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  • 1.
    Albert, Séréna
    et al.
    Stockholm University, Sweden.
    Hedberg, Per
    Stockholm University, Sweden .
    Motwani, Nisha H.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Sjöling, Sara
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Winder, Monika
    Stockholm University, Sweden.
    Nascimento, Francisco J A
    Stockholm University, Sweden.
    Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 24033Article in journal (Refereed)
    Abstract [en]

    In coastal aphotic sediments, organic matter (OM) input from phytoplankton is the primary food resource for benthic organisms. Current observations from temperate ecosystems like the Baltic Sea report a decline in spring bloom diatoms, while summer cyanobacteria blooms are becoming more frequent and intense. These climate-driven changes in phytoplankton communities may in turn have important consequences for benthic biodiversity and ecosystem functions, but such questions are not yet sufficiently explored experimentally. Here, in a 4-week experiment, we investigated the response of microeukaryotic and bacterial communities to different types of OM inputs comprising five ratios of two common phytoplankton species in the Baltic Sea, the diatom Skeletonema marinoi and filamentous cyanobacterium Nodularia spumigena. Metabarcoding analyses on 16S and 18S ribosomal RNA (rRNA) at the experiment termination revealed subtle but significant changes in diversity and community composition of microeukaryotes in response to settling OM quality. Sediment bacteria were less affected, although we observed a clear effect on denitrification gene expression (nirS and nosZ), which was positively correlated with increasing proportions of cyanobacteria. Altogether, these results suggest that future changes in OM input to the seafloor may have important effects on both the composition and function of microbenthic communities.

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  • 2.
    AlRashidi, Monif
    et al.
    University of Ha’il, Saudi Arabia.
    Abdelgadir, Mohanad
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Shobrak, Mohammed
    Taif University, Saudi Arabia.
    Habitat selection by the Spiny-tailed lizard (Uromastyx aegyptia): A view from spatial analysis2021In: Saudi Journal of Biological Sciences, ISSN 1319-562X, Vol. 28, no 9, p. 5034-5041Article in journal (Refereed)
    Abstract [en]

    Many factors affect the habitat selection for animal species, which in turn may greatly affect their distribution in different ecosystems. Understanding the processes that affect habitat selection is also critical for guiding and managing conservation initiatives. Our study aimed to assess the habitat selection by free-ranging Spiny-tailed lizard (Uromastyx aegyptia) by analyzing a geospatial data connecting its burrow parameters to different habitat characteristics within selected sites in Hail region, Saudi Arabia. We examined evidence and patterns of significant spatial clustering for (366) active burrows by linking their parameters (burrow entrance size, burrow entrance width and burrow entrance height), their reference geographical locations and, two habitat characteristics defined by soil type and vegetation cover. The objective of the analysis was to increase the understanding on the burrows aggregation process in the space and, to describe its possible relation to other spatial habitat configurations. Analysis of distances based on the Nearest Neighbor Index (NNI) and hotspots detection in Nearest neighbor hierarchical clustering (Nnh) suggested twelve (12) spatial clusters located within the study area. In addition, a spatial ordinary least square (OLS) and Poisson regression models revealed significant effects of soil type and vegetation cover on burrow parameters (OLS, p < 0.05; Poisson, p < 0.001), which indicate a strong association between burrows parameters and habitats characteristics. Findings from the study also suggest that other factors such as elevations, highways, and human settlement concentration spots could possibly play a major role in defining burrow spatial aggregation and furthermore have a significant impact on habitat selection.

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  • 3.
    Andersson Skog, Nils
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Bats in Urban Sweden: A multiple regression analysis of bats’ relationship to urbanization2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Human development continues to use up more physical space in the natural world, threatening the natural habitats of many organisms. To combat the loss of biodiversity science needs to explore what landscape features are important for different organisms so that we can incorporate these into the modern environment. As bats play an important role in many ecosystems and can reflect changes through trophic levels, analyzing their preferred habitats can help planners improve biological diversity of the urban habitat. Using acoustically identified bat sightings from Artportalen.se for the years 2017-2018, this paper studied the habitats of bats in Sweden. Through multiple regression analysis we examine the response in abundance and/or diversity of bats to physical and socio-cultural attributes of the urban habitat. We examined a total of 10160 bats from 18 species in 418 land cover locales and 306 demographical statistical areas with varying degrees of urbanization. Our results indicate that bat abundance and diversity decrease significantly with higher urbanization while deciduous forests are the most important land cover type for all bats. The results also indicate that wealthier areas have less abundance and diversity even when factoring in population density. Species specific analysis suggested that bat species who are better adapted at foraging in open vegetated landscapes and over water were less susceptible to the negative impacts of the urban habitat. We conclude that diverse habitats with a mixture of open vegetated areas, watercourses and broadleaf forests are the most important land features for a diverse bat fauna along with high connectivity via tree cover and linear landscape elements. If urban planning could incorporate these features into the urban habitat, some of the negative impacts of urbanization could be prevented. 

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  • 4.
    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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  • 5.
    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.

  • 6.
    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.

  • 7.
    Boss, John
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies. Karolinska Institute.
    Liedvogel, Miriam
    Lund University / Max Planck Institute for Evolutionary Biology, Plön, Germany.
    Lundberg, Max
    Lund University.
    Olsson, Peter
    Lund University.
    Reischke, Nils
    Lund University.
    Naurin, Sara
    Lund University.
    Åkesson, Susanne
    Lund University.
    Hasselquist, Dennis
    Lund University.
    Wright, Anthony
    Karolinska Institute.
    Grahn, Mats
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology.
    Bensch, Staffan
    Lund University.
    Gene expression in the brain of a migratory songbird during breeding and migration2016In: Movement Ecology, E-ISSN 2051-3933, Vol. 4, article id 4Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: We still have limited knowledge about the underlying genetic mechanisms that enable migrating species of birds to navigate the globe. Here we make an attempt to get insight into the genetic architecture controlling this complex innate behaviour. We contrast the gene expression profiles of two closely related songbird subspecies with divergent migratory phenotypes. In addition to comparing differences in migratory strategy we include a temporal component and contrast patterns between breeding adults and autumn migrating juvenile birds of both subspecies. The two willow warbler subspecies, Phylloscopus trochilus trochilus and P. t. acredula, are remarkably similar both in phenotype and genotype and have a narrow contact zone in central Scandinavia. Here we used a microarray gene chip representing 23,136 expressed sequence tags (ESTs) from the zebra finch Taeniopygia guttata to identify mRNA level differences in willow warbler brain tissue in relation to subspecies and season.

    RESULTS: Out of the 22,109 EST probe sets that remained after filtering poorly binding probes, we found 11,898 (51.8 %) probe sets that could be reliably and uniquely matched to a total of 6,758 orthologous zebra finch genes. The two subspecies showed very similar levels of gene expression with less than 0.1 % of the probe sets being significantly differentially expressed. In contrast, 3,045 (13.8 %) probe sets were found to be differently regulated between samples collected from breeding adults and autumn migrating juvenile birds. The genes found to be differentially expressed between seasons appeared to be enriched for functional roles in neuronal firing and neuronal synapse formation.

    CONCLUSIONS: Our results show that only few genes are differentially expressed between the subspecies. This suggests that the different migration strategies of the subspecies might be governed by few genes, or that the expression patterns of those genes are time-structured or tissue-specific in ways, which our approach fails to uncover. Our findings will be useful in the planning of new experiments designed to unravel the genes involved in the migratory program of birds.

