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  • 51.
    Björk, Mikael
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Ecological and physiological aspects of contaminant accumulation and transport by the filter-feeding mussel, Mytilus edulis1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis examines the influence of food availability on the bioaccumulation kinetics and the transport of hydrophobic organic contaminants (HOCs) by the Baltic Sea blue mussel, Mytilus edulis. In laboratory studies, food availability was found to significantly modify the rate of physiological processes involved in filter-feeding. This also influenced the rate of exposure to HOCs as determined by the amount of HOCs associated with the flux of water and food. The uptake rate of HOCs by the mussels was found to be positively related to the exposure rate, whereas HOC elimination appeared to be unaffected by differences in food availability. However, the amount of HOCs assimilated declined with increases in the exposure rate, and the largest increase in HOC tissue concentrations was found at an intermediate food availability.

    The role of the blue mussel in the cycling of carbon and HOCs was also investigated in the field and by a modelling approach. As filter-feeders the mussels consume near-bed suspended particulate organic matter that, in contaminated areas, contains high concentrations of HOCs. Filter-feeding activity and the subsequent release of faecal matter by the mussels increased the vertical flux of HOCs from the water column to the benthic community by at least 50% in the study area. Other significant routes of HOC transport by mussels in the coastal zone of the Baltic proper include transfer to predators, elimination of dissolved HOC, and elimination via spawning and transfer to zooplanktivores, as indicated in the established annual budget models.

    It is concluded that the filter-feeding activity of the mussels have a significant influence on HOC fluxes within both the organism and the ecosystem. The findings presented here emphasise the role of animal physiology in contaminant kinetics and have important implications for the experimental design and interpretation of laboratory bioaccumulation and toxicity studies, as well as field sampling and marine monitoring programmes.

  • 52.
    Björklund, Mats
    et al.
    Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University.
    Almqvist, Gustaf
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rapid spatial genetic differentiation in an invasive species, the round goby Neogobius melanostomus in the Baltic Sea2010In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 12, no 8, p. 2609-2618Article in journal (Refereed)
    Abstract [en]

    We analysed the pattern of genetic differentiation among six newly established (around 10 generations) sites of the round goby (Neogobius melanostomus) in the southern Baltic Sea by means of nine microsatellite loci and in total 183 individuals. All but one site were within 30 km from each other. We found statistically significant genetic differentiation in ten out of 15 comparisons after Bonferroni correction, and since the species is newly introduced this has happened in less than ten generations. The largest genetic differentiation was found between the two most divergent habitats, while sites with a similar habitat were not significantly differentiated. Estimates of gene flow (Nm) were low and ranged from 1.5 to 5.5. A large proportion of individuals were assigned to one site (Puck), suggesting that this site has acted as a source to the other sites.

  • 53.
    Blomqvist, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Marin ekologi.
    Green, M
    Lindström, Å
    The spring migration of Grey Plover Pluvialis squatarola in Sweden2007In: Ornis svecica, Vol. 17, p. 121-136Article in journal (Refereed)
  • 54.
    Blomqvist, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gunnars, A.
    Räddningsplan för Östersjön2008In: Kemivärlden Biotech med Kemisk Tidskrift, Vol. 4/2008, p. 28-30Article in journal (Other academic)
  • 55.
    Blomqvist, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gunnars, Anneli
    Älvdalen education centre.
    The geological past seawater records suggests enhanced modern marine phosphorus availability2010Other (Other academic)
  • 56.
    Blomqvist, Sven
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rydin, E.
    Hur fosforbindningen i Östersjöns bottensediment kan förbättras.2009Report (Other academic)
  • 57. Bodin, Örjan
    et al.
    Crona, Beatrice
    Ernstson, Henrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Social networks in natural resource management: what is there to learn from a structural perspective?2006In: Ecology and Society, ISSN 1708-3087, Vol. 11, no 2, p. r2-Article in journal (Refereed)
  • 58.
    Bodin, Örjan
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Naturresurshushållning.
    Norberg, Jon
    Stockholm University, Faculty of Science, Department of Systems Ecology. Naturresurshushållning.
    A network approach for analyzing spatially structured populations in fragmented landscape2007In: Landscape Ecology, Vol. 22, no 1, p. 31-44Article in journal (Refereed)
  • 59.
    Bodin, Örjan
    et al.
    Stockholm University, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Systems Ecology.
    Saura, Santiago
    Ranking individual habitat patches as connectivity providers: Integrating network analysis and patch removal experiments2010In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 221, no 19, p. 2393-2405Article in journal (Refereed)
    Abstract [en]

    Here we propose an integrated framework for modeling connectivity that can help ecologists, conservation planners and managers to identify patches that, more than others, contribute to uphold species dispersal and other ecological flows in a landscape context. We elaborate, extend and partly integrate recent network-based approaches for modeling and supporting the management of fragmented landscapes. In doing so, experimental patch removal techniques and network analytical approaches are merged into one integrated modeling framework for assessing the role of individual patches as connectivity providers. In particular, we focus the analyses on the habitat availability metrics PC and IIC and on the network metric Betweenness Centrality. The combination and extension of these metrics jointly assess both the immediate connectivity impacts of the loss of a particular patch and the resulting increased vulnerability of the network to subsequent disruptions. In using the framework to analyze the connectivity of two real landscapes in Madagascar and Catalonia (NE Spain), we suggest a procedure that can be used to rank individual habitat patches and show that the combined metrics reveal relevant and non-redundant information valuable to assert and quantify distinctive connectivity aspects of any given patch in the landscape. Hence, we argue that the proposed framework could facilitate more ecologically informed decision-making in managing fragmented landscapes. Finally, we discuss and highlight some of the advantages, limitations and key differences between the considered metrics.

  • 60.
    Bodin, Örjan
    et al.
    Stockholm University, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tengo, Maria
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Disentangling intangible social-ecological systems2012In: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 22, no 2, p. 430-439Article in journal (Refereed)
    Abstract [en]

    Contemporary environmental challenges call for new research approaches that include the human dimension when studying the natural environment. In spite of the recent development of several conceptual frameworks integrating human society with nature, there has been less methodological and theoretical progress on how to quantitatively study such social-ecological interdependencies. We propose a novel theoretical framework for addressing this gap that partly builds on the rapidly growing interdisciplinary research on complex networks. The framework makes it possible to unpack, define and formalize ways in which societies and nature are interdependent, and to empirically link this to specific governance challenges and opportunities using a range of theories from both the social and natural sciences in an integrated way. At the core of the framework is a set of basic building blocks (motifs) that each represents a simplified but non-trivial social-ecological systems (SES) consisting of two social actors and two ecological resources. The set represents all possible patterns of interdependency in a SES. Each unique motif is characterized in terms of social and ecological connectivity, resource sharing, and resource substitutability. By aligning theoretical insights related to the management of common-pool resources, metapopulation dynamics, and the problem of fit in SES with the set of motifs, we demonstrate the multi-theoretical ability of the framework in a case study of a rural agricultural landscape in southern Madagascar. Several mechanisms explaining the inhabitants' demonstrated ability to preserve their scattered forest patches in spite of strong pressures on land and forest resources are presented.

