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  • 401. Monard, Cecile
    et al.
    Gantner, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Stenlid, Jan
    Utilizing ITS1 and ITS2 to study environmental fungal diversity using pyrosequencing2013In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 84, no 1, p. 165-175Article in journal (Refereed)
    Abstract [en]

    The shorter reads generated by high-throughput sequencing has led to a focus on either the ITS1 or the ITS2 sublocus in fungal diversity analyses. Our study aimed to determine how making this choice would influence the datasets obtained and our vision of environmental fungal diversity. DNA was extracted from different environmental samples (water, sediments and soil) and the total internal transcribed spacer (ITS) locus was amplified. 454-sequencing was performed targeting both ITS1 and ITS2. No significant differences in the number of sequences, operational taxonomic units (OTUs) and in the dominant OTUs were detected but less diversity was observed in the ITS2 dataset. In the soil samples, differences in the fungal taxonomic identification were observed, with more Basidiomycota in the ITS1 dataset and more Ascomycota in the ITS2 dataset. Only one-third of the OTUs were detected in both datasets which could be due to (1) more short sequences removed in the ITS2 dataset, (2) different taxonomic affiliation depending on the sublocus used as BLASTn query and/or (3) selectivity in how a primer amplifies the true community. Although ITS1 and ITS2 datasets led to similar results at the fungal community level, for further in-depth diversity analysis this study suggests the analysis of both ITS regions, as they provided different information and were complementary.

  • 402.
    Mondav, Rhiannon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Development of an environmental functional gene microarray for soil microbial communities2010In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 76, no 21, p. 7161-7170Article in journal (Refereed)
    Abstract [en]

    Functional attributes of microbial communities are difficult to study, and most current techniques rely on DNA- and rRNA-based profiling of taxa and genes, including microarrays containing sequences of known microorganisms. To quantify gene expression in environmental samples in a culture-independent manner, we constructed an environmental functional gene microarray (E-FGA) consisting of 13,056 mRNA-enriched anonymous microbial clones from diverse microbial communities to profile microbial gene transcripts. A new normalization method using internal spot standards was devised to overcome spotting and hybridization bias, enabling direct comparisons of microarrays. To evaluate potential applications of this metatranscriptomic approach for studying microbes in environmental samples, we tested the E-FGA by profiling the microbial activity of agricultural soils with a low or high flux of N₂O. A total of 109 genes displayed expression that differed significantly between soils with low and high N₂O emissions. We conclude that mRNA-based approaches such as the one presented here may complement existing techniques for assessing functional attributes of microbial communities.

  • 403.
    Mondav, Rhiannon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia.
    McCalley, Carmody K
    Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA.
    Hodgkins, Suzanne B
    Department of Earth Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306-4320, USA.
    Frolking, Steve
    Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA.
    Saleska, Scott R
    Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
    Rich, Virginia I
    Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721, USA.
    Chanton, Jeff P
    Department of Earth Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306-4320, USA.
    Crill, Patrick M
    Department of Geology and Geochemistry, Stockholm University, Stockholm 10691, Sweden.
    Microbial network, phylogenetic diversity and community membership in the active layer across a permafrost thaw gradient2017In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, no 8, p. 3201-3218Article in journal (Refereed)
    Abstract [en]

    Biogenic production and release of methane (CH4 ) from thawing permafrost has the potential to be a strong source of radiative forcing. We investigated changes in the active layer microbial community of three sites representative of distinct permafrost thaw stages at a palsa mire in northern Sweden. The palsa site (intact permafrost and low radiative forcing signature) had a phylogenetically clustered community dominated by Acidobacteria and Proteobacteria. The bog (thawing permafrost and low radiative forcing signature) had lower alpha diversity and midrange phylogenetic clustering, characteristic of ecosystem disturbance affecting habitat filtering. Hydrogenotrophic methanogens and Acidobacteria dominated the bog shifting from palsa-like to fen-like at the waterline. The fen (no underlying permafrost, high radiative forcing signature) had the highest alpha, beta and phylogenetic diversity, was dominated by Proteobacteria and Euryarchaeota and was significantly enriched in methanogens. The Mire microbial network was modular with module cores consisting of clusters of Acidobacteria, Euryarchaeota or Xanthomonodales. Loss of underlying permafrost with associated hydrological shifts correlated to changes in microbial composition, alpha, beta and phylogenetic diversity associated with a higher radiative forcing signature. These results support the complex role of microbial interactions in mediating carbon budget changes and climate feedback in response to climate forcing.

  • 404.
    Mondav, Rhiannon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Woodcroft, Ben J.
    Kim, Eun-Hae
    McCalley, Carmody K.
    Hodgkins, Suzanne B.
    Crill, Patrick M.
    Chanton, Jeffrey
    Hurst, Gregory B.
    VerBerkmoes, Nathan C.
    Saleska, Scott R.
    Hugenholtz, Philip
    Rich, Virginia I.
    Tyson, Gene W.
    Discovery of a novel methanogen prevalent in thawing permafrost2014In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, article id 3212Article in journal (Refereed)
    Abstract [en]

    Thawing permafrost promotes microbial degradation of cryo-sequestered and new carbon leading to the biogenic production of methane, creating a positive feedback to climate change. Here we determine microbial community composition along a permafrost thaw gradient in northern Sweden. Partially thawed sites were frequently dominated by a single archaeal phylotype, Candidatus ‘Methanoflorens stordalenmirensis’ gen. nov. sp. nov., belonging to the uncultivated lineage ‘Rice Cluster II’ (Candidatus ‘Methanoflorentaceae’ fam. nov.). Metagenomic sequencing led to the recovery of its near-complete genome, revealing the genes necessary for hydrogenotrophic methanogenesis. These genes are highly expressed and methane carbon isotope data are consistent with hydrogenotrophic production of methane in the partially thawed site. In addition to permafrost wetlands, ‘Methanoflorentaceae’ are widespread in high methane-flux habitats suggesting that this lineage is both prevalent and a major contributor to global methane production. In thawing permafrost, Candidatus ‘M. stordalenmirensis’ appears to be a key mediator of methane-based positive feedback to climate warming.

  • 405.
    Moras, Simone
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Ayala, Ana I
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Historical modelling of changes in Lake Erken thermal conditions2019In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 23, no 12, p. 5001-5016Article in journal (Refereed)
    Abstract [en]

    Historical lake water temperature records are a valuable source of information to assess the influence of climate change on lake thermal structure. However, in most cases such records span a short period of time and/or are incomplete, providing a less credible assessment of change. In this study, the hydrodynamic GOTM (General Ocean Turbulence Model, a hydrodynamic model configured in lake mode) was used to reconstruct daily profiles of water temperature in Lake Erken (Sweden) over the period 1961-2017 using seven climatic parameters as forcing data: wind speed (WS), air temperature (Air T), atmospheric pressure (Air P), relative humidity (RH), cloud cover (CC), precipitation (DP), and shortwave radiation (SWR). The model was calibrated against observed water temperature data collected during the study interval, and the calibrated model revealed a good match between modelled and observed temperature (RMSE = 1.089 degrees C). From the long-term simulations of water temperature, this study focused on detecting possible trends in water temperature over the entire study interval 1961-2017 and in the sub-intervals 1961-1988 and 1989-2017, since an abrupt change in air temperature was detected in 1988. The analysis of the simulated temperature showed that epilimnetic temperature increased on average by 0.444 and 0.792 degrees C per decade in spring and autumn in the sub-interval 1989-2017 Summer epilimnetic temperature increased by 0.351 degrees C per decade over the entire interval 1961-2017. Hypolimnetic temperature increased significantly in spring over the entire interval 1961-2017, by 0.148 and by 0.816 degrees C per decade in autumn in the subinterval 1989-2016. Whole-lake temperature showed a significant increasing trend in the sub-interval 1989-2017 during spring (0.404 degrees C per decade) and autumn (0.789 degrees C per decade, interval 1989-2016), while a significant trend was detected in summer over the entire study interval 1961-2017 (0.239 degrees C per decade). Moreover, this study showed that that changes in the phenology of thermal stratification have occurred over the 57-year period of study. Since 1961, the stability of stratification (Schmidt stability) has increased by 5.365 J M-2 per decade. The duration of thermal stratification has increased by 7.297 d per decade, corresponding to an earlier onset of stratification of similar to 16 d and to a delay of stratification termination of similar to 26 d. The average thermocline depth during stratification became shallower by similar to 1.345 m, and surface-bottom temperature difference increased over time by 0.249 degrees C per decade. The creation of a daily time step water temperature dataset not only provided evidence of changes in Erken thermal structure over the last decades, but is also a valuable resource of information that can help in future research on the ecology of Lake Erken. The use of readily available meteorological data to reconstruct Lake Erken's past water temperature is shown to be a useful method to evaluate long-term changes in lake thermal structure, and it is a method that can be extended to other lakes.

