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  • 1.
    Albert, Séréna
    et al.
    Stockholm University, Sweden.
    Hedberg, Per
    Stockholm University, Sweden .
    Motwani, Nisha H.
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Sjöling, Sara
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 communities2021Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 11, nr 1, artikel-id 24033Artikel i tidskrift (Refereegranskat)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Shobrak, Mohammed
    Taif University, Saudi Arabia.
    Habitat selection by the Spiny-tailed lizard (Uromastyx aegyptia): A view from spatial analysis2021Ingår i: Saudi Journal of Biological Sciences, ISSN 1319-562X, Vol. 28, nr 9, s. 5034-5041Artikel i tidskrift (Refereegranskat)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Bats in Urban Sweden: A multiple regression analysis of bats’ relationship to urbanization2021Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 Sediments2022Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 8, artikel-id 811533Artikel i tidskrift (Refereegranskat)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Dynamics and fate of blue carbon in a mangrove-seagrass seascape: influence of landscape configuration and land-use change2021Ingår i: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 36, s. 1489-1509Artikel i tidskrift (Refereegranskat)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    The amount of light reaching the leaves in seagrass (Zostera marina) meadows2021Ingår i: PLOS ONE, E-ISSN 1932-6203, Vol. 16, nr 9, artikel-id e0257586Artikel i tidskrift (Refereegranskat)
    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.
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik. 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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Biologi.
    Bensch, Staffan
    Lund University.
    Gene expression in the brain of a migratory songbird during breeding and migration2016Ingår i: Movement Ecology, E-ISSN 2051-3933, Vol. 4, artikel-id 4Artikel i tidskrift (Refereegranskat)
    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 trout1999Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 55, nr 6, s. 1290-1303Artikel i tidskrift (Refereegranskat)
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Effects of seagrass overgrazing on sediment erosion and carbon sink capacity: Current Understanding And Future Priorities2021Ingår i: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 6, nr 6, s. 309-319Artikel i tidskrift (Refereegranskat)
    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.
    Dahl, Martin
    et al.
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Bernabeu, I.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC), Spain.
    Serrano, O.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC),Spain, Edith Cowan University, Australia.
    Leiva-Dueñas, C.
    Aarhus University, Denmark.
    Linderholm, H. W.
    University of Gothenburg, Sweden.
    Asplund, M. E.
    University of Gothenburg, Sweden.
    Björk, M.
    Stockholm University, Sweden.
    Ou, T.
    University of Gothenburg, Sweden.
    Svensson, J. R.
    University of Gothenburg, Sweden.
    Andrén, Elinor
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Andrén, Thomas
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Bergman, S.
    UiT—The Arctic University of Norway, Norway.
    Braun, Sara
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Eklöf, A.
    Stockholm University, Sweden.
    Ežerinskis, Z.
    Center for Physical Sciences and Technology, Lithuania.
    Garbaras, A.
    Center for Physical Sciences and Technology, Lithuania.
    Hällberg, P.
    Stockholm University, Sweden.
    Löfgren, E.
    Stockholm University, Sweden.
    Kylander, M. E.
    Stockholm University, Sweden.
    Masqué, P.
    Edith Cowan University, Australia, PrincipalityofMonaco,Monaco.
    Šapolaitė, J.
    Center for Physical Sciences and Technology, Lithuania.
    Smittenberg, R.
    Stockholm University, Sweden, Principality of Monaco, Monaco.
    Mateo, M. A.
    Consejo Superior de Investigaciones Científicas (CEAB‐CSIC), Spain, Edith Cowan University, Australia.
    A 2,000-Year Record of Eelgrass (Zostera marina L.): Colonization Shows Substantial Gains in Blue Carbon Storage and Nutrient Retention2024Ingår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 38, nr 3, artikel-id e2023GB008039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 11.
    Dinnétz, Patrik
    Stockholm university.
    Male sterility, Protogyny and Pollen-Pistil interference in Plantago maritima (Plantaginaceae) a wind-pollinated, self-incompatible perennial1997Ingår i: American Journal of Botany, ISSN 0002-9122, E-ISSN 1537-2197, Vol. 84, nr 11, s. 1588-1594Artikel i tidskrift (Refereegranskat)
    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.

  • 12.
    Dinnétz, Patrik
    et al.
    Stockholm university.
    Jerling, Lenn
    Stockholm university.
    Gynodioecy in Plantago maritima L.; no compensation for loss of male function1997Ingår i: Acta Botanica Neerlandica, ISSN 0044-5983, E-ISSN 1365-2001, Vol. 46, nr 2, s. 193-206Artikel i tidskrift (Refereegranskat)
    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.