  • 61.
    Bodin, Örjan
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tengö, Maria
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Norman, Anna
    Stockholm University, Stockholm Resilience Centre.
    Lundberg, Jakob
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    The value of small size: loss of forest patches and ecological thresholds in southern Madagascar2006In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 16, no 2, p. 440-451Article in journal (Refereed)
    Abstract [en]

    Many services generated by forest ecosystems provide essential support for human well-being. However, the vulnerability of these services to environmental change such as forest fragmentation are still poorly understood. We present spatial modeling of the generation of ecosystem services in a human-dominated landscape where forest habitat patches, protected by local taboos, are located in a matrix of cultivated land in southern Madagascar. Two ecosystem services dependent on the forest habitats were addressed: (1) crop pollination services by wild and semidomesticated bees (Apoidea), essential for local crop production of, for example, beans, and (2) seed dispersal services based on the presence of ring-tailed lemurs (Lemur catta). We studied the vulnerability of these ecosystem services to a plausible scenario of successive destruction of the smallest habitat patches. Our results indicate that, in spite of the fragmented nature of the landscape, the fraction of the landscape presently covered by both crop pollination and seed dispersal services is surprisingly high. It seems that the taboo system, though indirectly and unintentionally, contributes to upholding the generation of these services by protecting the forest patches. Both services are, however, predicted to be very vulnerable to the successive removal of small patches. For crop pollination, the rate of decrease in cover was significant even when only the smallest habitat patches were removed. The capacity for seed dispersal across the landscape displayed several thresholds with habitat patch removal. Our results suggest that, in order to maintain capacity for seed dispersal across the landscape and crop pollination cover in southern Androy, the geographical location of the remaining forest patches is more crucial than their size. We argue that in heavily fragmented production landscapes, small forest patches should increasingly be viewed as essential for maintaining ecosystem services, such as agricultural production, and also should be considered in the ongoing process of tripling the area of protected habitats in Madagascar.

  • 62.
    Bonaglia, Stefano
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Bartoli, Marco
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rahm, Lars
    Raymond, Caroline
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Svensson, Ola
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Shakeri Yekta, Sepehr
    Brüchert, Volker
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Effect of reoxygenation and Marenzelleria spp. bioturbation on Baltic Sea sediment metabolism2013In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 482, p. 43-55Article in journal (Refereed)
    Abstract [en]

    Nutrient reduction and the improvement of bottom water oxygen concentrations are thought to be key factors in the recovery of eutrophic aquatic ecosystems. The effects of reoxygenation and bioturbation of natural hypoxic sediments in the Baltic Sea were studied using a mesocosm experiment. Anoxic sediment box cores were collected from 100 m depth in Kanholmsfjärden (Stockholm Archipelago) and maintained in flow-through mesocosms with 3 treatments: (1) hypoxic: supplied with hypoxic water; (2) normoxic: supplied with oxic water; and (3) Marenzelleria: supplied with oxic water and the polychaete Marenzelleria spp. (2000 ind. m–2). After a 7 wk long conditioning period, net fluxes of dissolved O2, CH4, Fe2+, Mn2+, NH4+, NO2-, NO3-, PO43- and H4SiO4, and rates of nitrate ammonification (DNRA), denitrification and anammox were determined. Phosphate was taken up by the sediment in all treatments, and the uptake was highest in the normoxic treatment with Marenzelleria. Normoxic conditions stimulated the denitrification rate by a factor of 5. Denitrification efficiency was highest under normoxia (50%), intermediate in bioturbated sediments (16%), and very low in hypoxic sediments (4%). The shift from hypoxic to normoxic conditions resulted in a significantly higher retention of NH4+, H4SiO4 and Mn2+ in the sediment, but the bioturbation by Marenzelleria reversed this effect. Results from our study suggest that bioturbation by Marenzelleria stimulates the exchange of solutes between sediment and bottom water through irrigation and enhances bacterial sulfate reduction in the burrow walls. The latter may have a toxic effect on nitrifying bacteria, which, in turn, suppresses denitrification rates.

  • 63. Bonsdorff, Erik
    et al.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Varning för fiskepolitik à la Jönssonligan2007In: Svenskt Fiske, Vol. 1, p. 38-39Article in journal (Other (popular science, discussion, etc.))
  • 64.
    Borgström, S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Challenges of urban nature conservation.2008Licentiate thesis, monograph (Other academic)
  • 65.
    Borgström, Sara
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Den nyttiga grönskan2009In: Stockholm: den gröna storstaden. / [ed] Sörenson, Ulf, Stockholm: Lind & Co , 2009Chapter in book (Other (popular science, discussion, etc.))
  • 66.
    Borgström, Sara
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Naturen till din tjänst2007In: SNF årsbok, SNF, Stockholm , 2007Chapter in book (Other (popular science, discussion, etc.))
  • 67.
    Borgström, Sara
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Urban shades of green: Current patterns and future prospects of nature conservation in urban landscapes2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Urban nature provides local ecosystem services such as absorption of air pollutants, reduction of noise, and provision of places for recreation, and is therefore crucial to urban sustainable development. Nature conservation in cities is also part of the global effort to halt biodiversity decline. Urban landscapes, however, display     distinguishing social and ecological characteristics and therefore the implementation of nature conservation frameworks into cities, requires reconsideration of what nature to preserve, for whom and where. The aim of this thesis was to examine the current urban nature conservation with special focus on formally protected areas, and discuss their future role in the urban landscape. A social-ecological systems approach was used as framework and both quantitative and qualitative methods were applied. The studies were performed at local to regional scales in the southern part of Sweden. Four key questions were addressed: i) What are the characteristics of nature conservation in urban landscapes? ii) How does establishment of nature conservation areas affect the surrounding urban landscape? iii) In what ways are spatial and temporal scales recognized in practical management of nature conservation areas? and iv) How can the dichotomy of built up and nature conservation areas be overcome in urban planning? Nature reserves in urban, compared to rural landscapes were in general fewer, but larger and included a higher diversity of land covers. They were also based on a higher number and different kinds of objectives than rural nature reserves. Urbanisation adjacent to nature reserves followed the general urbanisation patterns in the cities and no additional increase in urban settlements could be detected. In general, there was a lack of social and ecological linkages between the nature conservation areas and the urban landscape and practical management showed a limited recognition of cross-scale interactions and meso-scales. Such conceptual and physical isolation risks decreasing the public support for nature conservation, cause biodiversity decline, and hence impact the generation of ecosystem services. A major future challenge is therefore to transform current conservation strategies to become a tool where urban nature is perceived, planned and managed as valuable and integrated parts of the city. To enable social-ecological synergies, future urban planning should address proactive approaches together with key components like active enhancement of multifunctional landscapes, cross-scale strategies and border zone management.