  • 406. Moss, Brian D.
    et al.
    Hering, Daniel
    Green, Andy J.
    Adoud, Ahmed
    Becares, Eloy
    Beklioglu, Meryem
    Bennion, Helen
    Boix, Dani
    Brucet, Sandra
    Carvalho, Laurence
    Clement, Bernard
    Davidson, Tom
    Declerck, Steven
    Dobson, Michael
    van Donk, Ellen
    Dudley, Bernard
    Feuchtmayr, Heidrun
    Friberg, Nikolai
    Grenouillet, Gael
    Hillebrand, Helmut
    Hobaek, Anders
    Irvine, Kenneth
    Jeppesen, Erik
    Johnson, Richard
    Jones, Iwan
    Kernan, Martin
    Lauridsen, Torben L.
    Manca, Marina
    Meerhof, Mariana
    Olafsson, Jon
    Ormerod, Steve
    Papastergiadou, Eva
    Penning, W.Ellis
    Ptacnik, Robert
    Quintana, Xavier
    Sandin, Leonard
    Seferlis, Miltiadis
    Simpson, Gavin
    Trigal, Cristina
    Verdonschot, Piet
    Verschoor, Antonie M.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Climate change and the future of freshwater biodiversity in Europe: a primer for policy-makers2009In: Freshwater Reviews, ISSN 1755-084X, Vol. 2, no 2, p. 103-130Article in journal (Refereed)
    Abstract [en]

    Earth's climate is changing, and by the end of the 21st century in Europe, average temperatures are likely to have risen by at least 2 °C, and more likely 4 °C with associated effects on patterns of precipitation and the frequency of extreme weather events. Attention among policy-makers is divided about how to minimise the change, how to mitigate its effects, how to maintain the natural resources on which societies depend and how to adapt human societies to the changes. Natural systems are still seen, through a long tradition of conservation management that is largely species-based, as amenable to adaptive management, and biodiversity, mostly perceived as the richness of plant and vertebrate communities, often forms a focus for planning. We argue that prediction of particular species changes will be possible only in a minority of cases but that prediction of trends in general structure and operation of four generic freshwater ecosystems (erosive rivers, depositional floodplain rivers, shallow lakes and deep lakes) in three broad zones of Europe (Mediterranean, Central and Arctic-Boreal) is practicable. Maintenance and rehabilitation of ecological structures and operations will inevitably and incidentally embrace restoration of appropriate levels of species biodiversity. Using expert judgement, based on an extensive literature, we have outlined, primarily for lay policy makers, the pristine features of these systems, their states under current human impacts, how these states are likely to alter with a warming of 2 °C to 4 °C and what might be done to mitigate this. We have avoided technical terms in the interests of communication, and although we have included full referencing as in academic papers, we have eliminated degrees of detail that could confuse broad policy-making

     

  • 407.
    Mostovaya, Alina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Dissolved organic matter in lakes: Chemical diversity and continuum of reactivity2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dissolved organic matter (DOM) is the largest pool of organic carbon in aquatic systems and an important component of the global carbon cycle. Large amounts of DOM are decomposed within lakes, resulting in fluxes of CO2 and CH4 to the atmosphere. Therefore, there is a considerable interest in understanding the controls of DOM decomposition in freshwaters. There is evidence that in lakes intrinsic controls related to DOM composition are of primary importance, yet our knowledge about molecular drivers of DOM degradation is limited. This thesis addresses the link between chemical composition and reactivity of lake DOM by applying an experimental approach, molecular-level DOM characterization, and kinetic modeling of DOM decay.

    The first study shows that photoinduced transformations and partial removal of colored aromatic components of DOM have profound effects on DOM degradation kinetics, mediated by the shifts in the relative share of rapidly and slowly degrading DOM fractions. Two following studies estimate exponential decay coefficients for each individual molecular formula identified within bulk DOM. A continuous distribution of exponential decay coefficients is found within bulk DOM, which directly corroborates the central and previously empirically untested assumption behind the reactivity continuum model of DOM decay. Further, individual decay rates are evaluated in connection to specific molecular properties. On average, highly unsaturated and phenolic compounds appear to be more persistent than compounds with higher aromatic content (plant polyphenols and polycondensed aromatics), and aliphatic compounds demonstrate the highest decay rates. The reactivity of aromatics additionally increases with increasing nominal oxidation state of carbon. Molecular analysis further indicates that increasing reactivity of DOM after UV exposure is caused by disintegration of supramolecular complexes. Study IV shows that changes in relative proportion of terrestrial versus algal DOM control degradability of DOM through seasons. Under ice, when algal-derived DOM is maximally depleted, DOM degradation potential converges to similarly low levels, regardless of lake type (productive or humic), and bacterial respiration primarily relies on terrestrial carbon. This suggests a general pattern of baseline metabolism across boreal lakes. I conclude that DOM is a dynamic reactivity continuum and a tight link exists between DOM behavior and compositional properties.

    List of papers
    1. Effects of compositional changes on reactivity continuum and decomposition kinetics of lake dissolved organic matter
    Open this publication in new window or tab >>Effects of compositional changes on reactivity continuum and decomposition kinetics of lake dissolved organic matter
    Show others...
    2016 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, no 7, p. 1733-1746Article in journal (Refereed) Published
    Abstract [en]

    To address the link between the composition and decomposition of freshwater dissolved organic matter (DOM), we manipulated the DOM from three boreal lakes using preincubations with UV light to cleave large aromatic molecules and polyvinylpyrrolidone (PVP) to remove colored phenolic compounds. Subsequently, we monitored the dissolved organic carbon (DOC) loss over 4months of microbial degradation in the dark to assess how compositional changes in DOM affected different aspects of the reactivity continuum, including the distribution of the apparent decay coefficients. We observed profound effects on decomposition kinetics, with pronounced shifts in the relative share of rapidly and more slowly decomposing fractions of the DOM. In the UV-exposed treatment initial apparent decay coefficient k(0) was almost threefold higher than in the control. Significantly higher relative DOC loss in the UV-exposed treatment was sustained for 2months of incubation, after which decay coefficients converged with those in the control. The PVP removed compounds with absorbance and fluorescence characteristics representative of aromatic compounds, which led to slower decomposition, compared to that in the control. Our results demonstrate the reactivity continuum underlying the decomposition of DOM in freshwaters and highlight the importance of intrinsic properties of DOM in determining its decomposition kinetics.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-304303 (URN)10.1002/2016JG003359 (DOI)000382581900002 ()
    Funder
    Swedish Research Council, 2011-3475-88773-67Knut and Alice Wallenberg Foundation
    Available from: 2016-10-04 Created: 2016-10-04 Last updated: 2017-11-30Bibliographically approved
    2. The emergence of the reactivity continuum of organic matter from kinetics of a multitude of individual molecular constituents
    Open this publication in new window or tab >>The emergence of the reactivity continuum of organic matter from kinetics of a multitude of individual molecular constituents
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    dissolved organic matter, reactivity continuum model, FT-ICR-MS
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-316887 (URN)
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-03-08
    3. Molecular determinants of dissolved organic matter reactivity in lake water
    Open this publication in new window or tab >>Molecular determinants of dissolved organic matter reactivity in lake water
    2017 (English)In: Frontiers in Earth Science, ISSN 2296-6463, Vol. 5, article id 106Article in journal (Refereed) Published
    Abstract [en]

    Lakes in the boreal region have been recognized as the biogeochemical hotspots, yet many questions regarding the regulators of organic matter processing in these systems remain open. Molecular composition can be an important determinant of dissolved organic matter (DOM) fate in freshwater systems, but many aspects of this relationship remain unclear due to the complexity of DOM and its interactions in the natural environment. Here, we combine ultrahigh resolution mass spectrometry (FT-ICR-MS) with kinetic modeling of decay of \textgreater1,300 individual DOM molecular formulae identified by mass spectrometry, to evaluate the role of specific molecular characteristics in decomposition of lake water DOM. Our data is derived from a 4 months microbial decomposition experiment, carried out on water from three Swedish lakes, with the set-up including natural lake water, as well as the lake water pretreated with UV light. The relative decay rate of every molecular formula was estimated by fitting a single exponential model to the change in FT-ICR-MS signal intensities over decomposition time.We found a continuous range of exponential decay coefficients (kexp)within different groups of compounds and show that for highly unsaturated and phenolic compounds the distribution of kexp was shifted toward the lowest values. Contrary to this general trend, plant-derived polyphenols and polycondensed aromatics were on average more reactive than compounds with an intermediate aromaticity. The decay rate of aromatic compounds increased with increasing nominal oxidation state of carbon, and molecular mass in some cases showed an inverse relationship with kexp in the UV-manipulated treatment. Further, we observe an increase in formulae-specific kexp as a result of the UV pretreatment. General trends in reactivity identified among major compound groups emphasize the importance of the intrinsic controllers of lake water DOMdecay. However, we additionally indicate that each compound group contained a wide spectrum of reactivities, suggesting that high resolution is needed to further ascertain the complex reasons behind DOM reactivity in lake water.

    Place, publisher, year, edition, pages
    Frontiers Media S.A., 2017
    Keywords
    Dissolved organic matter, FT-ICR-MS, molecular composition, DOM degradation
    National Category
    Geology
    Identifiers
    urn:nbn:se:uu:diva-316890 (URN)10.3389/feart.2017.00106 (DOI)000419451700001 ()
    Funder
    Swedish Research Council, 2011-3475-88773-67Knut and Alice Wallenberg Foundation, KAW 2013.0091
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2019-06-05Bibliographically approved
    4. Seasonal variability in dissolved organic carbon degradation in boreal lakes: links to composition, sources, and baseline metabolism
    Open this publication in new window or tab >>Seasonal variability in dissolved organic carbon degradation in boreal lakes: links to composition, sources, and baseline metabolism
    (English)Manuscript (preprint) (Other academic)
    Keywords
    DOC, bacterioplankton, boreal lakes, seasonality, carbon source, baseline metabolism
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-316892 (URN)
    Available from: 2017-03-08 Created: 2017-03-08 Last updated: 2017-03-08
  • 408.
    Mostovaya, Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hawkes, Jeffrey A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Dittmar, Thorsten
    Carl von Ossietzky Univ Oldenburg, Inst Chem & Biol Marine Environm, Res Grp Marine Geochem MPI Bridging Grp, Oldenburg, Germany.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Molecular determinants of dissolved organic matter reactivity in lake water2017In: Frontiers in Earth Science, ISSN 2296-6463, Vol. 5, article id 106Article in journal (Refereed)
    Abstract [en]

    Lakes in the boreal region have been recognized as the biogeochemical hotspots, yet many questions regarding the regulators of organic matter processing in these systems remain open. Molecular composition can be an important determinant of dissolved organic matter (DOM) fate in freshwater systems, but many aspects of this relationship remain unclear due to the complexity of DOM and its interactions in the natural environment. Here, we combine ultrahigh resolution mass spectrometry (FT-ICR-MS) with kinetic modeling of decay of \textgreater1,300 individual DOM molecular formulae identified by mass spectrometry, to evaluate the role of specific molecular characteristics in decomposition of lake water DOM. Our data is derived from a 4 months microbial decomposition experiment, carried out on water from three Swedish lakes, with the set-up including natural lake water, as well as the lake water pretreated with UV light. The relative decay rate of every molecular formula was estimated by fitting a single exponential model to the change in FT-ICR-MS signal intensities over decomposition time.We found a continuous range of exponential decay coefficients (kexp)within different groups of compounds and show that for highly unsaturated and phenolic compounds the distribution of kexp was shifted toward the lowest values. Contrary to this general trend, plant-derived polyphenols and polycondensed aromatics were on average more reactive than compounds with an intermediate aromaticity. The decay rate of aromatic compounds increased with increasing nominal oxidation state of carbon, and molecular mass in some cases showed an inverse relationship with kexp in the UV-manipulated treatment. Further, we observe an increase in formulae-specific kexp as a result of the UV pretreatment. General trends in reactivity identified among major compound groups emphasize the importance of the intrinsic controllers of lake water DOMdecay. However, we additionally indicate that each compound group contained a wide spectrum of reactivities, suggesting that high resolution is needed to further ascertain the complex reasons behind DOM reactivity in lake water.

