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  • 101.
    Bergman, Ingela
    et al.
    Silver Museum, Arjeplog, Sweden.
    Zackrisson, Olle
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Early Mesolithic Hunter–Gatherers and Landscape Acquisition by the Arctic Circle: The Ipmatis valley 7000 BC–1 AD2007In: Journal of Northern Studies, ISSN 1654-5915, Vol. 1, no 1-2, p. 123-142Article in journal (Refereed)
    Abstract [en]

    Archaeological and palaeoecological studies in the Arjeplog area of northern Sweden have verified the arrival of hunter–gatherers soon after deglaciation. After modelling and subsequently surveying the reconstructed shorelines of tilted watercourses, Early Mesolithic settlements dating to 86008000 BP (14C years BP) were discovered. Makrosubfossil-, pollen- and charcoal analyses of peat stratigrafies and lake sediments corroborated that deglaciation was completed more than 1000 years earlier than has previously been postulated. Pollen records show that the early postglacial environment included complex plant communities lacking present day analogies, providing optimal subsistence conditions for the pioneer settlers. Studies of charcoal influx into lake sediments indicate that fires were more frequent than ever after, contributing to a productive natural environment. Regional studies in the Ipmatis valley in combination with in-depth analyses of selected archaeological sites, display that hunter–gatherers made the resources of the valley an integral part of their subsistence at an early stage. Landscape acquisition included not only the adjustment to existing conditions, but the actual manipulation of the environment. The interdisciplinary research approach has produced unique sets of archaeological and palaeoecological data. Results open new perspectives on human pioneer colonisation and landscape acquisition in relation to deglaciation and the development of postglacial ecosystems. The variety of methods applied sets a new standard for future research on early societies in sub-arctic regions.

  • 102.
    Bergmark, Paulina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jørgensen, Dolly
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lophelia pertusa conservation in the North Sea using obsolete offshore structures as artificial reefs2014In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 516, p. 275-280Article in journal (Refereed)
    Abstract [en]

    Deep-water coral reefs are classified as vulnerable marine ecosystems, with trawling identified as the primary cause of reef destruction. Lophelia pertusa is the main reef-building species in deep-water coral reefs. In addition to occurring on natural hard substrates, the species has been previously observed on standing offshore oil and gas structures in the North Sea. In this study, we review the available published information about Lophelia growth on standing offshore oil and gas industry structures in the North Sea. We discuss the potential uses of obsolete offshore structures repurposed as artificial reefs for targeted Lophelia habitat. Our survey of previous studies indicates that artificial reefs created from obsolete structures have a strong potential to form Lophelia reef communities similar to those found on natural substrates, although the absence of the polychaete worm Eunice norvegica poses some concerns about the completeness of the coral communities that develop on artificial reef structures.

  • 103.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vrede, Tobias
    N-limited consumer growth and low nutrient regeneration N:P ratios in lakes with low N deposition2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 1, article id 9Article in journal (Refereed)
    Abstract [en]

    Nutrient limitation of primary producers and their consumers can have a large influence on ecosystem productivity. The nature and strength of nutrient limitation is driven both by external factors (e.g., nutrient loading) and internal processes (e.g., consumer-driven nutrient regeneration). Here we present results from a field study in 10 low productive headwater lakes in northern subarctic Sweden, where nitrogen (N) deposition is low and phytoplankton is primarily N-limited. We assessed the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of seston and zooplankton and estimated the N:P ratio of consumer-driven nutrient regeneration. Based on stoichiometric models, the estimated elemental imbalances between seston and zooplankton suggest that zooplankton were mainly N-limited and regenerated nutrients with low N:P ratios (median 11.9, atomic ratio). The predicted N:P regeneration ratios were consistent with results from phytoplankton nutrient limitation bioassays in mid-summer, i.e., the N:P regeneration was predicted to be low when phytoplankton were N-limited, and high when phytoplankton were P-limited. During other seasons, when water discharge was high, nutrient loading from the surrounding catchments apparently had the strongest effect on phytoplankton nutrient limitation. We propose that lakes with higher N:P ratios than the open ocean is an effect of N deposition, that N-limitation of consumers and phytoplankton is further enhanced by low nutrient regeneration N:P ratios, and that in the absence of N deposition, lake and ocean N:P stoichiometry are similar.

  • 104.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impacts Research Centre (CIRC), Umeå University, Abisko, Sweden.
    Light and nutrient control phytoplankton biomass responses to global change in northern lakes2019In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 25, no 6, p. 2021-2029Article in journal (Refereed)
    Abstract [en]

    Global change affects terrestrial loadings of colored dissolved organic carbon (DOC) and nutrients to northern lakes. Still, little is known about how phytoplankton respond to changes in light and nutrient availability across gradients in lake DOC. In this study, we used results from whole-lake studies in northern Sweden to show that annual mean phytoplankton biomass expressed unimodal curved relationships across lake DOC gradients, peaking at threshold DOC levels of around 11 mg/L. Whole-lake single nutrient enrichment in selected lakes caused elevated biomass, with most pronounced effect at the threshold DOC level. These patterns give support to the suggested dual control by DOC on phytoplankton via nutrient (positively) and light (negatively) availability and imply that the lakes' location along the DOC axis is critical in determining to what extent phytoplankton respond to changes in DOC and/or nutrient loadings. By using data from the large Swedish Lake Monitoring Survey, we further estimated that 80% of northern Swedish lakes are below the DOC threshold, potentially experiencing increased phytoplankton biomass with browning alone, and/or combined with nutrient enrichment. The results support the previous model results on effects of browning and eutrophication on lake phytoplankton, and provide important understanding of how northern lakes may respond to future global changes.

  • 105.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vrede, Tobias
    Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes2018In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 80, no 2, article id UNSP 24Article in journal (Refereed)
    Abstract [en]

    Contrasting carbon: nitrogen: phosphorus (C: N: P) stoichiometry between phytoplankton and zooplankton affect consumer growth and phytoplankton nutrient limitation via nutrient recycling by zooplankton. However, no study has assessed how regional differences in terrestrial loadings of organic matter affect plankton N: P stoichiometry and recycling in systems with low N deposition and N-limited phytoplankton. We address this question by using data from 14 unproductive headwater arctic and boreal lakes. We found that boreal lakes had higher lake water-and seston C, N and P concentrations than arctic lakes, whereas seston C: N, C: P and N: P ratios did not differ among regions. Boreal zooplankton were also richer in N and P relative to C, with lower somatic N: P ratios, compared to arctic lakes. Consequently, the estimated N: P imbalances between seston and zooplankton were negative in arctic lakes, indicating zooplankton feeding on phytoplankton of suboptimal N content, resulting in low consumer driven N: P recycling (medians arctic sub-mid and high altitude lakes: 11 and 13). In boreal lakes, estimated N: P imbalance did not differ from zero, with a seston N: P stoichiometry matching the N: P requirements of zooplankton, which resulted in higher consumer driven N: P recycling (median 18). Our results imply that regional climate induced catchment differences, through enhanced terrestrial nutrient inputs, affect plankton stoichiometry by raising consumer N: P recycling ratio and changing zooplankton from being mainly N-(arctic) to NP co-limited (boreal). Browning of lakes, in regions with low N deposition, may therefore promote large-scale regional changes in plankton nutrient limitation with potential feedbacks on pelagic food webs.

  • 106.
    Bergström, Lena
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Macroalgae in the Baltic Sea: responses to low salinity and nutrient enrichment in Ceramium and Fucus2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The brackish Baltic Sea is a marginal environment for both marine and freshwater species. The rate of ecological differentiation is presumably high due to strong selection pressure from a gradient of decreasing salinity that has been present in its current state for only about 3 000 years. Even more recently, increased nutrient loading due to human activities has affected the growth rate of species, with potential effects on their competitive interactions and responses to other regulating factors. I have investigated the potential effects of low salinity and nutrient enrichment on the distributional ranges of two marine macroalgae with a wide distribution in the Baltic Sea, the red alga Ceramium tenuicorne (Kütz.) Wærn and the brown alga Fucus vesiculosus L.

    A field study in the northern Baltic Sea indicated a strong relationship between the community structure of macroalgae and abiotic factors even on a small, local scale. The abiotic factors are potentially modulated by eutrophication, which may have a strong effect on the depth distribution and abundance of macroalgae. On a regional scale, laboratory experiments suggested that nutrient enrichment is unlikely to affect the distribution of Ceramium and Fucus along the salinity gradient. Growth in Ceramium from the Baltic Proper was enhanced by nitrate and phosphate, but the response did not override growth constraints due to low salinity. Ceramium from the Gulf of Bothnia had an inherently lower growth rate that was not positively affected by nitrate and phosphate increase. In Fucus vesiculosus, reproductive performance was impaired by nitrate and phosphate levels corresponding to ambient levels in eutrophicated areas of the Baltic Sea, when measured by their effect on zygote attachment, germination, and rhizoid development.

    The wide distribution of Ceramium in the inner Baltic Sea is probably related to local adaptation, rather than a generalized tolerance of different salinity levels. Ecotypic differences were observed when comparing strains from the Baltic Proper (salinity 7 psu) and the Gulf of Bothnia (4 psu). A high rate of vegetative reproduction was evident, although sexual reproduction was occasionally observed in salinity 4. In Fucus vesiculosus, genetic and morphological analyses of sympatric and allopatric populations of the common, vesicular, morphotype and a dwarf morphotype, characteristic for the Gulf of Bothnia, showed that the dwarf morphotype represents a separate evolutionary lineage. Also, vegetative reproduction was observed in Fucus for the first time, as supported by genetic and experimental data.

    The results show that the biota of the inner Baltic Sea may have unique adaptive and genetic properties, and that it is highly relevant to consider subspecies diversity in Baltic Sea management.

  • 107.
    Bergström, Lena
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Tatarenkov, Andrei
    Jönsson, Rita B
    Johannesson, Kerstin
    Kautsky, Lena
    Morphological and genetic differentiation of Fucus vesiculosus in the brackish Baltic SeaIn: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817Article in journal (Refereed)
  • 108.
    Bergström, Ulf
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Spatial heterogeneity and biotic interactions: scaling from experiments to natural systems2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Much of current ecological theory stems from experimental studies. These studies have often been conducted in closed systems, at spatial scales that are much smaller than the systems of interest. It is known that the outcome of these experiments may be seriously affected by artefacts associated with the caging procedures, as well as by the actual difference in spatial scale between experimental and target system. Yet, quantitative methods for estimating and removing artefacts of enclosure and for extrapolating experimental results to the scales of natural systems are largely lacking.