  • 68.
    Borgström, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Cousins, Sara
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Outside the boundary - land use changes in the surroundings of urban nature reserves2012In: Applied Geography, ISSN 0143-6228, E-ISSN 1873-7730, Vol. 32, no 2, p. 350-359Article in journal (Refereed)
    Abstract [en]

    The importance of the landscape surrounding a protected area for sustaining its values is frequently discussed in conservation literature. Studies on the interactions of urbanisation and nature conservation at the global scale suggest that protected nature attracts urbanisation, and that this in turn might negatively impact the area. However, studies specifically addressing such land use dynamics at city scale are largely missing. In this study we examine the change in proportion of built up area in two zones (500 m and 1000 m) surrounding 15 urban nature reserves in southern Sweden. By using comprehensive maps from the last 50 years, we compared the zones to the overall urbanisation in the cities to reveal discrepancies in land use surrounding the nature reserves. We found that the amount of built up area in the buffer zones surrounding nature reserves followed the same trend as the corresponding cities and this relation was stable over time, although the positive relationship was not significant. The establishment of nature reserves had no detectable effect on surrounding land use, however two distinguished groups of reserves were identified with either more or less built up area in buffers zones compared to cities. These differences were related to specific local drivers such as land ownership, land use history and nature reserve location. In contrast to earlier studies at global scale, our study did not show that nature reserves attract urbanisation. Instead, we stress that the great variety of contextual factors at the city scale makes quantitative analysis of this kind extremely difficult. However, a general neglect from planning and nature conservation agencies to recognise nature reserves’ dependence on the surrounding landscape configuration could be detrimental to sustain their values in the long-term. Hence we suggest that zones surrounding nature-protected areas should be planned and managed according to local land use history and current landscape conditions to enable and enhance necessary cross-boundary interactions.

  • 69.
    Borgström, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Angelstam, Per
    School of Forest Engineers, Swedish University of Agricultural Sciences.
    Alfsen-Norodom, Christine
    Columbia University, UENSCO Joint program on Biosphere and Society.
    Scale mismatches in management of urban landscapes2006In: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 11, no 2Article in journal (Refereed)
    Abstract [en]

    Urban landscapes constitute the future environment for most of the world’s human population.An increased understanding of the urbanization process and of the effects of urbanization at multiple scalesis, therefore, key to ensuring human well-being. In many conventional natural resource managementregimes, incomplete knowledge of ecosystem dynamics and institutional constraints often leads toinstitutional management frameworks that do not match the scale of ecological patterns and processes. Inthis paper, we argue that scale mismatches are particularly pronounced in urban landscapes. Urban greenspaces provide numerous important ecosystem services to urban citizens, and the management of theseurban green spaces, including recognition of scales, is crucial to the well-being of the citizens. From aqualitative study of the current management practices in five urban green spaces within the GreaterStockholm Metropolitan Area, Sweden, we found that 1) several spatial, temporal, and functional scalesare recognized, but the cross-scale interactions are often neglected, and 2) spatial and temporal meso-scalesare seldom given priority. One potential effect of the neglect of ecological cross-scale interactions in thesehighly fragmented landscapes is a gradual reduction in the capacity of the ecosystems to provide ecosystemservices. Two important strategies for overcoming urban scale mismatches are suggested: 1) developmentof an integrative view of the whole urban social–ecological landscape, and 2) creation of adaptivegovernance systems to support practical management.

  • 70.
    Borgström, Sara T.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Patterns and challenges of urban nature conservation - a study of southern Sweden2009In: Environment and planning A, ISSN 0308-518X, E-ISSN 1472-3409, Vol. 41, no 11, p. 2671-2685Article in journal (Refereed)
    Abstract [en]

    The current, dominating strategy of nature conservation within urban landscapes is to formally protect remaining patches of unexploited nature in nature reserves. However, integration of nature conservation frameworks into urban planning requires reconsideration of key issues, such as why, where, and how to protect nature in a purposeful way. As part of that process I statistically evaluate current nature conservation in 209 municipalities in southern Sweden by analysing the number, size, age, and land cover patterns of 1869 nature reserves in relation to the degree of urbanisation. The analyses reveal that in urban municipalities the nature reserves are fewer, but larger, and have a higher diversity of land covers. Having large nature reserves may be especially important in urban landscapes, since it is often highly fragmented. The land cover compositions show no differences between urban and rural nature reserves. However, urban nature reserves differ more from their surroundings compared with rural nature reserves, according to the identified changes in representation of land cover types with an increasing degree of urbanisation. The most urgent future challenge identified is to develop urban nature conservation strategies that are integrated into the urban context including other green areas and built-up areas, the land-use history, and the requirements for local ecosystem services across the landscape.

  • 71.
    Bradshaw, Clare
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Kautsky, Ulrik
    Kumblad, Linda
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Ecological stoichiometry and multi element transfer in a coastal ecosystem2012In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 15, no 4, p. 591-603Article in journal (Refereed)
    Abstract [en]

    Energy (carbon) flows and element cycling are fundamental, interlinked principles explaining ecosystem processes. The element balance in components, interactions and processes in ecosystems (ecological stoichiometry; ES) has been used to study trophic dynamics and element cycling. This study extends ES beyond its usual limits of C, N, and P and examines the distribution and transfer of 48 elements in 16 components of a coastal ecosystem, using empirical and modeling approaches. Major differences in elemental composition were demonstrated between abiotic and biotic compartments and trophic levels due to differences in taxonomy and ecological function. Mass balance modeling for each element, based on carbon fluxes and element:C ratios, was satisfactory for 92.5% of all element similar to compartment combinations despite the complexity of the ecosystem model. Model imbalances could mostly be explained by ecological processes, such as increased element uptake during the spring algal bloom. Energy flows in ecosystems can thus realistically estimate element transfer in the environment, as modeled uptake is constrained by metabolic rates and elements available. The dataset also allowed us to examine one of the key concepts of ES, homeostasis, for more elements than is normally possible. The relative concentrations of elements in organisms compared to their resources did not provide support for the theory that autotrophs show weak homeostasis and showed that the strength of homeostasis by consumers depends on the type of element (for example, macroelement, trace element). Large-scale, multi-element ecosystem studies are essential to evaluate and advance the framework of ES and the importance of ecological processes.

