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  • 251.
    Bergsten, Johannes
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Miller, Kelly B.
    Taxonomic revision of the Holarctic diving beetle genus Acilius Leach (Coleoptera: Dytiscidae)2006In: Systematic Entomology, ISSN 0307-6970, E-ISSN 1365-3113, Vol. 31, no 1, p. 145-197Article in journal (Refereed)
    Abstract [en]

    Abstract. A full taxonomic revision is presented of the Holarctic diving beetle genus Acilius Leach (Coleoptera: Dytiscidae) belonging to the subfamily Dytiscinae and tribe Aciliini. Acilius confusussp.n., previously confused with Acilius fraternus (Harris), is described from north-eastern U.S.A. Acilius latiusculus LeConte and Acilius simplex LeConte are new synonyms of Acilius abbreviatus Aubé. Lectotypes are designated for the following names: A. abbreviatus, A. semisulcatus Aubé, A. fraternus, A. guerryi d'Olsoufieff, A. sinensis Peschet, A. duvergeri Gobert, A. brevis Aubé, A. fasciatus (De Geer), A. maccullochii (Kirby), A. tomentosus Motschulsky, A. sulcatus blancki Peyerimhoff, A. subimpressus Motschulsky and A. laevisulcatus Motschulsky. In total, six Palaearctic and seven Nearctic species are recognized, none of which is Holarctic in distribution. Each species is presented with a diagnosis, full description, habitat preferences, conservation assessments, distribution data and a comprehensive bibliography. Distribution data are presented with a map and a list of countries, or for Nearctic and eastern Palaearctic species, states or larger provinces. A key to all Acilius species is included and each is fully illustrated. The general biology and a taxonomic history of the genus are provided. Acilius abbreviatus and A. semisulcatus are found to hybridize in a narrow zone through middle British Columbia and south-western Alberta, geographically comparable with a previously recognized hybrid zone of several other insect species pairs. More than 5000 specimens were examined.

  • 252.
    Bergsten, Johannes
    et al.
    Naturhistoriska riksmuseet.
    Nilsson, Anders N.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ronquist, Fredrik
    Naturhistoriska riksmuseet.
    Bayesian Tests of Topology Hypotheses with an Example from Diving Beetles2013In: Systematic Biology, ISSN 1063-5157, E-ISSN 1076-836X, Vol. 62, no 5, p. 660-673Article in journal (Refereed)
    Abstract [en]

    We review Bayesian approaches to model testing in general and to the assessment of topological hypotheses in particular. We show that the standard way of setting up Bayes factor tests of the monophyly of a group, or the placement of a sample sequence in a known reference tree, can be misleading. The reason for this is related to the well-known dependency of Bayes factors on model-specific priors. Specifically, when testing tree hypotheses it is important that each hypothesis is associated with an appropriate tree space in the prior. This can be achieved by using appropriately constrained searches or by filtering trees in the posterior sample, but in a more elaborate way than typically implemented. If it is difficult to find the appropriate tree sets to be contrasted, then the posterior model odds may be more informative than the Bayes factor. We illustrate the recommended techniques using an empirical test case addressing the issue of whether two genera of diving beetles (Coleoptera: Dytiscidae), Suphrodytes and Hydroporus, should be synonymized. Our refined Bayes factor tests, in contrast to standard analyses, show that there is strong support for Suphrodytes nesting inside Hydroporus, and the genera are therefore synonymized.

  • 253.
    Bergström, Anna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Grundvatten i Aitiks gruvområde: En utvärdering av grundvattenkvalitet och provtagningspunkter2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to evaluate the quality of the groundwater around the Aitik copper mine- one of Europe’s largest copper mine located 15 km outside of Gällivare, Sweden - as well the placement of the groundwater pipes around the area. The study also included a survey of what kind of terms, regarding groundwater that may become relevant in the future for an activity of Aitik’s size and type. Monitoring data was analysed between the years 2014 – 2018 for the parameters; pH, SO4, Cd, Co, Cu, Zn, Ni and U. The correlation between the parameters where tested and the monitoring data where compared to the Swedish Environmental Protection Agency criteria for groundwater as well to the groundwater chemistry from a reference area nearby, Liikavaara Östra. The result of the study shows that low pH raises the mobility of the metals Cd, Co, Cu, Zn and Ni. The result also indicates that SO4, Ni and Co are higher than the reference area but that the groundwater overall shows small signs of being affected by sulphide weathering. Therefore, metals can’t be excluded from originating from high background contents. The geographic analyse shows that the groundwater pipes are well placed in compared with the water flow direction and that two of the pipes can be excluded from sampling. Future terms regarding groundwater will likely regard protective measures and quantity restrictions. Still monitoring groundwater quality is very important to control environmental impact of the activity and to prevent deterioration of quality in the future.

  • 254.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Seasonal dynamics of bacteria and mixotrophic flagellates as related to input of allochthonous dissolved organic carbon2009In: International association of theoretical and applied limnology, vol 30, pt 6: proceedings / [ed] Jones, J & Faaborg, J, Stuttgart: Schweizerbart , 2009, p. 923-928Conference paper (Refereed)
  • 255.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Seasonal dynamics of bacteria and mixotrophic flagellates as related to input of allochthonous dissolved organic carbon: internal and external sources to the CO2 emission from a subarctic lake2009In: Verhandlungen / Internationale Vereinigung für Theoretische und Angewandte Limnologie, ISSN 0368-0770, Vol. 30, no 6, p. 923-928Article in journal (Refereed)
  • 256.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The use of TN:TP and DIN:TP ratios as indicators for phytoplankton nutrient limitation in oligotrophic lakes affected by N deposition2010In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 72, no 3, p. 277-281Article in journal (Refereed)
    Abstract [en]

    The stoichiometric composition of lake water chemistry affects nutrient limitation among phytoplankton. I show how TN:TP and DIN:TP ratios vary in oligotrophic lakes of Europe and the USA affected by different amounts of N deposition, and evaluate whether the DIN:TP ratio is a better indicator than the TN:TP ratio for discriminating between N and P limitation of phytoplankton. Data were compiled from boreal and low to high alpine lakes, and comprise epilimnetic lake water chemistry data (106 lakes) and results from short-term nutrient bioassay experiments (28 lakes). A large share (54%) of the oligotrophic lakes in the study had low TN:TP mass ratios (<25). DIN:TP ratios showed higher variability than TN:TP ratios. Variability in DIN:TP ratios was related to N deposition, but also to catchment characteristics. Data from short-term bioassay experiments with separate addition of N and P showed that the DIN:TP ratio was a better indicator than the TN:TP ratio for N and P limitation of phytoplankton. Phytoplankton shift from N to P limitation when DIN:TP mass ratios increase from 1.5 to 3.4. High DIN:TP ratios, indicating P limitation of phytoplankton, were generally found in alpine lakes with low to moderate N deposition and in boreal lakes with high to very high amounts of N deposition.

