klimatförändringarna är att varje land måste göra sin rättvisa andel av det globala klimatarbetet. Centralt i det internationella klimatramverket är att rika länder med höga historiska utsläpp, däribland Sverige, måste gå före resten av världen. Dessa länder måste också bidra till att finansiera klimatomställningen i länderna i det Globala Syd, som är minst ansvariga för klimatkrisen men drabbas hårdast. Denna rättviseprincip är tydlig i Parisavtalet och var en het diskussionsfråga under COP27 i Sharm el-Sheikh, men lyser med sin frånvaro i det svenska klimatarbetet. 

    Sverige har satt mål för att minska sina utsläpp. Men de är helt otillräckliga: minskningstakten är för låg och målen tillåter samtidigt att åtgärder skjuts på framtiden. Dessutom exkluderas merparten av Sveriges utsläpp från de svenska nationella utsläppsmålen; bland annat utelämnas utsläpp som svensk konsumtion orsakar utanför Sveriges gränser, utsläpp från utrikes transporter och utsläpp från markanvändning och skogsbruk, exempelvis utsläpp från förbränning av biobränslen eller utsläpp från dikade våtmarker (Prop. 2016/17:146 s.25-28).

    Sverige saknar dessutom ett eget mål för att öka upptaget av växthusgaser genom utökat skydd och restaurering av ekosystem, något som krävs för att begränsa de värsta konsekvenserna av klimatkrisen (IPCC s.32). Trots dessa låga ambitioner misslyckas Sverige med att nå sina utsläppsmål, konstaterar både Klimatpolitiska rådet och Naturvårdsverket. En klimatpolitik i linje med Parisavtalet kräver både att alla typer av växthusgasutsläpp minskar samtidigt som – inte i stället för – upptaget av växthusgaser maximeras: i dag misslyckas Sverige på bägge fronter.

    Slutsatsen är tydlig. Sverige vidtar inte de åtgärder som krävs för att skydda barns och ungdomars rättigheter enligt Europakonventionen till skydd för de mänskliga rättigheterna. Detta medför allvarliga risker för liv och hälsa för unga generationer, människor i andra länder och särskilt utsatta grupper. Detta kan inte fortsätta. Därför ställer vi oss bakom Auroras krav att Sverige börjar göra sin rättvisa andel och omedelbart sätter igång ett omfattande och långtgående klimatarbete som vilar på vetenskaplig grund och sätter rättvisa i centrum.

  • 22.
    Ngisiange, Noah
    et al.
    Stockholm University, Sweden; Kenya Marine and Fisheries Research Institute, Kenya.
    Tarimo, Barnabas
    University of Dar es Salaam, Tanzania.
    Daudi, Lillian
    Kenya Marine and Fisheries Research Institute, Kenya.
    Mwangi, Stephen
    Kenya Marine and Fisheries Research Institute, Kenya.
    Malesa, Fadhili
    University of Dar es Salaam, Tanzania.
    George, Rushingisha
    Tanzania Fisheries Research Institute, Tanzania.
    Kyewalyanga, Margareth S
    University of Dar es Salaam, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Osore, Melckzedeck
    Kenya Marine and Fisheries Research Institute, Kenya.
    Mwaluma, James
    Kenya Marine and Fisheries Research Institute, Kenya.
    Winder, Monika
    Stockholm University, Sweden.
    Seasonal fish larvae abundance and composition in seagrass habitats of coastal East Africa2024In: Scientific Reports, E-ISSN 2045-2322, Vol. 14, no 1, p. 11203-, article id 11203Article in journal (Refereed)
    Abstract [en]

    Seagrass habitats play a major role in fisheries productivity through nursery functions and feeding grounds for diverse fish species. However, little is known about the seasonal distribution of fish larvae at large spatial scales in coastal East Africa. We investigated drivers of the seasonal fish larvae abundance and composition in seagrass habitats in Kenya and Tanzania. We found a high diversity of fish larvae (54 families) inhabiting seagrass habitats that differed between sites and seasons. Fish larvae abundance were highest in Kenya, particularly during the northeast monsoon season. Overall, total larval abundances per site were low, reaching less than 190 individuals/100 m3 in Kenya and less than 40 individuals/100 m3 in Tanzania, likely related to the low productivity and strong hydrodynamic processes in this region. Our data suggests that most of the fish spawn year-round in these tropical waters as we did not find strong seasonal patterns. All sites had a high relative abundance of larvae from demersal spawning fishes, indicating that many fish species move to coastal sites for spawning. Primary productivity and dissolved oxygen, driven by hydrodynamics conditions are positively related to fish larvae productivity both in Kenya and Tanzania. These findings indicate that the occurrence of both resident and transient fish larvae in seagrass meadows is driven by strong hydrodynamic and tidal processes that transport fish larvae across adjacent habitats.