  • 409.
    Mostovaya, Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hawkes, Jeffrey A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Koehler, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Dittmar, Thorsten
    University of Oldenburg, Germany.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Emergence of the Reactivity Continuum of Organic Matter from Kinetics of a Multitude of Individual Molecular Constituents2017In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 51, no 20, p. 11571-11579Article in journal (Refereed)
    Abstract [en]

    The reactivity continuum (RC) model is a powerful statistical approach for describing the apparent kinetics of bulk organic matter (OM) decomposition. Here, we used ultrahigh resolution mass spectrometry data to evaluate the main premise of the RC model, namely that there is a continuous spectrum of reactivity within bulk OM, where each individual reactive type undergoes exponential decay. We performed a 120 day OM decomposition experiment on lake water, with an untreated control and a treatment preexposed to UV light, and described the loss of bulk dissolved organic carbon with RC modeling. The behavior of individual molecular formulas was described by fitting the single exponential model to the change in peak intensities over time. The range of the empirically derived apparent exponential decay coefficients (kexp) was indeed continuous. The character of the corresponding distribution, however, differed from the conceptual expectations, due to the effects of intrinsic averaging, overlaps in formula-specific loss and formation rates, and the limitation of the RC model to include apparently accumulating compounds in the analysis. Despite these limitations, both the RC model-simulated and empirical (mass spectrometry-derived) distributions of kexp captured the effects of preexposure to UV light. Overall, we present experimental evidence that the reactivity continuum within bulk OM emerges from a range of reactivity of numerous individual components. This constitutes direct empirical support for the major assumption behind the RC model of the natural OM decomposition.

  • 410.
    Mostovaya, Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hawkes, Jeffrey A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Koehler, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Dittmar, Thorsten
    Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Germany.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    The emergence of the reactivity continuum of organic matter from kinetics of a multitude of individual molecular constituentsManuscript (preprint) (Other academic)
  • 411.
    Mostovaya, Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Köhler, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Guillemette, François
    Florida State Univ, Dept Earth Ocean & Atmospher Sci, Tallahassee, FL 32306 USA.
    Brunberg, Anna-Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Tranvik, Lars J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Effects of compositional changes on reactivity continuum and decomposition kinetics of lake dissolved organic matter2016In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, no 7, p. 1733-1746Article in journal (Refereed)
    Abstract [en]

    To address the link between the composition and decomposition of freshwater dissolved organic matter (DOM), we manipulated the DOM from three boreal lakes using preincubations with UV light to cleave large aromatic molecules and polyvinylpyrrolidone (PVP) to remove colored phenolic compounds. Subsequently, we monitored the dissolved organic carbon (DOC) loss over 4months of microbial degradation in the dark to assess how compositional changes in DOM affected different aspects of the reactivity continuum, including the distribution of the apparent decay coefficients. We observed profound effects on decomposition kinetics, with pronounced shifts in the relative share of rapidly and more slowly decomposing fractions of the DOM. In the UV-exposed treatment initial apparent decay coefficient k(0) was almost threefold higher than in the control. Significantly higher relative DOC loss in the UV-exposed treatment was sustained for 2months of incubation, after which decay coefficients converged with those in the control. The PVP removed compounds with absorbance and fluorescence characteristics representative of aromatic compounds, which led to slower decomposition, compared to that in the control. Our results demonstrate the reactivity continuum underlying the decomposition of DOM in freshwaters and highlight the importance of intrinsic properties of DOM in determining its decomposition kinetics.

  • 412. Mukherjee, Shinjini
    et al.
    Juottonen, Heli
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Siivonen, Pauli
    Quesada, Cosme Lloret
    Tuom, Pirjo
    Pulkkine, Pertti
    Yrjälä, Kim
    Spatial patterns of microbial diversity and activity in an aged creosote-contaminated site2014In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 8, no 11, p. 2131-2142Article in journal (Refereed)
    Abstract [en]

    Restoration of polluted sites via in situ bioremediation relies heavily on the indigenous microbes and their activities. Spatial heterogeneity of microbial populations, contaminants and soil chemical parameters on such sites is a major hurdle in optimizing and implementing an appropriate bioremediation regime. We performed a grid-based sampling of an aged creosote-contaminated site followed by geostatistical modelling to illustrate the spatial patterns of microbial diversity and activity and to relate these patterns to the distribution of pollutants. Spatial distribution of bacterial groups unveiled patterns of niche differentiation regulated by patchy distribution of pollutants and an east-to-west pH gradient at the studied site. Proteobacteria clearly dominated in the hot spots of creosote pollution, whereas the abundance of Actinobacteria, TM7 and Planctomycetes was considerably reduced from the hot spots. The pH preferences of proteobacterial groups dominating in pollution could be recognized by examining the order and family-level responses. Acidobacterial classes came across as generalists in hydrocarbon pollution whose spatial distribution seemed to be regulated solely by the pH gradient. Although the community evenness decreased in the heavily polluted zones, basal respiration and fluorescein diacetate hydrolysis rates were higher, indicating the adaptation of specific indigenous microbial populations to hydrocarbon pollution. Combining the information from the kriged maps of microbial and soil chemistry data provided a comprehensive understanding of the long-term impacts of creosote pollution on the subsurface microbial communities. This study also highlighted the prospect of interpreting taxa-specific spatial patterns and applying them as indicators or proxies for monitoring polluted sites.

  • 413.
    Müller, Roger A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Futter, Martyn N.
    Swedish University of Agricultural Sciences (SLU).
    Sobek, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Nisell, J.
    Swedish University of Agricultural Sciences (SLU).
    Bishop, Kevin
    Swedish University of Agricultural Sciences (SLU).
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Water renewal along the aquatic continuum offsets cumulative retention by lakes: implications for the character of organic carbon in boreal lakes2013In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 75, no 4, p. 535-545Article in journal (Refereed)
    Abstract [en]

    The character of organic carbon (OC) in lake waters is strongly dependent on the time water has spent in the landscape as well as in the lake itself due to continuous biogeochemical OC transformation processes. A common view is that upstream lakes might prolong the water retention in the landscape, resulting in an altered OC character downstream. We calculated the number of lakes upstream for 24,742 Swedish lakes in seven river basins spanning from 56º to 68º N. For each of these lakes, we used a lake volume to discharge comparison on a landscape scale to account for upstream water retention by lakes (Tn tot). We found a surprisingly weak relationship between the number of lakes upstream and Tn tot. Accordingly, we found that the coloured fraction of organic carbon was not related to lake landscape position but significantly related to Tn tot when we analysed lake water chemical data from 1,559 lakes in the studied river basins. Thus, we conclude that water renewal along the aquatic continuum by lateral water inputs offsets cumulative retention by lakes. Based on our findings, we suggest integrating Tn tot in studies that address lake landscape position in the boreal zone to better understand variations in the character of organic carbon across lake districts.

  • 414.
    Müller, Roger A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Kothawala, Dolly N.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Podgrajsek, Eva
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Sahlée, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Köhler, Birgit
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Tranvik, Lars J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake2014In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 119, no 10, p. 1985-1998Article in journal (Refereed)
    Abstract [en]

    The short-term (hourly and daily) variation in chromophoric dissolved organic matter (CDOM) in lakes is largely unknown. We assessed the spectral characteristics of light absorption by CDOM in a eutrophic, humic shallow mixed lake of temperate Sweden at a high-frequency (30 min) interval and during a full growing season (May to October). Physical time series, such as solar radiation, temperature, wind, and partial pressures of carbon dioxide in water and air, were measured synchronously. We identified a strong radiation-induced summer CDOM loss (25 to 50%) that developed over 4 months, which was accompanied by strong changes in CDOM absorption spectral shape. The magnitude of the CDOM loss exceeded subhourly to daily variability by an order of magnitude. Applying Fourier analysis, we demonstrate that variation in CDOM remained largely unaffected by rapid shifts in weather, and no apparent response to in-lake dissolved organic carbon production was found. In autumn, CDOM occasionally showed variation at hourly to daily time scales, reaching a maximum daily coefficient of variation of 15%. We suggest that lake-internal effects on CDOM are quenched in humic lake waters by dominating effects associated with imported CDOM and solar exposure. Since humic lake waters belong to one of the most abundant lake types on Earth, our results have important implications for the understanding of global CDOM cycling.

  • 415.
    Müller, Roger André
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lake Dissolved Organic Matter Quantity and Quality: Variability across Temporal and Spatial Scales2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Surface waters receive large amounts of dissolved organic matter (DOM) via runoff from land. The DOM is rich in organic carbon that serves as an energy source for the aquatic biota. During uptake of this energy, aquatic organisms mineralize organic carbon. The resulting inorganic carbon is partially released to the atmosphere as carbon dioxide and methane that are greenhouse gases, and which are of concern for the ongoing global warming. The rate at which organic carbon is mineralized depends strongly on DOM quantity and quality that vary with respect to both time and space. In this thesis, DOM quantity and quality were addressed using spectroscopic methods that build on the absorptive and fluorescent properties of chromophoric DOM (CDOM). New techniques to measure CDOM absorption and fluorescence were applied and further developed that allowed us to present novel CDOM variability patterns. Addressing the lake-rich Scandinavian landscape, strong focus was placed on water retention by lakes that tightly links to lake DOM quantity and quality.