  • 13.
    Dinnétz, Patrik
    et al.
    Stockholm university.
    Jerling, Lenn
    Stockholm university.
    Spatial distribution of male sterility in Plantago maritima1998Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 81, s. 255-265Artikel i tidskrift (Refereegranskat)
    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.

  • 14.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Where the grass is greenest in seagrass seascapes depends on life history and simple species traits of fish2022Ingår i: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 266, artikel-id 107738Artikel i tidskrift (Refereegranskat)
    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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  • 15.
    Eggertsen, M.
    et al.
    Stockholm University, Sweden.
    Larsson, Josefine
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Porseryd, Tove
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 reef2021Ingår i: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 542, artikel-id 151606Artikel i tidskrift (Refereegranskat)
    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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  • 16.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 locations2021Ingår i: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 23, s. 1049-1067Artikel i tidskrift (Refereegranskat)
    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.

  • 17.
    Elma, Eylem
    et al.
    Newcastle University, UK; Stockholm University, Sweden.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 communities2023Ingår i: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 186, artikel-id 114479Artikel i tidskrift (Refereegranskat)
    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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  • 18.
    Elofsson, Katarina
    et al.
    Swedish University of Agricultural Sciences.
    Gren, I. -M
    Swedish University of Agricultural Sciences.
    Regulating invasive species with different life history2015Ingår i: Journal of Bioeconomics, ISSN 1387-6996, E-ISSN 1573-6989, Vol. 17, nr 2, s. 113-136Artikel i tidskrift (Refereegranskat)
    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).

  • 19.
    Elofsson, Katarina
    et al.
    Södertörns högskola, Institutionen för samhällsvetenskaper, Nationalekonomi. 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?2023Ingår i: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 204, artikel-id 107672Artikel i tidskrift (Refereegranskat)
    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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  • 20.
    Fanous, Nicola
    et al.
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Lohsar, Iqra
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Kartläggning av externa effekter vid etablering av storskaliga solcellsparker: En fallstudie av tre storskaliga solcellsparker2022Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det här är en stuide om externa effekter som kan uppstå vid etablering av solcellsparker och om hur sådana effekter kan påverka samhällsbeslut. Förnybara energikällor spelar en nyckeroll för att skapa en hållbar framtid, där storskaliga soclellsparker kan ses som ett hållbart alternativ till energikällor. Det finns en risk att Solcellsparker kan medföra globala och lokala negativa externa effekter och är därför intressant att studera. Studien bygger på en kvalitativ metod, där intervjuer med fya sakägare som har goda kunskaper och insikter om solcellsparker genomförts. Empiriskt material från fysisk planering, miljöbedömningar och andra pålitliga källor har använts för att besvara studiens frågeställningar. Resultaten visar att anläggningen av en solcellspark kan leda till en så kallad green vs. green-konflikt, där det finns olika intressen och åsikter. Genom att jämföra tre befintliga solcellsparker har vi sett vilken roll externa effekter spelar i beslutsfattande när det gäller att anlägga en solcellspark och hur väsentliga samhällintressen, till exempel livsmedelsförsörjning, också kan påverka beslut om att anlägga solcellsparker. Resultaten visar också att lokaliseringsprinicipen spelar en stor roll, genom att påverka vilka externa effekter som kan uppstå lokalt på platsen. 

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  • 21. Gorokhova, Elena
    et al.
    Edlund, Anna
    Södertörns högskola, Institutionen för livsvetenskaper.
    Hajdu, Susanna
    Zhivotova, Elena N.
    Nucleic acid levels in copepods: dynamic response to phytoplankton blooms in the northern Baltic proper2007Ingår i: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 349, s. 213-225Artikel i tidskrift (Refereegranskat)
    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.