  • 23.
    Nyangoko, B. P.
    et al.
    Stockholm University, Sweden; University of Dar es Salaam, Tanzania.
    Berg, H.
    Stockholm University, Sweden.
    Mangora, M. M.
    University of Dar es Salaam, Tanzania.
    Shalli, M. S.
    University of Dar es Salaam, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Local perceptions of changes in mangrove ecosystem services and their implications for livelihoods and management in the Rufiji Delta, Tanzania2022In: Ocean and Coastal Management, ISSN 0964-5691, E-ISSN 1873-524X, Vol. 219, article id 106065Article in journal (Refereed)
    Abstract [en]

    Understanding the status and trends of ecosystem services (ES) in a changing environment is important for identifying effective management measures of multifunctional mangrove ecosystems. Mangroves and their ES are jeopardized by a complex set of factors, with impacts that are experienced at local levels, especially in developing countries, where people often rely directly on natural capital for their livelihoods and well-being. This study was set to explore how local communities in the Rufiji Delta, situated in central coastal Tanzania, perceived the status and trends in mangrove ecosystem services (MES), associated drivers of change and the impacts of changes in MES on local livelihoods. A mixed methodological framework (including focus group discussions, key informant interviews, household surveys and direct observations) was used. People from villages close to mangroves rated the status of MES higher than those in villages distant from mangroves. Provisioning services (P) were often perceived to be in a worse and more declining state than regulating (R), cultural (C) and supporting services (S). A decrease in availability of poles and firewood (P), decline of fish habitats (S) and an increase in education value (C) were the most commonly perceived changes of MES in the study area. Illegal harvesting of mangrove poles, rice cultivation, climate change and inadequate management were seen as the most critical drivers of mangrove degradation, although the perceptions differed between sites. Rice farming was perceived to be a primary cause of mangrove loss by communities far from mangrove forests, while illegal exploitation was identified as the major driver by communities near mangroves. Fishing, collection of poles and honey were perceived as the most impacted livelihoodsdepending on MES. This together with the comparatively low status and declining trend of these MES indicate that they should be of high management priority as indicated by the first order management index used in this study.

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  • 24.
    Nyangoko, B. P.
    et al.
    Department of Physical Geography, Stockholm University, Stockholm, Sweden; Institute of Marine Sciences, University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Shalli, M. S.
    Institute of Marine Sciences, University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Mangora, M. M.
    Institute of Marine Sciences, University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Berg, H.
    Department of Physical Geography, Stockholm University, Stockholm, Sweden.
    Socioeconomic determinants of mangrove exploitation and management in the Pangani River Estuary, Tanzania2022In: Ecology & Society, E-ISSN 1708-3087, Vol. 27, no 2, article id 32Article in journal (Refereed)
    Abstract [en]

    Mangrove forests in Tanzania are gazetted as state forest reserves, implying that exploitation is controlled by the state. However, their continued degradation and loss is largely associated to the inadequate enforcement of management measures against uncontrolled extractive exploitation to support local livelihoods. Local management institutions are therefore advocated to enhance mangrove conservation. This study explored socioeconomic determinants of exploitation patterns and management of mangroves in the Pangani River Estuary, using two coastal communities (Bweni and Pangani Magharibi) as case study sites. Data were collected through focus group discussions, key informant interviews, household questionnaires, and field observations. Quantitative data were analyzed for both descriptive and statistical inferences, while qualitative information was subjected to content analysis. Residence time of household, household main occupation, household size, and cost of alternatives to mangroves as a source of domestic fuel were all factors positively associated with mangrove resource use. The two communities differed in their perceptions on the role of local institutions in management of mangroves. Over half of respondents (56%) in Bweni agreed that interventions by Beach Management Units (BMUs) enhanced mangrove conditions, whereas only about 16% of the respondents in Pangani Magharibi had similar perceptions. Overall, 55% of the respondents were not impressed with the performance of government institutions in implementing conservation measures for sustainable use of mangroves. Exploration and promotion of feasible alternative livelihood activities and improved stakeholders’ collaborative arrangements are recommended for sustainable exploitation and management of mangroves in the study area.