  • 257.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Algesten, G
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sobek, S
    Tranvik, L J
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Emission of CO2 from hydroelectric reservoirs in northern Sweden2004In: Archiv fur Hydrobiologie, Vol. 159, p. 25-42Article in journal (Refereed)
  • 258.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Bigler, Christian
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Stensdotter, U.
    Lindström, E.S.
    Composition and dispersal of riverine and lake phytoplankton communities in connected systems with different water retention times2008In: Freshwater Biology, Vol. 53, p. 2520–2529-Article in journal (Refereed)
    Abstract [en]

    1. Lake phytoplankton community structure may be influenced by both internal factors (predation, competition, resource constraints) and external ones, such as dispersal of materials and cells between connected habitats. However, little is known about the importance of cell dispersal for phytoplankton community structure in lakes.

    2. We investigated the abundance and dispersal of phytoplankton cells between connected rivers and lakes, and analysed whether similarities in phytoplankton community composition between rivers and lakes were primarily related to cell import rates or to characteristics of the local habitat. We focused on lakes along a gradient of theoretical water retention times (TWRT). Two data sets from Swedish lakes were used; a seasonal study of two connected boreal forest lakes, differing in TWRT, and a multi-lake study of 13 lakes with a continuous range of TWRTs.

    3. Phytoplankton cells were transported and dispersed in all investigated rivers. In the seasonal study, cell import rates and similarities in phytoplankton community composition between the lake and its inlet(s) were much higher in the lake with a shorter TWRT. Phytoplankton community structure in different habitats was associated with total organic carbon (TOC). This indicates that local habitat characteristics may be important in determining lake phytoplankton community composition, even in the presence of substantial cell import.

    4. The multi-lake study also showed a negative relationship between TWRT and similarities in phytoplankton community composition between inlets and lakes. Moreover, similarity in community structure was related to both cell import rates from inlet to lake and differences in habitat characteristics between inlet and lake. However, the variable most strongly correlated with community structure was TOC, indicating that species sorting rather than a mass effect was the most important mechanism underlying the correlation between community structure and retention time.

    5. Overall, our data suggest that local habitat characteristics may play a key role in determining community similarity in this set of lakes covering a large range of habitat connectedness. Due to the strong co-variations between cell dispersal and TOC, it was hard to unequivocally disentangle the different mechanisms; hence, there is a need for further studies of the role of dispersal for phytoplankton community structures.

  • 259.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Blomqvist, P
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Effects of atmospheric nitrogen deposition on nutrient limitation and phytoplankton biomass in unproductive Swedish lakes2005In: Limnology & Oceanography, Vol. 50, p. 987-994Article in journal (Refereed)
  • 260.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Faithfull Mathisen, Carolyn
    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.
    Nitrogen deposition and warming  – effects on phytoplankton nutrient limitation in subarctic lakes2013In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, no 8, p. 2557-2568Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to predict the combined effects of enhanced nitrogen (N) deposition and warming on phytoplankton development in high latitude and mountain lakes. Consequently, we assessed, in a series of enclosureexperiments, how lake water nutrient stoichiometry and phytoplankton nutrient limitation varied over the growingseason in 11 lakes situated along an altitudinal/climate gradient with low N-deposition (<1 kg N ha1yr1) in northern subarctic Sweden. Short-term bioassay experiments with N- and P-additions revealed that phytoplankton inhigh-alpine lakes were more prone to P-limitation, and with decreasing altitude became increasingly N- andNP-colimited. Nutrient limitation was additionally most obvious in midsummer. There was also a strong positivecorrelation between phytoplankton growth and water temperature in the bioassays. Although excess nutrients wereavailable in spring and autumn, on these occasions growth was likely constrained by low water temperatures. Theseresults imply that enhanced N-deposition over the Swedish mountain areas will, with the exception of high-alpinelakes, enhance biomass and drive phytoplankton from N- to P-limitation. However, if not accompanied by warming,N-input from deposition will stimulate limited phytoplankton growth due to low water temperatures during largeparts of the growing season. Direct effects of warming, allowing increased metabolic rates and an extension of thegrowing season, seem equally crucial to synergistically enhance phytoplankton development in these lakes.

  • 261.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Atmospheric nitrogen deposition has caused nitrogen enrichment and eutrophication of lakes in the northern hemisphere2006In: Global Change Biology, Vol. 12, p. 1-9Article in journal (Refereed)
  • 262.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bacterioplankton production in humic Lake Örträsket in relation to input of bacterial cells and input of allochthonous organic carbon2000In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 39, no 2, p. 101-115Article in journal (Refereed)
    Abstract [en]

    In order to compare riverine bacteria input with lake water bacterial production and grazing loss with output loss, a bacterial cell budget was constructed for humic Lake Ortrasket in northern Sweden. The riverine input of bacterial cells in 1997 represented 29% of the number of bacterial cells produced within the layer of the lake affected by inlet water. A large share of the in situ lake bacterial production was consumed by grazers, mainly flagellates, which stresses the importance of bacteria as energy mobilizers for the pelagic food web in the lake. The bacterial production in Lake Ortrasket, which is almost entirely dependent on humic material as an energy source, was clearly stimulated by high flow episodes which brought high amounts of little degraded material into the lake. During base flow condition the bacterial production in the inlet rivers was high, which led to an input of more degraded material to the lake. This material did not stimulate the lake bacterial production. Internal factors that determined the utilization of the allochthonous DOC in the lake were the retention time and the exposure to light and high temperatures. Thus, the potential for in situ production of bacteria in Lake Ortrasket was to a large extent a function of how precipitation and runoff conditions affected terrestrial losses and river transport of humic material.