  • 72.
    Bradshaw, Clare
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tjensvoll, Ingrid
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Sköld, M.
    Allan, I. J.
    Molvaer, J.
    Magnusson, J.
    Naes, K.
    Nilsson, H. C.
    Bottom trawling resuspends sediment and releases bioavailable contaminants in a polluted fjord2012In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 170, p. 232-241Article in journal (Refereed)
    Abstract [en]

    Sediments are sinks for contaminants in the world's oceans. At the same time, commercial bottom trawling is estimated to affect around 15 million km(2) of the world's seafloor every year. However, few studies have investigated whether this disturbance remobilises sediment-associated contaminants and, if so, whether these are bioavailable to aquatic organisms. This field study in a trawled contaminated Norwegian fjord showed that a single 1.8 km long trawl pass created a 3-5 million m(3) sediment plume containing around 9 t contaminated sediment; ie. 200 g dw m(-2) trawled, equivalent to c. 10% of the annual gross sedimentation rate. Substantial amounts of PCDD/Fs and non-ortho PCBs were released from the sediments, likely causing a semi-permanent contaminated sediment suspension in the bottom waters. PCDD/Fs from the sediments were also taken up by mussels which, during one month, accumulated them to levels above the EU maximum advised concentration for human consumption.

  • 73.
    Breitbarth, E
    et al.
    Univ Gothenburg, Dept Chem Analyt & Marine Chem.
    Gelting, J
    Lulea Univ Technol, Div Appl Geol.
    Walve, Jakob
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hoffmann, LJ
    Univ Gothenburg, Dept Chem Analyt & Marine Chem.
    Turner, DR
    Univ Gothenburg, Dept Chem Analyt & Marine Chem.
    Hassellov, M
    Univ Gothenburg, Dept Chem Analyt & Marine Chem.
    Ingri, J
    Lulea Univ Technol, Div Appl Geol.
    Dissolved iron (II) in the Baltic Sea surface water and implications for cyanobacterial bloom development2009In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 6, no 11, p. 2397-2420Article in journal (Refereed)
    Abstract [en]

    Iron chemistry measurements were conducted during summer 2007 at two distinct locations in the Baltic Sea (Gotland Deep and Landsort Deep) to evaluate the role of iron for cyanobacterial bloom development in these estuarine waters. Depth profiles of Fe(II) were measured by chemiluminescent flow injection analysis (CL-FIA). Up to 0.9 nmol Fe(II) L-1 were detected in light penetrated surface waters, which constitutes up to 20% to the dissolved Fe pool. This bioavailable iron source is a major contributor to the Fe requirements of Baltic Sea phytoplankton and apparently plays a major role for cyanobacterial bloom development during our study. Measured Fe(II) half life times in oxygenated water exceed predicted values and indicate organic Fe(II) complexation. Potential sources for Fe(II) ligands, including rainwater, are discussed. Fe(II) concentrations of up to 1.44 nmol L-1 were detected at water depths below the euphotic zone, but above the oxic anoxic interface. Mixed layer depths after strong wind events are not deep enough in summer time to penetrate the oxic-anoxic boundary layer. However, Fe(II) from anoxic bottom water may enter the sub-oxic zone via diapycnal mixing and diffusion.

  • 74.
    Calliari, D.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Andersen Borg, C.M.
    Thor, P.
    Gorokhova, E.
    Tiselius, P.
    Instantaneous salinity reductions affect the survival and clearance rates of the co-occurring copepods Acartia tonsa and A. clausi differently2008In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, Vol. 362, no 1, p. 18-25Article in journal (Refereed)
  • 75.
    Calliari, D.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Andersen, C.M.
    Thor, P.
    Gorokhova, E.
    Tiselius, P.
    Salinity modulates the energy balance and reproduction success of co-occurring copepods Acartia tonsa and A. clausi in different ways2006In: Marine Ecology Progress Series, ISSN 0171-8630, Vol. 312, p. 177-188Article in journal (Refereed)
  • 76. Calliari, Danilo
    et al.
    Andersen Borg, Marc
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Thor, Peter
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Tiselius, Peter
    Instantaneous salinity reductions affect the survival and feeding rates of the co-occuring copepods Acartia tonsa Dana and A. clausi Giesbrecht differently2008In: Journal of experimental marine biology and ecology, ISSN 0022-0981, Vol. 362, no 1, p. 18-25Article in journal (Refereed)
    Abstract [en]

    Salinity variability at short time scales constitutes a severe restriction to marine life in coastal and estuarine ecosystems. In these environments zooplankters may experience rapid salinity variations due to diverse processes, yet lethal or sub-lethal responses to such changes have been scarcely studied. We assessed short-term (12 h) survival and time-integrated clearance (F; mL ind(-1) h(-1)) and ingestion rates (1, mu gC ind(-1) h(-1)) after 1, 2, 4, 8 and 12 h of two widespread and abundant coastal copepods, Acartia tonsa and A. clausi, subjected to instant salinity changes from 32 PSU to 26, 20,14, 8 and 4 PSU (A. tonsa) and from 32 to 26, 20 and 14 PSU (A. clausi). We expected that A. tonsa, which occur naturally in environments where sharp salinity gradients are common would tolerate wider salinity changes than A. clausi, which less frequently encounter sharp gradients in nature. For A. tonsa mortality for the extreme haline shock (change from 32 to 4 PSU) was 31%, whereas A. clausi reached 22% Mortality already at a change from 32 to 14 PSU; in comparison, mortality for A. tonsa at the 32/14 PSU treatment was only 3%. F and I decreased significantly at extreme treatments, and the total clearance in experimental bottles with salinity shocked animals (F-tot, mL h(-1)) was only 5% of rates measured in non-shocked control bottles for A. tonsa (32/4 PSU change) and 20% for A. clausi (32/14 PSU change); corresponding total ingestion (I-tot, mu gC h(-1)) represented 9.5% of that in control bottles for A. tonsa and 24% for A. clausi. In comparison, the 32/14 PSU treatment did not affect either clearance or ingestion rates in A. tonsa. Results suggest that in the field A. tonsa is not likely to suffer significant mortalities due to sudden salinity reductions in the Surrounding medium - except under extreme circumstances- while A. clausi cannot tolerate changes > 18 PSU. However, in both species feeding activity could be severely compromised by salinity reductions. The decreased feeding rate may have direct implications for processes ranging from energy acquisition at individual level to organic matter transfers at ecosystem level and thus deserves more attention in experimental studies and population modelling.