  • 8.
    Carlsson, J.
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Olsén, K. Håkan
    Uppsala University, Sweden.
    Nilsson, J.
    Swedish University of Agricultural Sciences, Sweden.
    Øverli, O.
    Uppsala University, Sweden .
    Stabell, O. B.
    University of Tromsø, Norway.
    Microsatellites reveal fine-scale genetic structure in stream-living brown trout1999In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 55, no 6, p. 1290-1303Article in journal (Refereed)
    Abstract [en]

    Multilocus F(ST) estimates revealed a pronounced genetic structure at six microsatellite loci in brown trout Salmo trutta in Nordre Finnvikelv, with at least three breeding units that remained stable over time. Significant differences in allele frequencies were found between five sections within a 3-km range, even when no physical barriers prevented fish from migrating between sections. It is argued that geological structures may rise to patterns resembling isolation by distance. Seemingly, the most important factor causing genetic differentiation in Nordre Finnvikelv is genetic drift in small populations that are geologically subdivided by a tributary and by impassable waterfalls. Some correlation between previous behavioural observations and genetic structures were found.

  • 9.
    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.

  • 10.
    Dinnétz, Patrik
    Stockholm university.
    Male sterility, Protogyny and Pollen-Pistil interference in Plantago maritima (Plantaginaceae) a wind-pollinated, self-incompatible perennial1997In: American Journal of Botany, ISSN 0002-9122, E-ISSN 1537-2197, Vol. 84, no 11, p. 1588-1594Article in journal (Refereed)
    Abstract [en]

    Evolution and maintenance of male sterility in seed plants can be explained by the maternal inheritance of mitochondria, which encode the trait, and by adaptive functions that enhance female fecundity in male-sterile compared to hermaphrodite individuals. Protogyny and male sterility can independently decrease the negative effect of pollen–pistil interference in selfincompatible species. In Plantago maritima, which possesses both traits, protogyny increases seed set in hermaphrodite individuals. This is shown both by a significantly positive association between seed set and retarded dehiscence of the anthers and by a more than 50% reduction in seed set following self-pollination. Male sterility does not seem to increase seed set further, as female and hermaphrodite plants do not differ significantly in mean seed set per capsule. Bagging experiments demonstrate strong self-incompatibility in the study populations. Hence, in P. maritima male sterility seems neither to prevent selfing nor to reduce the effect of pollen–pistil interference. Females had significantly larger stigmas than hermaphrodites, but seed set varied negatively with stigma length among females, indicating that the evolution of unisexuality in P. maritima is not due to prefertilization sex allocation. I therefore conclude that the genetical system of nucleocytoplasmic determination of gender is the main cause for maintenance of male sterility in P. maritima.

  • 11.
    Dinnétz, Patrik
    et al.
    Stockholm university.
    Jerling, Lenn
    Stockholm university.
    Gynodioecy in Plantago maritima L.; no compensation for loss of male function1997In: Acta Botanica Neerlandica, ISSN 0044-5983, E-ISSN 1365-2001, Vol. 46, no 2, p. 193-206Article in journal (Refereed)
    Abstract [en]

    Size, allocation of biomass, seed production of hermaphrodites and male steriles as well as germination, growth rate and survival among their progeny were compared between male fertile and male sterile cytoplasmic genotypes of Plantago maritima. The cytoplasmic genomes in angiosperms are predominantly maternally inherited. Thus we used the progeny originating from the male fertile and male sterile mothers in order to examine the relative success of the mothers. The progeny was grown together at three different densities in a greenhouse competition experiment. The results were analysed in a hierarchical model with siblings as replicates of mothers and mothers as replicates of sex-morphs. Differences between sex morphs were very small, but they were consistent in that the progeny from male steriles always performed less well than did the progeny from hermaphrodites. Male sterile progeny matched the hermaphrodite progeny best at the lowest density, where there was no effect of sex type on the level of individual performance. One explanation why hermaphrodites perform relatively better at higher densities could be that they are more plastic in their response to competition induced stress. This was indicated by density dependent allocation pattern of biomass to different parts of the plants, where the progeny of hermaphrodites appeared to be more plastic. The results from this experiment, and other studies, supports the idea that male sterility, if nucleo-cytoplasmically determined, can persist in a population even without any fitness advantages for females.

  • 12.
    Dinnétz, Patrik
    et al.
    Stockholm university.
    Jerling, Lenn
    Stockholm university.
    Spatial distribution of male sterility in Plantago maritima1998In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 81, p. 255-265Article in journal (Refereed)
    Abstract [en]

    Sexual polymorphism in angiosperms can be explained both by the functional responses of male and female function to autogamy and geitonogamy, and by the conflict between the nuclear and cytoplasmic genomes. In predominantly hermaphrodite species, cytoplasmically determined male sterility may persist in a population because of maternal inheritance, i.e, the loss of male function does not change the fitness of the cytoplasmic genome. However, in populations with cytoplasmic male sterility, male fertility is often restored by nuclear genes. Therefore, in populations with genetical substructure, the frequencies of the different sex-morphs will fluctuate depending on the presence of both the male sterile cytoplasms, and of their specific nuclear restorer genes. In Plantagomaritima, we showed that the frequencies of male sterility were highest in regions with the highest population turnover rates and that male sterile individuals were more frequently found in the lower, less dense parts of the meadows. This indicates that male sterile cytoplasms have their highest probabilities to escape their nuclear restorer genes during recolonisation in disturbed regions within populations. We also found that male sterile individuals dispersed their seeds a little bit further than did the hermaphrodites. This can be interpreted as an adaptive response to the local occurrence of nuclear restorer genes.

  • 13.
    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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  • 14.
    Eggertsen, M.
    et al.
    Stockholm University, Sweden.
    Larsson, Josefine
    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.
    Åkerlund, C.
    Stockholm University, Sweden.
    Chacin, D. H.
    University of South Florida, USA.
    Berkström, C.
    Stockholm University, Sweden; Swedish University of Agricultural Sciences, Sweden.
    Jiddawi, N.
    Institute of Fisheries Research, Tanzania.
    Kautsky, N.
    Stockholm University, Sweden.
    Halling, C.
    Stockholm University, Sweden.
    Coral-macroalgal interactions: Herbivory and substrate type influence growth of the macroalgae Eucheuma denticulatum (NL Burman) Collins & Hervey, 1917 on a tropical coral reef2021In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 542, article id 151606Article in journal (Refereed)
    Abstract [en]

    Introduced macroalgae becoming invasive may alter ecological functions and habitats in recipient ecosystems. In the Western Indian Ocean (WIO), non-native strains of the native macroalgae Eucheuma denticulatum were introduced for farming practices and consequently spread into the surrounding seascape. We investigated potential effects of non-native and native strains of this macroalgae on a branching coral. We conducted a four-factor field experiment where we examined growth and holdfast development of introduced and native E. denticulatum on live and dead branches of Acropora sp. in the presence and absence of herbivores in Unguja Island, Zanzibar. Moreover, we estimated coral and macroalgae condition by visual examinations, gene expression analyses, and photosynthetic measurements. Macroalgae did not attach to any live coral and coral condition was not impacted by the presence of E. denticulatum, regardless of geographical origin. Instead, necrotic tissue on the macroalgae in areas of direct contact with corals indicated damage inflicted by the coral. The biomass of E. denticulatum did not differ between the replicates attached to live or dead corals in the experiment, yet biomass was strongly influenced by herbivory and replicates without protection from herbivores had a significantly lower biomass. In the absence of herbivory, introduced E. denticulatum had significantly higher growth rates than native algae based on wet weight measurements. These results contribute to an increased understanding of environmental effects by the farming of a non-native strain of algae on corals and stresses the importance to maintain viable populations of macroalgal feeding fishes in such areas.