  • 22.
    Halltin Nijm, Nadja
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik.
    Biodiversitet i naturliga kolsänkor: sammansättning av sedimentlevande djur samt kollagring i kustnära habitat2022Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Havet har en nyckelroll när det kommer till de ökade koldioxidutsläppen som tär på miljön då den är en naturlig kolsänka. Kustnära habitat och vegeterade områden såsom sjögräsängar har visat sig vara mycket effektiva på att fånga upp organiskt kol som lagras i bottensedimenten. Kapaciteten till att lagra kol i kustnära habitat varierar beroende på faktorer som t ex växtbiomassa, sedimentets kornstorlek och artsammansättningen av djur som hjälper till att bryta ner kolet. Däremot har djursammansättningen forskats om i begränsad utsträckning. Därför har denna studie valt att undersöka sammansättningen av sedimentlevande djur i kustnära habitat och dess relation till kolinnehållet. Sedimentkärnor samlades från de utvalda kustnära habitaten (Ruppia spp., nateväxter, ålgräs, ickevegeterad mjukbotten samt torrvass och våtvass) för att artidentifiera djuren och för att räkna ut det sedimentära organiska kolinnehållet. Resultatet visade signifikanta skillnader mellan alla habitats artsammansättningar förutom mellan nateväxter och Ruppia spp., nateväxter och ålgräs samt mellan ickevegeterad mjukbotten och torrvass. Arter som förekom och bidrog mest till variationen mellan och inom habitaten var Oligochaeta, Hydrobia spp., Chironomidae, Hediste diversicolor och Macoma balthica. Det hittades inget positivt samband mellan artsammansättningen och kollagringen i de kustnära habitaten eftersom vassområdena hade en låg artrikedom men ett högt kolinnehåll, medan nateväxthabitatet som hade störst artrikedom innehöll ett lågt kolinnehåll. Istället kan andra faktorer ha bidragit mer till habitatens kollagringar. Däremot förekom ett högt antal av Chironomidae i vassbältena som innehöll ett högre organiskt kolinnehåll. Anledningen till detta beror troligen på deras förmåga att klara av syrefattiga miljöer som rådde i vassbältena, snarare än att de bidrog till kollagringen. Eftersom kustnära habitat är effektiva kolsänkor är det viktigt att detta fortsätter forskas om för en ökad förståelse för vilka faktorer som påverkar deras kolsänkekapacitet.

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  • 23.
    Hedlund, Johanna S. U.
    Södertörns högskola, Institutionen för livsvetenskaper.
    Living with males: benefits and costs to females of resident males in Colobus vellerosus2009Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats
    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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  • 24.
    Henriksson, Oskar
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Mwandya, Augustine
    Sokoine University of Agriculture.
    Gullström, Martin
    Stockholm University.
    Thorberg, Marika
    Södertörns högskola, Institutionen för livsvetenskaper.
    Grahn, Mats
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Genetic Identification and Population Structure of Juvenile Mullet (Mugilidae) Collected for Aquaculture in East Africa2012Ingår i: Western Indian Ocean Journal of Marine Science, ISSN 0856-860X, E-ISSN 2683-6416, Vol. 11, nr 1, s. 41-54Artikel i tidskrift (Refereegranskat)
    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.

  • 25.
    Ismail, R. O.
    et al.
    Stockholm University, Sweden; University of Dar es Salaam, Tanzania.
    Asplund, M. E.
    University of Gothenburg, Sweden.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    George, R.
    Stockholm University, Sweden; Tanzania Fisheries Research Institute (TAFIRI), Tanzania.
    Dahl, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 experiment2023Ingår i: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 561, artikel-id 151864Artikel i tidskrift (Refereegranskat)
    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.

  • 26.
    Janzén, Therese
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Hammer, Monica
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Dinnétz, Patrik
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Factors responsible for Ixodes ricinus presence and abundance across a natural-urban gradient2023Dataset
    Abstract [sv]