  • 77. Carlson, Björn
    et al.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Utfiskningen av haven. Oansvarigt öppna för torskfiske i Östersjön.2009In: Dagens nyheterArticle in journal (Other (popular science, discussion, etc.))
  • 78.
    Cederwall, Hans
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Leonardsson, K
    Albertsson, J
    Dimming, A
    Magnusson, M
    Mjukbottenfauna - nytt index för jämförelse2007In: Havet, p. 62-67Article in journal (Other (popular science, discussion, etc.))
  • 79. Chapin, FS
    et al.
    Danell, K
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology. Naturresurshushållning.
    Folke, Carl
    Stockholm University, Faculty of Science, Department of Systems Ecology. Naturresurshushållning.
    Fresco, N
    Managing climate change impacts to enhance the resilience and sustainability of Fennoscandian forests2007In: Ambio, Vol. 36, no 7, p. 528-531Article in journal (Refereed)
  • 80. Cinner, J. E.
    et al.
    Mcclanahan, T. R.
    Graham, N. A. J.
    Daw, Tim
    Bodin, Örjan
    Stockholm University, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Systems Ecology.
    Maina, J.
    Stead, S. M.
    Wamukota, A.
    Brown, A.
    Vulnerability of coastal communities to key impacts of climate change on coral reef fisheries2012In: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 22, no 1, p. 12-20Article in journal (Refereed)
    Abstract [en]

    Coral reefs support the livelihood of millions of people especially those engaged in marine fisheries activities. Coral reefs are highly vulnerable to climate change induced stresses that have led to substantial coral mortality over large spatial scales. Such climate change impacts have the potential to lead to declines in marine fish production and compromise the livelihoods of fisheries dependent communities. Yet few studies have examined social vulnerability in the context of changes specific to coral reef ecosystems. In this paper, we examine three dimensions of vulnerability (exposure, sensitivity, and adaptive capacity) of 29 coastal communities across five western Indian Ocean countries to the impacts of coral bleaching on fishery returns. A key contribution is the development of a novel, network-based approach to examining sensitivity to changes in the fishery that incorporates linkages between fishery and non-fishery occupations. We find that key sources of vulnerability differ considerably within and between the five countries. Our approach allows the visualization of how these dimensions of vulnerability differ from site to site, providing important insights into the types of nuanced policy interventions that may help to reduce vulnerability at a specific location. To complement this, we develop framework of policy actions thought to reduce different aspects of vulnerability at varying spatial and temporal scales. Although our results are specific to reef fisheries impacts from coral bleaching, this approach provides a framework for other types of threats and different social-ecological systems more broadly.

  • 81. Cinner, Joshua E.
    et al.
    Bodin, Örjan
    Stockholm University, Stockholm Resilience Centre. Stockholm University, Faculty of Science, Department of Systems Ecology.
    Livelihood Diversification in Tropical Coastal Communities: A Network-Based Approach to Analyzing 'Livelihood Landscapes'2010In: PloS one, ISSN 1932-6203, Vol. 5, no 8, p. e11999-Article in journal (Refereed)
    Abstract [en]

    Background: Diverse livelihood portfolios are frequently viewed as a critical component of household economies in developing countries. Within the context of natural resources governance in particular, the capacity of individual households to engage in multiple occupations has been shown to influence important issues such as whether fishers would exit a declining fishery, how people react to policy, the types of resource management systems that may be applicable, and other decisions about natural resource use. Methodology/Principal Findings: This paper uses network analysis to provide a novel methodological framework for detailed systemic analysis of household livelihood portfolios. Paying particular attention to the role of natural resource-based occupations such as fisheries, we use network analyses to map occupations and their interrelationships-what we refer to as 'livelihood landscapes'. This network approach allows for the visualization of complex information about dependence on natural resources that can be aggregated at different scales. We then examine how the role of natural resource-based occupations changes along spectra of socioeconomic development and population density in 27 communities in 5 western Indian Ocean countries. Network statistics, including in-and out-degree centrality, the density of the network, and the level of network centralization are compared along a multivariate index of community-level socioeconomic development and a gradient of human population density. The combination of network analyses suggests an increase in household-level specialization with development for most occupational sectors, including fishing and farming, but that at the community-level, economies remained diversified. Conclusions/Significance: The novel modeling approach introduced here provides for various types of livelihood portfolio analyses at different scales of social aggregation. Our livelihood landscapes approach provides insights into communities' dependencies and usages of natural resources, and shows how patterns of occupational interrelationships relate to socioeconomic development and population density. A key question for future analysis is how the reduction of household occupational diversity, but maintenance of community diversity we see with increasing socioeconomic development influences key aspects of societies' vulnerability to environmental change or disasters.

  • 82. Clevestam, P. D.
    et al.
    Ogonowski, Martin
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Sjöberg, N. B.
    Wickström, H.
    Too short to spawn?: Implications of small body size and swimming distance on successful migration and maturation of the European eel Anguilla anguilla2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 4, p. 1073-1089Article in journal (Refereed)
    Abstract [en]

    Individual net fat reserves after migration and reproductive investments were calculated for migrating female silver eels Anguilla anguilla (n = 387) collected in the outlet region of the Baltic Sea during the autumn run. It is estimated that 20 center dot 4% of the A. anguilla had completely exhausted all initial fat reserves and that 45 center dot 0% of A. anguilla were within 90% of complete energy depletion after migration and reproduction. This study concludes that a combination of body size and distance (6900 km) to the spawning area in the Sargasso Sea explains the results. An increase in the costs of migration due to heavy infection with Anguillicoloides crassus was also evaluated in an additional scenario with results showing that 26 center dot 4% of the A. anguilla had completely depleted all fat reserves. It is hypothesized that a large proportion of female silver A. anguilla from the Baltic Sea catchment area will have inadequate or suboptimal reserves for successful migration and reproduction.

  • 83. Conley, Daniel J.
    et al.
    Björck, Svante
    Bonsdorff, Erik
    Carstensen, Jacob
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Gustafsson, Bo G.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Hietanen, Susanna
    Kortekaas, Marloes
    Kuosa, Harri
    Meier, H. E. Markus
    Muller-Karulis, Baerbel
    Nordberg, Kjell
    Norkko, Alf
    Nurnberg, Gertrud
    Pitkänen, Heikki
    Rabalais, Nancy N.
    Rosenberg, Rutger
    Savchuk, Oleg P.
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Slomp, Caroline P.
    Voss, Maren
    Wulff, Fredrik
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Zillén, Lovisa
    Hypoxia-Related Processes in the Baltic Sea2009In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 43, no 10, p. 3412-3420Article in journal (Refereed)
    Abstract [en]

    Hypoxia, a growing worldwide problem, has been intermittently present in the modern Baltic Sea since its formation ca. 8000 cal. yr BP. However, both the spatial extent and intensity of hypoxia have increased with anthropogenic eutrophication due to nutrient inputs. Physical processes, which control stratification and the renewal of oxygen in bottom waters, are important constraints on the formation and maintenance of hypoxia. Climate controlled inflows of saline water from the North Sea through the Danish Straits is a critical controlling factor governing the spatial extent and duration of hypoxia. Hypoxia regulates the biogeochemical cycles of both phosphorus (P) and nitrogen (N) in the water column and sediments. Significant amounts of P are currently released from sediments, an order of magnitude larger than anthropogenic inputs. The Baltic Sea is unique for coastal marine ecosystems experiencing N losses in hypoxic waters below the halocline. Although benthic communities in the Baltic Sea are naturally constrained by salinity gradients, hypoxia has resulted in habitat loss over vast areas and the elimination of benthic fauna, and has severely disrupted benthic food webs. Nutrient load reductions are needed to reduce the extent, severity, and effects of hypoxia.