    An analysis of 24,742 lakes from seven large Swedish river systems indicated that the majority of lakes in Sweden exchange their water within one year. From headwaters to the Sea, summed lake volumes in the catchments of lakes were found to increase at rates comparable to discharge, which indicated effective water renewal along flow. A strong relationship between lake water retention and CDOM was apparent and further investigated based on samples from a lake district to a regional scale.

    Results from in situ high-frequency monitoring of CDOM absorption in a eutrophic humic lake showed intra-annual variability patterns known from oligotrophic lake systems. The patterns for CDOM absorption contrasted results obtained for synchronously measured partial pressures of carbon dioxide that showed diurnal signals. Measurements of CDOM fluorescence and DOC concentrations indicated lake-internal DOM production. A comparison of these results with results from addressing 560 lakes distributed across Sweden, showed that a well-calibrated CDOM fluorescence measurement captures signals from lake-internal DOM production. I conclude that improved CDOM fluorescence measurements are promising to address lake-internally produced DOM.

    List of papers
    1. Water renewal along the aquatic continuum offsets cumulative retention by lakes: implications for the character of organic carbon in boreal lakes
    Open this publication in new window or tab >>Water renewal along the aquatic continuum offsets cumulative retention by lakes: implications for the character of organic carbon in boreal lakes
    Show others...
    2013 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 75, no 4, p. 535-545Article in journal (Refereed) Published
    Abstract [en]

    The character of organic carbon (OC) in lake waters is strongly dependent on the time water has spent in the landscape as well as in the lake itself due to continuous biogeochemical OC transformation processes. A common view is that upstream lakes might prolong the water retention in the landscape, resulting in an altered OC character downstream. We calculated the number of lakes upstream for 24,742 Swedish lakes in seven river basins spanning from 56º to 68º N. For each of these lakes, we used a lake volume to discharge comparison on a landscape scale to account for upstream water retention by lakes (Tn tot). We found a surprisingly weak relationship between the number of lakes upstream and Tn tot. Accordingly, we found that the coloured fraction of organic carbon was not related to lake landscape position but significantly related to Tn tot when we analysed lake water chemical data from 1,559 lakes in the studied river basins. Thus, we conclude that water renewal along the aquatic continuum by lateral water inputs offsets cumulative retention by lakes. Based on our findings, we suggest integrating Tn tot in studies that address lake landscape position in the boreal zone to better understand variations in the character of organic carbon across lake districts.

    Keywords
    Lake, Landscape, Time, Organic carbon, Colour
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-208615 (URN)10.1007/s00027-013-0298-3 (DOI)000324577500006 ()
    Available from: 2013-10-04 Created: 2013-10-04 Last updated: 2018-05-21Bibliographically approved
    2. Controls of dissolved organic matter quality: evidence from a large-scale boreal lake survey
    Open this publication in new window or tab >>Controls of dissolved organic matter quality: evidence from a large-scale boreal lake survey
    Show others...
    2014 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 20, no 4, p. 1101-1114Article in journal (Refereed) Published
    Abstract [en]

    Inland waters transport large amounts of dissolved organic matter (DOM) from terrestrial environments to the oceans, but DOM also reacts en route, with substantial water column losses by mineralization and sedimentation. For DOM transformations along the aquatic continuum, lakes play an important role as they retain waters in the landscape allowing for more time to alter DOM. We know DOM losses are significant at the global scale, yet little is known about how the reactivity of DOM varies across landscapes and climates. DOM reactivity is inherently linked to its chemical composition. We used fluorescence spectroscopy to explore DOM quality from 560 lakes distributed across Sweden and encompassed a wide climatic gradient typical of the boreal ecozone. Six fluorescence components were identified using parallel factor analysis (PARAFAC). The intensity and relative abundance of these components were analyzed in relation to lake chemistry, catchment, and climate characteristics. Land cover, particularly the percentage of water in the catchment, was a primary factor explaining variability in PARAFAC components. Likewise, lake water retention time influenced DOM quality. These results suggest that processes occurring in upstream water bodies, in addition to the lake itself, have a dominant influence on DOM quality. PARAFAC components with longer emission wavelengths, or red-shifted components, were most reactive. In contrast, protein-like components were most persistent within lakes. Generalized characteristics of PARAFAC components based on emission wavelength could ease future interpretation of fluorescence spectra. An important secondary influence on DOM quality was mean annual temperature, which ranged between −6.2 and +7.5 °C. These results suggest that DOM reactivity depends more heavily on the duration of time taken to pass through the landscape, rather than temperature. Projected increases in runoff in the boreal region may force lake DOM toward a higher overall amount and proportion of humic-like substances.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-214177 (URN)10.1111/gcb.12488 (DOI)000332069500008 ()
    Available from: 2014-01-07 Created: 2014-01-07 Last updated: 2017-12-06Bibliographically approved
    3. Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake
    Open this publication in new window or tab >>Hourly, daily, and seasonal variability in the absorption spectra of chromophoric dissolved organic matter in a eutrophic, humic lake
    Show others...
    2014 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 119, no 10, p. 1985-1998Article in journal (Refereed) Published
    Abstract [en]

    The short-term (hourly and daily) variation in chromophoric dissolved organic matter (CDOM) in lakes is largely unknown. We assessed the spectral characteristics of light absorption by CDOM in a eutrophic, humic shallow mixed lake of temperate Sweden at a high-frequency (30 min) interval and during a full growing season (May to October). Physical time series, such as solar radiation, temperature, wind, and partial pressures of carbon dioxide in water and air, were measured synchronously. We identified a strong radiation-induced summer CDOM loss (25 to 50%) that developed over 4 months, which was accompanied by strong changes in CDOM absorption spectral shape. The magnitude of the CDOM loss exceeded subhourly to daily variability by an order of magnitude. Applying Fourier analysis, we demonstrate that variation in CDOM remained largely unaffected by rapid shifts in weather, and no apparent response to in-lake dissolved organic carbon production was found. In autumn, CDOM occasionally showed variation at hourly to daily time scales, reaching a maximum daily coefficient of variation of 15%. We suggest that lake-internal effects on CDOM are quenched in humic lake waters by dominating effects associated with imported CDOM and solar exposure. Since humic lake waters belong to one of the most abundant lake types on Earth, our results have important implications for the understanding of global CDOM cycling.

    Keywords
    absorption spectra, CDOM, DOC, high frequency, photochemical degradation, lakes
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-235286 (URN)10.1002/2014JG002719 (DOI)000345229700005 ()
    Funder
    Swedish Research CouncilFormas
    Available from: 2014-10-30 Created: 2014-10-30 Last updated: 2017-12-05Bibliographically approved
    4. Coherent color increases among 24 heterogeneous lakes in a poorly-buffered lake district
    Open this publication in new window or tab >>Coherent color increases among 24 heterogeneous lakes in a poorly-buffered lake district
    (English)Manuscript (preprint) (Other academic)
    National Category
    Environmental Sciences
    Identifiers
    urn:nbn:se:uu:diva-242334 (URN)
    Available from: 2015-01-24 Created: 2015-01-24 Last updated: 2016-05-24
  • 416.
    Müller, Roger
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Loew, Simon
    Predisposition and cause of the catastrophic landslides of August 2005 in Brienz (Switzerland)2009In: Swiss Journal of Geosciences, ISSN 1661-8726, E-ISSN 1661-8734, Vol. 102, no 2, p. 331-344Article in journal (Refereed)
    Abstract [en]

    Very intensive rainfall in August 2005 (>300 mm/3 days) triggered moderately deep (2-10 m) landslides of about 50’000 m(3) volume each in two mountain torrent catchments above the village of Brienz (Berner Oberland, Switzerland). These landslides - originating in Trachtbach and Glyssibach catchments-transformed into extremely rapid (> 5 m/s) debris flows, which caused significant damage in inhabited areas; two persons lost their lives and about twenty-five families became homeless. The Brienz case was the most damaging one among many landslide disasters occurring during those rainy days in the Swiss Alps. In this paper we study in detail the predisposition and causes of the 2005 landslides in the Brienz area, based on field mapping, analysis of high resolution images and digital terrain models, derived from LIDAR and infrared measurements taken before and after the event. The features of these landslides are compared with past and dormant landslides in the mid-slope portion of the mountain chain north of Brienz, which has been the source of many catastrophic mass wasting events during the last centuries. Detailed field mapping shows that highly weathered series of strongly overconsolidated Mesozoic marls (Diphyoides Limestone & Vitznau Marls of Valanginian age) and their residual soils form the primary source for the sliding materials. The rupture surfaces of the moderately deep landslides often run at the transition from saprolite to weathered bedrock, with a dip angle of about 40 degrees in the landslide depletion area. These landslides transform into debris flows, where debris slides into strongly convergent hillslopes or directly into headwater channels. Weathering of the Valanginian Marls is very fast, leading to high frequency landsliding in areas where this formation is exposed or close to ground surface. As not all landslides transform into fast and long runout debris flows, colluvium from older landslides forms a second important material that becomes mobilized by heavy rainstorms. The depleted volume remaining today in the source areas of the Trachtbach and Glyssibach landslides amounts to about 30’000 m(3) each. These soil masses will be mobilized in future rainstorms. Mitigation actions have been implemented to reduce their damage potential in the Brienz area.