  • 263.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Blomqvist, P
    Drakare, S
    The influence of water colour and effective light climate on mixotrophic phytoflagellates in three small Swedish dystrophic lakes2000In: Verhandlungen / Internationale Vereinigung für Theoretische und Angewandte Limnologie, ISSN 0368-0770, Vol. 27, no 4, p. 1861-1965Article in journal (Refereed)
  • 264.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Drakare, Stina
    Blomqvist, Peter
    Occurrence of mixotrophic flagellates in relation to bacterioplankton production, light regime and availability of inorganic nutrients in unproductive lakes with differing humic contents2003In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 48, no 5, p. 868-877Article in journal (Refereed)
    Abstract [en]

    1. Field data from five unproductive Swedish lakes were used to investigate the occurrence of mixotrophic flagellates in relation to bacterioplankton, autotrophic phytoplankton, heterotrophic flagellates and abiotic environmental factors. Three different sources of data were used: (i) a 3-year study (1995-97) of the humic Lake Örträsket, (ii) seasonal measurements from five lakes with widely varying dissolved organic carbon (DOC) concentrations, and (iii) whole lake enrichment experiments with inorganic nutrients and organic carbon. 2. Mixotrophic flagellates usually dominated over autotrophic phytoplankton in Lake Örträsket in early summer, when both bacterial production and light levels were high. Comparative data from the five lakes demonstrated that the ratio between the biomasses of mixotrophic flagellates and autotrophic phytoplankton (the M/A-ratio) was positively correlated to bacterioplankton production, but not to the light regime. Whole lake carbon addition (white sugar) increased bacterial biomass, and production, reduced the biomass of autotrophs by a factor of 16, and increased the M/A-ratio from 0.03 to 3.4. Collectively, the results indicate that the dominance of mixotrophs among phytoplankton was positively related to bacterioplankton production. 3. Whole lake fertilisation with nitrogen (N) and phosphorus (P) demonstrated that the obligate autotrophic phytoplankton was limited by N. N-addition increased the biomass of the autotrophic phytoplankton but had no effect on mixotrophic flagellates or bacteria, and the M/A-ratio decreased from 1.2 to 0.6 after N-enrichment. Therefore, we suggest that bacteria under natural conditions, by utilising allochthonous DOC as an energy and carbon source, are able to outcompete autotrophs for available inorganic nutrients. Consequently, mixotrophic flagellates can become the dominant phytoplankters when phagotrophy permits them to use nutrients stored in bacterial biomass. 4. In Lake Ortrasket, the biomass of mixotrophs was usually higher than the biomass of heterotrophs during the summer. This dominance could not be explained by higher grazing rates among the mixotrophs. Instead, ratios between mixotrophic and heterotrophic biomass (the M/H-ratio) were positively related to light availability. Therefore, we suggest that photosynthesis can enable mixotrophic flagellates to outcompete heterotrophic flagellates.

  • 265.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Jonsson, Anders
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Jansson, Mats
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Phytoplankton responses to nitrogen and phosphorus enrichment in unproductive Swedish lakes along a gradient of atmospheric nitrogen deposition2008In: Aquatic Biology, Vol. 4, p. 55-64Article in journal (Refereed)
    Abstract [en]

    Lake sampling and in situ nutrient enrichment enclosure experiments with nitrogen (N) and phosphorus (P) were conducted in unproductive Swedish lakes along a gradient of increasing atmospheric N-deposition. The regional and seasonal patterns of nutrient limitation of phytoplankton were clearly related to the amounts of N-deposition and N-inputs the lakes received. In areas of low N-deposition in northern Sweden, N-limitation of phytoplankton was evident throughout the summer season due to high catchment N-retention and very low dissolved inorganic N (DIN) inputs during the early summer. High N-deposition in the south was accompanied by high lake DIN-concentrations during the early summer and subsequent P-limitation of phytoplankton. However, P-limitation did not persist over the summer and, as a consequence of a declining DIN-pool, the lakes switched to dual- and co-limitation by N and P, and then to N-limitation. Generally, the lakes were N-limited rather than P-limited during the summer. We conclude that N-limitation is probably a natural state of the unproductive lakes studied, but P-limitation of variable intensity and duration has been induced by elevated atmospheric N-deposition.

  • 266.
    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.

  • 267.
    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.

  • 268.
    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.

  • 269.
    Bergström, L
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Kautsky, L
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Local adaptation in Ceramium tenuicorne (Ceramiales, Rhodophyta). in the Baltic Sea2006In: J Phycol, Vol. 42, no 1Article in journal (Refereed)
  • 270.
    Bergström, L
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Tatarenkov, A
    Jönsson, R B
    Johannesson, K
    Kautsky, L
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Genetic and morphological identification of Fucus radicans sp. nov. (Fucales, Phaeophyceae) in the brackish Baltic Sea2005In: J. Phycol., Vol. 41, p. 1025-1038Article in journal (Refereed)
  • 271.
    Bergström, Sara
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bergets mekaniska hållfasthet i Aitikgruvan2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Throughout the years the mining company Boliden Mineral AB have had difficulties producing a working fine filter for their tailing pond at the Aitik copper mine. The problem with the fine filter occurs when it gets placed on the tailing pond wall. Coarse grains break down into fine grains and the entire composition of the fine filter is changed. The material that is used to produce the fine filter comes from the mine’s own waste rock supply. The primary waste rock in Aitik comprises of heterogeneous gneiss and pegmatite. To determine why the waste rock isn’t holding together well enough the mechanical strength of the rock is investigated. Huge differences for the mechanical strength both exist between the different rock types, but also in the different kinds of the gneiss. The effect of the explosions, used to mine the ore, and the crushing machine also impacts on the mechanical strength of the rock. Good mechanical strength is found in rock that has a high amount of secondary transformation like epidote and bad mechanical strength from foliated rock. To get the best mechanical properties it is suggested to exploit epidote transformed rock found in deformation zones, adjacent to the ore deposit or the pegmatite intrusions. It is also recommended to use less powerful charge when blasting rock material that will be used for production of the fine filter.