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  • 15.
    Eggertsen, M.
    et al.
    Stockholm University, Sweden.
    Tano, S. A.
    Stockholm University, Sweden.
    Chacin, D. H.
    University of South Florida, St. Petersburg, USA.
    Eklöf, J. S.
    Stockholm University, Sweden.
    Larsson, Josefine
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Berkström, C.
    Stockholm University, Swenden ; Swedish University of Agricultural Sciences, Sweden.
    Buriyo, A. S.
    University of Dar Es Salaam, Dar es Salaam, Tanzania.
    Halling, C.
    Stockholm University, Sweden.
    Different environmental variables predict distribution and cover of the introduced red seaweed Eucheuma denticulatum in two geographical locations2021In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 23, p. 1049-1067Article in journal (Refereed)
    Abstract [en]

    In this study we examined abiotic and biotic factors that could potentially influence the presence of a non-indigenous seaweed, Eucheuma denticulatum, in two locations, one outside (Kane’ohe Bay, Hawai’i, USA) and one within (Mafia Island, Tanzania) its natural geographical range. We hypothesized that the availability of hard substrate and the amount of wave exposure would explain distribution patterns, and that higher abundance of herbivorous fishes in Tanzania would exert stronger top–down control than in Hawai’i. To address these hypotheses, we surveyed E. denticulatum in sites subjected to different environmental conditions and used generalized linear mixed models (GLMM) to identify predictors of E. denticulatum presence. We also estimated grazing intensity on E. denticulatum by surveying the type and the amount of grazing scars. Finally, we used molecular tools to distinguish between indigenous and non-indigenous strains of E. denticulatum on Mafia Island. In Kane’ohe Bay, the likelihood of finding E. denticulatum increased with wave exposure, whereas on Mafia Island, the likelihood increased with cover of coral rubble, and decreased with distance from areas of introduction (AOI), but this decrease was less pronounced in the presence of coral rubble. Grazing intensity was higher in Kane’ohe Bay than on Mafia Island. However, we still suggest that efforts to reduce non-indigenous E. denticulatum should include protection of important herbivores in both sites because of the high levels of grazing close to AOI. Moreover, we recommend that areas with hard substrate and high structural complexity should be avoided when farming non-indigenous strains of E. denticulatum.

  • 16.
    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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  • 17.
    Elofsson, Katarina
    et al.
    Swedish University of Agricultural Sciences.
    Gren, I. -M
    Swedish University of Agricultural Sciences.
    Regulating invasive species with different life history2015In: Journal of Bioeconomics, ISSN 1387-6996, E-ISSN 1573-6989, Vol. 17, no 2, p. 113-136Article in journal (Refereed)
    Abstract [en]

    Invasive species often cause economic damage due to their impact on economically valuable resident species. We study optimal regulation in terms of simultaneous control and adaptation when the purpose is to manage an invasive species which competes for scarce resources with a resident species. The optimal policy includes both subsidies for control of an invasive species with zero commercial value, and harvesting taxes on the resident species which are adjusted in the presence of an invasion. A numerical age-structured optimization model is used to analyze the role of species’ life history, i.e. the degree of evolutionary specialization in survival or reproduction, for the choice of strategy and the associated economic instruments. Results show that, irrespective of life history, both policies are implemented in efficient solutions, but subsidies for controlling the invader are used to a larger extent when it is possible to target specific age classes of the invader. If a resident species is harvested non-selectively, the optimal subsidy for control of the invader is lower, and if the invader is specialized in survival the control subsidy mirrors the resident species harvest cycle. © 2014, The Author(s).

  • 18.
    Elofsson, Katarina
    et al.
    Södertörn University, School of Social Sciences, Economics. Aarhus University, Denmark.
    Hiron, M.
    Swedish University of Agricultural Sciences, Sweden.
    Kačergytė, I.
    Swedish University of Agricultural Sciences, Sweden.
    Pärt, T.
    Swedish University of Agricultural Sciences, Sweden.
    Ecological compensation of stochastic wetland biodiversity: National or regional policy schemes?2023In: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 204, article id 107672Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to compare policy schemes for ecological compensation applied at national and regional levels, using exploited inland wetlands as an example. We study whether uncertainty, due to natural variability and measurement difficulties, motivates compensation that is carried out in the same region as that of the exploited site, or whether it rather motivates nationwide compensation schemes. For this purpose, we develop an empirical, chance-constrained programming model of cost-effective wetland management. The model is spatially differentiated and accounts for heterogeneity in wetland quality across wetland types and regions. Wetland quality is defined by three alternative biodiversity indices: species richness, population-weighted species richness, and red-listed species richness, estimated from voluntarily reported data on breeding bird species observations. Results show that regional schemes are more expensive, in particular if the policy maker dislikes uncertainty and wants to prioritize uncommon species. Contrary to expectations from the theoretical analysis, regional schemes would lead to a higher risk-adjusted level of biodiversity at the national level. However, regionalization also implies that targets cannot be achieved if a high safety margin is imposed. Trading ratios are robust to the choice of wetland quality index.

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  • 19.
    Fanous, Nicola
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Lohsar, Iqra
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Kartläggning av externa effekter vid etablering av storskaliga solcellsparker: En fallstudie av tre storskaliga solcellsparker2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study examines the external effects that can arise from the establishment of solar parks and how these effects can influence societal decisions. Renewable energy sources play a key role in moving towards a sustainable future, where solar parks can be viewed as a sustainable energy source alternative. There is a risk that solar parks can lead to global and local negative externalitiets, which makes it very interesting to study. The study is based on a qualitative method, where interviews were conducted with four stakeholders, containing existing knowledge and insights about solar parks. Empirical materials were also utilized, which consisted of various materials from, environmental assessments, and other reliable sources, to answer our study questions. The results show that the establishment of solar parks can lead to a so called green vs. green- conflic, where there are contradicting interests and opinions. By comparing three existing solar parks, we were able tol understand what role external effects play in the decision making of establishing a solar park, and how public interests, such as food management can also influence this decision.  The results also show that the localization prinicple plays a huge role in influencing what external effects that might arise int that specific location. 