    För att förstå utbredningen av den vanliga fästingen Ixodes ricinus, undersökte vi hur både lokala faktorer och olika landskapsegenskaper påverkar förekomsten av fästingar i grönområden längs med urbaniseringsgradienten i Stockholms län, Sverige. Fästingar och fältdata samlades in under 2017 och 2019 och analyserades i relation till habitatdata och landskapsdata framtaget från geografiskt informationssystem (GIS). 2017 samlades fästingar och fältdata in från 12 olika platser i Stockholms län som ursprungligen hade valts som slumpmässiga kontroller till en annan studie men aldrig använts. 2019 samlades fästingar och fältdata in från 35 olika platser längs med urbaniseringsgradienten. Dessa 35 platser valdes slumpmässigt ut med hjälp av GIS. För att beräkna urbaniseringsgraden för varje plats, använde vi andelen exploaterad mark i en 1000m buffertzon. För de 12 första insamlingsplatserna under 2017 valde vi slumpmässigt ut 10 2m × 2m rutor för inventering av fästingar och fältdata. På de 35 platser som vi inventerade 2019, samlade vi in fästingar i 5 2m × 2m rutor. Vi besökte alla platser en gång och totalt inventerades 295 provtagningsrutor. För varje ruta noterade vi datum, tid, väderförhållande, antal fästingar, vegetationshöjd och trädstamstäthet runt varje ruta. För att ta fram landskapsdata skapades 10 buffertzoner från 100m till 1000m radies runt varje insamlingsplats i GIS tillsammans med Naturvårdverkets Nationella Marktäckedata. Dessa satellitkartor har en upplösning på 10m och har följande huvudkategorier 1) Skog, 2) Öppen mark, 3) Åkermark, 4) Öppen våtmark, 5) Exploaterad mark, och 6) Vatten. För att identifiera riskfaktorer valde vi att använda dessa huvudkategorier med undantag for kategorin Skog där vi valde att inkludera de åtta olika skogstyperna: Tallskog, Granskog, Barrblandskog, Lövblandad barrskog, Triviallövskog, Ädellövskog, Triviallövskog med ädellövsinslag och Temporärt ej skog. För att ta fram statistik och beräkna konfigurationen av landskapet runt varje insamlingsplats, använde vi marktäckedata från 1000m buffertzonen som exporterades till GeoTIFF-format och som sedan analyserades med FRAGSTATS version 4. Vi använde Shannons diversitetsindex (SHDI) för att uppskatta mångfalden av marktäcketyper runt varje insamlingsplats. För att mäta aggregeringen av de olika martäcketyperna i landskapet använde vi Contagion (CONTAG). Som ett mått på skogens konfiguration använde vi PLAND, som är proportionen av skog i landskapet och total edge (TE) som är den totala skogskantslängden. Alla statistiska analyser har gjorts med R, versionen 4.0.3. För att analysera effekterna av olika riskfaktorer på fästingförekomst i olika grönområden, använde vi generaliserade linjära mixade modeller med Poisson-fördelade residualer. Eftersom datasetet innehöll fler nollor än vad som förväntas enligt en Poisson eller negativ binomialfördelning som orsakar överdispersion, använde vi nollinflations-Poissonmodeller i paketet glmmTMB.

  • 27.
    Janzén, Thérese
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap. Södertörns högskola, Centrum för Östersjö- och Östeuropaforskning (CBEES), Baltic & East European Graduate School (BEEGS).
    Ticks - ecology, new hazards, and relevance for public health2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Fästingar är näst efter myggor de viktigaste vektorerna för spridning av sjukdomar både till människor och husdjur. I länderna runt Östersjön finns två medicinskt viktiga fästingarter som ökar i utbredning och antal, vilket också utgör ett ökat hot mot folkhälsan. Syftet med avhandlingen var att studera eko-epidemiologisk dynamik och viktiga mekanismer för spridningen av fästingar och fästingburna bakterier i en urban gradient.

    Grönområden i och runt städer utgör mötesplatser för människor, husdjur, fästingar och fästingburna patogener. I Stockholms län undersöktes effekterna av grönområdenas egenskaper på förekomst av fästingar och deras patogener utefter den urbana gradienten. Alla insamlade fästingar artbestämdes med molekylära metoder, och samtliga tillhörde arten Ixodes ricinus. Fästingar var vanliga i rurala områden och naturliga miljöer, men förekom även i urbana parker. Viktiga faktorer för förekomst av fästingar var den signifikant negativa effekten av vegetationshöjd vid insamlingsplatsen, och den signifikant positiva effekten av barrblandskog i det omgivande landskapet.

    I studien av patogener var prevalensen av Borrelia burgdorferi sensu lato 24% och för Anaplasma phagocytophilum 7.5%. Fästingar infekterade med B. miyamotoi påträffades vid några få platser med en prevalens på 0.9%. Den dominerande arten inom gruppen av B. burgdorfgeri (s.l.) var B. afzelii. Trädtäthet runt insamlingsplatsen hade en signifikant positiv effekt på prevalensen av B. burgdorferi (s.l.). Utbredningen av lövskogar och skogskanter hade signifikant positiva effekter på prevalensen av A. phagocytophilum, och fästingar infekterade med A. phagocytophilum förekom även i urbana parker. Den fästingburna sjukdomen granulocytär anaplasmos hos häst, ökade signifikant från 2002 till 2015, med flest fall på sensommar och tidig höst.