  • 272.
    Bergström, Stina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Telemedicin i Västerbottens läns landsting: Diffusion och kartläggning av telemedicin ur ett geografiskt perspektiv2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Telemedicine is the use of information and communication technology to provide clinical health care at a distance. This approach is usually adopted to bridge the distance in rural settings, but it is also a method to meet demographical and economical challenges. Västerbotten, a sparsely populated county with an ageing population, is in leading edge when it comes to telemedicine. The purpose of this report was to examine the diffusion and the inventory of telemedicine in the county council of Västerbotten from a geographical perspective. To gain a deeper understanding of diffusion and inventory of telemedicine, my purpose was also to examine these processes from an international and national perspective. Telemedicine and diffusion as concepts, and how these have been portrayed in the literature were studied, as well as the driving forces behind, and the barriers to further diffusion of telemedicine. The main focus in the report was telemedicine in the county council of Västerbotten and their ongoing inventory of telemedicine. The background of the inventory, how it is being performed and what the results have been up to this date were investigated. All these aspects were performed through interviews. An important factor to successful implementation of telemedicine, is the use of comprehensive and systematic performed evaluations of telemedicine activities. The inventory performed by the county council of Västerbotten is an important contribution to the lack of evidence in this area. Although, a major barrier to successful implementation and further diffusion of telemedicine, appears to be attitudes among health care staff.

  • 273.
    Bergström, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial scale, heterogeneity and functional responses2004In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 73, no 3, p. 487-493Article in journal (Refereed)
    Abstract [en]

    1. In a laboratory experiment, we studied the effect of arena size on the functional response of the mysid shrimp Neomysis integer preying on the cladoceran Polyphemus pediculus. The aim of the study was to examine mechanisms that cause the functional response to be scale-dependent, by documenting the spatial distribution and the movement behaviour of predator and prey.

    2. The attack rate was significantly higher in large arenas, while the handling time did not differ between arena sizes. The difference in attack rate could be explained by differences in aggregative behaviour of predator and prey and in swimming activity of the predator. It is suggested that distributions of animals are often affected by the walls of the experimental arenas and that this spatial heterogeneity is scale-dependent, which may have a considerable impact on estimates of ecological process rates.

    3. A method of correcting attack rate estimates for artefacts caused by such spatial heterogeneity is presented.

  • 274. Bergström, Ulf
    et al.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Leonardsson, Kjell
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Plugging space into predator-prey models: an empirical approach.2006In: Am Nat, ISSN 1537-5323, Vol. 167, no 2, p. 246-59Article in journal (Refereed)
  • 275. Bergvall, M
    et al.
    Grip, H
    Sjöstrom, J
    Laudon, Hjalmar
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    A steady-state approach to estimate rate and uncertainty.2007In: Ambio, Vol. 36, p. 512-519Article in journal (Refereed)
  • 276.
    Berner, Daniel
    et al.
    Basel, Switzerland.
    Thibert-Plante, Xavier
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Knoxville, TN, USA; Uppsala, Sweden.
    How mechanisms of habitat preference evolve and promote divergence with gene flow2015In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 28, no 9, p. 1641-1655Article in journal (Refereed)
    Abstract [en]

    Habitat preference may promote adaptive divergence and speciation, yet the conditions under which this is likely are insufficiently explored. We use individual-based simulations to study the evolution and consequence of habitat preference during divergence with gene flow, considering four different underlying genetically based behavioural mechanisms: natal habitat imprinting, phenotype-dependent, competition-dependent and direct genetic habitat preference. We find that the evolution of habitat preference generally requires initially high dispersal, is facilitated by asymmetry in population sizes between habitats, and is hindered by an increasing number of underlying genetic loci. Moreover, the probability of habitat preference to emerge and promote divergence differs greatly among the underlying mechanisms. Natal habitat imprinting evolves most easily and can allow full divergence in parameter ranges where no divergence is possible in the absence of habitat preference. The reason is that imprinting represents a one-allele mechanism of assortative mating linking dispersal behaviour very effectively to local selection. At the other extreme, direct genetic habitat preference, a two-allele mechanism, evolves under restricted conditions only, and even then facilitates divergence weakly. Overall, our results indicate that habitat preference can be a strong reproductive barrier promoting divergence with gene flow, but that this is highly contingent on the underlying preference mechanism.

  • 277. 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.

  • 278. Bernes, Claes
    et al.
    Bråthen, Kari Anne
    Forbes, Bruce C.
    Hofgaard, Annika
    Moen, Jon
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Speed, James D.M.
    What are the impacts of reindeer/caribou (Rangifer tarandus L.) on arctic and alpine vegetation?: A systematic review protocol2013In: Environmental Evidence, ISSN 2047-2382, Vol. 2, article id 6Article in journal (Refereed)
    Abstract [en]

    Background: Reindeer and caribou (both belonging to the species Rangifer tarandus L.) are among the most important large herbivores in Eurasia’s and North America’s arctic, alpine and boreal zones. In Sweden, the impact of reindeer grazing on arctic and alpine vegetation has recently been re-evaluated. In the 1990s, records of grazing-related vegetation degradation helped to form a widespread perception that some mountain areas were overgrazed. However, later analyses have shown no evidence of large-scale overutilisation of reindeer ranges in the Swedish mountains.

    The present-day consensus is that overgrazing has been temporary and local, and that it rarely has caused permanent damage, but it is imperative to examine the scientific support for these views. Moreover, the Swedish Parliament has adopted an environmental quality objective according to which it is essential to preserve ‘a mountain landscape characterised by grazing’. No details have been given on how this goal is to be interpreted, which is another reason why the significance of reindeer grazing for arctic/alpine vegetation needs to be assessed.

    This protocol presents the methodology that will be used in a systematic review of the impact of reindeer herbivory in arctic and alpine ecosystems. The focus will be on Fennoscandia, but data from other parts of the range of R. tarandus will be used when deemed appropriate.

    Methods: The review will be based on primary field studies that compare vegetation subject to different degrees of reindeer/caribou herbivory (including grazing and browsing as well as trampling). Such comparisons can be either temporal, spatial or both. The review will cover impacts of herbivory in arctic, subarctic, alpine and subalpine areas (including the forest-tundra ecotone) across the range of R. tarandus, but not in boreal forests. Relevant aspects of vegetation include cover (abundance), biomass, diversity (e.g. species richness), structure, composition (including functional groups) and productivity.