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  • 20. Gorokhova, Elena
    et al.
    Edlund, Anna
    Södertörn University, School of Life Sciences.
    Hajdu, Susanna
    Zhivotova, Elena N.
    Nucleic acid levels in copepods: dynamic response to phytoplankton blooms in the northern Baltic proper2007In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 349, p. 213-225Article in journal (Refereed)
    Abstract [en]

    We examined changes in nucleic acids and concomitant population development of the copepods Acartia bifilosa and Eurytemora affinis in relation to the progress of the phytoplankton spring bloom in the northern Baltic proper. Individual RNA and DNA concentrations and their ratios in female copepods as well as copepod abundance and population structure were analyzed in 2 coastal areas that differed in the degree of eutrophication and phytoplankton development. During the study period (February to June 2002), bloom conditions were evident, with chlorophyll (chl) a values being 42% higher in the eutrophic area than in the reference area. In both areas, diatoms dominated; in the reference area, they were replaced by dinoflagellates toward the end of the bloom. Copepod RNA-DNA concentrations increased rapidly at the onset of the bloom and gradually decreased thereafter. Moreover, in the eutrophic area, both copepods had higher RNA content and RNA:DNA ratios throughout the study period, suggesting higher productivity in this area. In both species, we found positive correlations between RNA-based indices and chl a. Thus, as suggested by RNA dynamics, growth rates of A. bifilosa and E. affinis appear to respond rapidly to both temporal variation in spring phytoplankton stock and spatial variation due to the magnitude of the bloom. In addition, we found that species-specific RNA dynamics and RNA-chl a relationships differed between species, indicating possible differences in feeding preferences and growth potential.

  • 21.
    Halltin Nijm, Nadja
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies.
    Biodiversitet i naturliga kolsänkor: sammansättning av sedimentlevande djur samt kollagring i kustnära habitat2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The ocean plays an important role regarding carbon dioxide emissions due to its ability to act as a natural carbon sink. Coastal vegetated habitats such as seagrass beds are known to be effective at sequestering organic carbon stored in their bottom sediments. The carbon sink capacity in coastal vegetated habitats varies depending on factors such as biomass, sediment grain size and zoobenthos species composition. However, the species composition in the sediments has been researched to a limited extent. This study has therefore chosen to examine the composition of benthic invertebrates in coastal habitats and its relationship to the carbon sink capacity. Sediment cores were collected from different coastal habitats (Ruppia spp., pondweed, eelgrass, unvegetated soft bottom and dry- and wet reeds) to identify the species of the animals and to calculate the sedimentary carbon content. The results showed significant differences between the species compositions of all habitats except between pondweed and Ruppia spp., pondweed and eelgrass as well as between unvegetated soft bottom and dry reeds. Species that occurred and contributed to the majority of variation between and within habitats were Oligochaeta, Hydrobia spp., Chironomidae, Hediste diversicolor and Macoma balthica. No evident positive correlation was found between species composition and carbon storage in the coastal habitats since the reed belts contained few species but a high carbon content, while the pondweed habitat, which had the highest species richness, contained a low carbon content. Thus, other factors may have had a greater impact on the carbon content of the habitats. However, many individuals of Chironomidae occurred in the reed belts that contained a high organic carbon content. It is worth mentioning that their ability to cope with oxygen poor environments (that the reed belts suffered) may be the reason for the abundance of Chironomidae, rather than their capacity to store carbon. Since coastal habitats are efficient carbon sinks, future research is crucial for an increased understanding of which factors influence their carbon sink capacity.

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  • 22.
    Hedlund, Johanna S. U.
    Södertörn University College, School of Life Sciences.
    Living with males: benefits and costs to females of resident males in Colobus vellerosus2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Only in primates is permanent male-female association the most widespread social structure of all. The continuous presence of resident males in the social group can have significant impacts on female fitness, both in forms of costs and benefits. In this study I investigate particular short-term benefits and costs of resident males to females in a population of ursine colobus (Colobus vellerosus). I hypothesise that for females permanent association with males result in certain benefits and certain costs, exceeding those provided or imposed by other females. The results indicate that female derive greater benefits from males than from females during intergroup encounters and in the form of vigilance since males were the main participants in intergroup encounter and were more vigilant than females. I could not confirm any type of behaviour employed by resident males that is costly to females. However, the rarity and subtleness of some costly male behaviours imply that more data is needed before making a conclusion on their absence or occurrence in this population and I purpose that herding behaviour could occur at my study site. Moreover, multi-male groups (MM-groups) showed higher rates of vigilance than single-male groups (SM-groups) and had a tendency to experiencing fewer intergroup encounters than SM-groups. I interpret the former as a result of the demanding social conditions in the MM-groups. The latter indicate that females may benefit from MM-group living through a decrease in intergroup encounters.

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  • 23.
    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.

  • 24.
    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.

  • 25.
    Janzén, Therese
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Hammer, Monica
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Dinnétz, Patrik
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Factors responsible for Ixodes ricinus presence and abundance across a natural-urban gradient2023Data set
    Abstract [en]

    In 2017, ticks and field data were collected from 12 different sites in Stockholm County originally chosen as random controls for another study but was never used. In 2019, we collected ticks and field data at 35 randomly selected sites along the natural-urban gradient. To calculate and urbanization index, we used the proportion of artificial surfaces surrounding each site. All sampling sites were visited once with a total of 295 sampling plots inventoried for ticks and field data. For each sampling plot, we recorded date, time, temperature, weather conditions, number of ticks, vegetation height and tree stem density surrounding the inventory plot. To retrieve large landscape characteristics, we established 10 buffer zones ranging from 100m to 1000m around each sampling site in GIS using satellite land cover maps (retrieved from: https://www.naturvardsverket.se/verktyg-och-tjanster/kartor-och-karttjanster/nationella-marktackedata/ladda-ner-nationella-marktackedata/). These maps have a spatial resolution of 10m and include the following main categories 1) Forest and seminatural areas, 2) Open areas, 3) Arable land, 4) Wetlands, 5) Artificial surfaces and 6) Inland and marine water. These main categories are further divided into subcategories with detailed information regarding the different land cover classes. In the analyses, we used the main categories, with the exception of Forest and seminatural areas where we included eight individual forest types: Pine forest, Spruce forest, Mixed coniferous forest, Mixed forest, Broadleaved forest, Broadleaved hardwood forest, Broadleaved forest with hardwood forest and Temporarily non-forest. To calculate landscape configuration metrics at each sampling site, we used land cover data from the GIS buffers with a 1000m radius, exported to GeoTIFF format and analyzed them with FRAGSTATS version 4. For landscape heterogeneity we used Shannons’ diversity index (SHDI) and to measure the aggregation of landscape attributes we used Contagion (CONTAG). As measures of forest configuration, we used percent of forest cover (PLAND) and total forest edge length (TE). All statistical analyses were performed with R version 4.0.3. To analyze the effect of possible risk factors for tick abundance in different greenspaces across the natural-urban gradient, we used generalized linear mixed models assuming Poisson distributed residuals. As the data contained a larger proportion of zeros than would be expected according to a Poisson or a negative binomial distribution causing overdispersion, we fitted zero-inflated Poisson models using the package glmmTMB (generalized linear mixed models using Template Model Builder).

  • 26.
    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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  • 27.
    Kolseth, Anna-Karin
    Södertörn University, School of Life Sciences. Uppsala universitet.
    Evolutionary Processes and Spatial Genetic Variation in Euphrasia stricta on the Baltic Island of Gotland2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The identification of processes governing genetic structure at different spatial scales remains a major challenge in evolutionary biology and is of considerable applied interest in conservation biology. In Euphrasia stricta five varieties have been identified (brevipila, gotlandica, stricta, suecica and tenuis) based on differences in habitat, phenology and morphology. In this thesis, I examined genetic variation at AFLP and microsatellite marker loci in relation to variation in habitat and morphology within and among varieties of E. stricta on the island Gotland in the Baltic Sea. The results are discussed in relation to evolutionary processes acting within this species complex.