    Folkhälsorisker för fästingburna sjukdomar i ett urbant grönområde uppskattades med hjälp av information om fästingförekomst, patogenprevalens, befolkningstäthet och besöksantal. Resultatet visade en måttlig till hög risk för fästingburna sjukdomar i hela det undersökta grönområdet. Vid intervjuer med besökare påvisades en hög medvetenhet om fästingar och fästingspridda sjukdomar, men att skyddsåtgärder endast tillämpades vid specifika fritidsaktiviteter såsom bärplockning.

    Resultatet från avhandlingen visar på en betydande risk för spridning av fästingburna sjukdomar längs med hela den urbana gradienten, inklusive områden som traditionellt ansetts ha en låg risk. Resultaten som visar på eko-epidemiologiska mekanismer för spridning av granulocytär anaplasmos hos häst är relevanta också ur ett folkhälsoperspektiv eftersom bakterierna orsakar sjukdom även hos människor. Trots risker med fästingar och deras sjukdomar är grönområden ytterst viktiga för folkhälsan utifrån andra hälsoaspekter, men det behövs initiativ och medvetenhet för att motverka riskerna.

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    Ticks: ecology, new hazards and relevance for public health
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  • 28.
    Kalokora, Olivia J
    et al.
    Dar es Salaam University College of Education (DUCE), Tanzania.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 storage2022Ingår i: Ecology and Evolution, E-ISSN 2045-7758, Vol. 12, nr 2, artikel-id e8579Artikel i tidskrift (Refereegranskat)
    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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  • 29.
    Kolseth, Anna-Karin
    Södertörns högskola, Institutionen för livsvetenskaper. Uppsala universitet.
    Evolutionary Processes and Spatial Genetic Variation in Euphrasia stricta on the Baltic Island of Gotland2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

  • 30.
    Lind, Emma E
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi. Södertörns högskola, Institutionen för livsvetenskaper, Molekylärbiologi.
    Grahn, Mats
    Södertörns högskola, Institutionen för livsvetenskaper, Miljövetenskap. Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Directional genetic selection by pulp mill effluent on multiple natural populations of three-spined stickleback (Gasterosteus aculeatus)2011Ingår i: Ecotoxicology, ISSN 0963-9292, E-ISSN 1573-3017, Vol. 20, s. 503-512Artikel i tidskrift (Refereegranskat)
    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.

  • 31.
    Lorentsson, Susanne
    et al.
    Uppsala university.
    Mattsson, Jan-Eric
    Uppsala university.
    New reports of soredia dispersed by ants, Formica cunicularia1999Ingår i: The Lichenologist, ISSN 0024-2829, E-ISSN 1096-1135, Vol. 31, s. 204-207Artikel i tidskrift (Refereegranskat)
  • 32.
    Lundberg, Max
    et al.
    Lund University.
    Boss, John
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Biologi. Karolinska Institute, Karolinska University Hospital.
    Canbäck, Björn
    Lund University.
    Liedvogel, Miriam
    Lund University.
    Larson, Keith W
    Lund University.
    Grahn, Mats
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Biologi.
    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.2013Ingår i: BMC Genomics, E-ISSN 1471-2164, Vol. 14, artikel-id 330Artikel i tidskrift (Refereegranskat)
    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.

  • 33.
    Lättman, Håkan
    et al.
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap.
    Mattsson, Jan-Eric
    Södertörns högskola, Institutionen för kemi, biologi, geografi och miljövetenskap, Biologi.
    Milberg, Per
    IFM Biology, Conservation Ecology Group, Linköping University.
    Rapid changes in the epiphytic macrolichen flora in southern Sweden2004Konferensbidrag (Övrigt vetenskapligt)
  • 34.
    Löfroth, Therese
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Merinero, Sonia
    Universidad Rey Juan Carlos, Spain.
    Johansson, Johanna
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    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 forests2024Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 53, nr 1, s. 20-33Artikel i tidskrift (Refereegranskat)
    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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  • 35.
    Mattsson, Jan-Eric
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Hansson, Ann-Charlotte
    Södertörns högskola, Institutionen för livsvetenskaper.
    Lindblom, Louise
    University of Bergen, Museum of Natural History.
    Genetic diversity and substrate preferences in Hypogymnia physodes in northern Europe2006Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 36.
    Mattsson, Jan-Eric
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Vinter, Tiina
    Södertörns högskola, Institutionen för livsvetenskaper.
    Lönn, Mikael
    Södertörns högskola, Institutionen för livsvetenskaper.
    Macrolichen diversity in relation to diversity of woody plants2006Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 37.
    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?2019Ingår i: PLOS ONE, E-ISSN 1932-6203, Vol. 14, nr 4, artikel-id e0215594Artikel i tidskrift (Refereegranskat)
    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.