  • 84. Conley, Daniel J.
    et al.
    Carstensen, Jacob
    Aigars, Juris
    Axe, Philip
    Bonsdorff, Erik
    Eremina, Tatjana
    Haahti, Britt-Marie
    Humborg, Christoph
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Jonsson, Per
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Kotta, Jonne
    Lannegren, Christer
    Larsson, Ulf
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Maximov, Alexey
    Medina, Miguel Rodriguez
    Stockholm University, Stockholm Resilience Centre, Baltic Nest Institute.
    Lysiak-Pastuszak, Elzbieta
    Remeikaite-Nikiene, Nijole
    Walve, Jakob
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Wilhelms, Sunhild
    Zillen, Lovisa
    Hypoxia is increasing in the coastal zone of the Baltic Sea2011In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 45, no 16, p. 6777-6783Article in journal (Refereed)
    Abstract [en]

    Hypoxia is a well-described phenomenon in the offshore waters of the Baltic Sea with both the spatial extent and intensity of hypoxia known to have increased due to anthropogenic eutrophication, however, an unknown amount of hypoxia is present in the coastal zone. Here we report on the widespread unprecedented occurrence of hypoxia across the coastal zone of the Baltic Sea. We have identified 115 sites that have experienced hypoxia during the period 1955-2009 increasing the global total to ca. 500 sites, with the Baltic Sea coastal zone containing over 20% of all known sites worldwide. Most sites experienced episodic hypoxia, which is a precursor to development of seasonal hypoxia. The Baltic Sea coastal zone displays an alarming trend with hypoxia steadily increasing with time since the 1950s effecting nutrient biogeochemical processes, ecosystem services, and coastal habitat.

  • 85.
    Cornelissen, Gerard
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Amstaetter, Katja
    Hauge, Audun
    Schaanning, Morten
    Beylich, Bjornar
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Breedveld, Gijs D.
    Oen, Amy M. P.
    Eek, Espen
    Large-Scale Field Study on Thin-Layer Capping of Marine PCDD/F-Contaminated Sediments in Grenlandfjords, Norway: Physicochemical Effects2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 21, p. 12030-12037Article in journal (Refereed)
    Abstract [en]

    A large-scale field experiment on in situ thin-layer capping was carried out in the polychlorinated dibenzodioxin, and dibenzofuran (PCDD/F) contaminated Grenlandsfjords, Norway The main focus of the,trial Was to,test the effectiveness of active caps (targeted thickness of 2.5 cm) consisting of powdered activated carbon (AC) mixed into locally dredged clean clay. Nonactive caps (targed thickness of 5 cm) consisting of clay without, AC as well as crushed limestone were also tested Fields with areas of 10 000 to 40 000 m(2) were established at 30 to 100 m water depth. Auxiliary shaken laboratory batch experiments showed that 2% of the applied powdered AC substantially reduced PCDD/F porewater concentrations, by >90% for tetra-, penta- and hexa-clorinated congeners to 60-70% for octachlorinated ones. In situ AC profiles revealed that the AC was mixed into the sediment to 3 to 5 cm depth in 20 months. Only around 25% of the AC was found inside the pilot fields. Sediment-to-water PCDD/F fluxes measured by in situ diffusion chambers were significantly lower at the capped fields than at reference fields in the same fjord, reductions being largest for the limestone (50-90%) followed by clay (50-70%), and the AC + clay (60%). Also reductions in overlying aqueous PCDD/F concentrations measured by passive samplers were significant in most cases (20-40% reduction), probably because of the large size of the trial fields. The AC was less effective in the field than in the laboratory, probably due to prolonged sediment-to-AC mass transfer times for PCDD/Fs and field factors such as integrity of the cap, new deposition Of contaminated sediment particles, and bioturbation. The present field data indicate that slightly thicker layers of limestone and dredged clay can show as good physicochemical effectiveness as thin caps of AC mixed with clay, at least for PCDD/Fs during the first two years after cap placement.

  • 86.
    Cornelissen, Gerard
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Krusa, Marie Elmquist
    Breedveld, Gijs D.
    Eek, Espen
    Oen, Amy M. P.
    Arp, Hans Peter H.
    Raymond, Caroline
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Samuelsson, Göran
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hedman, Jenny E.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Stokland, Oystein
    Gunnarsson, Jonas S.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Remediation of Contaminated Marine Sediment Using Thin-Layer Capping with Activated Carbon-A Field Experiment in Trondheim Harbor, Norway2011In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 45, no 14, p. 6110-6116Article in journal (Refereed)
    Abstract [en]

    In situ amendment of contaminated sediments using activated carbon (AC) is a recent remediation technique, where the strong sorption of contaminants to added AC reduces their release from sediments and uptake into organisms. The current study describes a marine underwater field pilot study in Trondheim harbor, Norway, in which powdered AC alone or in combination with sand or clay was tested as a thin-layer capping material for polycyclic aromatic hydrocarbon (PAH)-contaminated sediment. Several novel elements were included, such as measuring PAH fluxes, no active mixing of AC into the sediment, and the testing of new manners of placing a thin AC cap on sediment, such as AC+clay and AC+sand combinations. Innovative chemical and biological monitoring methods were deployed to test capping effectiveness. In situ sediment-to-water PAH fluxes were measured using recently developed benthic flux chambers. Compared to the reference field, AC capping reduced fluxes by a factor of 2-10. Pore water PAH concentration profiles were measured in situ using anew passive sampler technique, and yielded a reduction factor of 2-3 compared to the reference field. The benthic macrofauna composition and biodiversity were affected by the AC amendments, AC + clay having a lower impact on the benthic taxa than AC-only or AC + sand. In addition, AC + clay gave the highest AC recoveries (60% vs 30% for AC-only and AC + sand) and strongest reductions in sediment-to-water PAH fluxes and porewater concentrations. Thus, application of an AC-clay mixture is recommended as the optimal choice of the currently tested thin-layer capping methods for PAHs, and more research on optimizing its implementation is needed.