    In a study conducted at the regional scale, the two early-flowering varieties suecica and tenuis each formed a genetically distinct group, while the three late-flowering varieties brevipila, gotlandica and stricta formed a third group. The results suggest that suecica and tenuis have ancient origins since they are genetically different both from the brevipila/gotlandica/stricta group and from each other despite their similar habitat preferences. This pattern was obtained using both marker systems. Discrepancies between AFLP and microsatellites were found in patterns of isolation by distance and in estimates of expected heterozygosity, He.

    Focusing on the mixed genetic group brevipila/gotlandica/stricta and the causes behind their clustering together despite differences in morphology and habitat preferences, I performed a study at a smaller geographic scale. Studying a population of E. stricta I found that, although gene flow within the population was strong, it had not prevented the formation of genetic groups associated with micro-habitat properties.

    An important result for conservation of the rare variety suecica is its distinct genetic separation from variety tenuis. If the aim of conservation is to preserve the uniqueness of suecica, the two varieties should be treated as separated entities.

  • 28.
    Lind, Emma E
    et al.
    Södertörn University, School of Life Sciences, Biology. Södertörn University, School of Life Sciences, Molecular biology.
    Grahn, Mats
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Biology.
    Directional genetic selection by pulp mill effluent on multiple natural populations of three-spined stickleback (Gasterosteus aculeatus)2011In: Ecotoxicology, ISSN 0963-9292, E-ISSN 1573-3017, Vol. 20, p. 503-512Article in journal (Refereed)
    Abstract [en]

    Contamination can cause a rapid environmental change which may require populations to respond with evolutionary changes. To evaluate the effects of pulp mill effluents on population genetics, we sampled three-spined sticklebacks (Gasterosteus aculeatus) near four pulp mills and four adjacent reference sites and analyzed Amplified Fragment Length Polymorphism (AFLP) to compare genetic variability. A fine scale genetic structure was detected and samples from polluted sites separated from reference sites in multidimensional scaling plots (P < 0.005, 1000 permutations) and locus-by-locus Analysis of Molecular Variance (AMOVA) further confirmed that habitats are significantly separated (F(ST) = 0.021, P < 0.01, 1023 permutations). The amount of genetic variation between populations did not differ between habitats, and populations from both habitats had similar levels of heterozygosity (polluted sites Nei's Hs = 0.11, reference sites Nei's Hs = 0.11). Still, pairwise F(ST): s between three, out of four, pairs of polluted-reference sites were significant. A F(ST)-outlier analysis showed that 21 (8.4%) loci were statistically different from a neutral distribution at the P < 0.05 level and therefore indicated to be under divergent selection. When removing 13 F(ST)-outlier loci, significant at the P < 0.01 level, differentiation between habitats disappeared in a multidimensional scaling plot. In conclusion, pulp mill effluence has acted as a selective agent on natural populations of G. aculeatus, causing a convergence in genotype composition change at multiple sites in an open environment.

  • 29.
    Lorentsson, Susanne
    et al.
    Uppsala university.
    Mattsson, Jan-Eric
    Uppsala university.
    New reports of soredia dispersed by ants, Formica cunicularia1999In: The Lichenologist, ISSN 0024-2829, E-ISSN 1096-1135, Vol. 31, p. 204-207Article in journal (Refereed)
  • 30.
    Lundberg, Max
    et al.
    Lund University.
    Boss, John
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology. Karolinska Institute, Karolinska University Hospital.
    Canbäck, Björn
    Lund University.
    Liedvogel, Miriam
    Lund University.
    Larson, Keith W
    Lund University.
    Grahn, Mats
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Biology.
    Åkesson, Susanne
    Lund University.
    Bensch, Staffan
    Lund University.
    Wright, Anthony Ph
    Karolinska Institute, Karolinska University Hospital.
    Characterisation of a transcriptome to find sequence differences between two differentially migrating subspecies of the willow warbler Phylloscopus trochilus.2013In: BMC Genomics, E-ISSN 1471-2164, Vol. 14, article id 330Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Animal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration.

    RESULTS: The transcriptome sequencing resulted in 1.8 million reads following filtering steps. Most of the reads (84%) were successfully mapped to the genome of the zebra finch Taeniopygia gutatta. The mapped reads were situated within at least 12,101 predicted zebra finch genes, with the greatest sequencing depth in exons. Reads that were mapped to intergenic regions were generally located close to predicted genes and possibly located in uncharacterized untranslated regions (UTRs). Out of 85,000 single nucleotide polymorphisms (SNPs) with a minimum sequencing depth of eight reads from each of two subspecies-specific pools, only 55 showed high differentiation, confirming previous studies showing that most of the genetic variation is shared between the subspecies. Validation of a subset of the most highly differentiated SNPs using Sanger sequencing demonstrated that several of them also were differentiated between an independent set of individuals of each subspecies. These SNPs were clustered in two chromosome regions that are likely to be influenced by divergent selection between the subspecies and that could potentially be associated with adaptations to their different migratory strategies.

    CONCLUSIONS: Our study represents the first large-scale sequencing analysis aiming at detecting genes underlying migratory phenotypes in birds and provides new candidates for genes potentially involved in migration.

  • 31.
    Lättman, Håkan
    et al.
    Södertörn University, School of Chemistry, Biology, Geography and Environmental Science.
    Mattsson, Jan-Eric
    Södertörn University, School of Chemistry, Biology, Geography and Environmental Science, Biology.
    Milberg, Per
    IFM Biology, Conservation Ecology Group, Linköping University.
    Rapid changes in the epiphytic macrolichen flora in southern Sweden2004Conference paper (Other academic)
  • 32.
    Löfroth, Therese
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Merinero, Sonia
    Universidad Rey Juan Carlos, Spain.
    Johansson, Johanna
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science.
    Nordström, Eva-Maria
    Swedish University of Agricultural Sciences, Sweden.
    Sahlström, Emma
    Swedish University of Agricultural Sciences, Sweden.
    Sjögren, Jörgen
    Swedish University of Agricultural Sciences, Sweden.
    Ranius, Thomas
    Swedish University of Agricultural Sciences, Sweden.
    Land-sparing benefits biodiversity while land-sharing benefits ecosystem services: Stakeholders’ perspectives on biodiversity conservation strategies in boreal forests2024In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 53, no 1, p. 20-33Article in journal (Refereed)
    Abstract [en]

    Biodiversity conservation and economic profit from forests can be combined by various land-sparing and land-sharing approaches. Using a semi-structured survey, we evaluated support for scenarios representing contrasting conservation strategies in a managed boreal forest landscape. Land-sparing approaches were supported by the conservation organisation, regional administrations and the forest company, mainly motivated by the benefit for biodiversity based on ecological theory. Land-sharing approaches were supported by one recreational organisation, some municipalities and the forest owners’ association, mainly motivated by the delivery of ecosystem services. Stakeholder groups using certain ecosystem services had motivations that we related to an anthropocentric mindset, while others focused more on species conservation, which can be related both to an anthropocentric or an ecocentric mindsets. Forest conservation planning should consider stakeholders’ preferences to handle land-use conflicts. Since reaching consensus among multiple stakeholders seems unfeasible, a combination of land-sparing and land-sharing approaches is probably the best compromise.