    The aim of this thesis was to confront some of the problems encountered when scaling from experiments to nature in studies on predator-prey systems, with focus on effects of changes in spatial heterogeneity. Specifically, I examined mechanisms that may cause consumption rate estimates to depend on the size of the experimental arena. I also studied methods for scaling up these process rate estimates to natural predator-prey systems. The studies were performed on invertebrate predator-prey systems found in the northern Baltic Sea. Initially, a descriptive study of small-scale distribution patterns was performed, in order to get background information on how the behaviour of the organisms was manifested in the spatial structure of the community. Experimental studies of two predator-prey systems exposed an artefact that may be widespread in experiments aiming at quantifying biotic interactions. It is caused by predator and prey aggregating along the walls of the experimental containers. This behaviour affects the encounter rate between predator and prey, thereby causing consumption rates to be scale-dependent. Opposing the common belief that larger arenas always produce less biased results, this scale effect may instead be reduced by decreasing arena size. An alternative method for estimating the magnitude of, and subsequently removing, the artefact caused by aggregation along the arena wall was presented.

    Once unbiased estimates of process functions have been derived, the next step is to scale up the functions to natural systems. This extrapolation entails a considerable increase in spatial heterogeneity, which may have important implications for the dynamics of the system. Moment approximation provides a method of taking the heterogeneity of natural populations into account in the extrapolation process. In the last study of the thesis, the concepts of moment approximation and how to estimate relevant heterogeneity were explained, and it was shown how the method may be used for adding space as a component to a dynamic predator-prey model. It was concluded that moment approximation provides a simple and useful technique for dealing with effects of spatial variation, and that a major benefit of the method is that it provides a way of visualising how heterogeneity affects ecological processes.

  • 109. Bernardo-Madrid, Rubén
    et al.
    Calatayud, Joaquín
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Life Science, Universidad de Alcalá, Alcalá de Henares, Spain; Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain.
    González-Suárez, Manuela
    Rosvall, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Lucas, Pablo M.
    Rueda, Marta
    Antonelli, Alexandre
    Revilla, Eloy
    Human activity is altering the world's zoogeographical regions2019In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 22, no 8, p. 1297-1305Article in journal (Refereed)
    Abstract [en]

    Zoogeographical regions, or zooregions, are areas of the Earth defined by species pools that reflect ecological, historical and evolutionary processes acting over millions of years. Consequently, researchers have assumed that zooregions are robust and unlikely to change on a human timescale. However, the increasing number of human‐mediated introductions and extinctions can challenge this assumption. By delineating zooregions with a network‐based algorithm, here we show that introductions and extinctions are altering the zooregions we know today. Introductions are homogenising the Eurasian and African mammal zooregions and also triggering less intuitive effects in birds and amphibians, such as dividing and redefining zooregions representing the Old and New World. Furthermore, these Old and New World amphibian zooregions are no longer detected when considering introductions plus extinctions of the most threatened species. Our findings highlight the profound and far‐reaching impact of human activity and call for identifying and protecting the uniqueness of biotic assemblages.

  • 110. Bernes, Claes
    et al.
    Brathen, Kari Anne
    Forbes, Bruce C.
    Speed, James D. M.
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    What are the impacts of reindeer/caribou (Rangifer tarandus L.) on arctic and alpine vegetation?: A systematic review2015In: Environmental Evidence, ISSN 2047-2382, E-ISSN 2047-2382, Vol. 4, no 4Article, review/survey (Refereed)
    Abstract [en]

    Background: The reindeer (or caribou, Rangifer tarandus L.) has a natural range extending over much of Eurasia's and North America's arctic, alpine and boreal zones, yet its impact on vegetation is still unclear. This lack of a common understanding hampers both the management of wild and semi-domesticated reindeer populations and the preservation of biodiversity. To achieve a common platform, we have undertaken a systematic review of published studies that compare vegetation at sites with different reindeer densities. Besides biodiversity, we focused on effects on major plant growth forms. Methods: Searches for literature were made using online publication databases, search engines, specialist websites and bibliographies of literature reviews. Search terms were developed in English, Finnish, Norwegian, Russian and Swedish. Identified articles were screened for relevance based on titles, abstracts and full text using inclusion criteria set out in an a priori protocol. Relevant articles were then subject to critical appraisal of susceptibility to bias. Data on outcomes such as abundance, biomass, cover and species richness of vegetation were extracted together with metadata on site properties and other potential effect modifiers. Results: Our searches identified more than 6,000 articles. After screening for relevance, 100 of them remained. Critical appraisal excluded 60 articles, leaving 40 articles with 41 independent studies. Almost two thirds of these studies had been conducted in Fennoscandia. Meta-analysis could be made of data from 31 of the studies. Overall, effects of reindeer on species richness of vascular plants depended on temperature, ranging from negative at low temperature to positive at high temperature. Effects on forbs, graminoids, woody species, and bryophytes were weak or non-significant, whereas the effect on lichens was negative. However, many individual studies showed clear positive or negative effects, but the available information was insufficient to explain this context dependence. Conclusions: We see two pressing matters emerging from our study. First, there is a lack of research with which to build a circumpolar understanding of grazing effects, which calls for more studies using a common protocol to quantify reindeer impacts. Secondly, the highly context-dependent outcomes suggest that research and management have to consider local conditions. For instance, predictions of what a management decision would mean for the effects of reindeer on vegetation will have to take the variation of vegetation types and dominant growth forms, productivity, and grazing history into account. Policy and management have to go hand-in-hand with research in individual cases if the dynamics between plants, animals, and humans are to be sufficiently understood.

  • 111.
    Bernes, Claes
    et al.
    1 Mistra Council for Evidence-Based Environmental Management, Royal Swedish Academy of Sciences.
    Carpenter, Stephen
    University of Wisconsin, USA.
    Gårdmark, Anna
    Swedish University of Agricultural Sciences.
    Larsson, Per
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Skov, Christian
    Technical University of Denmark, Denmark.
    Speed, James
    Norwegian University of Science and Technology, Norway.
    Van Donk, Ellen
    Netherlands Institute of Ecology, The Netherlands.
    What is the influence of a reduction of planktivorous and benthivorous fish on water quality in temperate eutrophic lakes?: A systematic review2015In: Environmental Evidence, ISSN 2047-2382, E-ISSN 2047-2382, Vol. 4, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    Background

    In recent decades, many attempts have been made to restore eutrophic lakes through biomanipulation. Reducing the populations of planktivorous and benthivorous fish (either directly or through stocking of piscivorous fish) may induce ecosystem changes that increase water transparency and decrease the risk of algal blooms and fish kills, at least in the short term. However, the generality of biomanipulation effects on water quality across lake types and geographical regions is not known. Therefore, we have undertaken a systematic review of such effects in eutrophic lakes in temperate regions throughout the world.

    Methods

    Searches for literature were made using online publication databases, search engines, specialist websites and bibliographies of literature reviews. Search terms were developed in English, Danish, Dutch and Swedish. Identified articles were screened for relevance using inclusion criteria set out in an a priori protocol. To reduce the risk of bias, we then critically appraised the combined evidence found on each biomanipulation. Data were extracted on outcomes such as Secchi depth and chlorophyll a concentration before, during and/or after manipulation, and on effect modifiers such as lake properties and amounts of fish removed or stocked.

    Results

    Our searches identified more than 14,500 articles. After screening for relevance, 233 of them remained. After exclusions based on critical appraisal, our evidence base included useful data on 128 biomanipulations in 123 lakes. Of these interventions, 85% had been made in Europe and 15% in North America. Meta-analysis showed that removal of planktivores and benthivores (with or without piscivore stocking) leads to increased Secchi depth and decreased chlorophyll a concentration during intervention and the first three years afterwards. Piscivore stocking alone has no significant effect. The response of chlorophyll a levels to biomanipulation is stronger in lakes where fish removal is intense, and in lakes which are small and/or have high pre-manipulation concentrations of total phosphorus.

    Conclusions

    Our review improves on previous reviews of biomanipulation in that we identified a large number of case studies from many parts of the world and used a consistent, repeatable process to screen them for relevance and susceptibility to bias. Our results indicate that removal of planktivorous and benthivorous fish is a useful means of improving water quality in eutrophic lakes. Biomanipulation tends to be particularly successful in relatively small lakes with short retention times and high phosphorus levels. More thorough fish removal increases the efficacy of biomanipulation. Nonetheless successes and failures have occurred across a wide range of conditions.

  • 112.
    Bernhardsson, Carolina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Molecular population genetics of inducible defense genes in Populus tremula2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Plant-herbivore interactions are among the most common of ecological interactions. It is therefore not surprising that plants have evolved multiple mechanisms to defend themselves, using both constitutive chemical and physical barriers and by induced responses which are only expressed after herbivory has occurred. Herbivores, on the other hand, respond to these plant defenses by evolving counter-adaptations which makes defenses less effective or even useless. Adaptation can occur at different geographical scales, with varying coevolutionary interactions across a spatially heterogenous landscape. By looking at the underlying genes responsible for these defensive traits and herbivore related phenotypic traits, it is possible to investigate the coevolutionary history of these plant- herbivore interactions. Here I use molecular population genetic tools to investigate the evolutionary history of several inducible defense genes in European Aspen (Populus tremula) in Sweden. Two genes, belonging to the Polyphenol oxidase gene-family (PPO1 and PPO2), show skews in their site frequency spectrum together with patterns of diversity and divergence from an outgroup which correspond to signatures of adaptive evolution (Paper II). 71 single nucleotide polymorphisms (SNPs) from seven inducible defense genes (PPO1-PPO3, TI2-TI5) show elevated levels of population differentiation compared to control genes (genes not involved in plant defense), and 10 of these defense SNPs show strong signatures of natural selection (Paper III). These 71 defense SNPs also divides a sample of Swedish P. tremula trees into three distinct geographical groups, corresponding to a Southern, Central and Northern cluster, a patterns that is not present in control SNPs (Paper III). The same geographical pattern, with a distinct Northern cluster, is also observed in several phenotypic traits related to herbivory in our common garden in Sävar (Paper IV). These phenotypic traits show patterns of apparent local maladaptation of the herbivore community to the host population which could indicate the presence of “information coevolution” between plants and herbivores (Paper IV). 15 unique defense SNPs also show significant associations to eight phenotypic traits but the causal effects of these SNP associations may be confounded by the geographic structure found in both the underlying genes and in the phenotypic traits. The co-occurrence of population structure in both defense genes and herbivore community traits may be the result from historical events during the post-glacial recolonization of Sweden.