  • 279.
    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.

  • 280. Bernhard, E
    et al.
    Bunn, S E
    Hart, D D
    Malmqvist, Björn
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Muotka, T
    Naiman, R J
    Pringle, C
    Reuss, M
    van Wilgen, B
    Perspective: The challenge of ecologically sustainable water management2006In: Water Policy, Vol. 8, p. 475-479Article in journal (Refereed)
  • 281.
    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.

  • 282.
    Bernhardsson, Carolina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The POF protein in Drosophila binds the 4th chromosome to counteract heterochromatic influence2005Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 283.
    Bernhardsson, Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Geographic structure and adaptive population differentiation in herbivore defence genes in European aspen (Populus tremula L., Salicaceae)2012In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 21, no 9, p. 2197-2207Article in journal (Refereed)
    Abstract [en]

    When a phenotypic trait is subjected to spatially variable selection and local adaptation, the underlying genes controlling the trait are also expected to show strong patterns of genetic differentiation since alternative alleles are favored in different geographical locations. Here we study 71 SNPs from seven genes associated with inducible defense responses in a sample of P. tremula collected from across Sweden. Four of these genes (PPO2, TI2, TI4 and TI5) show substantial population differentiation and a PCA conducted on the defense SNPs divides the Swedish population into three distinct clusters. Several defense SNPs show latitudinal clines, although these were not robust to multiple testing. However, five SNPs (located within TI4 and TI5) show strong longitudinal clines that remain significant after multiple test correction. Genetic geographical variation, supporting local adaptation, has earlier been confirmed in genes involved in the photoperiod pathway in P. tremula, but this is, to our knowledge, one of the first times that geographic variation has been found in genes involved in plant defense against antagonists.

  • 284.
    Bernhardsson, Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ingvarsson, Pär K
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Molecular population genetics of elicitor-induced resistance genes in European aspen (Populus tremula L., Salicaceae)2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 9, p. e24867-Article in journal (Refereed)
    Abstract [en]

    Owing to their long life span and ecological dominance in many communities, forest trees are subject to attack from a diverse array of herbivores throughout their range, and have therefore developed a large number of both constitutive and inducible defenses. We used molecular population genetics methods to examine the evolution of eight genes in European aspen, Populus tremula, that are all associated with defensive responses against pests and/or pathogens, and have earlier been shown to become strongly up-regulated in poplars as a response to wounding and insect herbivory. Our results show that the majority of these defense genes show patterns of intraspecific polymorphism and site-frequency spectra that are consistent with a neutral model of evolution. However, two of the genes, both belonging to a small gene family of polyphenol oxidases, show multiple deviations from the neutral model. The gene PPO1 has a 600 bp region with a highly elevated K(A)/K(S) ratio and reduced synonymous diversity. PPO1 also shows a skew toward intermediate frequency variants in the SFS, and a pronounced fixation of non-synonymous mutations, all pointing to the fact that PPO1 has been subjected to recurrent selective sweeps. The gene PPO2 shows a marked excess of high frequency, derived variants and shows many of the same trends as PPO1 does, even though the pattern is less pronounced, suggesting that PPO2 might have been the target of a recent selective sweep. Our results supports data from both Populus and other species which have found that the the majority of defense-associated genes show few signs of selection but that a number of genes involved in mediating defense against herbivores show signs of adaptive evolution.

  • 285.
    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.

  • 286.
    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.

  • 287.
    Bernhardsson, Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Science, Umeå, Sweden; Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden.
    Vidalis, Amaryllis
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Population Genetics, Center of Life and Food Sciences Weihenstephan, Technische Universität München.
    Wang, Xi
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden.
    Scofield, Douglas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Uppsala Multidisciplinary Center for Advanced Computational Science; Department of Ecology and Genetics: Evolutionary Biology, Uppsala University, Uppsala, Sweden.
    Schiffthaler, Bastian
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Baison, John
    Street, Nathaniel
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Garcia-Gil, M. Rosario
    Ingvarsson, Pär K.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Science, Uppsala, Sweden.
    An Ultra-Dense Haploid Genetic Map for Evaluating the Highly Fragmented Genome Assembly of Norway Spruce (Picea abies)2019In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, Vol. 9, no 5, p. 1623-1632Article in journal (Refereed)
    Abstract [en]

    Norway spruce (Picea abies (L.) Karst.) is a conifer species of substanital economic and ecological importance. In common with most conifers, the P. abies genome is very large (similar to 20 Gbp) and contains a high fraction of repetitive DNA. The current P. abies genome assembly (v1.0) covers approximately 60% of the total genome size but is highly fragmented, consisting of >10 million scaffolds. The genome annotation contains 66,632 gene models that are at least partially validated (), however, the fragmented nature of the assembly means that there is currently little information available on how these genes are physically distributed over the 12 P. abies chromosomes. By creating an ultra-dense genetic linkage map, we anchored and ordered scaffolds into linkage groups, which complements the fine-scale information available in assembly contigs. Our ultra-dense haploid consensus genetic map consists of 21,056 markers derived from 14,336 scaffolds that contain 17,079 gene models (25.6% of the validated gene models) that we have anchored to the 12 linkage groups. We used data from three independent component maps, as well as comparisons with previously published Picea maps to evaluate the accuracy and marker ordering of the linkage groups. We demonstrate that approximately 3.8% of the anchored scaffolds and 1.6% of the gene models covered by the consensus map have likely assembly errors as they contain genetic markers that map to different regions within or between linkage groups. We further evaluate the utility of the genetic map for the conifer research community by using an independent data set of unrelated individuals to assess genome-wide variation in genetic diversity using the genomic regions anchored to linkage groups. The results show that our map is sufficiently dense to enable detailed evolutionary analyses across the P. abies genome.