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  • 33.
    Mattsson, Jan-Eric
    et al.
    Södertörn University, School of Life Sciences, Biology.
    Hansson, Ann-Charlotte
    Södertörn University, School of Life Sciences.
    Lindblom, Louise
    University of Bergen, Museum of Natural History.
    Genetic diversity and substrate preferences in Hypogymnia physodes in northern Europe2006Conference paper (Other academic)
    Abstract [en]

    Genetic variation in lichens has mainly been examined in rare or threatened species or species with an otherwise fragmented geographical distribution. The main objectives have often been to compare the diversity between populations in relation to nature conservation issues. In addition, most studied species are sexual reproductive and, hence, produce small spores which may disperse over long distances. More common species have usually been neglected, although they are more easily collected, both because collecting results in a comparatively small disturbance of the populations and because they occur in a larger selection of habitats. Here we present a study on the genetic variation in the lichenized ascomycete Hypogymnia physodes in Northern Europe based on nrDNA data. The species was selected as it probably is the most common lichen in the area, it is corticolous, found on almost all woody plants in most habitats, and has a predominantly asexual dispersal mode. The material was collected in Estonia, Finland, and Sweden as a part of a larger project aiming at identifying localities with high biodiversity of interest for nature conservation projects. We examined the correlations between genetic diversity and substrate ecology as well as spatial distances. An important result is the large genetic variation within a mainly asexual lichen species. The results also show genetic similarity between specimens from similar substrates.

  • 34.
    Mattsson, Jan-Eric
    et al.
    Södertörn University, School of Life Sciences, Biology.
    Vinter, Tiina
    Södertörn University, School of Life Sciences.
    Lönn, Mikael
    Södertörn University, School of Life Sciences.
    Macrolichen diversity in relation to diversity of woody plants2006Conference paper (Other academic)
    Abstract [en]

    In studies concerning nature conservation issues common lichen species have usually been neglected although collecting of these results gives comparatively small disturbance of the populations and is easily done. Instead rare or threatened species or species usually have been used as indicators of sites with high biodiversity. Here, the macrolichen diversity is compared with the diversity of woody plants and other characteristics of different sites in Estonia, Finland and Sweden as a part of a larger project including comparative studies on habitats with presumably high species diversity The site selection was based on the occurrence of Daphne mezereum which usually occurs in semi-open habitats in transitions zones containing species from the surrounding biotopes. One of the main objectives with the study was to develop a fairly rapid method of evaluation of biodiversity using easily identified species. As total inventories are time consuming and reflects snapshots of a certain occasion it is beneficial to use other methods which may give a little less but sufficient information for many purposes, e.g., estimations on biodiversity. The ecological and evolutionary processes that shape diversity and distributions are general and results are assumed to be translatable from the target species to other species. The combination of data from a small number of species may constitute a useful monitoring protocol for lichens and higher plants. In total about 50 lichen species and 25 substrates are included and analyzed in the study. Most of the most common lichens are sorediate or isidiate and asexually reproducing and occur on several substrates. The relation between the diversity of lichen and woody plants is presented.

  • 35.
    Menichetti, Lorenzo
    et al.
    Swedish University of Agricultural Sciences, Uppsala.
    Touzot, Laura
    Université Claude Bernard Lyon, Lyon, France .
    Elofsson, Katarina
    Department of Economics, Uppsala, Sweden .
    Hyvönen, Riitta
    Swedish University of Agricultural Sciences, Uppsala.
    Kätterer, Thomas
    Swedish University of Agricultural Sciences, Uppsala.
    Kjellander, Petter
    Swedish University of Agricultural Sciences, Riddarhyttan.
    Interactions between a population of fallow deer (Dama dama), humans and crops in a managed composite temperate landscape in southern Sweden: Conflict or opportunity?2019In: PLOS ONE, E-ISSN 1932-6203, Vol. 14, no 4, article id e0215594Article in journal (Refereed)
    Abstract [en]

    Landscapes composed of agricultural land mixed with forest are desirable since they provide a wide range of diversified ecosystem services, unlike specialized agricultural landscapes, but that creates a trade-off between these land uses since wildlife usually feed on crops and reduce yields. In Nordic countries, where human population density is low and game hunting can be a viable economic alternative, mixed landscape systems are particularly interesting. To evaluate the economic sustainability of such systems we need to quantify wildlife damage to crops. One important species, being popular among Swedish hunters and therefore economically valuable, is fallow deer (Dama dama). Our objective was to evaluate the economic sustainability of mixed landscape systems including cultivated fields and commercial hunting of fallow deer. We studied the effects of excluding fallow deer by using 86 exclosures and adjacent plots in winter wheat and oat fields in south-west Sweden. We analyzed yield losses and interactions between spatial and temporal grazing patterns, anthropogenic landscape features, and topological characteristics of the landscape. We found that animals avoided exposed spots, irrespective of distance from human activity. We also found a seasonal grazing pattern related to the different growing periods of winter wheat (more grazed, emerging in autumn) and spring oat (less grazed, emerging in spring). We then compared the costs of crop damage against the commercial value of fallow deer hunting. The damage amounted to 375 ±196 € ha-1 for wheat and 152 ±138 € ha-1 for oat, corresponding to a total cost per animal of 82.7 ±81.0 €, while each animal had an estimated market value of approximately 100 €. Therefore the value of fallow deer presence compensated for the associated cost of crop damage. Profit could be further improved in this case by adopting additional management strategies. In general our study confirmed the economic feasibility of this particular mixed land management.

  • 36.
    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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  • 37.
    Mseddi, K.
    et al.
    Department of Biology, Faculty of Science, University of Sfax, Tunisia; Department of Biology, Faculty of Science, University of Hail, Saudi Arabia.
    Alghamdi, A.
    Department of Biology, Faculty of Science, University of Hail, Saudi Arabia.
    Abdelgadir, Mohanad
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Department of Biology, Faculty of Science, University of Hail, Saudi Arabia.
    Sharawy, S.
    Department of Biology, Faculty of Science, University of Hail, Saudi Arabia.
    Chaieb, M.
    Department of Biology, Faculty of Science, University of Sfax, Tunisia.
    Miller, T.
    Centre for Middle Eastern Plants, Royal Botanic Garden Edinburgh, Edinburgh, UK.
    Phytodiversity distribution in relation to altitudinal gradient in Salma Mountains – Saudi Arabia2021In: Global Ecology and Conservation, ISSN 2351-9894, Vol. 27, article id e01525Article in journal (Refereed)
    Abstract [en]

    This study was conducted to assess the phytodiversity distribution in relation to altitudinal gradient in Salma Mountains, a naturally protected habitat in Ha'il region in the north of Saudi Arabia. Seventeen (17) sampling sites covering three altitudinal zones (i.e. valley, foot and top mountain) were randomly selected within the study area. Within each site and altitudinal zone, the floristic composition and the potential plant species of economic values were assessed and evaluated. A total number of 163 plant species belong to 101 genera and 41 families were identified in this study. Their economic values were also classified into forage (32%), edible (8.7%), medicinal (21.3%), ornamental (30.7%), weeds (18%) and rare species (14%). In addition, results obtained from different altitudinal zones of Salma Mountains, showed that 24 species were spread in the adjacent valley to the mountains, where 32 species spreading at the foot of the mountains and 40 found occupying the top of the mountains. The rest of species have been found to occupy larger geographical distribution in all altitudinal parts. Across the altitudinal gradients, species richness has been found to be consistent with a monotonically increasing pattern with a high richness at high altitudes. The current study suggests that such naturally protected ecosystem can provide a refuge for native plant species and serve as seed bank for a future restoration program in Ha'il region and other similar habitats in Saudi Arabia.

