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  • 1. Brothers, Soren M
    et al.
    Hilt, Sabine
    Attermeyer, Katrin
    Grossart, Hans Peter
    Kosten, Sarian
    Lischke, Betty
    Mehner, Thomas
    Meyer, Nils
    Scharnweber, Kristin
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin.
    Köhler, Jan
    A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake2013In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 4, no 11, article id 137Article in journal (Refereed)
    Abstract [en]

    Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in- or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80% of the C input was permanently buried in the turbid lake sediments, compared to 40% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C.

  • 2.
    Little, Chelsea J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Eawag, CH-8600 Dubendorf, Switzerland..
    Jagerbrand, Annika K.
    Swedish Natl Rd & Transport Res Inst, VTI, S-10215 Stockholm, Sweden..
    Molau, Ulf
    Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    Alatalo, Juha M.
    Uppsala Univ, Dept Ecol & Genet, S-62167 Visby, Sweden..
    Community and species-specific responses to simulated global change in two subarctic-alpine plant communities2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 11, article id 227Article in journal (Refereed)
    Abstract [en]

    Long-term observational studies have detected greening and shrub encroachment in the subarctic attributed to current climate change, while global change simulations have showed that community composition and productivity may shift drastically in arctic, subarctic, and alpine tundra plant communities in the future. However, responses to global change can be highly species-and context-dependent. We examined community-level and species-specific responses to a six-year factorial temperature and nutrient (nitrogen and phosphorus) amendment experiment in two alpine plant communities in northern Sweden: a species-poor dwarf shrub heath, and a more species-rich meadow. We hypothesized that abundance responses to global change would be variable within commonly defined vascular plant functional groups (e.g., forbs, evergreen shrubs, deciduous shrubs) and that new species would appear in experimental plots over time due to the ameliorated growing conditions. We found that within most functional groups, species were highly individualistic with respect to the global change simulation, particularly within the forbs, whereas within the shrubs, responses were neutral to negative and widely variable in magnitude. In the heath community the response of the graminoid functional group was driven almost entirely by the grass Calamagrostis lapponica, which increased in abundance by an order of magnitude in the combined temperature and nutrient treatment. Furthermore, community context was important for species' responses to the simulations. Abundance of the pan-arctic species Carex bigelowii and Vaccinium vitis-idaea responded primarily to the temperature treatment in the meadow community whereas the nutrient treatment had stronger effects in the heath community. Over six growing seasons, more new species appeared in the experimental plots than in control plots in the meadow community, whereas in the heath community only one new species appeared. Our results from two closely situated but different plant communities show that functional groups do not predict individual species responses to simulated global change, and that these responses depend to a large extent on pre-existing physical conditions as well as biotic interactions such as competition and facilitation. It may be difficult to apply general trends of global change responses to specific local communities.

  • 3.
    Magnusson, M.
    et al.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden..
    Ecke, F.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden.;Sweden Univ Agr Sci, Dept Aquat Sci & Assessment, SE-75007 Uppsala, Sweden..
    Khalil, H.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden..
    Olsson, G.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden..
    Evander, M.
    Umea Univ, Dept Clin Microbiol, SE-90185 Umea, Sweden..
    Niklasson, Bo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology.
    Hornfeldt, B.
    Swedish Univ Agr Sci, Dept Wildlife Fish & Environm Studies, SE-90183 Umea, Sweden..
    Spatial and temporal variation of hantavirus bank vole infection in managed forest landscapes2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 9, article id 163Article in journal (Refereed)
    Abstract [en]

    Zoonoses are major contributors to emerging infectious diseases globally. Hemorrhagic fever with renal syndrome (HFRS) is a zoonosis caused by rodent-borne hantaviruses. In Europe, Puumala hantavirus (PUUV) carried and shed by the bank vole (Myodes glareolus), is the most common cause of HFRS. We explore the relationship of PUUV infection in bank voles, as measured by PUUV antibody detection, with habitat and landscape scale properties during two successive vole cycles in boreal Sweden. Our analysis revealed that PUUV infection in the population was not uniform between cycles and across different landscapes. The mean density index of PUUV antibody positive and negative bank voles were highest in old forest, second highest in cut-over forest (approx. 0-30 years old) and lowest on mires. Most importantly, old forest was the core habitat, where PUUV antibody positive bank voles were found through the low density phase and the transition between successive vole cycles. In spring, occurrence of antibody positive voles was negatively related to the proportion of cut-over forest in the surrounding landscape, suggesting that large scale human induced land-use change altered the occurrence of PUUV infection in voles which has not been shown before. Dependence of PUUV infection on habitat and landscape structure, and the variation in infection load within and between cycles are of importance for human risk assessment.