  • 417.
    Müller, Roger
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Weyhenmeyer, Gesa
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Haaland, Ståle
    Riise, Gunnhild
    Coherent color increases among 24 heterogeneous lakes in a poorly-buffered lake districtManuscript (preprint) (Other academic)
  • 418.
    Münzner, Karla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Gonyostomum semen i svenska sjöar - förekomst och problem2019Report (Other academic)
    Abstract [sv]

    Gonyostomum semen är en skadlig alg som kan ge upphov till algblomningar mestadels i bruna sjöar, som är den vanligaste sjötypen i Sverige. Algen kan orsaka problem för samhället på grund av det slem som algen utsöndrar, vilket kan bl. a. leda till mindre attraktiva badplatser och igensättning av filter i vattenreningsverk. Vi presenterar en enkät angående svenska länsstyrelsers uppfattning om G. semen och de eventuella problem algblomningarna kan orsaka. 15 länsstyrelser svarade på enkäten, och i rapporten presenterar vi deras svar. De länsstyrelser som besvarat enkäten är medvetna om förekomst av G. semens inom länet, och antal G. semen-sjöar som länsstyrelserna anger är oftast jämförbara med data från andra övervakningsprogram. Bara två länsstyrelser rapporterar om problem i samband med G. semen, och ingen länsstyrelse bedömer G. semen som ett problem för vattenförvaltningen i nuläget. Problem med blomningar som nämnts i andra källor (t.ex. vetenskapliga artiklar och övervakningsrapporter) uppstår sällan enligt resutaten av vår enkät. G. semen kan dock bli relevant för länsstyrelsernas bedömning av vattenkvalitet, eftersom G. semens förekomst kan påverka statusklassificeringen av sjöar enligt EUs regelverk, med resultatet att G. semen-sjöar får sämre bedömning angående vattenstatus än de faktiskt har. Det finns i nuläget två möjligheter för att undvika detta: att använda specifika referensvärden för G. semen-sjöar för total biomassan och klorofyll-a enligt Havs- och vattenmyndighetens rekommendation, eller att inkludera trofiskt planktonindex (TPI) och antal cyanobakterier i procent istället för klorofyll-a koncentrationer som ett bedömningskriterium för G. semen-sjöar.

  • 419.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Blenckner, Thorsten
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Physical and chemical properties determine zebra mussel invasion success in lakes2011In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 669, no 1, p. 227-236Article in journal (Refereed)
    Abstract [en]

    To address the question whether the abundance of an invasive species can be explained by physical and chemical properties of the invaded ecosystems, we gathered density data of invasive zebra mussels and the physical and chemical data of ecosystems they invaded. We assembled published data from 55 European and 13 North American lakes and developed a model for zebra mussel density using a generalized additive model (GAM) approach. Our model revealed that the joint effect of surface area, total phosphorus and calcium concentrations explained 62% of the variation in Dreissena density. Our study indicates that large and less productive North American lakes can support larger local populations of zebra mussels. Our results suggest that the proliferation of an exotic species in an area can partially be explained by physical and chemical properties of the recipient environment.

  • 420. Naddafi, Rahmat
    et al.
    Goedkoop, Willem
    Grandin, Ulf
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Variation in tissue stoichiometry and condition index of zebra mussels in invaded Swedish lakes2012In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 14, no 10, p. 2117-2131Article in journal (Refereed)
    Abstract [en]

    We examined the spatial variation in carbon:nitrogen:phosphorus (C:N:P) stoichiometry and condition index of the zebra mussel (Dreissena polymorpha), non-indigenous species, in four Swedish lakes with different productivity. Within-lake variability was observed in tissue C:N molar ratios of Dreissena in all lakes and in tissue C:P ratio only in three lakes. Depth had no effect on tissue C:P and N:P ratios of Dreissena. A positive correlation was found between C:N:P stoichiometry of seston and elemental composition of zebra mussel in one of the lakes. Tissue C:N and N:P ratios were the main factors that related to zebra mussel condition index. Zebra mussel condition was positively related to tissue C:N ratio. Smaller Dreissena had higher C:N ratio than larger Dreissena in two of the four lakes. Zebra mussels in the lake with highest productivity had lower C:P and N:P ratios than zebra mussels in the lake with lowest productivity. Our study suggests that the zebra mussel may modify their phosphorus content in relation to lake trophic state, and therefore cope with stoichiometric constraints which may explain the invasion success of this and other related species.

  • 421.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Pettersson, Kurt
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Effect of zebra mussel , an exotic freshwater species, on seston stoichiometry2008In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Article in journal (Refereed)
  • 422.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Predation and physical environment structure the density and population size structure of zebra mussels2010In: Journal of The North American Benthological Society, ISSN 0887-3593, E-ISSN 1937-237X, Vol. 29, no 2, p. 444-453Article in journal (Refereed)
    Abstract [en]

    The zebra mussel (Dreissena polymorpha) provides one example of successful invaders in novel environments. However, little attention has been devoted to exploring the factors regulating zebra mussel density and population size structure at the local scale. We tested effects of physicochemical factors and fish predation on the density of zebra mussels at several sites and between years in a natural lake. Water depth and roach (Rutilus rutilus) density were the most important variables affecting local zebra mussel density. Substrate was also an important factor but affected Dreissena density only at the shallowest depth examined (2 m), which also supported a large population of the mussels. Mean shell length of Dreissena increased with water depth. Our results indicate that predation pressure, intraspecific competition, and food limitation might be responsible for variation in zebra mussel density and population size structure in space and time and that fish predation might have strong top-down effects on zebra mussel populations.

  • 423.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition2007In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, no 5, p. 823-842Article in journal (Refereed)
    Abstract [en]

    To investigate the impact of zebra mussels (Dreissena polymorpha) on phytoplankton community composition, temporal variability in selective feeding by the mussels was determined from April to November 2005 in a natural lake using Delayed Fluorescence (DF) excitation spectroscopy. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics; mussels showed a consistent preference for cryptophytes and avoidance of chlorophytes and cyanobacteria. Diatoms, chrysophytes and dinoflagellates responded differentially to zebra mussel grazing depending on their size. Analysis of excreted products of the zebra mussels revealed that in addition to chlorophytes and cyanobacteria, phytoplankton >50 μm and very small phytoplankton (≤7 μm) were largely expelled in pseudofaeces. The zebra mussel is a selective filter-feeder that alters its feeding behaviour in relation to phytoplankton composition to capture and ingest high quality phytoplankton, especially when phytoplankton occur in preferred size ranges. Flexibility of zebra mussel feeding behaviour and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences.

  • 424.
    Natchimuthu, Sivakiruthika
    et al.
    Linkoping Univ, Dept Themat Studies Environm Change, S-58183 Linkoping, Sweden.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Klemedtsson, Leif
    Univ Gothenburg, Dept Earth Sci, S-40530 Gothenburg, Sweden.
    Bastviken, David
    Linkoping Univ, Dept Themat Studies Environm Change, S-58183 Linkoping, Sweden.
    Spatio-temporal patterns of stream methane and carbon dioxide emissions in a hemiboreal catchment in Southwest Sweden2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 39729Article in journal (Refereed)
    Abstract [en]

    Global stream and river greenhouse gas emissions seem to be as large as the oceanic C uptake. However, stream and river emissions are uncertain until both spatial and temporal variability have been quantified. Here we investigated in detail the stream CH4 and CO2emissions within a hemiboreal catchment in Southwest Sweden primarily covered by coniferous forest. Gas transfer velocities (k600), CH4 and CO2 concentrations were measured with multiple methods. Our data supported modelling approaches accounting for various stream slopes, water velocities and discharge. The results revealed large but partially predictable spatio-temporal variabilities in k600, dissolved gas concentrations, and emissions. The variability in CO2 emission was best explained by the variability in k, while dissolved CH4concentrations explained most of the variability in CH4 emission, having implications for future measurements. There were disproportionately large emissions from high slope stream reaches including waterfalls, and from high discharge events. In the catchment, stream reaches with low slope and time periods of moderate discharge dominated (90% of area and 69% of time). Measurements in these stream areas and time periods only accounted for <36% of the total estimated emissions. Hence, not accounting for local or episodic high emissions can lead to substantially underestimated emissions.

  • 425.
    Natt, Michael
    et al.
    James Cook Univ, ARC Ctr Excellence Coral Reef Studies, Townsville, Qld, Australia.;James Cook Univ, Dept Marine Biol & Aquaculture, Townsville, Qld, Australia..
    Lönnstedt, Oona
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    McCormick, Mark I.
    James Cook Univ, ARC Ctr Excellence Coral Reef Studies, Townsville, Qld, Australia.;James Cook Univ, Dept Marine Biol & Aquaculture, Townsville, Qld, Australia..
    Coral reef fish predator maintains olfactory acuity in degraded coral habitats2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 6, article id e0179300Article in journal (Refereed)
    Abstract [en]

    Coral reefs around the world are rapidly degrading due to a range of environmental stress ors. Habitat degradation modifies the sensory landscape within which predator-prey interactions occur, with implications for olfactory-mediated behaviours. Predator na ve settlement stage damselfish rely on conspecific damage-released odours (i.e., alarm odours) to inform risk assessments. Yet, species such as the Ambon damselfish, Pomacentrus amboinensis, become unable to respond appropriately to these cues when living in dead-degraded coral habitats, leading to increased mortality through loss of vigilance. Reef fish predators also rely on odours from damaged prey to locate, assess prey quality and engage in prey-stealing, but it is unknown whether their responses are also modified by the change to dead degraded coral habitats. Implications for prey clearly depend on how their predatory counterparts are affected, therefore the present study tested whether olfactory-mediated foraging responses in the dusky dottyback, Pseudochromis fuscus, a common predator of P. amboinensis, were similarly affected by coral degradation. A y-maze was used to measure the ability of Ps. fuscus to detect and move towards odours, against different background water sources. Ps. fuscus were exposed to damage-released odours from juvenile P. amboinensis, or a control cue of seawater, against a background of seawater treated with either healthy or dead-degraded hard coral. Predators exhibited an increased time allocation to the chambers of y-mazes injected with damage-released odours, with comparable levels of response in both healthy and dead-degraded coral treated waters. In control treatments, where damage-released odours were replaced with a control seawater cue, fish showed no increased preference for either chamber of the y-maze. Our results suggest that olfactory-mediated foraging behaviours may persist in Ps. fuscus within dead-degraded coral habitats. Ps. fuscus may consequently gain a sensory advantage over P. amboinensis, potentially altering the outcome of predator-prey interactions.