  • 25.
    Nyangoko, Baraka P.
    et al.
    Stockholm University; University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Berg, Håkan
    Stockholm University.
    Mangora, Mwita M.
    University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Shalli, Mwanahija S.
    University of Dar es Salaam, Buyu Campus, Zanzibar, Tanzania.
    Community perceptions of mangrove ecosystem services and their determinants in the Rufiji Delta, Tanzania2021In: Sustainability, E-ISSN 2071-1050, Vol. 13, no 1, p. 1-23, article id 63Article in journal (Refereed)
    Abstract [en]

    Understanding how local communities perceive and depend on mangrove ecosystem services (MES) is important for translating and incorporating their benefits, priorities, and preferences into conservation and decision-making processes. We used focus group discussions, key informant interviews, household questionnaires, and direct observations to explore how local communities in the Rufiji Delta perceive a multitude of MES and factors influencing their perceptions. Sixteen MES were identified by the respondents. Provisioning services were the most highly identified services, accounting for 67% of the overall responses, followed by regulating (53%), cultural (45%), and supporting (45%) services. Poles for building, firewood for cooking, coastal protection, and habitats for fisheries were perceived as the most important MES to sustain local livelihoods, although the perceptions differed between sites. Distance from household homes to mangroves and residence time were significant predictors of the local communities’ awareness of all identified MES. Gender of household heads and performance of local management committees also determined the local communities’ awareness of provisioning, regulating, and cultural services. We conclude that perceptions of MES are context-specific and influenced by multiple factors. We believe a deeper understanding of local stakeholders’ preferences for MES can help strengthen the link between local communities and conservation actors and can provide a basis for sustainable management of mangrove forests.

  • 26.
    Nyangoko, Baraka P.
    et al.
    Stockholm University, Sweden.;University of Dar es Salaam, Tanzania.
    Berg, Håkan
    Stockholm University, Sweden.
    Mangora, Mwita M.
    University of Dar es Salaam, Tanzania.
    Shalli, Mwanahija S.
    University of Dar es Salaam, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Community perceptions of climate change and ecosystem-based adaptation in the mangrove ecosystem of the Rufiji Delta, Tanzania2022In: Climate and Development, ISSN 1756-5529, E-ISSN 1756-5537, Vol. 14, no 10, p. 896-908Article in journal (Refereed)
    Abstract [en]

    Mangroves are increasingly recognized for their role in supporting adaptation to climate change and variability. However, knowledge about how climate change and variability affect mangrove ecosystem services (MES) and their role in supporting coastal communities to adaption is limited in Tanzania. We used participatory rural appraisal methods and field observations to explore local communities' perceptions of climate change and variability, and ecosystem-based adaptation (EbA) strategies in the mangroves of the Rufiji Delta, Tanzania. Decrease in rainfall, increased temperatures, coastal flooding, and the incidence of sea level rise were identified as key variables associated with a changing climate in the delta. Perceived climatic stresses included damaged fish breeding sites, altered climate regulation and a decrease in coastal protection and flood control. Decline in crop, fish and honey production were perceived as the main impacts on community livelihoods, although there were significant differences across occupational groups. Dependence on MES in times of shocks, such as when agriculture production fails, switching of occupation, crop diversification, fishing in deep waters and migration to other areas provided potential adaptation options. Although the reported perceptions related to climate change or variability are not explicit, they both have negative consequences to mangrove dependent communities' livelihoods.

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    fulltext
  • 27.
    Perry, Diana
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Tamarit, Elena
    University of Gothenburg, Sweden.
    Sundell, Erika
    Swedish University of Agricultural Sciences, Sweden.
    Axelsson, Michael
    University of Gothenburg, Sweden.
    Bergman, Sanne
    UiT – the Arctic University of Norway, Norway.
    Gräns, Albin
    Swedish University of Agricultural Sciences, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Sturve, Joachim
    University of Gothenburg, Sweden.
    Wennhage, Håkan
    Swedish University of Agricultural Sciences, Sweden.
    Physiological responses of Atlantic cod to climate change indicate that coastal ecotypes may be better adapted to tolerate ocean stressors2024In: Scientific Reports, E-ISSN 2045-2322, Vol. 14, no 1, article id 12896Article in journal (Refereed)
    Abstract [en]