  • 87.
    Cousins, Sara A. O.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Stockholm University, Faculty of Science, Department of Botany. växtekologi.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Remnant grassland habitats as source communities for plant diversification in agricultural landscapes2008In: BIOLOGICAL CONSERVATION, Vol. 141, p. 233-240Article in journal (Refereed)
    Abstract [en]

    Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. These fields normally contain a fraction of the plant species richness compared to semi-natural grasslands. However, small remnant habitats have been suggested as important for plant species diversity and conservation as they may function as refugia for grassland specialists in fragmented and highly modified agricultural landscapes. In this study, we examined whether plant communities on small remnant habitats, i.e. midfield islets, can function as sources for grassland species to disperse out into surrounding grazed ex-fields (former arable fields). We examined species richness and grassland specialists (species favoured by grazing) and their ability to colonize fields after 5 and 11 years of grazing. The fields that had been grazed for a shorter time were fairly species-poor with few grassland specialists. A longer period of grazing had a positive effect on total and small-scale species diversity in both islets and fields. Species composition became more similar with time, and the number of grassland specialists in both habitats increased. We found that grassland specialists dispersed step-wise into the fields, and the number of grassland specialists decreased with distance from the source. Our study suggests that remnant habitats, such as midfield islets, do function as a source community for grassland specialists and enhance diversification of grassland species when grazing is introduced. For long-term conservation of plant species, incorporating small refugia into larger grazing complexes may thus enhance species richness.

  • 88.
    Cousins, Sara A. O.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Mattsson, Sofia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Land use history and site location are more important for grassland species richness than local soil properties2009In: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 27, p. 483-489Article in journal (Refereed)
    Abstract [en]

    Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. Grazing ex-arable fields contain a fraction of the plant species richness confined to semi-natural grasslands. Still, they have been suggested as potential target sites for re-creation of semi-natural grasslands. We asked to what extent does fine-scale variation in soil conditions, management history and site location effect local plant diversity in grazed ex-arable fields. We examined local soil conditions such as texture, pH, organic carbon, nitrogen (N) and extractable phosphate (P) and effects on plant richness in ten pairs of grazed ex-fields and neighbouring semi-natural grasslands in different rural landscapes. Each grassland pair where in the same paddock. A multivariate test showed that site location and land use history explained more of differences in species richness than local soil property variables. Plant species richness was positively associated to grazed ex-fields with low pH, low N and P levels. Sites with high plant richness in semi-natural grasslands also had more species in the adjacent grazed ex-fields, compared to sites neighbouring less species-rich semi-natural grasslands. Although both soil properties and species richness were different in grazed ex-fields compared to semi-natural grassland, the site location within a landscape, and vicinity to species-rich grasslands, can override effects of soil properties. In conclusion, if properly located, ex-arable fields may be an important habitat to maintain plant diversity at larger spatio-temporal scales and should considered as potential sites for grassland restoration.

  • 89.
    Crona, Beatrice
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Bodin, Örjan
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Power Asymmetries in Small-Scale Fisheries: a Barrier to GovernanceTransformability?2010In: Ecology and society, Vol. 15, no 4Article in journal (Refereed)
  • 90.
    Crona, Beatrice
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Nyström, Magnus
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Folke, Carl
    Stockholm University, Stockholm Resilience Centre.
    Jiddawi, Narriman
    Middlemen, a critical social-ecological link in coastal communities of Kenya and Zanzibar2010In: Marine Policy, ISSN 0308-597X, E-ISSN 1872-9460, Vol. 34, no 4, p. 761-771Article in journal (Refereed)
    Abstract [en]

    This paper analyzes the middlemen-fishermen link in coastal communities along the coast of southern Kenya and Zanzibar, and explores effects of reciprocal agreements and credit arrangements on social-ecological feedbacks of coastal systems The existence and generality of such arrangements are mapped and their effect on resource use and ecosystem dynamics is then explored Data show that credit arrangements are widespread and that fishermen are bound by reciprocal agreements and financial guarantees during periods of lower catches that provide short-term stabilizing social effects These arrangements create incentives which disconnect resource extraction from ecosystem dynamics and impede development of sustainable use practices The role of middlemen is seldom accounted for in fisheries governance Scenarios for the development of small-scale fisheries in the region are outlined and the function of middlemen is discussed considering the influence of external drivers Policies that incorporate middlemen are recommended to improve the governance of fish stocks and coastal ecosystems in East Africa.

  • 91.
    Crona, Beatrice
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rönnbäck, Patrik
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Community structure and temporal variability of juvenile fish assemblages in natural and replanted mangroves, Sonneratia alba Sm., of Gazi Bay, Kenya2007In: Estuarine Coastal and Shelf Science, Vol. 74, p. 44-52Article in journal (Refereed)
  • 92. Crépin, Anne-Sophie
    et al.
    Norberg, Jon
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Maler, Karl-Göran
    Coupled economic-ecological systems with slow and fast dynamics - Modelling and analysis method2011In: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 70, no 8, p. 1448-1458Article in journal (Refereed)
    Abstract [en]

    The purpose of this article is to contribute to the exploration of non-convex dynamics in coupled human-nature systems. We study welfare issues associated with the management of a human-nature complex adaptive system with a threshold and a stochastic driver. We exemplify with a specific system where we link changes in the number and diversity of birds to the abundance of a pest (insects) that causes damages to goods and services valuable to human beings. We present a method that simplifies the analysis and helps us discuss different management models that combine direct and indirect controls of the pest. This allows us to show that 1) the choice of control method depends in a highly non-linear way on biodiversity characteristics and 2) the socially optimal outcome may not be reachable using price instruments. Hence the price vs. quantity debate needs to be revisited using a complex adaptive system lens.

  • 93.
    Crépin, Ann-Sophie
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Science, Beijer Institute of Ecological Economics, Sweden.
    Norberg, Jon
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Folke, Carl
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Science, Beijer Institute of Ecological Economics, Sweden.
    Kautsky, Nils
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Troell, Max
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Science, Beijer Institute of Ecological Economics, Sweden.
    Social-ecological systems as complex adaptive systems: modeling and policy implications2013In: Environment and Development Economics, ISSN 1355-770X, E-ISSN 1469-4395, Vol. 18, no 2, p. 111-132Article in journal (Refereed)
    Abstract [en]

    Systems linking people and nature, known as social-ecological systems, are increasingly understood as complex adaptive systems. Essential features of these complex adaptive systems – such as nonlinear feedbacks, strategic interactions, individual and spatial heterogeneity, and varying time scales – pose substantial challenges for modeling. However, ignoring these characteristics can distort our picture of how these systems work, causing policies to be less effective or even counterproductive. In this paper we present recent developments in modeling social-ecological systems, illustrate some of these challenges with examples related to coral reefs and grasslands, and identify the implications for economic and policy analysis.