  • 426. Newton, Ryan J.
    et al.
    Jones, Stuart E.
    Eiler, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    McMahon, Katherine D.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    A Guide to the Natural History of Freshwater Lake Bacteria2011In: Microbiology and molecular biology reviews, ISSN 1092-2172, E-ISSN 1098-5557, Vol. 75, no 1, p. 14-49Article, review/survey (Refereed)
    Abstract [en]

    Freshwater bacteria are at the hub of biogeochemical cycles and control water quality in lakes. Despite this, little is known about the identity and ecology of functionally significant lake bacteria. Molecular studies have identified many abundant lake bacteria, but there is a large variation in the taxonomic or phylogenetic breadths among the methods used for this exploration. Because of this, an inconsistent and overlapping naming structure has developed for freshwater bacteria, creating a significant obstacle to identifying coherent ecological traits among these groups. A discourse that unites the field is sorely needed. Here we present a new freshwater lake phylogeny constructed from all published 16S rRNA gene sequences from lake epilimnia and propose a unifying vocabulary to discuss freshwater taxa. With this new vocabulary in place, we review the current information on the ecology, ecophysiology, and distribution of lake bacteria and highlight newly identified phylotypes. In the second part of our review, we conduct meta-analyses on the compiled data, identifying distribution patterns for bacterial phylotypes among biomes and across environmental gradients in lakes. We conclude by emphasizing the role that this review can play in providing a coherent framework for future studies.

  • 427.
    Niklasdotter Scherrer, Kim Josefin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Univ Ctr Svalbard, Dept Arctic Biol, Longyearbyen, Norway; Univ Autonoma Barcelona, Inst Ciencia & Tecnol Ambientals, Cerdanyola Del Valles, Spain.
    Kortsch, S.
    UiT Arctic Univ Norway, Fac Biosci Fisheries & Econ, Tromsø, Norway.
    Varpe, Ø.
    Univ Ctr Svalbard, Dept Arctic Biol, Longyearbyen, Norway; Akvaplan Niva, Fram Ctr, Tromsø, Norway.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Gulliksen, B.
    UiT Arctic Univ Norway, Fac Biosci Fisheries & Econ, Tromsø, Norway.
    Primicerio, R.
    UiT Arctic Univ Norway, Fac Biosci Fisheries & Econ, Tromsø, Norway.
    Mechanistic model identifies increasing light availability due to sea ice reductions as cause for increasing macroalgae cover in the Arctic2019In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, no 1, p. 330-341Article in journal (Refereed)
    Abstract [en]

    In the Arctic, rising seawater temperatures and increasing underwater light caused by reductions in sea ice cover are expected to change the structure of arctic marine communities. Substantial, sometimes sudden, increases in macroalgal productivity and biomass have already been observed in arctic rocky bottom communities. These macroalgal responses have been attributed to increasing temperature and light, but the relative importance of the suggested drivers of change has not yet been assessed. In this study, we used a mechanistic competition model to unravel the effects of temperature and light on benthic community structure and algae dominance, focusing on key algae species: red calcareous algae and macroalgal fronds. We find that light is the primary driver of increases in macroalgal coverage, whereas increased seawater temperature plays a secondary role. Shifts leading to macroalgae dominated communities may be mediated by competitive interactions, and are likely due to three light-related processes: earlier sea ice break-out at high latitudes can result in an exponential increase in the cumulative amount of light that enters the water column during a year; threshold effect in light requirements for algal growth; and light requirements of calcareous algae being substantially lower than those of macroalgae. With continued warming, our modeling results suggest that reduced sea ice coverage and increased light availability will favor dominance of macroalgae, which due to their key ecological role are expected to alter the structure and functioning of arctic rocky bottom ecosystems.

  • 428.
    Nikolausz, Marcell
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Kappelmeyer, Uwe
    Székely, Anna
    Rusznyák, Anna
    Márialigeti, Károly
    Kästner, Matthias
    Diurnal redox fluctuation and microbial activity in the rhizosphere of wetland plants2008In: European journal of soil biology, ISSN 1164-5563, E-ISSN 1778-3615, Vol. 44, no 3, p. 324-333Article in journal (Refereed)
    Abstract [en]

    Wetland plants release oxygen through the aerenchyma system to the roots, providing oxic habitats in the rhizosphere. The consumption of the oxygen during the night establishes a diurnal fluctuation of the redox conditions (-320 mV to +300 mV) that explains the coexistence of aerobic and anaerobic microorganisms in the rhizosphere. The redox fluctuation and its effect on the activity of rhizosphere microorganisms were investigated by RNA-based fingerprinting techniques in a laboratory scale reactor planted with Juncus effusus. The denaturing gradient gel electrophoresis (DGGE) patterns of 16S rRNA obtained with "universal" primers were very similar regardless of the time of sampling, indicating that the overall ribosome level of the predominantly active members did not change significantly. The amoA transcript DGGE patterns showed moderate diurnal dynamics with specific bands observed either in day or night samples. However, the majority of amoA genes were continuously expressed, indicating that the activity of functional genes may only partly be a measure sensitive enough for tracing the physiological activity on a short time scale. The results indicate that loose regulation of functional genes can be the main strategy for accommodation to fluctuating environmental conditions. The spatial separation of microbial activities as a result of diurnal fluctuating oxygen availability probably contributes to niche differentiation in the rhizosphere but this is difficult to track it at transcriptome level. © 2008 Elsevier Masson SAS. All rights reserved.

  • 429. Nilsson, A.P.
    et al.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Finding food and staying alive2018In: Biology and ecology of pike / [ed] Christian Skov; P. Anders Nilsson, Boca Raton, FL: CRC Press, 2018, p. 9-31Chapter in book (Other academic)
    Abstract [en]

    This book sets out to bridge the order scales among pike researchers, populations, communities, management, and fisheries. It emphasizes the progress of pike research during the last two decades, during which the order-bridging approach emerged. This framework underpins the text and the message, to convey its importance to pike research and to fish research in general. In addition, a considerable part of the book is devoted to management implications and highlights aspects of human dimensions in recreational fisheries.

  • 430.
    Nilsson, Louise K. J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Microbiology. Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Sharma, Anil
    International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
    Bhatnagar, Raj K.
    International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Terenius, Olle
    Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Presence of Aedes and Anopheles mosquito larvae is correlated to bacteria found in domestic water-storage containers2018In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 94, no 6, article id fiy058Article in journal (Refereed)
    Abstract [en]

    Water-storage containers are common in households where access to water is scarce and often act as breeding sites for vector mosquitoes. Bacteria in these containers may be important for attracting or repelling ovipositing mosquitoes. We hypothesized that bacterial community composition in water-storage containers would represent either inhibitory or suitable environmental conditions for mosquito larvae. To investigate this, we characterized the bacterial community composition in water-storage containers and correlated these communities to Aedes and Anopheles larval densities. Water samples were collected over two years from 13 containers in an Indian village and analyzed by high throughput 16S rRNA gene amplicon sequencing. Comparisons of bacterial community composition between water with and without mosquito larvae showed that Xanthomonadaceae, Comamonadaceae and Burkholderiaceae were more common (P < 0.05) in absence of larvae, while Lachnospiraceae, Synechococcaceae, Alcaligenaceae and Cryomorphaceae were more common (P < 0.05) in presence of larvae. Indicator analysis identified operational taxonomic units designated as CL500–29 marine group (Acidimicrobiaceae) and FukuN101 (Microbacteriaceae) for absence and presence of larvae, respectively. These results contribute to the understanding of which bacteria, directly or indirectly, can be linked to absence or presence of mosquitoes around households and set the basis for potential measures to be taken against these vector mosquitoes.

  • 431.
    Nissling, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Larsson, R
    Population specific sperm production in flounder Platichtys flesus - adaptation to salinity at spawning2018In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649Article in journal (Refereed)
  • 432.
    Nissling, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Larsson, Roger
    SLU Aqua, Inst Marine Res, Lysekil, Sweden.
    Population specific sperm production in European flounder Platichthys flesus: Adaptation to salinity at spawning2018In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 93, no 1, p. 47-52Article in journal (Refereed)
    Abstract [en]

    Marine teleosts inhabiting the brackish Baltic Sea have adapted to the less saline water with activation of spermatozoa at low salinity hypo-osmotic conditions but with shorter longevity and lower swimming speed that affect the fertilization capacity. Aiming to elucidate if the fertilization capacity may be maintained by increasing the number of spermatozoa produced, testis size for the euryhaline flounder Platichthys flesus with external fertilization was assessed along a salinity gradient; with spawning at a salinity of c. 7, 10-18 and 30-35. Fulton's condition factor K = 0.881 +/- 0.085 (mean +/- S.D.), 0.833 +/- 0.096 and 0.851 +/- 0.086, for fish spawning at salinities of c. 7, 10-18 and 30-35, respectively, with no difference between areas, i.e. analysed fish were in similar nutritional condition. A general linear model, with testes dry mass as the dependent variable and somatic mass as covariate resulted in a significant difference between areas-populations with larger testes for P. flesus spawning at a salinity of c. 7 but no difference between fish spawning at a salinity of 10-18 and 30-35. The result suggests that adaptation by increasing the number of spermatozoa produced may be a key mechanism for marine teleosts spawning in areas with low salinities to sustain the fertilization capacity as shown here for the euryhaline P. flesus.

  • 433.
    Nissling, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Nyberg, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Petereit, Christoph
    GEOMAR Helmholtz Ctr Ocean Res Kiel, D-24105 Kiel, Germany..
    Egg buoyancy of flounder, Platichthys flesus, in the Baltic Sea-adaptation to salinity and implications for egg survival2017In: Fisheries Research, ISSN 0165-7836, E-ISSN 1872-6763, Vol. 191, p. 179-189Article in journal (Refereed)
    Abstract [en]

    Vertical distribution of eggs as determined by the egg buoyancy, i.e. the difference in specific gravity between the egg and the ambient water, have profound implications for the reproductive success and hence recruitment in fish. Here variability in egg specific gravity of flounder, Platichthys flesus, was studied along a salinity gradient and by comparing two reproductive strategies, spawning pelagic or demersal eggs. Egg characteristics of 209 egg batches (covering ICES subdivisions (SD) 22-29 in the brackish water Baltic Sea) was used to reveal the significance of egg diameter and egg dry weight for egg specific gravity (ESG), subpopulations, and egg survival probabilities of pelagic eggs following a major saline water inflow event. As an adaptation to salinity, ESG (at 7 degrees C) differed (p <0.001) between areas; three subpopulations of flounder with pelagic eggs: 1.0152 +/- 0.0021 (mean +/- sd)g cm(-3) in SD 22, 1.0116 +/- 0.0013 g cm(-3) in SD 24 and 25, and 1.0096 +/- 0.0007 g cm(-3) in SD 26 and 28, contrasting to flounder with demersal eggs, 1.0161 +/- 0.0008 g cm(-3). Egg diameter differed (p <0.001) between subpopulations; from 1.08 +/- 0.06 mm (SD 22) to 1.26 +/- 0.06 mm (SD 26 and 28) for pelagic eggs and 1.02 +/- 0.04 mm for demersal eggs, whereas egg dry weight was similar; 37.9 +/- 5.0 mu g (SD 22) and 37.2 +/- 3.9 mu g (SD 28) for pelagic, and 36.5 +/- 6.5 mu g for demersal eggs. Both egg diameter and egg dry weight were identified as explanatory variables, explaining 87% of the variation in ESG. ESG changed during ontogeny; a slight decrease initially but an increase prior to hatching. Egg survival probabilities judged by combining ESG and hydrographic data suggested higher egg survival in SD 25 (26 vs 100%) and SD 26 (32 vs 99%) but not in SD 28 (0 and 3%) after the inflow event, i.e. highly fluctuating habitat suitability. The results confirm the significance of ESG for egg survival and show that variability in ESG as and adaptation to salinity is determined mainly by water content manifested as differences in egg diameter; increase in diameter with decreasing salinity for pelagic eggs, and decreased diameter resulting in demersal eggs.