    Healthy ecosystems and species have some degree of resilience to changing conditions, however as the frequency and severity of environmental changes increase, resilience may be diminished or lost. In Sweden, one example of a species with reduced resilience is the Atlantic cod (Gadus morhua). This species has been subjected to overfishing, and with additional pressures such as habitat degradation and changing environmental conditions there has been little to no recovery, despite more than a decade of management actions. Given the historical ecological, economical, and cultural significance of cod, it is important to understand how Atlantic cod respond to global climate change to recover and sustainably manage this species in the future. A multi-stressor experiment was conducted to evaluate physiological responses of juvenile cod exposed to warming, ocean acidification, and freshening, changes expected to occur in their nursery habitat. The response to single drivers showed variable effects related to fish biometrics and increased levels of oxidative stress dependent parameters. Importantly, two separate responses were seen within a single treatment for the multi-stressor and freshening groups. These within-treatment differences were correlated to genotype, with the offshore ecotype having a heightened stress response compared to the coastal ecotype, which may be better adapted to tolerate future changes. These results demonstrate that, while Atlantic cod have some tolerance for future changes, ecotypes respond differently, and cumulative effects of multiple stressors may lead to deleterious effects for this important species.

  • 28.
    Pittman, S. J.
    et al.
    Univ Oxford, Sch Geog & Environm, Oxford Seascape Ecol Lab, Oxford OX1 3QY, England.;Project Seascape CIC, Plymouth PL2 1RP, Devon, England..
    Yates, K. L.
    Univ Salford, Sch Sci, Manchester M5 4WT, Lancs, England..
    Bouchet, P. J.
    Univ St Andrews, Sch Math & Stat, St Andrews KY16 9SS, KY, Scotland.;Univ St Andrews, Ctr Res Ecol & Environm Modelling, St Andrews KY16 9LZ, KY, Scotland..
    Alvarez-Berastegui, D.
    Balearic Isl Coastal Observing & Forecasting Syst, Palma De Mallorca 07121, Mallorca, Spain..
    Andrefouet, S.
    Univ Nouvelle Caledonie, Inst Rech Dev, Univ La Reunion, Ctr Natl Rech Sci,UMR 9220 ENTROPIE,IFREMER, Noumea, New Caledonia..
    Bell, S. S.
    Univ S Florida, Dept Integrat Biol, Florida, FL 33620 USA..
    Berkström, C.
    Swedish Univ Agr Sci, Inst Coastal Res, Dept Aquat Resources, Skolgatan 6, S-74242 Oregrund, Sweden.;Stockholm Univ, Dept Ecol Environm & Plant Sci DEEP, S-10691 Stockholm, Sweden..
    Boström, C.
    Abo Akad Univ, Environm & Marine Biol, Artillerigatan 6, Turku 20520, Finland..
    Brown, C. J.
    Dalhousie Univ, Dept Oceanog, Halifax, NS B3H 4R2, Canada..
    Connolly, R. M.
    Griffith Univ, Sch Environm & Sci, Australian Rivers Inst Coast & Estuaries, Queensland, Qld 4222, Australia..
    Devillers, R.
    Univ Montpellier, Univ Antilles, Univ Guyane, Univ Renion,Inst Rech Dev,UMR 228 ESPACE DEV,IRD, F-34393 Montpellier, France..
    Eggleston, D.
    North Carolina State Univ, Dept Marine Earth Atmospher Sci, Raleigh, NC 27695 USA..
    Gilby, B. L.
    Univ Sunshine Coast, Sch Sci & Engn, Maroochydore, Qld 4558, Australia..
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Halpern, B. S.
    Univ Calif Santa Barbara, Natl Ctr Ecol Anal & Synth, Santa Barbara, CA 93101 USA.;Univ Calif Santa Barbara, Bren Sch Environm Sci & Management, Santa Barbara, CA 93106 USA..
    Hidalgo, M.
    Ctr Oceanogrf Balears, Inst Espanol Oceanograf, Ecosyst Oceanog Grp GRECO, Palma De Mallorca 07015, Mallorca, Spain..
    Holstein, D.
    Louisiana State Univ, Dept Oceanog & Coastal Sci, Baton Rouge, LA 70803 USA..
    Hovel, K.
    San Diego State Univ, Coastal & Marine Inst, Dept Biol, San Diego, CA 92101 USA..
    Huettmann, F.
    Univ Alaska Fairbanks, Inst Arctic Biol, Biol & Wildlife Dept, EWHALE Lab, Fairbanks, AK 99775 USA..
    Jackson, E. L.
    Cent Queensland Univ, Coastal Marine Ecosyst Res Ctr, Gladstone, Qld 4680, Australia..