  • 94. Cumming, G.
    et al.
    Norberg, J.
    Stockholm University, Faculty of Science, Department of Systems Ecology. interfaculty units, Stockholm Resilience Centre.
    Scale and Complex Systems2008In: Complexity theory for a sustainable future, Columbia university press. NY , 2008Chapter in book (Refereed)
  • 95. Cumming, Graeme S.
    et al.
    Bodin, Örjan
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Ernstson, Henrik
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Elmqvist, Thomas
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Network analysis in conservation biogeography: challenges and opportunities2010In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 16, no 3, p. 414-425Article in journal (Refereed)
    Abstract [en]

    Aims  To highlight the potential value of network analysis for conservation biogeography and to focus attention on some of the challenges that lie ahead in applying it to conservation problems.

    Location  Global.

    Methods  We briefly review existing literature and then focus on five important challenges for the further development of network-based approaches in the field.

    Results  Our five challenges include (i) understanding cross-scale and cross-level linkages in ecological systems (top–down and bottom–up effects, such as trophic cascades, have been demonstrated in food webs but are poorly understood in nested hierarchies such as reserve networks and stream catchments), (ii) capturing dynamic aspects of ecological systems and networks (with a few exceptions we have little grasp of how important whole-network attributes change as the composition of nodes and links changes), (iii) integrating ecological aspects of network theory with metacommunity frameworks and multiple node functions and roles (can we link the spatial patterns of habitat patches in fragmented landscapes, the parallel networks of interacting species using those patches and community-level interactions as defined by metacommunity theory in a single framework?), (iv) integrating the analysis of social and ecological networks (particularly, can they be analysed as a single interacting system?) and (v) laying an empirical foundation for network analysis in conservation biogeography (this will require a larger data bank of well-studied networks from diverse habitats and systems).

    Main conclusions  Recent research has identified a variety of approaches that we expect to contribute to progress in each of our five challenge areas. We anticipate that some of the most exciting outcomes of attempts to meet these challenges will be frameworks that unite areas of research, such as food web analysis and metacommunity theory, that have developed independently.

  • 96.
    Dahl, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Lind, Charlotta Rubio
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Gorokhova, Elena
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eklund, Britta
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Breitholtz, Magnus
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Food quality effects on copepod growth and development: Implications for bioassays in ecotoxicological testing2009In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 72, no 2, p. 351-357Article in journal (Refereed)
    Abstract [en]

    We evaluated effects of six algal species in 25 combinations on growth and reproduction of the harpacticoid copepod Nitocra spinipes. In the first lifecycle test, Rhodomonas salina, Phaeodactylum tricornutum, and Dunaliella tertiolecta were used. The results showed that R. salina was the best food, whereas P. tricornutum (0% development success) and D. tertiolecta (41.7% malformations) were poor food items. In the second lifecycle test, a mixture of R. salina, Tetraselmis suecica, and Thalassiosira weisflogii (selected from screening tests) was tested together with a mono-diet of R. salina. Also in this test, copepods fed R. salina performed better (i.e. had higher survival and reproductive success) compared with the other treatment. We conclude that R. salina is appropriate to use as food in toxicity testing with N. spinipes, whereas some of the algae commonly used as feed in ecotoxicological tests with other copepods had detrimental effects on the development, reproduction, and survival of N. spinipes.

  • 97.
    Dahlgren, Kristin
    et al.
    Umeå Univ, Dept Ecol & Environm Sci.
    Andersson, Agneta
    Umeå Univ, Dept Ecol & Environm Sci.
    Larsson, Ulf
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hajdu, Susanna
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Båmstedt, Ulf
    Umeå Univ, Dept Ecol & Environm Sci.
    Planktonic production and carbon transfer efficiency along a north-south gradient in the Baltic Sea2010In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 409, p. 77-94Article in journal (Refereed)
    Abstract [en]

    A 1 yr study was conducted along a brackish-water production gradient to enhance the understanding of factors governing pelagic food web function. This was achieved by measuring carbon transfer efficiency (TE) from the basal resource to an intermediate trophic level. TE was defined as mesozooplankton carbon consumption rate divided by production at the basal trophic level, which is composed of phytoplankton and bacteria. A north-south transect in the Baltic Sea was used as a model system, with 2 stations each in the Bothnian Bay, Bothnian Sea and Baltic Proper being sampled 5 to 8x during 2006. In addition, data from monitoring programmes were used, which comprised 10 to 22 samplings stn(-1). TE was expected to be governed by the size distribution of phytoplankton and due to the nutrient gradient, we expected to find an optimal cell size, and thus also a high TE, in the intermediate-productive Bothnian Sea. The basal production during summer/autumn increased 5-fold from north to south, while the mesozooplankton carbon consumption rate exhibited a peak in the Bothnian Sea, being similar to 3x higher than in both Bothnian Bay and Baltic Proper. TE was found to be intermediate in the Bothnian Bay (average: 0.8), highest in the Bothnian Sea (1.6), and lowest in the Baltic Proper (0.2). We suggest that the variation in carbon transfer efficiency can be explained by the composition of the phytoplankton community, the abundance balance between copepods and cladocerans, as well as the species composition of mesozooplankton in relation to the size structure of phytoplankton.

  • 98.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    A social-ecological systems approach to coastal marine resources in the tropics: Synthesis of institutional dynamics from the Chwaka Bay case in Zanzibar, Tanzania.2009In: Meeting Global Challenges in Research Cooperation. / [ed] CDS, Uppsala: Collegium of Development Studies , 2009Chapter in book (Other academic)
  • 99.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Beyond regulations in fisheries management: the dilemmas of the “beach recorders” Bwana Dikos in Zanzibar, Tanzania2006In: Ecology and Society, Vol. 11, no 2, p. no. 35-Article in journal (Refereed)
  • 100.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Governance for sustainability: insights from marine resource use in a tropical setting in the western indian ocean2012In: Coastal Management, ISSN 0892-0753, E-ISSN 1521-0421, Vol. 40, no 6, p. 612-633Article in journal (Refereed)
    Abstract [en]

    The last decade has seen a shift in the Natural Resource Management discourse, a shift from management to governance. Governance is held forward as a prime solution to problems associated with the sustainability of natural resources, including fisheries and other marine resources. Several countries in the Western Indian Ocean are framing governance solutions as a response to coastal/marine resource depletion and environmental degradation, but the challenges are huge and success stories remain few. This study provides an analysis of the governance situation in Chwaka Bay, Zanzibar, Tanzania. It presents the governance actors and how governance is expressed in terms of hierarchy (state), heterarchy (self-organized networks of resource users), and anarchy (market). The analysis illustrates the extreme difficulties of using governance approaches to steer human behavior to solve environmental problems and achieve sustainability. The study also provides some insights when considering the use of governance as a tool for the designing and/or steering social-ecological systems in subsistence contexts with weak formal institutions. These include the consideration of governance as an intrinsic part of complex societal processes, the idealization of governance as a template for redressing management failure and broader issues such as the importance of meta-governance.

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