  • 434.
    Nissling, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Thorsen, A.
    Inst Marine Res, POB 1870, N-5817 Bergen, Norway..
    da Silva, F. F. G.
    Inst Marine Res, POB 1870, N-5817 Bergen, Norway.;Tech Univ Denmark, Natl Inst Aquat Resources, Alle 1, DK-2920 Charlottenlund, Denmark..
    Fecundity regulation by atresia in turbot Scophthalmus maximus in the Baltic Sea2016In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 88, no 4, p. 1301-1320Article in journal (Refereed)
    Abstract [en]

    Down-regulation of fecundity through oocyte resorption was assessed in Baltic Sea turbot Scophthalmus maximus at three locations in the period from late vitellogenesis in April to spawning during June to July. The mean +/- s.d. total length of the sampled fish was 327 +/- 31cm and mean +/- s.d. age was 62 +/- 15years. Measurements of atresia were performed using the profile method' with the intensity of atresia adjusted according to the dissector method' (106% adjustment; coefficient of determination was 0675 between methods). Both prevalence (portion of fish with atresia) and intensity (calculated as the average proportion of atretic cells in fish displaying atresia) of atresia were low in prespawning fish, but high from onset of spawning throughout the spawning period. Atretic oocytes categorized as in early alpha and in late alpha state occurred irrespective of maturity stage from late prespawning individuals up to late spawning fish, showing that oocytes may become atretic throughout the spawning period. Observed prevalence of atresia throughout the spawning period was almost 40% with an intensity of c. 20%. This indicates extensive down-regulation, i.e. considerably lower realized (number of eggs spawned) v. potential fecundity (number of developing oocytes), suggesting significant variability in reproductive potential. The extent of fecundity regulation in relation to fish condition (Fulton's condition factor) is discussed, suggesting an association between levels of atresia and fish condition.

  • 435.
    Nissling, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Thorsen, Anders
    da Silva, Filipa F.G
    Fecundity regulation in relation to habitat utilisation of two sympatric flounder (Platichtys flesus) populations in the brackish water Baltic Sea2015In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 95, p. 188-195Article in journal (Refereed)
    Abstract [en]

    Two populations of flounder (Platichtys flesus) with different life history traits inhabit the brackish water Baltic Sea. Both types share feeding areas in coastal waters during summer-autumn but utilise different habitats for spawning in spring, namely offshore spawning with pelagic eggs and coastal spawning with demersal eggs respectively. Fecundity regulation by atresia was assessed as prevalence (portion of fish with atresia) and intensity (calculated as the average intensity of atresia in these fish) during the reproductive cycle following start of gonad development in the autumn up to spawning in spring, and evaluated in relation to fish condition (Fulton's condition factor reflecting energy reserves of the fish) and feeding incidence of the respective population. Peaking in winter (December–February), fecundity regulation was significantly higher for coastal spawning flounder than for flounder spawning offshore. For coastal spawners, the prevalence was 45–90% with an intensity of 6.4–9.3% vs. 0–25% and an intensity of 2.1–3.4% for offshore spawners during winter. Further, fecundity regulation ceased prior to spawning for offshore spawners but continued for coastal spawners. For coastal spawners, the prevalence was 12–29% and an intensity of 2.5–6.1% during spawning. The change in fish condition was strongly related to feeding incidence and differed between populations. As feeding ceased, condition of offshore spawners decreased during winter up to spawning, whereas condition of coastal spawners decreased during autumn but was maintained as feeding started again prior to spawning. Thus, habitat utilisation according to spawning strategy affects the timing of fecundity down-regulation reflecting availability of resources, namely limited food resources in deep areas and higher availability in coastal areas. Offshore spawning flounder display characteristics typical for a capital spawner with ceasing of feeding and oocyte down-regulation well before spawning, whereas coastal spawning flounder can be characterised as intermediate between a capital and income spawner with feeding prior to and during spawning along with continuous fecundity-regulation.

  • 436. Nonaka, E.
    et al.
    Brännström, R.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Assortative mating can limit the evolution of phenotypic plasticity2014In: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 28, no 6, p. 1057-1074Article in journal (Refereed)
    Abstract [en]

    Phenotypic plasticity, the ability to adjust phenotype to the exposed environment, is often advantageous for organisms living in heterogeneous environments. Although the degree of plasticity appears limited in nature, many studies have reported low costs of plasticity in various species. Existing studies argue for ecological, genetic, or physiological costs or selection eliminating plasticity with high costs, but have not considered costs arising from sexual selection. Here, we show that sexual selection caused by mate choice can impede the evolution of phenotypic plasticity in a trait used for mate choice. Plasticity can remain low to moderate even in the absence of physiological or genetic costs, when individuals phenotypically adapted to contrasting environments through plasticity can mate with each other and choose mates based on phenotypic similarity. Because the non-choosy sex (i.e., males) with lower degrees of plasticity are more favored in matings by the choosy sex (i.e., females) adapted to different environments, directional selection toward higher degrees of plasticity is constrained by sexual selection. This occurs at intermediate strengths of female choosiness in the range of the parameter value we examined. Our results demonstrate that mate choice is a potential source of an indirect cost to phenotypic plasticity in a sexually selected plastic trait.

  • 437.
    Nydahl, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Groundwater carbon within a boreal catchment - spatiotemporal variability of a hidden aquatic carbon pool2019Data set
    Abstract [en]

    Groundwater is an essential resource providing water for societies and sustaining surface waters. Although groundwater at intermediate depth could be highly influential at regulating lake and river surface water chemistry, studies quantifying organic and inorganic carbon (C) species in intermediate depth groundwater are still rare. Here, we quantified dissolved and gaseous C species in the groundwater of a boreal catchment at 3 to 20 m depth. We found that the partial pressure of carbon dioxide (pCO2), the stable carbon isotopic composition of dissolved inorganic carbon (δ13C-DIC) and pH showed a dependency with depth. δ13C-DIC, and between pCO2 and pH. We attribute the negative pCO2-pH relationship along the depth gradient to increased silicate weathering and decreased soil respiration. Silicate weathering consumes carbon dioxide (CO2) and release base cations, leading to increased pH and decreased pCO2. We observed a positive relationship between δ13C-DIC and depth, potentially due to diffusion-related fractionation in addition to isotopic discrimination during soil respiration. Soil CO2 may diffuse downward, resulting in a fractionation of the δ13C-DIC. Additionally, the dissolved organic carbon (DOC) at greater depth may be recalcitrant consisting of old degraded material with a greater fraction of the heavier C isotope. Our study provides increased knowledge about the C biogeochemistry of groundwater at intermediate depth, which is important since these waters likely contribute to the widespread CO2 oversaturation in boreal surface waters.

  • 438.
    Nydahl, Anna Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Carbon Dioxide in Inland Waters: Drivers and Mechanisms Across Spatial and Temporal Scales2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Inland waters are an essential component of the global carbon cycle as they are very active sites for carbon transformation processes. Much of this carbon is transformed into the greenhouse gas carbon dioxide (CO2) and emitted into the atmosphere. The biogeochemical and hydrological mechanisms driving CO2 concentrations in inland waters are manifold. Although some of them have been studied in detail, there are still knowledge gaps regarding the relative importance of the different CO2-driving mechanisms, both on a spatial and a temporal scale. The main aim of this thesis was to fill some of the knowledge gaps by studying long- and short-term effects of enhanced dissolved organic carbon (DOC) concentrations on surface water partial pressure of CO2 (pCO2) as well as to investigate both internal (i.e., within the water body) and external (i.e., catchment) drivers of pCO2 in inland waters. Based on analyses of long-term data from more than 300 boreal lakes and streams and on results from two mesocosm experiments as well as a detailed catchment study, one of the main results of the thesis was that DOC concentrations were, on a temporal scale, generally uncoupled to pCO2. Indeed, additions of allochthonous DOC to lake water could result in increased pCO2 in waters but not as originally expected by stimulation of bacterial activity but instead by light driven suppression of primary production, at least in mesotrophic waters. Changes in the carbonate system was also found to be a main driver for surface water pCO2. Finally, also external processes such as groundwater inputs contributed substantially to variations of surface water pCO2. In a detailed study on carbon in groundwater, pCO2 in groundwater was found to decrease with soil depth and correlated negatively with pH, which increased with soil depth. Conclusively, this thesis show that pCO2 does not follow the trends of increased DOC in boreal surface waters but instead correlates with changes in primary production and shifts in the carbonate system. Additionally, the dominating mechanisms driving pCO2 clearly differ between lakes and streams. Consequently, simulations of future CO2 dynamics and emissions from inland waters cannot rely on DOC concentrations as a pCO2 predictor, but rather need to incorporate several pCO2 driving mechanisms, and consider the difference between lakes and streams.