  • 38.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Population genetics of the hound needlefish Tylosurus crocodilus (Belonidae) indicate high connectivity in Tanzanian coastal waters2023Ingår i: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 19, nr 4-5, s. 261-270Artikel i tidskrift (Refereegranskat)
    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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  • 39.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap. 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 Arabia2021Ingår i: Global Ecology and Conservation, ISSN 2351-9894, Vol. 27, artikel-id e01525Artikel i tidskrift (Refereegranskat)
    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.

  • 40.
    Nechiporuk, Dmitrii
    Södertörns högskola, Centrum för Östersjö- och Östeuropaforskning (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 morja2014Bok (Övrigt vetenskapligt)
  • 41.
    Ngisiange, Noah
    et al.
    Stockholm University, Sweden; Kenya Marine and Fisheries Research Institute, Kenya.
    Tarimo, Barnabas
    University of Dar es Salaam, Tanzania.
    Daudi, Lillian
    Kenya Marine and Fisheries Research Institute, Kenya.
    Mwangi, Stephen
    Kenya Marine and Fisheries Research Institute, Kenya.
    Malesa, Fadhili
    University of Dar es Salaam, Tanzania.
    George, Rushingisha
    Tanzania Fisheries Research Institute, Tanzania.
    Kyewalyanga, Margareth S
    University of Dar es Salaam, Tanzania.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Osore, Melckzedeck
    Kenya Marine and Fisheries Research Institute, Kenya.
    Mwaluma, James
    Kenya Marine and Fisheries Research Institute, Kenya.
    Winder, Monika
    Stockholm University, Sweden.
    Seasonal fish larvae abundance and composition in seagrass habitats of coastal East Africa2024Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 14, nr 1, s. 11203-, artikel-id 11203Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 42.
    Nordström, Susanne
    et al.
    Södertörns högskola, Institutionen för livsvetenskaper.
    Mattsson, Jan-Eric
    Södertörns högskola, Institutionen för livsvetenskaper, Biologi.
    Important factors for the creation of nature reserves2005Konferensbidrag (Övrigt vetenskapligt)
  • 43.
    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
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Community perceptions of climate change and ecosystem-based adaptation in the mangrove ecosystem of the Rufiji Delta, Tanzania2022Ingår i: Climate and Development, ISSN 1756-5529, E-ISSN 1756-5537, Vol. 14, nr 10, s. 896-908Artikel i tidskrift (Refereegranskat)
    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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  • 44. Olsén, K. Håkan
    Development of the olfactory organ of the Arctic charr, Salvelinus alpinus (L.) (Teleostei, Salmonidae)1993Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 71, nr 10, s. 1973-1984Artikel i tidskrift (Refereegranskat)
    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.

  • 45.
    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.).1998Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 56, nr 2, s. 319-327Artikel i tidskrift (Refereegranskat)
    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.

  • 46.
    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 charr1997Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 51, nr 2, s. 422-435Artikel i tidskrift (Refereegranskat)
    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.

  • 47.
    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) parr1996Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 7, nr 4, s. 445-450Artikel i tidskrift (Refereegranskat)
    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.

  • 48.
    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.).1996Ingår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 22, nr 4, s. 773-786Artikel i tidskrift (Refereegranskat)
    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.

  • 49.
    Perry, Diana
    et al.
    Swedish University of Agricultural Sciences, Sweden.
    Tamarit, Elena
    University of Gothenburg, Sweden.
    Sundell, Erika
    Swedish University of Agricultural Sciences, Sweden.
    Axelsson, Michael
    University of Gothenburg, Sweden.
    Bergman, Sanne
    UiT – the Arctic University of Norway, Norway.
    Gräns, Albin
    Swedish University of Agricultural Sciences, Sweden.
    Gullström, Martin
    Södertörns högskola, Institutionen för naturvetenskap, miljö och teknik, Miljövetenskap.
    Sturve, Joachim
    University of Gothenburg, Sweden.
    Wennhage, Håkan
    Swedish University of Agricultural Sciences, Sweden.
    Physiological responses of Atlantic cod to climate change indicate that coastal ecotypes may be better adapted to tolerate ocean stressors2024Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 14, nr 1, artikel-id 12896Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 50.
    Persson, Martin
    Södertörns högskola, Institutionen för livsvetenskaper.
    Changes in condition of herring (Clupea harengus) in Swedish coastal waters2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    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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