  • 288.
    Bernulf, Jonna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Utvärdering av kalkbehandlad sulfidjord i Ersmark, Umeå2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Acid sulfate soils cover a relatively large area of Sweden, especially the coast along Gulf of Botnia. As these soils in contact with oxygen they start to oxidize and the sulphide is converted to sulphate, leading to a strong acidification. Today, these acid sulfate soils often end up on landfills, which is not a sustainable solution as it is both costly and there is a risk of leakage. A company based in Umea has developed a method for neutralizing acid sulphate soil with hope that it can be reused as plant soil, by adding sand and calcium as well as organic matter. At present, the process is only half-finished as the organic matter is not yet added. This study determined how the treatment worked so far, how much sulphide and neutralizing potential remains in the soil, as well as a number of metals and nutrients commonly and preferably found in plant soil. The treated sulfide soil was compared with a plant soil nearby, along with comparison of data from four different studies elsewhere on sulphide soil and results from samples taken before the sulphide soil was treated. Results show that pH value was higher than before the treatment and total sulfur content had decreased, but is still twice as high compared to the plant soil. Sulphide is still found in the soil, but also a fair amount of calcium carbonate, which shows that the reaction is not completed but that the soil has the potential to be further neutralized. Metal content in the treated sulfide soil is similar to the plant soil. The humus content is at 1.3 % and lower than recommended. Depending on area of use the humus content has to increase, more or less. Based on the results of the analyzes, the treated soil cannot be used as plant soil at the present time. This because of the organic matter that has not yet been added, and that there is still sulphide left in the soil.

  • 289. Bertos-Fortis, Mireia
    et al.
    Farnelid, Hanna M.
    Lindh, Markus V.
    Casini, Michele
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pinhassi, Jarone
    Legrand, Catherine
    Unscrambling Cyanobacteria Community Dynamics Related to Environmental Factors2016In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, article id 625Article in journal (Refereed)
    Abstract [en]

    Future climate scenarios in the Baltic Sea project an increase of cyanobacterial bloom frequency and duration, attributed to eutrophication and climate change. Some cyanobacteria can be toxic and their impact on ecosystem services is relevant for a sustainable sea. Yet, there is limited understanding of the mechanisms regulating cyanobacterial diversity and biogeography. Here we unravel successional patterns and changes in cyanobacterial community structure using a 2-year monthly time series during the productive season in a 100 km coastal-offshore transect using microscopy and high-throughput sequencing of 16S rRNA gene fragments. A total of 565 cyanobacterial OTUs were found, of which 231 where filamentous/colonial and 334 picocyanobacterial. Spatial differences in community structure between coastal and offshore waters were minor. An "epidemic population structure" (dominance of a single cluster) was found for Aphanizomenon/Dolichospermum within the filamentous/colonial cyanobacterial community. In summer, this cluster simultaneously occurred with opportunistic clusters/OTUs, e.g., Nodulana spumigena and Pseudanabaena. Picocyanobacteria, Synechococcus/Cyanobium, formed a consistent but highly diverse group. Overall, the potential drivers structuring summer cyanobacterial communities were temperature and salinity. However, the different responses to environmental factors among and within genera suggest high niche specificity for individual OTUs. The recruitment and occurrence of potentially toxic filamentous/colonial clusters was likely related to disturbance such as mixing events and short-term shifts in salinity, and not solely dependent on increasing temperature and nitrogen-limiting conditions. Nutrients did not explain further the changes in cyanobacterial community composition. Novel occurrence patterns were identified as a strong seasonal succession revealing a tight coupling between the emergence of opportunistic picocyanobacteria and the bloom of filamentous/colonial clusters. These findings highlight that if environmental conditions can partially explain the presence of opportunistic picocyanobacteria, microbial and trophic interactions with filamentous/colonial cyanobacteria should also be considered as potential shaping factors for single-celled communities. Regional climate change scenarios in the Baltic Sea predict environmental shifts leading to higher temperature and lower salinity; conditions identified here as favorable for opportunistic filamentous/colonial cyanobacteria. Altogether, the diversity and complexity of cyanobacterial communities reported here is far greater than previously known, emphasizing the importance of microbial interactions between filamentous and picocyanobacteria in the context of environmental disturbances.

  • 290. Beyens , L.
    et al.
    Ledeganck , P.
    Graae , B. J.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Nijs , I.
    Are soil biota buffered against climatic extremes? An experimental test on testate amoebae in arctic tundra (Qeqertarsuaq, West Greenland)2009In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 32, p. 453-462Article in journal (Refereed)
    Abstract [en]

    Climate warming is likely to have pronounced impacts on soil biota in arctic ecosystems. In a warmer climate, heatwaves are more frequent and intense, but it is unclear to what extent soil communities are buffered against this. We studied the effects of an artificially induced heatwave on the structure of testate amoebae communities in dry heath tundra in Qeqertarsuaq (Disko Island, West Greenland) during the summer of 2003. While the heatwave was severe enough to induce significant leaf mortality in the aboveground vegetation, overall testate amoebae abundance did not react to the difference in temperature. However, in the heated plots transient shifts in species populations occurred during the exposure, followed by increases in species richness weeks after the heatwave had ended. The most important taxa appearing after the heating period belonged to bacterivorous genera, in agreement with a transient peak in bacterial colony forming units, caused by the heatwave. Lobose testate amoebae resisted the heating and its associated desiccation better than their filose counterparts.

  • 291.
    Bidleman, Terry
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agosta, Kathleen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Brorström-Lundén, Eva
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hansson, Katarina
    Laudon, Hjalmar
    Newton, Seth
    Nygren, Olle
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ripszam, Matyas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiberg, Karin
    Atmospheric pathways of chlorinated pesticides and natural bromoanisoles in the northern Baltic Sea and its catchment2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. Suppl 3, no 44, p. 472-483Article in journal (Refereed)
    Abstract [en]

    Long-range atmospheric transport is a major pathway for delivering persistent organic pollutants to the oceans. Atmospheric deposition and volatilization of chlorinated pesticides and algae-produced bromoanisoles (BAs) were estimated for Bothnian Bay, northern Baltic Sea, based on air and water concentrations measured in 2011-2012. Pesticide fluxes were estimated using monthly air and water temperatures and assuming 4 months ice cover when no exchange occurs. Fluxes were predicted to increase by about 50 % under a 2069-2099 prediction scenario of higher temperatures and no ice. Total atmospheric loadings to Bothnian Bay and its catchment were derived from air-sea gas exchange and "bulk'' (precipitation ? dry particle) deposition, resulting in net gains of 53 and 46 kg year(-1) for endosulfans and hexachlorocyclohexanes, respectively, and net loss of 10 kg year(-1) for chlordanes. Volatilization of BAs releases bromine to the atmosphere and may limit their residence time in Bothnian Bay. This initial study provides baseline information for future investigations of climate change on biogeochemical cycles in the northern Baltic Sea and its catchment.