  • 4.
    Marklund, Maria H. K.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. School of Biological Sciences and The Environment Institute, University of Adelaide, North Terrace, SA 5005, Australia.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Habitat coupling mediates trophic cascades in an aquatic community2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 9Article in journal (Refereed)
    Abstract [en]

    Trophic cascades and other indirect effects can significantly mediate community interactions. Movement of energy between systems has been shown to be important for trophic cascades in food webs, where coupling between habitats can be important for food web stability and species evenness. To investigate the effects of habitat coupling on the stability and dynamics of chlorophyll a (used as a proxy for phytoplankton biomass), mediated by the abundance and composition of zooplankton and macroinvertebrates, we manipulated habitat use by the predator perch. We show a greater indirect effect of predation on phytoplankton abundance when no habitat coupling occurs, indicating a stronger predation effect and a decrease in zooplankton grazing pressure leading to an increase in phytoplankton biomass. Although we found a significant effect on chlorophyll a between the treatments, this effect was not evident in the abundance of prey resources of perch (zooplankton and macroinvertebrates). Other indirect effects, not measured in this study, such as compositional changes in prey groups, could potentially explain the lack of effect in prey resources. While there is a strong theoretical argument for the stabilizing effects of habitat coupling, empirical evidence is scarce. Our study offers tentative support for these theoretical predictions in a natural system.

  • 5. Peacock, Mike
    et al.
    Audet, Joachim
    Jordan, Sabine
    Smeds, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Wallin, Marcus B.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Greenhouse gas emissions from urban ponds are driven by nutrient status and hydrology2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 3, article id e02643Article in journal (Refereed)
    Abstract [en]

    Inland waters emit significant quantities of greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2) to the atmosphere. On a global scale, these emissions are large enough that their contribution to climate change is now recognized by the Intergovernmental Panel on Climate Change. Much of the past focus on GHG emissions from inland waters has focused on lakes, reservoirs, and rivers, and the role of small, artificial waterbodies such as ponds has been overlooked. To investigate the spatial variation in GHG fluxes from artificial ponds, we conducted a synoptic survey of forty urban ponds in a Swedish city. We measured dissolved concentrations of CH4 and CO2, and made complementary measurements of water chemistry. We found that CH4 concentrations were greatest in high‐nutrient ponds (measured as total phosphorus and total organic carbon). For CO2, higher concentrations were associated with silicon and calcium, suggesting that groundwater inputs lead to elevated CO2. When converted to diffusive GHG fluxes, mean emissions were 30.3 mg CH4·m−2·d−1 and 752 mg CO2·m−2·d−1. Although these fluxes are moderately high on an areal basis, upscaling them to all Swedish urban ponds gives an emission of 8336 t CO2eq/yr (±1689) equivalent to 0.1% of Swedish agricultural GHG emissions. Artificial ponds could be important GHG sources in countries with larger proportions of urban land.

  • 6.
    Pedrotti, E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Ingmar, T.
    Hytteborn, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Turunen, P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Granath, Gustaf
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    Fine-scale dynamics and community stability in boreal peatlands: revisiting a fen and a bog in Sweden after 50 years2014In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 5, no 10, p. 133-Article in journal (Refereed)
    Abstract [en]

    Multi-decadal studies of community and ecosystemdynamics are rare; however, this time frame is most relevant for assessing the impact of anthropogenic influences and climate change on ecosystems. For this reason, we investigated changes in vegetation and microtopography over 52 years in two contrasting mire ecosystems, one ombrotrophic (bog) and one minerotrophic (fen), representing different successional stages and contrasting hydrological settings. In both peatlands, floristic composition was recorded in the same permanent plots (n = 55-56, 0.25 m(2)) in both 1960 and 2012 and microtopography was mapped over a large area (ca. 2500 m(2)) that encompassed these same plots. We quantified and compared the community-level changes and internal spatial dynamics, tested associations between pH/microtopography and community/species change, and examined how the area and location of hummock microforms had changed over time. The bog exhibited little site level change in vegetation, where few species changed significantly in cover and plot frequency. However, detailed analyses revealed some large within-plot changes over time in the bog, illustrating that bogs can be highly dynamic systems at a fine scale. In contrast, the rich fen experienced a clear directional change; specifically, bryophyte abundance decreased by 70% and brown mosses were almost extinct. Although pH had decreased over time at the rich fen, this decrease at the plot-level was not associated with the decline of brown moss abundance. The microtopographic structure did not change substantially at the bog where similar to 70% was covered by lawn/hummocks; however, in the rich fen hummocks expanded (from 10% to 16% cover) and moved or expanded down slope. Our study suggests, that at the site-level, the bog ecosystem was more resistant to environmental changes over time compared to the rich fen, as evidenced by shifts in vegetation and microtopography. The contrasting scales of vegetation dynamics observed within a bog (i.e., within-plot changes vs. site-level) indicate that plant-environment feedbacks contribute to the peatland level stability. While in rich fens, internal feedbacks may be weaker and the ecosystem's vegetation and microtopographic structure are vulnerable to shifting hydrological fluxes.