  • 113.
    Bernhardsson, Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Robinson, Kathryn M.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Abreu, Ilka N.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Albrectsen, Benedicte R.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Univ Copenhagen, Sect Plant Biochem, Dept Plant & Environm Sci, DK-1871 Frederiksberg, Denmark.
    Ingvarsson, Pär K.
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Geographic structure in metabolome and herbivore community co-occurs with genetic structure in plant defence genes2013In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 16, no 6, p. 791-798Article in journal (Refereed)
    Abstract [en]

    Plantherbivore interactions vary across the landscape and have been hypothesised to promote local adaption in plants to the prevailing herbivore regime. Herbivores that feed on European aspen (Populus tremula) change across regional scales and selection on host defence genes may thus change at comparable scales. We have previously observed strong population differentiation in a set of inducible defence genes in Swedish P. tremula. Here, we study the geographic patterns of abundance and diversity of herbivorous insects, the untargeted metabolome of the foliage and genetic variation in a set of wound-induced genes and show that the geographic structure co-occurs in all three data sets. In response to this structure, we observe local maladaptation of herbivores, with fewer herbivores on local trees than on trees originated from more distant localities. Finally, we also identify 28 significant associations between single nucleotide polymorphisms SNPs from defence genes and a number of the herbivore traits and metabolic profiles.

  • 114.
    Bernhardsson, Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Robinson, Kathryn M.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Abreu, Ilka N.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Jansson, Stefan
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Ingvarsson, Pär K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Albrectsen, Benedicte R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Population differentiation in arthropod community structure and phenotypic association with inducible defense genes in European Aspen (Populus tremula L., salicaceae)Manuscript (preprint) (Other academic)
    Abstract [en]

    Plant-herbivore interactions are known to vary across a landscape due to both variation in abiotic and biotic factors. Such spatial variation tends to promoting local adaption of plants to the prevailing herbivore regime. Here we use data from a common garden to look for patterns across populations in the abundance and diversity of herbivorous insects. We also screen for variation in the untargeted metabolome of the foliage of a subset of the same trees. We also search for phenotypic associations between genetic variation in a number of wound-induced genes and phenotypic variation in herbivore abundance, diversity and in metabolomes. We observe significant genetic variation in a number of herbivore-related traits but low correlations between traits. We do observe substantial genetic structure in both herbivore community structure and in metabolic profiles and this structure is aligned with genetic structure we have previously documented for a set of defense genes. We also identify a number of significant associations between SNPs from wound-induced defense genes and a number of the herbivore traits and metabolic profiles. However, these associations are likely not causal, but are rather caused by the underlying population structure we observe. These results highlight to the importance of historical processes and the need to better understand both the current-day geographic distribution of different herbivore species as well as the post-glacial colonization history of both plants and herbivores.

  • 115.
    Bertos-Fortis, Mireia
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Baltic Sea phytoplankton in a changing environment2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Future climate scenarios in the Baltic Sea project increasing sea surface temperature, as well as increasing precipitation and river runoff resulting in decreased salinity. These changes can severely impact the dynamics and function of brackish water communities, specifically phytoplankton. Phytoplankton are a significant source of organic matter to other trophic levels, and some species can be toxic. Their response to future climate conditions is of great relevance for the health of humans and aquatic ecosystems. The aim of this thesis was to assess the potential for climate-induced changes, such as decreasing salinity, to affect phytoplankton dynamics, physiology and chemical profiles in the Baltic Sea.

         Phytoplankton successional patterns in the Baltic Proper consist of a spring bloom where diatoms and dinoflagellates co-occur and a summer bloom dominated by filamentous/colonial cyanobacteria. The consensus is that future warmer conditions will promote filamentous/colonial cyanobacteria blooms. This thesis shows that phytoplankton biomass in the spring bloom was lower in years with milder winters compared with cold winters. This suggests that in terms of annual carbon export to higher trophic levels, loss of biomass from the spring bloom is unlikely to be compensated by summer cyanobacteria. High frequency sampling of phytoplankton performed in this thesis revealed a strong relationship between the dynamics of pico- and filamentous cyanobacteria. Large genetic diversity was found in cyanobacterial populations with high niche differentiation among the same species. At community level, high temperature and low salinity were the main factors shaping the summer cyanobacterial composition. These conditions may promote the predominance of opportunistic filamentous cyanobacteria, e.g. Nodularia spumigena. This species produces various bioactive compounds, including non-ribosomal peptides such as the hepatotoxin nodularin. In this work, N. spumigena subpopulations evolved different physiological strategies, including chemical profiles, to cope with salinity stress. This high phenotypic plasticity ensures survival in future climate conditions. Under salinity stress, some subpopulations displayed shorter filaments as a trade-off. This indicates that the future freshening of the Baltic Sea may promote grazing on filamentous cyanobacteria and modify carbon flows in the ecosystem. In this thesis, Baltic N. spumigena chemotypes and genotypes grouped into two main clusters without influence of geographical origin. Thus, chemical profiling can be used to explore conspecific diversity in closely genetically related N. spumigena subpopulations.

         Overall, this thesis has significantly expanded the knowledge on phytoplankton community and population responses to short- and long-term environmental changes, relevant to project the impacts of future climate conditions in the Baltic Sea.

  • 116. Bienau, Miriam J.
    et al.
    Hattermann, Dirk
    Kroencke, Michael
    Kretz, Lena
    Otte, Annette
    Eiserhardt, Wolf L.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Graae, Bente J.
    Durka, Walter
    Eckstein, R. Lutz
    Snow cover consistently affects growth and reproduction of Empetrum hermaphroditum across latitudinal and local climatic gradients2014In: Alpine Botany, ISSN 1664-2201, E-ISSN 1664-221X, Vol. 124, no 2, p. 115-129Article in journal (Refereed)
    Abstract [en]

    Arctic ecosystems face strong changes in snow conditions due to global warming. In contrast to habitat specialists, species occupying a wide range of microhabitats under different snow conditions may better cope with such changes. We studied how growth and reproduction of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitat types differing in winter snow depth and summer irradiation, and whether the observed patterns were consistent along a local climatic gradient (sub-continental vs. sub-oceanic climates) and along a latitudinal gradient (northern Sweden vs. central Norway). Habitat type explained most of the variation in growth and reproduction. Shoots from shallow snow cover and high summer irradiation habitats had higher numbers of flowers and fruits, lower ramet heights, shorter shoot segments, lower numbers of lateral shoots and total biomass but higher leaf density and higher relative leaf allocation than shoots from habitats with higher snow depth and lower summer irradiation. In addition, biomass, leaf allocation and leaf life expectancy were strongly affected by latitude, whereas local climate had strong effects on seed number and seed mass. Empetrum showed high phenotypic trait variation, with a consistent match between local habitat conditions and its growth and reproduction. Although study areas varied strongly with respect to latitude and local climatic conditions, response patterns of growth and reproduction to habitats with different environmental conditions were consistent. Large elasticity of traits suggests that Empetrum may have the potential to cope with changing snow conditions expected in the course of climate change.

  • 117. Bienau, Miriam J.
    et al.
    Kroencke, Michael
    Eiserhardt, Wolf L.
    Otte, Annette
    Graae, Bente J.
    Hagen, Dagmar
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Durka, Walter
    Eckstein, R. Lutz
    Synchronous flowering despite differences in snowmelt timing among habitats of Empetrum hermaphroditum2015In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 69, p. 129-136Article in journal (Refereed)
    Abstract [en]

    The topography within arctic-alpine landscapes is very heterogeneous, resulting in diverse snow distribution patterns, with different snowmelt timing in spring. This may influence the phenological development of arctic and alpine plant species and asynchronous flowering may promote adaptation of plants to their local environments. We studied how flowering phenology of the dominant dwarf shrub Empetrum hermaphroditum varied among three habitats (exposed ridges, sheltered depressions and birch forest) differing in winter snow depth and thus snowmelt timing in spring, and whether the observed patterns were consistent across three different study areas. Despite significant differences in snowmelt timing between habitats, full flowering of E. hermaphroditum was nearly synchronous between the habitats, and implies a high flowering overlap. Our data show that exposed ridges, which had a long lag phase between snowmelt and flowering, experienced different temperature and light conditions than the two late melting habitats between snowmelt and flowering. Our study demonstrates that small scale variation seems matter less to flowering of Empetrum than interannual differences in snowmelt timing.

  • 118. Biester, Harald
    et al.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Martinez Cortizas, Antonio
    Mercury in mires2006In: Peatlands: Evolution and Records of Environmental and Climate Changes / [ed] Mike J. Smith, Paolo Paron and James S. Griffiths, Elsevier, 2006, p. 465-478Chapter in book (Refereed)
    Abstract [en]

    This chapter illustrates that a better understanding of the behavior of mercury in the environment is needed for a number of reasons. For example, increased biomagnification of mercury in aquatic food chains, especially in fish, and enhanced accumulation in remote areas such as the Arctic have been observed in the last few decades. Mercury toxicity in aquatic ecosystems is of particular concern, with the role of methylmercury (MeHg) being critical. This compound can be concentrated by more than a million times in the aquatic food chain. Biogeochemical studies and monitoring programs that include direct measurements of wet deposition or indirect measurements based on biomonitoring of forest mosses, have established that anthropogenic activities have affected the global cycling of mercury. Although a precise link has yet to be made between the increased content of mercury in biota and the increased accumulation rates observed in natural environmental archives, such as peat, lake sediments, and glacial ice, there is broad consensus that these archives provide a means to reconstruct atmospheric deposition trends at local, regional, and global scales.

  • 119.
    Bindler, Richard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Yu, Ruilian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. College of Chemical Engineering, Huaqiao University, Xiamen, Fujian 361021, P.R. China.
    Hansson, Sophia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Classen, Neele
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mining, Metallurgy and the Historical Origin of Mercury Pollution in Lakes and Watercourses in Central Sweden2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 15, p. 7984-7991Article in journal (Refereed)
    Abstract [en]

    In Central Sweden an estimated 80% of the lakes contain fish exceeding health guidelines for mercury. This area overlaps extensively with the Bergslagen ore region, where intensive mining of iron ores and massive sulfide ores occurred over the past millennium. Although only a few mines still operate today, thousands of mineral occurrences and mining sites are documented in the region. Here, we present data on long-term mercury pollution in 16 sediment records from 15 lakes, which indicate that direct release of mercury to lakes and watercourses was already significant prior to industrialization (<AD 1800). Thirteen of our lakes show increases in mercury from 3-fold-equivalent to the enrichment factor in many remote lakes today-to as much as 60-fold already during the period AD 1500-1800, with the highest values in the three lakes most closely connected to major mines. Although the timing and magnitude of the historical increases in mercury are heterogeneous among lakes, the data provide unambiguous evidence for an incidental release of mercury along with other mining metals to lakes and watercourses, which suggests that the present-day problem of elevated mercury concentrations in the Bergslagen region can trace its roots back to historical mining.