  • 292.
    Bidleman, Terry
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jantunen, Liisa M.
    Kucklick, John R.
    Kylin, Henrik
    Letcher, Robert J.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wong, Fiona
    A review of halogenated natural products in Arctic, Subarctic and Nordic ecosystems2019In: Emerging Contaminants, ISSN 2405-6650, E-ISSN 2405-6642, Vol. 5, p. 89-115Article in journal (Refereed)
    Abstract [en]

    Halogenated natural products (HNPs) are organic compounds containing bromine, chlorine, iodine, and rarely fluorine. HNPs comprise many classes of compounds, ranging in complexity from halocarbons to higher molecular weight compounds, which often contain oxygen and/or nitrogen atoms in addition to halogens. Many HNPs are biosynthesized by marine bacteria, macroalgae, phytoplankton, tunicates, corals, worms, sponges and other invertebrates. This paper reviews HNPs in Arctic, Subarctic and Nordic ecosystems and is based on sections of Chapter 2.16 in the Arctic Monitoring and Assessment Program (AMAP) assessment Chemicals of Emerging Arctic Concern (AMAP, 2017) which deal with the higher molecular weight HNPs. Material is updated and expanded to include more Nordic examples. Much of the chapter is devoted to “bromophenolic” HNPs, viz bromophenols (BPs) and transformation products bromoanisoles (BAs), hydroxylated and methoxylated bromodiphenyl ethers (OH-BDEs, MeO-BDEs) and polybrominated dibenzo-p-dioxins (PBDDs), since these HNPs are most frequently reported. Others discussed are 2,2′ -dimethoxy-3,3′ ,5,5′ -tetrabromobiphenyl (2,2′ -dimethoxy-BB80), polyhalogenated 1′- methyl-1,2′-bipyrroles (PMBPs), polyhalogenated 1,1′ -dimethyl-2,2′ -bipyrroles (PDBPs), polyhalogenated N-methylpyrroles (PMPs), polyhalogenated N-methylindoles (PMIs), bromoheptyl- and bromooctyl pyrroles, (1R,2S,4R,5R,1′E)-2-bromo-1-bromomethyl-1,4-dichloro-5-(2′-chloroethenyl)-5- methylcyclohexane (mixed halogenated compound MHC-1), polybrominated hexahydroxanthene derivatives (PBHDs) and polyhalogenated carbazoles (PHCs). Aspects of HNPs covered are physicochemical properties, sources and production, transformation processes, concentrations and trends in the physical environment and biota (marine and freshwater). Toxic properties of some HNPs and a discussion of how climate change might affect HNPs production and distribution are also included. The review concludes with a summary of research needs to better understand the role of HNPs as “chemicals of emerging Arctic concern”.

  • 293.
    Bidleman, Terry F.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agosta, Kathleen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Liljelind, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hegmans, Alyse
    Jantunen, Liisa M.
    Nygren, Olle
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Poole, Justen
    Ripszam, Matyas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sea-air exchange of bromoanisoles and methoxylated bromodiphenylethers in the Northern Baltic2016In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 112, no 1-2, p. 58-64Article in journal (Refereed)
    Abstract [en]

    Halogenated natural products in biota of the Baltic Sea include bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). We identified biogenic 6-MeO-BDE47 and 2'-MeO-BDE68 in Baltic water and air for the first time using gas chromatography - high resolution mass spectrometry. Partial pressures in air were related to temperature by: log p/Pa=m/T(K)+b. We determined Henry's law constants (HLCs) of 2,4-dibromoanisole (2,4-DiBA) and 2,4,6-tribromoanisole (2,4,6-TriBA) from 5 to 30°C and revised our assessment of gas exchange in the northern Baltic. The new water/air fugacity ratios (FRs) were lower, but still indicated net volatilization in May-June for 2,4-DiBA and May - September for 2,4,6-TriBA. The net flux (negative) of BAs from Bothnian Bay (38,000km2) between May - September was revised from -1319 to -532kg. FRs of MeO-BDEs were >1, suggesting volatilization, although this is tentative due to uncertainties in their HLCs and binding to dissolved organic carbon.

  • 294.
    Bidleman, Terry F.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agosta, Kathleen
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nygren, Olle
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ripszam, Matyas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Air-water exchange of brominated anisoles in the northern baltic sea2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 11, p. 6124-6132Article in journal (Refereed)
    Abstract [en]

    Bromophenols produced by marine algae undergo O-methylation to form bromoanisoles (BAs), which are exchanged between water and air. BAs were determined in surface water of the northern Baltic Sea (Gulf of Bothnia, consisting of Bothnian Bay and Bothnian Sea) during 2011-2013 and on a transect of the entire Baltic in September 2013. The abundance decreased in the following order: 2,4,6-tribromoanisole (2,4,6-TBA) > 2,4-dibromoanisole (2,4-DBA) ≫ 2,6-dibromoanisole (2,6-DBA). Concentrations of 2,4-DBA and 2,4,6-TBA in September were higher in the southern than in the northern Baltic and correlated well with the higher salinity in the south. This suggests south-to-north advection and dilution with fresh riverine water enroute, and/or lower production in the north. The abundance in air over the northern Baltic also decreased in the following order: 2,4,6-TBA > 2,4-DBA. However, 2,6-DBA was estimated as a lower limit due to breakthrough from polyurethane foam traps used for sampling. Water/air fugacity ratios ranged from 3.4 to 7.6 for 2,4-DBA and from 18 to 94 for 2,4,6-TBA, indicating net volatilization. Flux estimates using the two-film model suggested that volatilization removes 980-1360 kg of total BAs from Bothnian Bay (38000 km(2)) between May and September. The release of bromine from outgassing of BAs could be up to 4-6% of bromine fluxes from previously reported volatilization of bromomethanes and bromochloromethanes.