  • 38.
    Nechiporuk, Dmitrii
    Södertörn University, Centre for Baltic and East European Studies (CBEES).
    Пограничные земли, общие воды: история трансграничного сотрудничества России, Балтийских стран и ЕС по оздоровлению экосистемы Балтийского моря = Pograničnye zemli, obščie vody : istorija transgraničnogo sotrudničestva Rossii, Baltijskich stran i ES po ozdorovleniju ėkosistemy Baltijskogo morja2014Book (Other academic)
  • 39.
    Nordström, Susanne
    et al.
    Södertörn University, School of Life Sciences.
    Mattsson, Jan-Eric
    Södertörn University, School of Life Sciences, Biology.
    Important factors for the creation of nature reserves2005Conference paper (Other academic)
  • 40.
    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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  • 41. Olsén, K. Håkan
    Development of the olfactory organ of the Arctic charr, Salvelinus alpinus (L.) (Teleostei, Salmonidae)1993In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 71, no 10, p. 1973-1984Article in journal (Refereed)
    Abstract [en]

    The structure of the olfactory epithelium in developing Arctic charr, Salvelinus alpinus, was studied by light and scanning electron microscopy. Embryos, larvae, free-swimming fry, and individuals up to the age of 96 months after hatching were studied. In larvae about 10 days after hatching, microvillar and ciliated olfactory receptor cells were located in a pit and no nares were differentiated. Fifty days after hatching, two nares were present on each side of the head, and about 20 days later one or two lamellae had started to differentiate and were visible as an elevation in the caudal part of the floor of the olfactory chamber. Six months after hatching there were 5 – 10 club-shaped lamellae, which in older fish acquired a more disk-like appearance. The number and size of lamellae increased with the size of the fish, reaching the maximum number, 10 – 15 per rosette, 18 – 30 months after hatching. At 18 months, secondary folding of the lamellae had started. Eighteen months later, differentiated secondary lamellae were present and most of the central raphe was composed of indifferent epithelium. The olfactory receptors were located in the depressions between the secondary folds. The development of the olfactory organ is discussed in relation to the results of behavioural studies.

  • 42.
    Olsén, K. Håkan
    et al.
    Department of Environmental Toxicology, Uppsala University.
    Grahn, Mats
    Molecular Population Biology Laboratory, Department of Animal Ecology, Lund University.
    Lohm, Jakob
    Molecular Population Biology Laboratory, Department of Animal Ecology, Lund University.
    Langefors, Åsa
    Molecular Population Biology Laboratory, Department of Animal Ecology, Lund University.
    MHC and kin discrimination in juvenile Arctic charr, Salvelinus alpinus (L.).1998In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 56, no 2, p. 319-327Article in journal (Refereed)
    Abstract [en]

    Kin recognition and discrimination are thought to occur in several species of various taxonomic groups. In salmonid fish, juveniles can discriminate between odours of siblings and nonsiblings from the same population even if the odour donors and the test fish have been reared separately since fertilization. This indicates that some genetic factor is important in the recognition process. The mechanisms behind kin recognition and discrimination have not yet been described. In the present study, we performed fluviarium tests to examine whether kin recognition and discrimination in juvenile Arctic charr are influenced by the major histocompatibility complex (MHC). Prior to the fluviarium tests, exon 2 of an MHC class II B gene in charr was analysed with denaturing gradient gel electrophoresis (DGGE) and individual genotypes were determined. In the fluviarium, when fish had the choice between water scented by an MHC identical sibling and a sibling with a different MHC genotype they preferred water from identical siblings. Moreover, water scented by an MHC different sibling was preferred to water from an MHC different nonsibling. However, we observed no discrimination when the test fish shared one allele with the nonsibling donor but no alleles with the sibling donor. Our results indicate that the MHC has a significant influence on the odours used for kin recognition and discrimination in juvenile Arctic charr.

  • 43.
    Olsén, K. Håkan
    et al.
    Uppsala universitet, Institutionen för evolutionsbiologi.
    Järvi, Torbjörn
    Institute of Freshwater Research, Sweden; Department of Zoology, University of Stockholm, Sweden.
    Effects of kinship on aggression and RNA content in juvenile Arctic charr1997In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 51, no 2, p. 422-435Article in journal (Refereed)
    Abstract [en]

    The behaviour of juvenile Arctic charr Salvelinus alpinus was studied in groups of four siblings composed of familiar and unfamiliar individuals or in mixed groups of four where both siblings and unrelated individuals were present. The frequency of aggressive acts was significantly higher in the mixed groups compared to the pure sibling groups and the difference was present at all levels of the hierarchy rank order, based on a dominance index, except the lowest ranked individuals. The difference was significant after but not before feeding, implying that competition with non-kin for a food resource increased the aggression. No significant difference in weight gain was observed between sibling and mixed groups during the 6 days of the experiment, but the RNA contents of lateral musculature in dominant individuals from sibling groups were significantly higher than the corresponding fish in the mixed group, suggesting a difference in growth rate when the experiments ended. No significant difference in RNA content was observed between subordinate fish of the two treatments, i.e. siblings v. mixed.

  • 44.
    Olsén, K. Håkan
    et al.
    Department of Limnology, Vertebrate Physiology & Behaviour Unit, Uppsala University.
    Järvi, Torbjörn
    Institute of Freshwater Research, Swedish National Board of Fisheries, Drottningholm, Sweden.
    Löf, Anna-Carin
    Fisheries Research Station, Swedish National Board of Fisheries Brobacken, Älvkarleby, Sweden.
    Aggressiveness and kinship in brown trout (Salmo trutta) parr1996In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 7, no 4, p. 445-450Article in journal (Refereed)
    Abstract [en]

    In a series of experiments, kin-biased behavior of young brown trout (Salmo trutta) was observed. The aggressiveness shown by groups of familiar siblings (siblings reared together since fertilization) and groups of unfamiliar siblings (siblings reared apart since fertilization) was significantly lower compared to that of mixed groups of two unrelated sibling groups (offspring of two different pairs of parents). The evolution of kin-biased behavior, as shown by a reduction in aggressiveness, is assumed to have evolved through a kin-selective mechanism.

  • 45.
    Olsén, K. Håkan
    et al.
    Department of Limnology, Vertebrate Physiology & Behaviour Unit, Uppsala University.
    Winberg, Svante
    Department of Limnology, Vertebrate Physiology & Behaviour Unit, Uppsala University.
    Learning and sibling odor preference in juvenile arctic char,Salvelinus alpinus (L.).1996In: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 22, no 4, p. 773-786Article in journal (Refereed)
    Abstract [en]

    The importance of learning for sibling odor preference in juvenile Arctic char was analyzed in the present study. Fish were reared in the following eight conditions: (1) communally with siblings for 15 months; (2) communally with siblings for 17 months; (3) in isolation since fertilization; (4) in isolation since fertilization and exposed to sibling scent during the whole rearing period; (5) in isolation since fertilization and exposed to sibling scent from time of free swimming; (6) in isolation since fertilization and exposed to sibling scent during the whole rearing period, except two months without scent until testing; (7) in isolation since fertilization and exposed to sibling scent from time of free swimming, except two months without scent until testing; and (8) communally with siblings followed by a two-month isolation until testing. Char were followed individually in a Y-maze (fluviarium test) with a video-computer-based image analysis system for 12 hr. Sibling-scented water was supplied to one lateral half of the test area and water from non-siblings on the opposite half. Isolated individuals without any preexposure to siblings showed no significant preference. Test fish reared with siblings and those that had been reared in isolation but exposed to sibling scent until testing preferred water conditioned by their own siblings. Isolated fish that had been exposed to sibling scent since fertilization, or since free swimming, followed by a two-month period with only pure water, showed no significant preference. Char isolated for two months after being communally reared preferred water scented by siblings. The results demonstrated that behavioral discrimination between siblings and nonsibling odors occurred after total isolation (isolated both from siblings and sibling odors) only in individuals that had been communally reared. This may suggest that social interactions are important for learning and long-term memory of sibling odors in Arctic char.