  • 120. Bistrom, Olof
    et al.
    Nilsson, Anders N.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bergsten, Johannes
    Taxonomic revision of Afrotropical Laccophilus Leach, 1815 (Coleoptera, Dytiscidae)2015In: ZooKeys, ISSN 1313-2989, E-ISSN 1313-2970, no 542, p. 1-379Article in journal (Refereed)
    Abstract [en]

    The African species of the genus Laccophilus Leach, 1815, are revised, on the basis of study of adult specimens. In all, 105 species are now recognized. A phenetic character-analysis was undertaken, which resulted in a split of the genus into 17 species groups. Diagnoses and a description of each species are given together with keys for identification of species groups and species. We also provide habitus photos, illustration of male genitalia and distribution maps for all species. New species are described as follows: L. grossus sp. n. (Angola, Namibia), L. rocchii sp. n. (Tanzania, Namibia, Botswana, Mozambique), L. ferrugo sp. n. (Mozambique), L. furthi sp. n. (Madagascar), L. isamberti sp. n. (Madagascar), L. inobservatus sp. n. (Gambia, Senegal, Mali, Niger, Sudan, Chad, Ethiopia, Burkina Faso, Ivory Coast, Ghana, Nigeria, Cameroon, Zaire and Asia: Yemen), L. cryptos sp. n. (Zaire, Mozambique, Zimbabwe, Namibia, Botswana, South Africa), L. enigmaticus sp. n. (Nigeria, Sudan), L. bellus sp. n. (Benin, Nigeria), L. guentheri sp. n. (Guinea, Ghana), L. guineensis sp. n. (Guinea), L. decorosus sp. n. (Uganda), L. empheres sp. n. (Kenya), L. inconstans sp. n. (Guinea, Ivory Coast, Ghana, Nigeria, Cameroon), L. brancuccii sp. n. (Central African Republic), L. incomptus sp. n. (Cameroon), L. australis sp. n. (Tanzania, South Africa), L. minimus sp. n. (Namibia), L. eboris sp. n. (Ivory Coast), L. insularum sp. n. (Madagascar), L. occidentalis sp. n. (Gambia, Senegal, Mali, Guinea, Sierra Leone, Ivory Coast, Ghana, Benin, Nigeria, Central African Republic, Zaire) and L. transversovittatus sp. n. (Madagascar). L. restrictus Sharp, 1882, is restored as good species; not junior synonym of L. pictipennis Sharp, 1882. New synonyms are established as follows: L. continentalis Gschwendtner, 1935 = L. perplexus Omer- Cooper, 1970, syn. n., L. taeniolatus Regimbart, 1889 = L. congener Omer-Cooper, 1957, syn. n., L. adspersus Boheman, 1848 = L. vitshumbii Guignot, 1959, syn. n. = L. adspersus nigeriensis Omer-Cooper, 1970, syn. n. = L. adspersus sudanensis Omer-Cooper, 1970, syn. n., L. modestus Regimbart, 1895 = L. espanyoli Hernando, 1990, syn. n., L. flaveolus Regimbart, 1906 = L. pampinatus Guignot, 1941, syn. n., L. trilineola Regimbart, 1889 = L. simulator Omer-Cooper, 1958, syn. n., L. mediocris Guignot, 1952 = L. meii Rocchi, 2000, syn. n., L. epinephes Guignot, 1955 = L. castaneus Guignot, 1956, syn. n., L. saegeri Guignot, 1958 = L. comoensis Pederzani & Reintjes, 2002, syn. n., L. restrictus Sharp, 1882 = L. evanescens Regimbart, 1895, syn. n., L. incrassatus Gschwendtner, 1933 = L. virgatus Guignot, 1953, syn. n., L. cyclopis Sharp, 1882 = L. shephardi Omer-Cooper, 1965, syn. n., L. burgeoni Gschwendtner, 1930 = L. wittei Guignot, 1952, syn. n., L. secundus Regimbart, 1895 = L. torquatus Guignot, 1956, syn. n., L. desintegratus Regimbart, 1895 = L. sanguinosus Regimbart, 1895, syn. n. and L. flavopictus Regimbart, 1889 = L. bergeri Guignot, 1953, syn. n. = L. segmentatus Omer-Cooper, 1957, syn. n. Lectotypes are designated for the following taxa: L. productus Regimbart, 1906, L. ruficollis Zimmermann, 1919, L. sordidus Sharp, 1882, L. alluaudi Regimbart, 1899, L. pictipennis Sharp, 1882, L. wehnckei Sharp, 1882, L. continentalis Gschwendtner, 1935, L. simplicistriatus Gschwendtner, 1932, L. complicatus Sharp, 1882, L. rivulosus Klug, 1833, L. ampliatus Regimbart, 1895, L. pilitarsis Regimbart, 1906, L. adspersus Boheman, 1848, L. livens Regimbart, 1895, L. modestus Regimbart, 1895, L. nodieri Regimbart, 1895, L. flaveolus Regimbart, 1906, L. pallescens Regimbart, 1903, L. restrictus Sharp, 1882, L. vermiculosus Gerstaecker, 1867, L. mocquerysi Regimbart, 1895, L. bizonatus Regimbart, 1895, L. tschoffeni Regimbart, 1895, L. persimilis Regimbart, 1895, L. poecilus Klug, 1834, L. lateralis Sharp, 1882, L. lateralis var. polygrammus Regimbart, 1903, L. cyclopis Sharp, 1882, L. shephardi Omer-Cooper, 1965, L. conjunctus Guignot, 1950, L. grammicus Sharp, 1882, L. flavoscriptus Regimbart, 1895, L. flavosignatus Regimbart, 1895, L. brevicollis Sharp, 1882, L. secundus Regimbart, L. desintegratus Regimbart, 1895, L. gutticollis Regimbart, 1895, L. luctuosus Sharp, 1882 and L. inornatus Zimmermann, 1926. Laccophilus remex Guignot, 1952, comprises a species complex with uncertain taxonomic delimitation; the complex includes L. concisus Guignot, 1953, L. turneri Omer-Cooper, 1957 and L. praeteritus Omer-Cooper, 1957, as tentative synonyms of L. remex Guignot, 1952.

  • 121. Bjorklund, Jesper A.
    et al.
    Gunnarson, Bjorn E.
    Krusic, Paul J.
    Grudd, Hakan
    Josefsson, Torbjörn
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ostlund, Lars
    Linderholm, Hans W.
    Advances towards improved low-frequency tree-ring reconstructions, using an updated Pinus sylvestris L. MXD network from the Scandinavian Mountains2013In: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 113, no 3-4, p. 697-710Article in journal (Refereed)
    Abstract [en]

    The dendrochronological use of the parameter maximum density (MXD) in Pinus Sylvestris L., at high latitudes, has provided valuable insights into past summer temperature variations. Few long MXD chronologies, from climatically coherent regions, exist today, with the exception being in northern Europe. Five, 500-year-long, Fennoscandian, MXD chronologies were compared with regard to their common variability and climate sensitivity. They were used to test Signal-free standardization techniques, to improve inferences of low-frequency temperature variations. Climate analysis showed that, in accordance with previous studies on MXD in Fennoscandia, the summer temperature signal is robust (R (2) > 50 %) and reliable over this climatically coherent region. A combination of Individual standardization and regional curve standardization is recommended to refine long-term variability from these MXD chronologies and relieve problems arising from low replication and standardization end-effects.

  • 122. Bjorkman, Anne D.
    et al.
    Myers-Smith, Isla H.
    Elmendorf, Sarah C.
    Normand, Signe
    Thomas, Haydn J. D.
    Alatalo, Juha M.
    Alexander, Heather
    Anadon-Rosell, Alba
    Angers-Blondin, Sandra
    Bai, Yang
    Baruah, Gaurav
    te Beest, Mariska
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Environmental Sciences, Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, The Netherlands.
    Berner, Logan
    Bjork, Robert G.
    Blok, Daan
    Bruelheide, Helge
    Buchwal, Agata
    Buras, Allan
    Carbognani, Michele
    Christie, Katherine
    Collier, Laura S.
    Cooper, Elisabeth J.
    Cornelissen, J. Hans C.
    Dickinson, Katharine J. M.
    Dullinger, Stefan
    Elberling, Bo
    Eskelinen, Anu
    Forbes, Bruce C.
    Frei, Esther R.
    Iturrate-Garcia, Maitane
    Good, Megan K.
    Grau, Oriol
    Green, Peter
    Greve, Michelle
    Grogan, Paul
    Haider, Sylvia
    Hajek, Tomas
    Hallinger, Martin
    Happonen, Konsta
    Harper, Karen A.
    Heijmans, Monique M. P. D.
    Henry, Gregory H. R.
    Hermanutz, Luise
    Hewitt, Rebecca E.
    Hollister, Robert D.
    Hudson, James
    Huelber, Karl
    Iversen, Colleen M.
    Jaroszynska, Francesca
    Jimenez-Alfaro, Borja
    Johnstone, Jill
    Jorgensen, Rasmus Halfdan
    Kaarlejarvi, Elina
    Klady, Rebecca
    Klimesova, Jitka
    Korsten, Annika
    Kuleza, Sara
    Kulonen, Aino
    Lamarque, Laurent J.
    Lantz, Trevor
    Lavalle, Amanda
    Lembrechts, Jonas J.
    Levesque, Esther
    Little, Chelsea J.
    Luoto, Miska
    Macek, Petr
    Mack, Michelle C.
    Mathakutha, Rabia
    Michelsen, Anders
    Milbau, Ann
    Molau, Ulf
    Morgan, John W.
    Morsdorf, Martin Alfons
    Nabe-Nielsen, Jacob
    Nielsen, Sigrid Scholer
    Ninot, Josep M.
    Oberbauer, Steven F.
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Onipchenko, Vladimir G.
    Petraglia, Alessandro
    Pickering, Catherine
    Prevey, Janet S.
    Rixen, Christian
    Rumpf, Sabine B.
    Schaepman-Strub, Gabriela
    Semenchuk, Philipp
    Shetti, Rohan
    Soudzilovskaia, Nadejda A.
    Spasojevic, Marko J.
    Speed, James David Mervyn
    Street, Lorna E.
    Suding, Katharine
    Tape, Ken D.
    Tomaselli, Marcello
    Trant, Andrew
    Treier, Urs A.
    Tremblay, Jean-Pierre
    Tremblay, Maxime
    Venn, Susanna
    Virkkala, Anna-Maria
    Vowles, Tage
    Weijers, Stef
    Wilmking, Martin
    Wipf, Sonja
    Zamin, Tara
    Tundra Trait Team: a database of plant traits spanning the tundra biome2018In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 27, no 12, p. 1402-1411Article in journal (Refereed)
    Abstract [en]

    Motivation: The Tundra Trait Team (TTT) database includes field‐based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade‐offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters.

    Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (> 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density.

    Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub‐Antarctic Marion Island. More than 99% of observations are georeferenced.

    Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods.

    Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species.

    Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.