  • 7.
    Richert, Inga
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Yager, Patricia L.
    Dinasquet, Julie
    Logares, Ramiro
    Riemann, Lasse
    Wendeberg, Annelie
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Scofield, Douglas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Summer comes to the Southern Ocean: How phytoplankton shape bacterioplankton communities far into the deep dark sea2019In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 3, article id e02641Article in journal (Refereed)
  • 8.
    Scharnweber, Kristin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Strandberg, Ursula
    Univ Eastern Finland, Dept Biol, Yliopistokatu 7,POB 111, Joensuu 80101, Finland; Ryerson Univ, Dept Biol & Chem, 350 Victoria St, Toronto, ON M5B 2K3, Canada.
    Marklund, Maria Helena Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Univ Adelaide, Inst Environm, Water Res Ctr, Dept Earth & Environm Sci, Adelaide, SA 5005, Australia.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Combining resource use assessment techniques reveals trade-offs in trophic specialization of polymorphic perch2016In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 7, no 8, article id e01387Article in journal (Refereed)
    Abstract [en]

    Trophic polymorphism has found to be common in many taxa and is a suggested mechanism of ecological speciation. To characterize the trophic linkages of specific morphotypes of organisms as well as a time-integrated niche use, several methods are available. In this study, we present data of multiple techniques to investigate the trophic divergence of Eurasian perch (Perca fluviatilis) that displays well-studied trophic polymorphism associated with littoral and pelagic habitats in lakes. We combined bulk stable isotope and fatty acid analyses on the muscle tissue of perch from three different lakes in Sweden with analyses of stomach content. By comparing the three methods, we aimed at providing a broad and highly resolved picture on the trophic divergence in freshwater fish. The degree in morphological divergence varied between perch caught in the three different lakes. Generally, perch caught in the pelagic zone were more streamlined compared to the ones caught in the littoral zone that had a deeper body, as shown by geometric morphometrics. The three diet assessment methods revealed different levels of information. Data on stomach content showed some preferences for specific dietary items in littoral and pelagic perch, but general trophic specialization could not be concluded due to the small sample size. Analyses of delta C-13 and delta N-15, however, confirmed these results as a long-term pattern connected to specific habitat use in two of the three lakes. Fatty acid signatures of perch reflected partly those of the prey items of the specific habitats. Although the proportions of the essential fatty acid 22:6n-3 were lower in littoral resources, the proportions in littoral fish were similar to the ones caught in the pelagic zone. We concluded that although a fundamental contribution from littoral resources exists in littoral phenotypes, a minor reliance on pelagic prey items is obviously needed to provide essential compounds. Thus, by combining the methods to characterize direct resource use (i.e., stomach analyses) with others that utilize trophic biomarkers (i.e., analyses of stable isotopes and fatty acids), we were able to illustrate the degree of variation in trophic divergence of perch but also shed some light on potential trade-offs that are related to resource specialization in freshwater fish.

  • 9. Villellas, Jesus
    et al.
    Berjano, Regina
    Terrab, Anass
    Garcia, Maria B.
    Divergence between phenotypic and genetic variation within populations of a common herb across Europe2014In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 5, no 5, p. 56-Article in journal (Refereed)
    Abstract [en]

    Analyzing the pattern and causes of phenotypic and genetic variation within and among populations might help to understand life history variability in plants, and to predict their responses to changing environmental conditions. Here we compare phenotypic variation and genetic diversity of the widespread herb Plantago coronopus across Europe, and evaluate their relationship with environmental and geographical factors. Genetic diversity was estimated in 18 populations from molecular markers with AFLP. Phenotypic variation was measured in a subset of 11 populations on six life history traits (plant size, plant growth, fecundity, seed mass, mucilage production and ratio between two functionally different seed morphs). To account for ecological and geographical correlates, we estimated variability in local temperature, precipitation and intraspecific competition, and accounted for the central vs. peripheral position of populations. Phenotypic variation and genetic diversity were not significantly correlated within populations throughout the species' range. Phenotypic variation was positively linked to precipitation variability, whereas genetic diversity was correlated with the position of populations, suggesting that both types of variation are shaped by different processes. Precipitation seems to have acted as a selective agent for variation within populations in most life history traits, whereas the species' post-glacial demographic history has likely reduced genetic diversity in northern peripheral populations with respect to central ones. The positive association between precipitation variability and phenotypic variation also suggests that plant populations may have higher adaptive potential in ecologically variable rather than stable environments. Our study offers an additional criterion when predicting the future performance of species under environmental changes.

  • 10.
    Östman, Örjan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Interspecific competition affects genetic structure but not genetic diversity of Daphnia magna2011In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 2, no 3, article id UNSP 34Article in journal (Refereed)
    Abstract [en]

    There are multiple forces structuring the genetic diversity of populations, and numerous studies have investigated the effects of the environment, space and stochastic processes. The effect of variation in interspecific interactions on genetic diversity and structure has rarely been assessed. Here, in a mescosm experiment, I studied clonal diversity and composition of the water-flea Daphnia magna in presence and absence of the sympatric interspecific competitors D. longispina and D. pulex. The results showed little effect of interspecific competition per se on clonal diversity of D. magna. Instead, the observed minimum population size was the most important factor for clonal diversity. But variation in interspecific competition had an effect on the clonal composition, and the presence of both interspecific competitors changed the clonal composition of D. magna. Thus, I conclude that interspecific competition had little effect on genetic diversity of D. magna but an evident effect on the genotypic composition, which may be important for the genetic diversity and structure on larger spatio-temporal scales.

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