  • 295.
    Bidleman, Terry F.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Brugel, Sonia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Ericson, Lars
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Haglund, Peter
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kupryianchyk, Darya
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lau, Danny C. P.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Liljelind, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundin, Lisa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tysklind, Anders
    Tysklind, Mats
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bromoanisoles and Methoxylated Bromodiphenyl Ethers in Macroalgae from Nordic Coastal Regions2019In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, p. 881-892Article in journal (Refereed)
    Abstract [en]

    Marine macroalgae are used worldwide for human consumption, animal feed, cosmetics and agriculture. In addition to beneficial nutrients, macroalgae contain halogenated natural products (HNPs), some of which have toxic properties similar to those of well-known anthropogenic contaminants. Sixteen species of red, green and brown macroalgae were collected in 2017–2018 from coastal waters of the northern Baltic Sea, Sweden Atlantic and Norway Atlantic, and analyzed for bromoanisoles (BAs) and methoxylated bromodiphenyl ethers (MeO-BDEs). Target compounds were quantified by gas chromatography-low resolution mass spectrometry (GC-LRMS), with qualitative confirmation in selected species by GC-high resolution mass spectrometry (GC-HRMS). Quantified compounds were 2,4-diBA, 2,4,6-triBA, 2′-MeO-BDE68, 6-MeO-BDE47, and two tribromo-MeO-BDEs and one tetrabromo-MeO-BDE with unknown bromine substituent positions. Semiquantitative results for pentabromo-MeO-BDEs were also obtained for a few species by GC-HRMS. Three extraction methods were compared; soaking in methanol, soaking in methanol–dichloromethane, and blending with mixed solvents. Extraction yields of BAs did not differ significantly (p > 0.05) with the three methods and the two soaking methods gave equivalent yields of MeO-BDEs. Extraction efficiencies of MeO-BDEs were significantly lower using the blend method (p < 0.05). For reasons of simplicity and efficiency, the soaking methods are preferred. Concentrations varied by orders of magnitude among species: ∑2BAs 57 to 57 700 and ∑5MeO-BDEs < 10 to 476 pg g−1 wet weight (ww). Macroalgae standing out with ∑2BAs >1000 pg g−1 ww were Ascophyllum nodosumCeramium tenuicorneCeramium virgatumFucus radicansFucus serratusFucus vesiculosusSaccharina latissimaLaminaria digitata, and Acrosiphonia/Spongomorpha sp. Species A. nodosumC. tenuicorneChara virgataF. radicans and F. vesiculosus (Sweden Atlantic only) had ∑5MeO-BDEs >100 pg g−1ww. Profiles of individual compounds showed distinct differences among species and locations.

  • 296. 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.

  • 297. 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.

  • 298. 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.

  • 299. Biester, Harald
    et al.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Martinez-Cortizas, Antonio
    Engström, daniel R
    Modeling the Past Atmospheric Deposition of Mercury Using Natural Archives2007In: Environ. Sci. Technol., Vol. 41, no 14, p. 4851-4860Article in journal (Refereed)
    Abstract [en]

    Historical records of mercury (Hg) accumulation in lake sediments and peat bogs are often used to estimate human impacts on the biogeochemical cycling of mercury. On the basis of studies of lake sediments, modern atmospheric mercury deposition rates are estimated to have increased by a factor of 3-5 compared to background values: i.e., from about 3-3.5 g Hg m-2 yr-1 to 10-20 g Hg m-2 yr-1. However, recent studies of the historical mercury record in peat bogs suggest significantly higher increases (9-400 fold, median 40×), i.e., from about 0.6-1.7 g Hg m-2 yr -1 to 8-184 g Hg m-2 yr -1. We compared published data of background and modern mercury accumulation rates derived from globally distributed lake sediments and peat bogs and discuss reasons for the differences observed in absolute values and in the relative increase in the industrial age. Direct measurements of modern wet mercury deposition rates in remote areas are presently about 1-4 g m-2 yr -1, but were possibly as high as 20 g Hg m-2 yr -1 during the 1980s. These values are closer to the estimates of past deposition determined from lake sediments, which suggests that modern mercury accumulation rates derived from peat bogs tend to over-estimate deposition. We suggest that smearing of 210Pb in the uppermost peat sections contributes to an underestimation of peat ages, which is the most important reason for the overestimation of mercury accumulation rates in many bogs. The lower background mercury accumulation rates in peat as compared to lake sediments we believe is the result of nonquantitative retention and loss of mercury during peat diagenesis. As many processes controlling time-resolved mercury accumulation in mires are still poorly understood, lake sediments appear to be the more reliable archive for estimating historical mercury accumulation rates.

  • 300.
    Bigler , Christian
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Von Gunten, L.
    Lotter , A.F.
    Hausmann , S.
    Blass , A.
    Ohlendorf , C.
    Sturm , M.
    Quantifying human-induced eutrophication in Swiss mountain lakes since AD 1800 using diatoms2007In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 17, no 8, p. 1141-1154Article in journal (Refereed)
    Abstract [en]

    Sedimentary diatom assemblages from three lakes in the southeastern Swiss Alps were analysed at high temporal resolution since AD 1800. Altered land-use patterns, increasing population and exploitation through tourism are clearly reflected in annually laminated sediments of Lej da San Murezzan (Lake St Moritz) and Lej da Silvaplauna (Lake Silvaplana). Diatom assemblages originally dominated by Cyclotella taxa are replaced by taxa indicating higher total phosphorus (TP) concentrations, such as Asterionella formosa, Fragilaria crotonensis and Stephanodiscus parvus. In Lej da la Tscheppa, located well above the treeline in a catchment that was hardly exposed to human impact, Cyclotella comensis prevails throughout the entire sediment sequence. Quantitative estimates of past TP concentrations were inferred using a newly developed regional diatom-TP inference model based on 119 modern samples. In Lej da la Tscheppa diatoms imply stable, low TP concentrations (~10 µg/l), which can be considered as natural background concentration. Elevated TP levels are inferred for Lej da San Murezzan (max. 60 µg/l) since AD 1910 and for Lej da Silvaplauna (max. 40 µg/l) since AD 1950, corroborated by changes in sedimentary biogenic silica concentration and organic carbon content. Since ~AD 1970 improved waste water management led to a considerable reduction in TP loading in Lej da Silvaplauna and Lej da San Murezzan.

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