  • 123. Blaser, Wilma J.
    et al.
    Sitters, Judith
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hart, Simon P.
    Edwards, Peter J.
    Venterink, Harry Olde
    Facilitative or competitive effects of woody plants on understorey vegetation depend on N-fixation, canopy shape and rainfall2013In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 101, no 6, p. 1598-1603Article in journal (Refereed)
    Abstract [en]

    A recent meta-analysis suggested that differences in rainfall are a cause of variation in tree-grass interactions in savannas, with trees facilitating growth of understorey grasses in low-rainfall areas, but competing with them under higher rainfall. We hypothesized that this effect of rainfall upon understorey productivity is modified by differences in the growth form of the woody plants (i.e. the height of the lower canopy) or by their capacity to fix nitrogen. We performed a meta-analysis of the effects of woody plants on understorey productivity, incorporating canopy height and N-fixation, and their interaction with rainfall. N-fixing woody plants enhanced understorey productivity, whereas non-fixers had a neutral or negative effect, depending on high or low canopy, respectively. We found a strong negative correlation between rainfall and the degree to which trees enhanced understorey productivity, but only for trees with a high canopy.Synthesis. The effect of woody plants on understorey productivity depends not only on rainfall, but also on their growth form and their capacity to fix N. Facilitation occurs mostly when woody plants ameliorate both water and nitrogen conditions. However, a low canopy suppresses understorey vegetation by competing for light, regardless of water and nutrient relations.

  • 124.
    Blochel, Alexander
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Factors influencing ground lichen height in the Boreal-zone: The effects of reindeer husbandry and forestry industries in northern Sweden2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are indications that lichen-rich areas in northern Sweden, commonly used for winter grazing by semi-domesticated reindeer (Rangifer tarandus), has declined by 30-50% since the 1950s. This is mainly believed to be because of a rise in clear-cutting activities during that time period. With fewer areas for the reindeer to conduct their winter grazing it is important to know how grazing activities potentially affect the ground lichen. This report investigates what variables, such as tree density and reindeer grazing intensity, affect the height of five ground lichens; four Cladonia and one Cetraria species. The research was conducted in Norrbotten and Västerbotten, with a total of 55 sample plots, during the month of July 2015. Previous National Forest Inventory plots with a ground cover of at least 25% reindeer lichen were used. The commonly found species were Cladonia rangiferina and Cladonia arbuscula/mitis. Grazing intensity from reindeer had a low explanatory power on the variation in the mat-forming lichen height in boreal forests if considered by itself (R2=0.05, p=0.06). Instead, reindeer grazing effects became more evident when considering an interaction with the tree density of the forest. Tree density and grazing pressure have an important role for lichen height, but there probably are more variables which, directly or indirectly, affect lichen height. Tree density also effects the amount of reindeer found in the area and seems to be of great importance when reindeer graze during the winter.

  • 125.
    Blochel, Alexander
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Population demography’s potential effect on stoichiometry: Assessing the growth rate hypothesis with demography2017Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The elemental composition within structured insect populations was tested by creating a new method to analyze how variables (survival, growth and fecundity) within a population matrix could potentially affect the stoichiometric regime of a structured population at steady state. This was done by focusing on if the growth rate hypothesis, which states that there is a linear relationship between an individual growth rate and the percent of phosphorus within the individual, works at a population level. This was analyzed by creating and combining two matrices: the matrix-population containing the variables and a matrix containing the element phosphorus and dry weight. Data from a beetle species, Chrysomela tremulae F., was used as a guideline to create eight stoichiometric generic populations, where survival, growth and fecundity were tested in each of the eight generic populations. The results showed deviations from the growth rate hypothesis, suggesting that the hypothesis does not always work within structured populations. However, more research is needed to predict exactly how this hypothesis works in populations. Overall, this new method for analyzing stoichiometry within structured populations is a useful analytical tool, but there is a need for analyzing the results from these models in a more efficient way.

  • 126.
    Blomberg, Patrik
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Non-target Effects of Genetically Modified Trees2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To date, few studies have focused on the effects of genetically modified trees (GM trees) on the environment. One concern with GM trees is that they may have unanticipated effects on non-target organisms, i.e. effects on organisms that are not direct targets of the genetically modified trait. The main objective of this thesis was to study potential non-target effects from the interaction between GM trees and natural enemies, including phytopathogens and herbivorous insects.

    To study this I used a system consisting of GM trees featuring changes in growth-related characteristics, and naturally occurring enemies. The GM trees used were the aspen hybrids Populus tremula x tremuloides: one unmodified wild type clone T89 (control) and transgenic lines with altered expression of gibberellin (GA 20-oxidase), sucrose (SPS) or pectin (PME); and Populus tremula x alba: one unmodified wild type clone INRA 717-1-B4 (control) and lines modified to suppress the activity of the enzymes in the lignin biosynthetic pathway, i.e. CAD, COMT, CCR or CCoAOMT. The natural enemies used were the parasitic phytopathogens Melampsora pinitorqua, M. populnea and Venturia tremulae, and the herbivorous leaf-beetle Phratora vitellinae. To address this question inoculation experiments, feeding preference experiments, analyses of secondary chemistry and field inventories were performed.

    The results of the studies showed that the GM trees significantly affected the interaction with the natural enemies, both in the laboratory as well as in the field. For instance, both M. pinitorqua and V. tremulae showed an altered disease incidence on the GM trees of P. tremula x tremuloides compared to the unmodified wild type T89, where all tested transgenic lines exhibited altered susceptibility to the pathogens. However, there were also differences in aggressiveness to the aspens depending on pathogen population. The results from the field inventory showed that lines within all tested transgenic construct, COMT, CAD, CCoAOMT and CCR of P. tremula x alba differed significantly from the wild type INRA 717-1-B4 in susceptibility to M. populnea. In addition, the susceptibility to the rust also differed significantly between lines carrying the same transgenic constructs. Furthermore, we found that overexpression of SPS in P. tremula x tremuloides, unintentionally induced changes in plant secondary chemistry, where the GM-line SPS33A exhibited the largest deviation from the wild type T89 in contents of plant phenolics and nitrogen, and that these changes coincide with a concurrent decrease in herbivory by P. vitellinae on this line.

    I argue that the altered interactions are the result of physiological changes in the trees. They can originate from direct effects i.e. altered expression of the modified trait, indirect effects of the genetic modification process e.g. pleiotropy, or effects from the transformation process e.g. position effects, to which the tested natural enemies respond.

    The result stresses the importance of further research on the causes and mechanisms responsible for the altered interaction between GM trees and non-target organisms, as well as evaluating the potential environmental effects of cultivation of GM trees in the field. Such research will require collaboration between researchers from different disciplines, such as plant ecology and physiology, functional genomics, proteomics and metabolomics.

  • 127. Blumenstein, Kathrin
    et al.
    Albrectsen, Benedicte R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Martin, Juan A.
    Hultberg, Malin
    Sieber, Thomas N.
    Helander, Marjo
    Witzell, Johanna
    Nutritional niche overlap potentiates the use of endophytes in biocontrol of a tree disease2015In: BioControl (Dordrecht), ISSN 1386-6141, E-ISSN 1573-8248, Vol. 60, no 5, p. 655-667Article in journal (Refereed)
    Abstract [en]

    Asymptomatic endophytic fungi are often regarded as potent biocontrol agents in plants, but the competitive interactions between endophytes and other microbes within the same host plant are poorly understood. We tested a hypothesis that as compared to asymptomatic endophytes, an aggressive pathogen inhabiting the same host is able to utilize carbon substrates more efficiently. Using phenotype microarray, we determined the carbon utilization profiles of the highly virulent Dutch elm disease (DED) pathogen Ophiostoma novo-ulmi, and four asymptomatic elm (Ulmus spp.) endophyte isolates that were selected based on their differential association to the DED-susceptibility pattern of the host elms. The competitive interactions between isolates were evaluated using a niche overlap index. In contrast to our hypothesis, the studied endophytes exhibited extensive niche overlap with the pathogen, suggesting that some endophyte strains might protect elms against DED-pathogen through competition for substrates and provide new tools for biocontrol of DED.

  • 128.
    Blume-Werry, Gesche
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The hidden life of plants: fine root dynamics in northern ecosystems2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fine roots constitute a large part of the primary production in northern (arctic and boreal) ecosystems, and are key players in ecosystem fluxes of water, nutrients and carbon. Data on root dynamics are generally rare, especially so in northern ecosystems. However, those ecosystems undergo the most rapid climatic changes on the planet and a profound understanding of form, function and dynamics of roots in such ecosystems is essential.

    This thesis aimed to advance our knowledge about fine root dynamics in northern ecosystems, with a focus on fine root phenology in natural plant communities and how climate change might alter it. Factors considered included thickness and duration of snow cover, thawing of permafrost, as well as natural gradients in temperature. Experiments and observational studies were located around Abisko (68°21' N, 18°45' E), and in a boreal forest close to Vindeln (64°14'N, 19°46'E), northern Sweden. Root responses included root growth, total root length, and root litter input, always involving seasonal changes therein, measured with minirhizotrons. Root biomass was also determined with destructive soil sampling. Additionally, aboveground response parameters, such as phenology and growth, and environmental parameters, such as air and soil temperatures, were assessed.

    This thesis reveals that aboveground patterns or responses cannot be directly translated belowground and urges a decoupling of above- and belowground phenology in terrestrial biosphere models. Specifically, root growth occurred outside of the photosynthetically active period of tundra plants. Moreover, patterns observed in arctic and boreal ecosystems diverged from those of temperate systems, and models including root parameters may thus need specific parameterization for northern ecosystems. In addition, this thesis showed that plant communities differ in root properties, and that changes in plant community compositions can thus induce changes in root dynamics and functioning. This underlines the importance of a thorough understanding of root dynamics in different plant community types in order to understand and predict how changes in plant communities in response to climate change will translate into root dynamics. Overall, this thesis describes root dynamics in response to a variety of factors, because a deeper knowledge about root dynamics will enable a better understanding of ecosystem processes, as well as improve model prediction of how northern ecosystems will respond to climate change.

  • 129.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Roland
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Root phenology unresponsive to earlier snowmelt despite advanced aboveground phenology in two subarctic plant communitiesManuscript (preprint) (Other academic)
    Abstract [en]

    Earlier snowmelt at high latitudes advances aboveground plant phenology, thereby affecting water, nutrient and carbon cycles. Despite the key role of fine roots in these ecosystem processes, phenological responses to earlier snowmelt have never been assessed belowground. We experimentally advanced snowmelt in two contrasting plant community types (heath and meadow) in northern Sweden and measured above- and belowground phenology (leaf-out, flowering and fine root growth). We expected earlier snowmelt to advance both above- and belowground phenology, and shrub-dominated heath to be more responsive than meadow. Snow melted on average nine days earlier in the manipulated plots than in controls, and soil temperatures were on average 0.9 °C higher during the snowmelt period of three weeks. This resulted in small advances in aboveground phenology, but contrary to our expectations, root phenology was unresponsive, with root growth generally starting before leaf-out. Both plant community types responded similarly to the snowmelt treatment, despite strong differences in dominating plant functional types, and root properties, such as root length and turnover. The lack of a response in root phenology, despite warmer soil temperatures and aboveground phenological advances, adds evidence that aboveground plant responses might not be directly translated to belowground plant responses, and that our understanding of factors driving belowground phenology is still limited, although of major importance for water, nutrient and carbon cycling.