    James, W. R.
    Univ Louisiana, Dept Biol, Lafayette, LA 70504 USA..
    Kellner, J. B.
    Int Council Explorat Sea ICES, DK-1553 Copenhagen V, Denmark..
    Kot, C. Y.
    Duke Univ, Nicholas Sch Environm, Marine Geospatial Ecol Lab, Beaufort, NC 28516 USA..
    Lecours, V
    Univ Florida, Sch Forest Resources & Conservat, Geomat Program & Fisheries & Aquat Sci Program, Florida, FL 32611 USA..
    Lepczyk, C.
    Auburn Univ, Sch Forestry & Wildlife Sci, Auburn, AL 36849 USA..
    Nagelkerken, I
    Univ Adelaide, Sch Biol Sci, Southern Seas Ecol Labs, South Australia, SA 5005, Australia.;Univ Adelaide, Environm Inst, Southern Seas Ecol Labs, South Australia, SA 5005, Australia..
    Nelson, J.
    Louisiana State Univ, Dept Oceanog & Coastal Sci, Baton Rouge, LA 70803 USA..
    Olds, A. D.
    Univ Sunshine Coast, Sch Sci & Engn, Maroochydore, Qld 4558, Australia..
    Santos, R. O.
    Florida Int Univ, Inst Environm, Miami, FL 33199 USA..
    Scales, K. L.
    Univ Sunshine Coast, Sch Sci & Engn, Maroochydore, Qld 4558, Australia..
    Schneider, D. C.
    Mem Univ Newfoundland, Dept Ocean Sci, Newfoundland, NF A1B 3X7, Canada..
    Schilling, H. T.
    Univ New South Wales, Sch Biol Earth Environm Sci, Sydney, NSW, Australia.;Sydney Inst Marine Sci, Mosman, NSW 2088, Australia..
    Simenstad, C.
    Univ Washington, Sch Aquat & Fishery Sci, Seattle, WA 98195 USA..
    Suthers, I. M.
    Univ New South Wales, Sch Biol Earth Environm Sci, Sydney, NSW, Australia.;Sydney Inst Marine Sci, Mosman, NSW 2088, Australia..
    Treml, E. A.
    Deakin Univ, Ctr Integrat Ecol, Sch Life & Environm Sci, Victoria, Vic 3216, Australia..
    Wedding, L. M.
    Univ Oxford, Sch Geog & Environm, Oxford Seascape Ecol Lab, Oxford OX1 3QY, England..
    Yates, P.
    Sydney Inst Marine Sci, Mosman, NSW 2088, Australia.;Dept Agr Water & Environm, Marine & Freshwater Species Conservat Biodivers C, Canberra, ACT 2601, Australia..
    Young, M.
    Deakin Univ, Ctr Integrat Ecol, Sch Life & Environm Sci, Victoria, Vic 3216, Australia..
    Seascape ecology: identifying research priorities for an emerging ocean sustainability science2021In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 663, p. 1-29Article in journal (Refereed)
    Abstract [en]

    Seascape ecology, the marine-centric counterpart to landscape ecology, is rapidly emerging as an interdisciplinary and spatially explicit ecological science with relevance to marine management, bio-diversity conservation, and restoration. While important progress in this field has been made in the past decade, there has been no coherent prioritisation of key research questions to help set the future research agenda for seascape ecology. We used a 2-stage modified Delphi method to solicit applied research questions from academic experts in seascape ecology and then asked respondents to identify priority questions across 9 interrelated research themes using 2 rounds of selection. We also invited senior management/conservation practitioners to prioritise the same research questions. Analyses highlighted congruence and discrepancies in perceived priorities for applied research. Themes related to both ecological concepts and management practice, and those identified as priorities include seascape change, seascape connectivity, spatial and temporal scale, ecosystem-based management, and emerging technologies and metrics. Highest-priority questions (upper tercile) received 50% agreement between respondent groups, and lowest priorities (lower tercile) received 58% agreement. Across all 3 priority tiers, 36 of the 55 questions were within a +/- 10% band of agreement. We present the most important applied research questions as determined by the proportion of votes received. For each theme, we provide a synthesis of the research challenges and the potential role of seascape ecology. These priority questions and themes serve as a roadmap for advancing applied seascape ecology during, and beyond, the UN Decade of Ocean Science for Sustainable Development (2021-2030).