  • 46.
    Persson, Martin
    Södertörn University College, School of Life Sciences.
    Changes in condition of herring (Clupea harengus) in Swedish coastal waters2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The condition of the herring (Clupea harengus) in the Baltic Sea has decreased during the past 30-40 years. This decrease could be explained by different factors; (1) change in diet due to changes in zooplankton community, (2) changes in water temperature and salinity, (3) increasing nutrient inputs and (4) competition for food with other species such as sprat (Sprattus sprattus). In this study the change in condition was analysed using the Fulton’s condition index, and by looking at age and sex of the fish as well as the season and locationthe fish was caught, the differences between these factors were presented. Data from the national Swedish contaminant monitoring programme where used from four locations in the Baltic Sea and two locations at the Swedish West coast. The data was analysed using multiple regressions in R Commander. The result show that the condition, and the temporal trends in condition value, varies at different locations, with higher condition values and increasing temporal trends at the Swedish West coast, compared to the Baltic Sea with lower condition values and where three of four locations show decreasing temporal trends. The condition varied between spring and autumn caught herring as well, while age and sex showed less significant differences.

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  • 47.
    Petersson, E
    et al.
    National Board of Fisheries, Sweden ; Uppsala University, Sweden.
    Järvi, T
    National Board of Fisheries, Sweden ; Uppsala University, Sweden.
    Olsén, Håkan
    Uppsala University, Sweden.
    Mayer, I
    Stockholm University, Sweden.
    Hedenskog, M
    National Board of Fisheries, Sweden.
    Male-male competition and female choice in brown trout1999In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 57, p. 777-783Article in journal (Refereed)
    Abstract [en]

    In some salmonid species, the females have been assumed to choose their mates on the size of the male's adipose fin. This hypothesis was tested in a stream water aquarium, in which 19 brown trout, Salmo trutta, females were allowed to choose between two males of the same body size but with different adipose fin sizes. The two males were separated from each other in cages. After the female had started to prepare her nest close to one of them, the males were released and allowed to fight each other for the opportunity to spawn. Out of 19 females, 14 prepared a nest closest to the male with the larger adipose fin. However, only six of the 14 females spawned with this male. Males that spawned were more dominant (i.e. were more likely to win fights). When the female spawned with the male she chose, he was less aggressive towards her than when she spawned with the other male. There were no significant differences in the plasma levels of testosterone (T) and 11-ketotestosterone (11-KT) between the chosen males and those not chosen. However, the dominant males had significantly higher plasma levels of T and 11-KT both before and after the experiment. The results support the view that female brown trout exhibit mate choice, but their choice is overruled by male-male competition.

  • 48.
    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).

  • 49.
    Plue, Jan
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Stockholm University / University of Leuven, Heverlee, Belgium.
    Aavik, T.
    Tartu University, Tartu, Estonia.
    Cousins, S. A. O.
    Stockholm University.
    Grazing networks promote plant functional connectivity among isolated grassland communities2019In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 25, no 1, p. 102-115Article in journal (Refereed)
    Abstract [en]

    Aim: Habitat loss threatens plant diversity globally. Lack of plant functional connectivity between isolated populations is often pinpointed as one of the major underlying mechanisms driving subsequent species extinctions. Therefore, landscape-scale conservation management promoting functional connectivity needs to be implemented urgently. Supporting the movement of seed dispersal vectors such as grazing animals may help safeguard local and regional plant diversity in fragmented landscapes. However, the efficacy of such management remains to be thoroughly assessed. Location: Stockholm archipelago, Sweden. Methods: We test how grazing animals may serve as mobile corridors within rotational grazing networks promoting plant functional connectivity via directed seed dispersal. Using landscape genetics, we compare isolated populations of the grassland perennial Campanula rotundifolia located in either active or abandoned grazing networks, to test if spatial patterns in their genetic diversity, differentiation and allele frequencies relate to the presence or absence of connectivity via rotational grazing management. Results: Grazing networks imprinted strong landscape-scale spatial patterning in pairwise population genetic differentiation and within-population genetic diversity. Isolated C. rotundifolia populations functionally connected by grazing animals held higher genetic diversity compared to populations no longer connected by grazing livestock. Gene flow linked to the directed seed dispersal was higher between populations within grazing networks, confirmed by their increased allele richness. We found a predictable, nested loss of genetic diversity among C. rotundifolia populations in abandoned grazing networks. Main conclusions: Grazing animals were important seed dispersal vectors, functionally connecting isolated grassland communities, so being vital to the successful long-term persistence and conservation of not only species but also genetic diversity. Crucially, the study underlines the possibilities of using domestic livestock as mobile corridors within rotational grazing networks as an effective tool to manage, conserve and restore both genetic and species diversity among isolated plant communities in fragmented landscapes.

  • 50.
    Plue, Jan
    et al.
    Södertörn University, School of Natural Sciences, Technology and Environmental Studies, Environmental Science. Stockholm University / University of Bremen, Germany.
    De Frenne, P.
    Ghent University, Belgum.
    Acharya, K.
    Norwegian University of Science and Technology, Norway.
    Brunet, J.
    SLU.
    Chabrerie, O.
    Jules Verne University of Picardie, Amiens Cedex, France.
    Decocq, G.
    University of Bremen, Germany.
    Diekmann, M.
    Norwegian University of Science and Technology, Norway.
    Graae, B. J.
    Heinken, T.
    University of Potsdam, Potsdam, Germany.
    Hermy, M.
    University of Leuven, Leuven, Belgium.
    Kolb, A.
    University of Bremen, Germany.
    Lemke, I.
    University of Bremen, Germany.
    Liira, J.
    University of Tartu, Tartu, Estonia.
    Naaf, T.
    Institute of Land Use Systems, Müncheberg, Germany.
    Verheyen, K.
    Ghent University, Belgium.
    Wulf, M.
    Institute of Land Use Systems, Müncheberg, Germany.
    Cousins, S. A. O.
    Stockholm University.
    Where does the community start, and where does it end?: Including the seed bank to reassess forest herb layer responses to the environment2017In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 28, no 2, p. 424-435Article in journal (Refereed)
    Abstract [en]

    Question: Below-ground processes are key determinants of above-ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above-ground diversity patterns, bypassing below-ground plant diversity stored in seed banks. As seed banks may shape above-ground plant communities, we question whether concurrently analysing the above- and below-ground species assemblages may potentially enhance our understanding of community responses to environmental variation. Location: Temperate deciduous forests along a 2000 km latitudinal gradient in NW Europe. Methods: Herb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer–seed bank community. Results: Seed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and β-diversity of the combined herb layer–seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover. Conclusions: The seed bank is a below-ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co-exist as a single community by means of the so-called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above- and below-ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.

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