  • 130.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kreyling, Juergen
    Greifswald University.
    Laudon, Hjalmar
    Sveriges Lantbruksuniversitet Umeå.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Research Institute for Nature and Forest INBO, Kliniekstraat 25, 1070 Brussels, Belgium.
    Short-term climate change manipulation effects do not scale up to long-term legacies: effects of an absent snow cover on boreal forest plants2016In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 104, no 6, p. 1638-1648Article in journal (Refereed)
    Abstract [en]

    1. Despite time-lags and nonlinearity in ecological processes, the majority of our knowledge about ecosystem responses to long-term changes in climate originates from relatively short-term experiments.

    2. We utilized the longest ongoing snow removal experiment in the world and an additional set of new plots at the same location in northern Sweden to simultaneously measure the effects of longterm (11 winters) and short-term (1 winter) absence of snow cover on boreal forest understorey plants, including the effects on root growth and phenology.

    3. Short-term absence of snow reduced vascular plant cover in the understorey by 42%, reduced fine root biomass by 16%, reduced shoot growth by up to 53% and induced tissue damage on two common dwarf shrubs. In the long-term manipulation, more substantial effects on understorey plant cover (92% reduced) and standing fine root biomass (39% reduced) were observed, whereas other response parameters, such as tissue damage, were observed less. Fine root growth was generally reduced, and its initiation delayed by c. 3 (short-term) to 6 weeks (long-term manipulation).

    4. Synthesis. We show that one extreme winter with a reduced snow cover can already induce ecologically significant alterations. We also show that long-term changes were smaller than suggested by an extrapolation of short-term manipulation results (using a constant proportional decline). In addition, some of those negative responses, such as frost damage and shoot growth, were even absolutely stronger in the short-term compared to the long-term manipulation. This suggests adaptation or survival of only those individuals that are able to cope with these extreme winter conditions, and that the short-term manipulation alone would overpredict long-term impacts. These results highlight both the ecological importance of snow cover in this boreal forest, and the value of combining short- and long-term experiments side by side in climate change research.

  • 131.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, Greifswald, Germany.
    Lindén, Elin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Andresen, Lisa
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Classen, Aimée T.
    Sanders, Nathan J.
    von Oppen, Jonathan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sundqvist, Maja K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Center for Macroecology, Evolution and Climate, The Natural History Museum of Denmark, University of Copenhagen, Copenhagen K, Denmark.
    Proportion of fine roots, but not plant biomass allocation below ground, increases with elevation in arctic tundra2018In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 29, no 2, p. 226-235Article in journal (Refereed)
    Abstract [en]

    Questions: Roots represent a considerable proportion of biomass, primary production and litter input in arctic tundra, and plant allocation of biomass to above- or below-ground tissue in response to climate change is a key factor in the future C balance of these ecosystems. According to optimality theory plants allocate C to the above- or below-ground structure that captures the most limiting resource. We used an elevational gradient to test this theory and as a space-for-time substitution to inform on tundra carbon allocation patterns under a shifting climate, by exploring if increasing elevation was positively related to the root:shoot ratio, as well as a larger plant allocation to adsorptive over storage roots.

    Location: Arctic tundra heath dominated by Empetrum hermaphroditum close to Abisko, Sweden.

    Methods: We measured root:shoot and fine:coarse root ratios of the plant communities along an elevational gradient by sampling above- and below-ground biomass, further separating root biomass into fine (<1 mm) and coarse roots.

    Results: Plant biomass was higher at the lower elevations, but the root:shoot ratio did not vary with elevation. Resource allocation to fine relative to coarse roots increased with elevation, resulting in a fine:coarse root ratio that more than doubled with increasing elevation.

    Conclusions: Contrary to previous works, the root:shoot ratio along this elevational gradient remained stable. However, communities along our study system were dominated by the same species at each elevation, which suggests that when changes in the root:shoot ratio occur with elevation these changes may be driven by differences in allocation patterns among species and thus turnover in plant community structure. Our results further reveal that the allocation of biomass to fine relative to coarse roots can differ between locations along an elevational gradient, even when overall above- vs below-ground biomass allocation does not. Given the functionally different roles of fine vs coarse roots this could have large implications for below-ground C cycling. Our results highlight the importance of direct effects vs indirect effects (such as changes in plant community composition and nutrient availability) of climate change for future C allocation above and below ground.

  • 132.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, Germany.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Research Institute for Nature and Forest INBO, Brussels, Belgium.
    Teuber, Laurenz M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald, Germany.
    Johansson, Margareta
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dwelling in the deep – strongly increased root growth and rooting depth enhance plant interactions with thawing permafrost soil2019In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 223, no 3, p. 1328-1339Article in journal (Refereed)
    Abstract [en]

    Climate‐warming‐induced permafrost thaw exposes large amounts of carbon and nitrogen in soil at considerable depths, below the seasonally thawing active layer. The extent to which plant roots can reach and interact with these hitherto detached, deep carbon and nitrogen stores remains unknown.

    We aimed to quantify how permafrost thaw affects root dynamics across soil depths and plant functional types compared with above‐ground abundance, and potential consequences for plant–soil interactions.

    A decade of experimental permafrost thaw strongly increased total root length and growth in the active layer, and deep roots invaded the newly thawed permafrost underneath. Root litter input to soil across all depths was 10 times greater with permafrost thaw. Root growth timing was unaffected by experimental permafrost thaw but peaked later in deeper soil, reflecting the seasonally receding thaw front. Deep‐rooting species could sequester 15N added at the base of the ambient active layer in October, which was after root growth had ceased.

    Deep soil organic matter that has long been locked up in permafrost is thus no longer detached from plant processes upon thaw. Whether via nutrient uptake, carbon storage, or rhizosphere priming, plant root interactions with thawing permafrost soils may feed back on our climate both positively and negatively.

  • 133.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Teuber, Laurenz M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Margareta, Johansson
    Lund University.
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dwelling in the deep – permafrost thawing strongly increases plant root growth and root litter inputManuscript (preprint) (Other academic)
    Abstract [en]

    Plant roots play a key role in ecosystem carbon and nutrient cycling. Climate warming induced thawing of permafrost exposes large amounts of carbon and nitrogen at greater soil depths that hitherto have been detached from plant influences. Whether plant roots can reach and interact with these carbon and nitrogen sources upon permafrost thaw remains unknown. Here, we use a long-term permafrost thaw experiment and a short-term deep fertilization experiment in northern Sweden to assess changes in vegetation composition and root dynamics (deep nitrogen uptake, root depth distribution, root growth and phenology, root mortality and litter input) related to permafrost thaw, both in active layer and in newly thawed permafrost. We show that Eriophorum vaginatum and Rubus chamaemorus, both relatively deep-rooting species, can take up nitrogen released at depth of permafrost thaw, despite the late release time in autumn when plant activity is expected to have ceased. Also, root dynamics changed drastically after a decade of experimental permafrost thaw. Total root length, root growth and root litter input all strongly increased, not only in the active layer but also in the newly thawed permafrost, and the timing of root growth was related to the seasonality of soil thaw. These responses were driven by Eriophorum vaginatum, which differed greatly in root dynamics compared to the other species and thus worked as an ecosystem engineer. This study demonstrates that soil organic matter currently locked-up at depth in permafrost is no longer detached from plant processes upon thaw. Given the pivotal role that roots have in the carbon cycle and the importance of the large carbon stocks in arctic soils, the changes observed here have the potential to feedback onto the global climate system.

  • 134.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wilson, Scott D.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2 Canada.
    Kreyling, Juergen
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Research Institute for Nature and Forest INBO, Kliniekstraat 25, 1070 Brussels, Belgium.
    The hidden season: growing season is 50% longer below than above ground along an arctic elevation gradient2016In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 209, no 3, p. 978-986Article in journal (Refereed)
    Abstract [en]

    There is compelling evidence from experiments and observations that climate warming prolongs the growing season in arctic regions. Until now, the start, peak, and end of the growing season, which are used to model influences of vegetation on biogeochemical cycles, were commonly quantified using above-ground phenological data. Yet, over 80% of the plant biomass in arctic regions can be below ground, and the timing of root growth affects biogeochemical processes by influencing plant water and nutrient uptake, soil carbon input and microbial activity. We measured timing of above- and below-ground production in three plant communities along an arctic elevation gradient over two growing seasons. Below-ground production peaked later in the season and was more temporally uniform than above-ground production. Most importantly, the growing season continued c. 50% longer below than above ground. Our results strongly suggest that traditional above-ground estimates of phenology in arctic regions, including remotely sensed information, are not as complete a representation of whole-plant production intensity or duration, as studies that include root phenology. We therefore argue for explicit consideration of root phenology in studies of carbon and nutrient cycling, in terrestrial biosphere models, and scenarios of how arctic ecosystems will respond to climate warming.

  • 135.
    Blåhed, Ida-Maria
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Direct and indirect effects of herbivory on tree recruitment from seeds in tundra-forest ecotone in northern Sweden2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 136.
    Bognounou, Fidele
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hulme, Philip E.
    Oksanen, Lauri
    Suominen, Otso
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Role of climate and herbivory on native and alien conifer seedling recruitment at and above the Fennoscandian tree line2018In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 29, no 4, p. 573-584Article in journal (Refereed)
    Abstract [en]

    Questions: We investigated the importance of climate and herbivory on native and alien conifer colonization of the birch-dominated Fennoscandian tree line by addressing the following questions: (a) are tree line and tundra habitats similarly suitable for conifer seedling recruitment; (b) do ungulate and rodent herbivores differentially impact seedling recruitment; and (c) how does the role of habitat and herbivory on seedling recruitment vary across a marked climate gradient?

    Location: Northern Fennoscandia, Sweden (Vassijaure and Paddus), and Norway (Joatka and Seiland).

    Methods: We conducted an experiment to assess the emergence rate, survival probability and height development of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and Siberian larch (Larix sibirica) seedlings. Three experimental plots (i.e., open control, reindeer exclosure and complete vertebrate exclosure) were established in both tree line and tundra habitats at each of the four locations. Seeds of the three conifer species were sown in each plot in June 1999 during three consecutive years. The surviving seedlings were counted in August to September 1999, 2000, 2001, 2002 and 2007. The height of all seedlings was measured in 2007.

    Results: Our study reveals that Norway spruce, Scots pine and Siberian larch can regenerate from seed at and above the current tree line in northern Fennoscandia. Their performance was generally higher above tree line in tundra than at tree line, but depended on species identity, climate aridity and mammal herbivory, particularly by rodents. These results suggest that the species composition and latitudinal limit of the tree line in the future might depend not only on direct effects of the future climate on the current tree line species, but also on the intensity of alien and native conifer introductions, as well as changes in herbivore populations.