  • 29.
    Rasmusson, Lina M.
    et al.
    Gothenburg university, Sweden.
    Nualla-ong, Aekkaraj
    Prince Songkla University, Thailand.
    Wutiruk, Tarawit
    Prince Songkla University, Thailand.
    Björk, Mats
    Stockholm University, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Buapet, Pimchanok
    Prince Songkla University, Thailand.
    Sensitivity of Photosynthesis to Warming in Two Similar Species of the Aquatic Angiosperm Ruppia from Tropical and Temperate Habitats2021In: Sustainability, E-ISSN 2071-1050, Vol. 13, no 16, article id 9433Article in journal (Refereed)
    Abstract [en]

    Climate change-related events, such as marine heatwaves, are increasing seawater temperatures, thereby putting pressure on marine biota. The cosmopolitan distribution and significant contribution to marine primary production by the genus Ruppia makes them interesting organisms to study thermal tolerance and local adaptation. In this study, we investigated the photosynthetic responses in Ruppia to the predicted future warming in two contrasting bioregions, temperate Sweden and tropical Thailand. Through DNA barcoding, specimens were determined to Ruppia cirrhosa for Sweden and Ruppia maritima for Thailand. Photosynthetic responses were assessed using pulse amplitude-modulated fluorometry, firstly in short time incubations at 18, 23, 28, and 33 degrees C in the Swedish set-up and 28, 33, 38, and 43 degrees C in the Thai set-up. Subsequent experiments were conducted to compare the short time effects to longer, five-day incubations in 28 degrees C for Swedish plants and 40 degrees C for Thai plants. Swedish R. cirrhosa displayed minor response, while Thai R. maritima was more sensitive to both direct and prolonged temperature stress with a drastic decrease in the photosynthetic parameters leading to mortality. The results indicate that in predicted warming scenarios, Swedish R. cirrhosa may sustain an efficient photosynthesis and potentially outcompete more heat-sensitive species. However, populations of the similar R. maritima in tropical environments may suffer a decline as their productivity will be highly reduced.

  • 30.
    Silas, Mathew O.
    et al.
    Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania.
    Kishe, Mary A.
    Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania.
    Semba, Masumbuko R.
    Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania.
    Kuboja, Bigeyo N.
    Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania.
    Ngatunga, Benjamin
    Tanzania Tuna Fishery National Alliance, Dar es Salaam, Tanzania.
    Mgeleka, Said S.
    Fisheries Research Institute (TAFIRI), Dar es Salaam, Tanzania; Stockholm University, Sweden.
    Linderholm, Hans W.
    University of Gothenburg, Sweden.
    Dahl, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Seascape configuration influences big blue octopus (Octopus cyanea) catches: Implications for a sustainable fishery2023In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 264, article id 106716Article in journal (Refereed)
    Abstract [en]

    Seascape configuration is known to influence fish distribution and abundance in coastal waters. However, there is little information regarding how the shape of the coastal seascape influences catches of landed fisheries species, particularly so in the understudied western Indian Ocean (WIO). With focus on big blue octopus (Octopus cyanea), which is a widely found cephalopod species in the WIO, we compared landed catches (biomass, catch rate, and density) in submerged and exposed reefs, and explored the influence of proximity to fishing villages and reef habitat size on octopus landings. We used fishery-dependent data collected between 2018 and 2020 from eight landing sites spread across the Tanzanian coast. We found a strong relationship between biomass of octopus catch and distance from fished reefs to fishing villages, with higher fished biomass on reefs farther away. Octopus densities were higher, while catch rates were lower, on reefs very close to (within one km distance from) fishing villages compared to more distant reefs. In general, submerged reefs provided higher catches than exposed reefs. The low octopus catches on the exposed reefs were attributed to high fishing pressure, while submerged reefs that are only accessible through diving provide optimal areas for octopuses to grow. Octopus catches were, however, not significantly affected by reef size. The findings suggest that management policies should proportionate fishing efforts to ensure sustainable exploitation of reefs and associated fishery resources.