    Conclusion: If sufficient seeds of Norway spruce, Scots pine and Siberian larch should reach the current tree line, their performances will increase with a warmer and wetter climate, and this effect will be markedly modulated by herbivores (particularly rodents). Further work is required to extend these results to determine the ability of these conifers to become tree line-forming species in the future.

  • 137. Bohdalkova, Leona
    et al.
    Novak, Martin
    Buzek, Frantisek
    Kreisinger, Jakub
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pazderu, Katerina
    Pacherova, Petra
    The response of a mid- and high latitude peat bog to predicted climate change: methane production in a 12-month peat incubation2014In: Mitigation and Adaptation Strategies for Global Change, ISSN 1381-2386, E-ISSN 1573-1596, Vol. 19, no 7, p. 997-1010Article in journal (Refereed)
    Abstract [en]

    There are fears that global warming will lead to degradation of peatlands, higher emissions of greenhouse gases from peat, and accelerated warming. Anaerobic decomposition of organic soils produces methane (CH4), a potent greenhouse gas. Two peat bogs differing in mean annual temperature, Velke Darko (VD, Czech Republic, 7.2 A degrees C), and Stor myran (SA, Sweden, 4.0 A degrees C), were selected for a comparative study of how organic soils in different climatic zones will respond to warmer and drier conditions. Twenty peat cores from each bog were incubated in growth chambers. Under present-day summer conditions, VD produced 14 times more CH4 than SA. Two different warming scenarios were used. Peat-core replicates were kept at temperatures of 11 versus 16 A degrees C, and 11 versus 22 A degrees C. From 11 to 16 A degrees C, the CH4 production slightly decreased at SA, and slightly increased at VD. From 11 to 22 A degrees C, the CH4 production increased 9 times at SA, but slightly decreased at VD. After an 8-month incubation, peat cores under drying conditions (water table at -14 cm) were compared to samples with original water table (-2 cm). Drying conditions led to a steeper reduction in CH4 production at VD, compared to SA. The CH4 production decreased more than 100 times at VD. Then, the combined effect of simultaneous warming and drying at 11 and 22 A degrees C was studied. We did not find any significant effect of interactions between increasing temperature and decreasing water table level. Overall, the warmer site VD responded more strongly to the simulated climate change than the colder site SA.

  • 138. Bolnick, Daniel I
    et al.
    Svanbäck, Richard
    Araújo, Márcio S.
    Persson, Lennart
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Comparative support for the niche variation hypothesis that more generalized populations also are more heterogeneous2007In: Proceedings of the National Academy of Sciences, Vol. 104, no 24, p. 10075-10079Article in journal (Refereed)
    Abstract [en]

    There is extensive evidence that some species of ecological generalists, which use a wide diversity of resources, are in fact heterogeneous collections of relatively specialized individuals. This within-population variation, or "individual specialization," is a key requirement for frequency-dependent interactions that may drive a variety of types of evolutionary diversification and may influence the population dynamics and ecological interactions of species. Consequently, it is important to understand when individual specialization is likely to be strong or weak. The niche variation hypothesis (NVH) suggests that populations tend to become more generalized when they are released from interspecific competition. This niche expansion was proposed to arise via increased variation among individuals rather than increased individual niche breadth. Consequently, we expect ecological generalists to exhibit stronger individual specialization, but this correlation has been repeatedly rejected by empiricists. The drawback with previous empirical tests of the NVH is that they use morphological variation as a proxy for niche variation, ignoring the role of behavior and complex phenotype–function relationships. Here, we used diet data to directly estimate niche variation among individuals. Consistent with the NVH, we show that more generalized populations also exhibit more niche variation. This trend is quite general, appearing in all five case studies examined: three-spine stickleback, Eurasian perch, Anolis lizards, intertidal gastropods, and a community of neotropical frogs. Our results suggest that generalist populations may tend to be more ecologically variable. Whether this translates into greater genetic variation, evolvability, or ecological stability remains to be determined.

  • 139. Bolnick, Daniel
    et al.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Fordyce, James
    Yang, Louie
    Davis, Jeremy
    Hulsey, Darrin
    Forister, Matthew
    The ecology of individuals: incidence and implications of individual specialization2003In: American Naturalist, Vol. 161, p. 1-28Article in journal (Refereed)
  • 140. Bonk, Alicja
    et al.
    Kinder, Małgorzata
    Enters, Dirk
    Grosjean, Martin
    Meyer-Jacob, Carsten
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tylmann, Wojciech
    Sedimentological and geochemical responses of Lake Żabińskie (north-eastern Poland) to erosion changes during the last millennium2016In: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 56, no 2-3, p. 239-252Article in journal (Refereed)
    Abstract [en]

    Increased erosion triggered by land-use changes is a major process that influences lake sedimentation. We explored the record of erosion intensity in annually laminated sediments of Lake Żabińskie, northeast Poland. A 1000-year-long, annually resolved suite of sedimentological (varve thickness, sediment accumulation rate) and geochemical data (scanning XRF, loss on ignition, biogenic silica) was analyzed with multivariate statistics. PCA indicated erosion was a major process responsible for changes in the chemical composition of the sediments. Analysis of sedimentary facies enabled identification of major phases of erosion that influenced lake sedimentation. These phases are consistent with the history of land use, inferred from pollen analysis. From AD 1000 to 1610, conditions around and in Lake Żabińskie were relatively stable, with low erosion intensity in the catchment and a dominance of carbonate sedimentation. Between AD 1610 and 1740, higher lake productivity and increased delivery of minerogenic material were caused by development of settlements in the region and widespread deforestation. The most prominent changes were observed between AD 1740 and 1880, when further land clearance and increased agricultural activity caused intensified soil erosion and higher lake productivity. Landscape clearance also created better conditions for water column mixing, which led to changes in redox conditions in the hypolimnion. The most recent period (AD 1880–2010) was characterized by partial reforestation and a gradual decrease in the intensity of erosional processes.

  • 141.
    Bouzarovski, Stefan
    et al.
    School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham.
    Salukvadze, Joseph
    Department of Human Geography, Tbilisi State University, Faculty of Social and Political Studies.
    Gentile, Michael
    Umeå University, Faculty of Social Sciences, Department of Social and Economic Geography.
    A socially resilient urban transition?: The contested landscapes of apartment building extensions in two post-communist cities2011In: Urban Studies, ISSN 0042-0980, E-ISSN 1360-063X, Vol. 48, no 13, p. 2689-2714Article in journal (Refereed)
    Abstract [en]

    Even though social processes across the globe are increasingly being theorised through a resilience lens, this has rarely been the case within the domain of everyday life in the city. The resilience debate also remains highly geographically selective, as regions that have undergone far-reaching systemic change over the past 20 years-including the post-communist states of the former Soviet Union and eastern and central Europe (ECE)-generally remain omitted from it. In order to address such knowledge gaps, an investigation is made of the relationships between social resilience and micro-level socio-spatial change in the built environment of the post-communist city, by focusing on the institutional, spatial and economic underpinnings of apartment building extensions (ABEs) on multistorey residential buildings in the Macedonian capital of Skopje and the Georgian capital of Tbilisi. Both cities contain a wide variety of ABEs, whose reinforced concrete frame constructions often rival the host buildings in terms of size and function. By exploring the architectural and social landscapes created by the extensions, it is hoped to highlight their embeddedness in a set of policy decisions and coping strategies, as well as their controversial implications on the present and future use of urban space.

  • 142. Boyero, Luz
    et al.
    Graca, Manuel A. S.
    Tonin, Alan M.
    Perez, Javier
    Swafford, Andrew J.
    Ferreira, Veronica
    Landeira-Dabarca, Andrea
    Alexandrou, Markos A.
    Gessner, Mark O.
    Mckie, Brendan G.
    Albarino, Ricardo J.
    Barmuta, Leon A.
    Callisto, Marcos
    Chara, Julian
    Chauvet, Eric
    Colon-Gaud, Checo
    Dudgeon, David
    Encalada, Andrea C.
    Figueroa, Ricardo
    Flecker, Alexander S.
    Fleituch, Tadeusz
    Frainer, André
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway.
    Goncalves, Jose F., Jr.
    Helson, Julie E.
    Iwata, Tomoya
    Mathooko, Jude
    M'Erimba, Charles
    Pringle, Catherine M.
    Ramirez, Alonso
    Swan, Christopher M.
    Yule, Catherine M.
    Pearson, Richard G.
    Riparian plant litter quality increases with latitude2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 10562Article in journal (Refereed)
    Abstract [en]

    Plant litter represents a major basal resource in streams, where its decomposition is partly regulated by litter traits. Litter-trait variation may determine the latitudinal gradient in decomposition in streams, which is mainly microbial in the tropics and detritivore-mediated at high latitudes. However, this hypothesis remains untested, as we lack information on large-scale trait variation for riparian litter. Variation cannot easily be inferred from existing leaf-trait databases, since nutrient resorption can cause traits of litter and green leaves to diverge. Here we present the first global-scale assessment of riparian litter quality by determining latitudinal variation (spanning 107 degrees) in litter traits (nutrient concentrations; physical and chemical defences) of 151 species from 24 regions and their relationships with environmental factors and phylogeny. We hypothesized that litter quality would increase with latitude (despite variation within regions) and traits would be correlated to produce 'syndromes' resulting from phylogeny and environmental variation. We found lower litter quality and higher nitrogen: phosphorus ratios in the tropics. Traits were linked but showed no phylogenetic signal, suggesting that syndromes were environmentally determined. Poorer litter quality and greater phosphorus limitation towards the equator may restrict detritivore-mediated decomposition, contributing to the predominance of microbial decomposers in tropical streams.

  • 143. Bragee, P.
    et al.
    Mazier, F.
    Nielsen, A. B.
    Rosén, Peter
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Fredh, D.
    Brostrom, A.
    Graneli, W.
    Hammarlund, D.
    Historical TOC concentration minima during peak sulfur deposition in two Swedish lakes2015In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, no 2, p. 307-322Article in journal (Refereed)
    Abstract [en]

    Decadal-scale variations in total organic carbon (TOC) concentration in lake water since AD1200 in two small lakes in southern Sweden were reconstructed based on visible-near-infrared spectroscopy (VNIRS) of their recent sediment successions. In order to assess the impacts of local land-use changes, regional variations in sulfur, and nitrogen deposition and climate variations on the inferred changes in TOC concentration, the same sediment records were subjected to multi-proxy palaeolimnological analyses. Changes in lake-water pH were inferred from diatom analysis, whereas pollen-based land-use reconstructions (Landscape Reconstruction Algorithm) together with geochemical records provided information on catchment-scale environmental changes, and comparisons were made with available records of climate and population density. Our long-term reconstructions reveal that inferred lake-water TOC concentrations were generally high prior to AD1900, with additional variability coupled mainly to changes in forest cover and agricultural land-use intensity. The last century showed significant changes, and unusually low TOC concentrations were inferred at AD1930-1990, followed by a recent increase, largely consistent with monitoring data. Variations in sulfur emissions, with an increase in the early 1900s to a peak around AD1980 and a subsequent decrease, were identified as an important driver of these dynamics at both sites, while processes related to the introduction of modern forestry and recent increases in precipitation and temperature may have contributed, but the effects differed between the sites. The increase in lake-water TOC concentration from around AD1980 may therefore reflect a recovery process. Given that the effects of sulfur deposition now subside and that the recovery of lake-water TOC concentrations has reached pre-industrial levels, other forcing mechanisms related to land management and climate change may become the main drivers of TOC concentration changes in boreal lake waters in the future.