  • 31.
    Silas, Matthew O.
    et al.
    Stockholm University, Sweden; Tanzania Fisheries Research Institute,Tanzania.
    Semba, Masumbuko L.
    Nelson Mandela African Institution of Science and Technology, Tanzania.
    Mgeleka, Said S.
    Stockholm University, Sweden; Tanzania Fisheries Research Institute,Tanzania.
    Van Well, Lisa
    Swedish Geotechnical Institute, Sweden.
    Linderholm, Hans W.
    University of Gothenburg, Sweden.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Using fishers’ local ecological knowledge for management of small-scale fisheries in data-poor regions: Comparing seasonal interview and field observation records in East Africa2023In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 264, article id 106721Article in journal (Refereed)
    Abstract [en]

    Fishers, scientists and policy makers need to describe, understand and “agree on” variations in fish catches caused by exploitation and climate change for effective fisheries management. To achieve this, relevant data with sufficient spatiotemporal resolution is a necessity. In regions of the Global South, such as the Western Indian Ocean (WIO), fish catch data useful for management is scarce or non-existing. Still, the potential of local ecological knowledge to provide such information has not been fully utilised in these regions. In this study, we evaluated fishers’ local ecological knowledge (based on interviews) against detailed seasonal fish catch variability data based on catch per unit effort (CPUE) records. Because of the importance of the monsoon seasons for marine resource variability, differences in fish catches during the northeast (NE) and southeast (SE) monsoon seasons were investigated. Fishers’ perceptions generally agreed with catch data records, both showing that the NE monsoon season generally provides higher catch rates than the SE monsoon season. The fishers’ perceptions at two of the landing sites (Nyamisati and Shangani) contradict the recorded observations by showing highest fish catches during the SE monsoon season. It was clear, however, that fishers’ perceptions in these two sites focused on the most valuable target species (prawn and tuna in Nyamisati and Shangani, respectively) rather than total catches. In this particular case, fishers’ perceptions facilitated the significance of taking target species into consideration. The findings of this study highlight the importance of integrating local ecological knowledge into scientific research to help understand the complex dynamics of coastal fisheries and improve the management of data-poor fisheries. 

  • 32.
    Tarimo, Barnabas
    et al.
    Stockholm University, Sweden; University of Dar Es Salaam, Zanzibar, Tanzania.
    Winder, Monika
    Stockholm University, Sweden.
    Mtolera, Matern S. P.
    University of Dar Es Salaam, Zanzibar, Tanzania.
    Muhando, Christopher A.
    University of Dar Es Salaam, Zanzibar, Tanzania.
    Gullström, Martin
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Seasonal distribution of fish larvae in mangrove-seagrass seascapes of Zanzibar (Tanzania)2022In: Scientific Reports, E-ISSN 2045-2322, Vol. 12, no 1, article id 4196Article in journal (Refereed)
    Abstract [en]

    Fish larvae supply in nearshore vegetated habitats, such as seagrass meadows and mangroves, contributes significantly to sustainable fish stocks. Yet, little information is available on distribution patterns of fish larvae in mangrove and seagrass habitats of the western Indian Ocean. The present study investigated the abundance, diversity and assemblage composition of fish larvae in mangrove creeks, inshore seagrass meadows (located adjacent to mangroves) and nearshore seagrass meadows (located in-between mangroves and coral reefs) in two coastal seascapes of Zanzibar (Tanzania) across seasons for 1 year. The highest mean abundances of fish larvae were recorded in mangrove creeks, while nearshore- and inshore seagrass meadows showed similar mean abundance levels. Generally, fish larvae representing 42 families were identified, with the fourteen most abundant families comprising 83% of all specimens. Fish larvae communities were dominated by specimens of the postflexion growth stage in all habitats, except in mangrove creeks in one of the two seascapes (i.e. Chwaka Bay) from April through June when abundances of the preflexion and very small-sized individuals were exceptionally high. Slightly higher fish larvae abundances were observed in mangroves during the southeast monsoon compared to the northeast monsoon, and there were also differences across months within monsoon periods for all three habitats studied. Assemblage composition of larvae did, however, not vary significantly in time or space. Our findings suggest that mangroves and seagrass meadows are highly linked shallow-water habitats with high retention of fish larvae contributing to similarity in assemblage compositions across shallow coastal seascapes. Conservation and management efforts should prioritize connected shallow-water seascapes for protection of fish larvae and to uphold sustainable coastal fisheries.

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