  • 144. Bravo, Andrea G.
    et al.
    Loizeau, Jean-Luc
    Dranguet, Perrine
    Makri, Stamatina
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ungureanu, Viorel Gh.
    Slaveykova, Vera I.
    Cosio, Claudia
    Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania)2016In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 23, no 11, p. 10529-10541Article in journal (Refereed)
    Abstract [en]

    Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl- concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

  • 145. Bravo, Andrea G.
    et al.
    Peura, Sari
    Buck, Moritz
    Ahmed, Omneya
    Mateos-Rivera, Alejandro
    Ortega, Sonia Herrero
    Schaefer, Jeffra K.
    Bouchet, Sylvain
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tolu, Julie
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bertilsson, Stefan
    Methanogens and iron-reducing bacteria: the overlooked members of mercury-methylating microbial communities in boreal lakes2018In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 84, no 23, article id e01774-18Article in journal (Refereed)
    Abstract [en]

    ABSTRACT: Methylmercury is a potent human neurotoxin which biomagnifies in aquatic food webs. Although anaerobic microorganisms containing the hgcA gene potentially mediate the formation of methylmercury in natural environments, the diversity of these mercury-methylating microbial communities remains largely unexplored. Previous studies have implicated sulfate-reducing bacteria as the main mercury methylators in aquatic ecosystems. In the present study, we characterized the diversity of mercury-methylating microbial communities of boreal lake sediments using high-throughput sequencing of 16S rRNA and hgcA genes. Our results show that in the lake sediments, Methanomicrobiales and Geobacteraceae also represent abundant members of the mercury-methylating communities. In fact, incubation experiments with a mercury isotopic tracer and molybdate revealed that only between 38% and 45% of mercury methylation was attributed to sulfate reduction. These results suggest that methanogens and iron-reducing bacteria may contribute to more than half of the mercury methylation in boreal lakes.

    IMPORTANCE: Despite the global awareness that mercury, and methylmercury in particular, is a neurotoxin to which millions of people continue to be exposed, there are sizable gaps in the understanding of the processes and organisms involved in methylmercury formation in aquatic ecosystems. In the present study, we shed light on the diversity of the microorganisms responsible for methylmercury formation in boreal lake sediments. All the microorganisms identified are associated with the processing of organic matter in aquatic systems. Moreover, our results show that the well-known mercury-methylating sulfate-reducing bacteria constituted only a minor portion of the potential mercury methylators. In contrast, methanogens and iron-reducing bacteria were important contributors to methylmercury formation, highlighting their role in mercury cycling in the environment.

  • 146.
    Breitling, Rainer
    et al.
    Faculty of Life Sciences, University of Manchester, UK.
    Buckland, Philip I.
    Umeå University, Faculty of Arts, Department of historical, philosophical and religious studies, Environmental Archaeology Lab.
    Epigean spiders at Abisko Scientific Research Station in Swedish Lapland (Arachnida:Araneae)2015In: Arachnology, ISSN 2050-9928, E-ISSN 2050-9936, Vol. 16, no 8, p. 287-293Article in journal (Refereed)
    Abstract [en]

    The Torneträsk area, including the Abisko National Park, Sweden, is arachnologically one of the best explored sites of Fennoscandia. Here we report the results of pitfall trapping at Abisko Scientific Research Station during the summers of 2004 and 2005, recording 791 individuals of 62 species of spiders. As expected, at the species level, samples were dominated by members of the Linyphiidae, while at the level of individuals Pardosa hyperborea and other lycosids were dominant. Two subsites, on heath and bog, differed substantially in their species profile: 7 species were statistically overrepresented on the drier heath site, while 2 species showed a strong preference for the wetter bog site. The samples also contained the first reported lateral gynadromorph of Archaeodictyna consecuta (Dictynidae). This study, from 195 km north of the Arctic Circle, provides important reference data for continued studies on the long-term effects of climate change on arctic ecosystems.

  • 147. Brett, Michael T.
    et al.
    Bunn, Stuart E.
    Chandra, Sudeep
    Galloway, Aaron W. E.
    Guo, Fen
    Kainz, Martin J.
    Kankaala, Paula
    Lau, Danny C. P.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moulton, Timothy P.
    Power, Mary E.
    Rasmussen, Joseph B.
    Taipale, Sami J.
    Thorp, James H.
    Wehr, John D.
    How important are terrestrial organic carbon inputs for secondary production in freshwater ecosystems?2017In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 62, no 5, p. 833-853Article, review/survey (Refereed)
    Abstract [en]

    1. Many freshwater systems receive substantial inputs of terrestrial organic matter. Terrestrially derived dissolved organic carbon (t-DOC) inputs can modify light availability, the spatial distribution of primary production, heat, and oxygen in aquatic systems, as well as inorganic nutrient bioavailability. It is also well-established that some terrestrial inputs (such as invertebrates and fruits) provide high-quality food resources for consumers in some systems. 2. In small to moderate-sized streams, leaf litter inputs average approximately three times greater than the autochthonous production. Conversely, in oligo/mesotrophic lakes algal production is typically five times greater than the available flux of allochthonous basal resources. 3. Terrestrial particulate organic carbon (t-POC) inputs to lakes and rivers are comprised of 80%-90% biochemically recalcitrant lignocellulose, which is highly resistant to enzymatic breakdown by animal consumers. Further, t-POC and heterotrophic bacteria lack essential biochemical compounds that are critical for rapid growth and reproduction in aquatic invertebrates and fishes. Several studies have directly shown that these resources have very low food quality for herbivorous zooplankton and benthic invertebrates 4. Much of the nitrogen assimilated by stream consumers is probably of algal origin, even in systems where there appears to be a significant terrestrial carbon contribution. Amino acid stable isotope analyses for large river food webs indicate that most upper trophic level essential amino acids are derived from algae. Similarly, profiles of essential fatty acids in consumers show a strong dependence on the algal food resources. 5. Primary production to respiration ratios are not a meaningful index to assess consumer allochthony because respiration represents an oxidised carbon flux that cannot be utilised by animal consumers. Rather, the relative importance of allochthonous subsidies for upper trophic level production should be addressed by considering the rates at which terrestrial and autochthonous resources are consumed and the growth efficiency supported by this food. 6. Ultimately, the biochemical composition of a particular basal resource, and not just its quantity or origin, determines how readily this material is incorporated into upper trophic level consumers. Because of its highly favourable biochemical composition and greater availability, we conclude that microalgal production supports most animal production in freshwater ecosystems.

  • 148.
    Brinck, Katharina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Information Entropy and Ecological Energetics: Predicting and Analysing Structure and Energy Flow in Ecological Networks applying the Concept of MaxEnt2014Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Ecological networks are complex systems forming hierarchical structures in which energy and matter is transferred between the network’s compartments. Predicting energy flows in food webs usually involves complex parameter-rich models. In this thesis, the application of the principle of maximum entropy (MaxEnt) to obtain least biased probability distributions based on prior knowledge is proposed as an alternative to predict the most likely energy flows in food webs from the network topology alone. This approach not only simplifies the characterisation of food web flow patterns based on little empirical knowledge but can also be used to investigate the role of bottom-up and top-down controlling forces in ecosystems resulting from the emergent phenomena based on the complex interactions on the level of species and individuals. The integrative measure of “flow extent”, incorporating both bottom- up and top-down controlling forces on ecosystems, is proposed as a principle behind ecosystem evolution and evaluated against empirical data on food web structure. It could be demonstrated that the method of predicting energy flow with the help of MaxEnt is very flexible, applicable to many different setting and types of questions in ecology, and therefore providing a powerful tool for modelling the energy transfer in ecosystems. Further research has to show in how far the most likely flow patterns are realised in real-word ecosystems. The concept of flow extent maximisation as a selection principle during ecosystem evolution can enhance the understanding of emergent phenomena in complex ecosystems and maybe help to draw a link between thermodynamics and ecology. 

  • 149.
    Brindefalk, Bjorn
    et al.
    Stockholm University.
    Ekman, Martin
    Stockholm University.
    Ininbergs, Karolina
    Stockholm University.
    Dupont, Christopher L.
    J Craig Venter Inst, USA.
    Yooseph, Shibu
    J Craig Venter Inst, USA.
    Pinhassi, Jarone
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Bergman, Birgitta
    Stockholm University.
    Distribution and expression of microbial rhodopsins in the Baltic Sea and adjacent waters2016In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 18, no 12, p. 4442-4455Article in journal (Refereed)
    Abstract [en]

    Rhodopsins are light-driven ion-pumping membrane proteins found in many organisms and are proposed to be of global importance for oceanic microbial energy generation. Several studies have focused on marine environments, with less exploration of rhodopsins in brackish waters. We investigated microbial rhodopsins in the Baltic Sea using size-fractionated metagenomic and metatranscriptomic datasets collected along a salinity gradient spanning from similar to 0 to 35 PSU. The normalised genomic abundance of rhodopsins in Bacteria, as well as rhodopsin gene expression, was highest in the smallest size fraction (0.1-0.8 mu m), relative to the medium (0.8-3.0 mu m) and large (> 3.0 mu m) size fractions. The abundance of rhodopsins in the two smaller size fractions displayed a positive correlation with salinity. Proteobacteria and Bacteroidetes rhodopsins were the most abundant while Actinobacteria rhodopsins, or actinorhodopsins, were common at lower salinities. Phylogenetic analysis indicated that rhodopsins have adapted independently to the marine-brackish transition on multiple occasions, giving rise to green light-adapted variants from ancestral blue light-adapted ones. A notable diversity of viral-like rhodopsins was also detected in the dataset and potentially linked with eukaryotic phytoplankton blooms. Finally, a new clade of likely proton-pumping rhodopsin with non-canonical amino acids in the spectral tuning and proton accepting site was identified.

  • 150.
    Brodin, Tomas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Drugs cause fishy behavior2013In: TrAC. Trends in analytical chemistry, ISSN 0165-9936, E-ISSN 1879-3142, Vol. 45, p. IX-IXArticle in journal (Other (popular science, discussion, etc.))
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