    List of papers
    1. No long-term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams and rivers
    Open this publication in new window or tab >>No long-term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams and rivers
    2017 (English)In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 31, no 6, p. 985-995Article in journal (Refereed) Published
    Abstract [en]

    Concentrations of dissolved organic carbon (DOC) from terrestrial sources have been increasing in freshwaters across large parts of the boreal region. According to results from large-scale field and detailed laboratory studies, such a DOC increase could potentially stimulate carbon dioxide (CO2) production, subsequently increasing the partial pressure of CO2 (pCO2) in freshwaters. However, the response of pCO2 to the presently observed long-term increase in DOC in freshwaters is still unknown. Here we tested whether the commonly found spatial DOC-pCO2 relationship is also valid on a temporal scale. Analyzing time series of water chemical data from 71 lakes, 30 streams, and 4 river mouths distributed across all of Sweden over a 17 year period, we observed significant DOC concentration increases in 39 lakes, 15 streams, and 4 river mouths. Significant pCO2 increases were, however, only observed in six of these 58 waters, indicating that long-term DOC increases in Swedish waters are disconnected from temporal pCO2 trends. We suggest that the uncoupling of trends in DOC concentration and pCO2 are a result of increased surface water runoff. When surface water runoff increases, there is likely less CO2 relative to DOC imported from soils into waters due to a changed balance between surface and groundwater flow. Additionally, increased surface water runoff causes faster water flushing through the landscape giving less time for in situ CO2 production in freshwaters. We conclude that pCO2 is presently not following DOC concentration trends, which has important implications for modeling future CO2 emissions from boreal waters.

    Place, publisher, year, edition, pages
    American Geophysical Union (AGU), 2017
    National Category
    Environmental Sciences
    Identifiers
    urn:nbn:se:uu:diva-323413 (URN)10.1002/2016GB005539 (DOI)000405103600004 ()
    Funder
    EU, Horizon 2020, 643052Knut and Alice Wallenberg Foundation, KAW 2013.0091Swedish Research Council, 2016-04153
    Available from: 2017-06-07 Created: 2017-06-07 Last updated: 2019-08-15Bibliographically approved
    2. Colored organic matter increases CO2 in meso-eutrophic lake water through altered light climate and acidity
    Open this publication in new window or tab >>Colored organic matter increases CO2 in meso-eutrophic lake water through altered light climate and acidity
    Show others...
    2019 (English)In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, no 2, p. 744-756Article in journal (Refereed) Published
    Abstract [en]

    Many surface waters across the boreal region are browning due to increased concentrations of colored allochthonous dissolved organic carbon (DOC). Browning may stimulate heterotrophic metabolism, may have a shading effect constraining primary production, and may acidify the water leading to decreased pH with a subsequent shift in the carbonate system. All these effects are expected to result in increased lake water carbon dioxide (CO2) concentrations. We tested here these expectations by assessing the effects of both altered allochthonous DOC input and light conditions through shading on lake water CO2 concentrations. We used two mesocosm experiments with water from the meso‐eutrophic Lake Erken, Sweden, to determine the relative importance of bacterial activities, primary production, and shifts in the carbonate system on CO2 concentrations. We found that DOC addition and shading resulted in a significant increase in partial pressure of CO2 (pCO2) in all mesocosms. Surprisingly, there was no relationship between bacterial activities and pCO2. Instead the experimental reduction of light by DOC and/or shading decreased the photosynthesis to respiration ratio leading to increased pCO2. Another driving force behind the observed pCO2 increase was a significant decrease in pH, caused by a decline in photosynthesis and the input of acidic DOC. Considering that colored allochthonous DOC may increase in a warmer and wetter climate, our results could also apply for whole lake ecosystems and pCO2 may increase in many lakes through a reduction in the rate of photosynthesis and decreased pH.

    National Category
    Oceanography, Hydrology and Water Resources
    Identifiers
    urn:nbn:se:uu:diva-366220 (URN)10.1002/lno.11072 (DOI)000461865500022 ()
    Available from: 2018-11-18 Created: 2018-11-18 Last updated: 2019-08-15Bibliographically approved
    3. Groundwater carbon within a boreal catchment – spatiotemporal variability of a hidden aquatic carbon pool
    Open this publication in new window or tab >>Groundwater carbon within a boreal catchment – spatiotemporal variability of a hidden aquatic carbon pool
    2020 (English)In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 125, no 1Article in journal (Refereed) Published
    National Category
    Biological Sciences
    Research subject
    Biology with specialization in Limnology
    Identifiers
    urn:nbn:se:uu:diva-390878 (URN)10.1029/2019JG005244 (DOI)
    Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2020-02-06Bibliographically approved
    4. Highly variable explanations of long-term pCO2 increases in boreal lakes and streams
    Open this publication in new window or tab >>Highly variable explanations of long-term pCO2 increases in boreal lakes and streams
    (English)In: Article in journal (Other academic) Submitted
    National Category
    Biological Sciences
    Research subject
    Biology with specialization in Limnology
    Identifiers
    urn:nbn:se:uu:diva-390881 (URN)
    Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2019-08-15
  • 439.
    Nydahl, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Wallin, Marcus B.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    No long-term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams and rivers2017In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 31, no 6, p. 985-995Article in journal (Refereed)
    Abstract [en]

    Concentrations of dissolved organic carbon (DOC) from terrestrial sources have been increasing in freshwaters across large parts of the boreal region. According to results from large-scale field and detailed laboratory studies, such a DOC increase could potentially stimulate carbon dioxide (CO2) production, subsequently increasing the partial pressure of CO2 (pCO2) in freshwaters. However, the response of pCO2 to the presently observed long-term increase in DOC in freshwaters is still unknown. Here we tested whether the commonly found spatial DOC-pCO2 relationship is also valid on a temporal scale. Analyzing time series of water chemical data from 71 lakes, 30 streams, and 4 river mouths distributed across all of Sweden over a 17 year period, we observed significant DOC concentration increases in 39 lakes, 15 streams, and 4 river mouths. Significant pCO2 increases were, however, only observed in six of these 58 waters, indicating that long-term DOC increases in Swedish waters are disconnected from temporal pCO2 trends. We suggest that the uncoupling of trends in DOC concentration and pCO2 are a result of increased surface water runoff. When surface water runoff increases, there is likely less CO2 relative to DOC imported from soils into waters due to a changed balance between surface and groundwater flow. Additionally, increased surface water runoff causes faster water flushing through the landscape giving less time for in situ CO2 production in freshwaters. We conclude that pCO2 is presently not following DOC concentration trends, which has important implications for modeling future CO2 emissions from boreal waters.

  • 440.
    Nydahl, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Laudon, Hjalmar
    Institutionen för skogens ekologi och skötsel, SLU, Umeå.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Groundwater carbon within a boreal catchment – spatiotemporal variability of a hidden aquatic carbon pool2020In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 125, no 1Article in journal (Refereed)
  • 441.
    Nydahl, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hiller, Carolin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Attermeyer, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Garrison, Julie A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Chaguaceda, Fernando
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Scharnweber, Kristin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Colored organic matter increases CO2 in meso-eutrophic lake water through altered light climate and acidity2019In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, no 2, p. 744-756Article in journal (Refereed)
    Abstract [en]

    Many surface waters across the boreal region are browning due to increased concentrations of colored allochthonous dissolved organic carbon (DOC). Browning may stimulate heterotrophic metabolism, may have a shading effect constraining primary production, and may acidify the water leading to decreased pH with a subsequent shift in the carbonate system. All these effects are expected to result in increased lake water carbon dioxide (CO2) concentrations. We tested here these expectations by assessing the effects of both altered allochthonous DOC input and light conditions through shading on lake water CO2 concentrations. We used two mesocosm experiments with water from the meso‐eutrophic Lake Erken, Sweden, to determine the relative importance of bacterial activities, primary production, and shifts in the carbonate system on CO2 concentrations. We found that DOC addition and shading resulted in a significant increase in partial pressure of CO2 (pCO2) in all mesocosms. Surprisingly, there was no relationship between bacterial activities and pCO2. Instead the experimental reduction of light by DOC and/or shading decreased the photosynthesis to respiration ratio leading to increased pCO2. Another driving force behind the observed pCO2 increase was a significant decrease in pH, caused by a decline in photosynthesis and the input of acidic DOC. Considering that colored allochthonous DOC may increase in a warmer and wetter climate, our results could also apply for whole lake ecosystems and pCO2 may increase in many lakes through a reduction in the rate of photosynthesis and decreased pH.

  • 442.
    Nydahl, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Wallin, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Highly variable explanations of long-term pCO2 increases in boreal lakes and streamsIn: Article in journal (Other academic)
  • 443. Nõges, Peeter
    et al.
    Adrian, Rita
    Anneville, Orlane
    Arvola, Lauri
    Blenckner, Thorsten
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    George, Glen
    Jankowski, Thomas
    Järvinen, Marko
    Maberly, Stephen
    Padisák, Judit
    Straile, Dietmar
    Teubner, Katrin
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    The impact of the changing climate on seasonal dynamics of phytoplankton2010In: The impact of climate change on European lakes / [ed] Glen George, Dordrecht: Springer , 2010, p. 253-274Chapter in book (Other academic)
  • 444. Obertegger, Ulrike
    et al.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Pindo, Massimo
    Larger, Simone
    Flaim, Giovanna
    Temporal variability of bacterioplankton is habitat driven2018In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 27, no 21, p. 4322-4335Article in journal (Refereed)
    Abstract [en]

    Temporal dynamics of bacterioplankton are rarely investigated for multiple habitats and years within individual lakes, limiting our understanding of the variability of bacterioplankton community (BC) composition with respect to environmental factors. We assessed the BC composition of a littoral and two pelagic habitats (euphotic zone and hypolimnion) of Lake Tovel monthly from April 2014 to May 2017 by high-throughput sequencing of the V3?V4 hypervariable region of the 16S rRNA gene. The three habitats differed in temperature, light, oxygen and hydrology. In particular, the littoral was the most hydrologically unstable because it receives most of the lake inflow, the hypolimnion was the most stable because of its hydrologically sheltered position, and the pelagic euphotic habitat was intermediate. Consequently, we hypothesized different temporal patterns of BC composition for all three habitats according to their environmental differences. We applied PERMANOVA, nonmetric multidimensional scaling and source?sink analysis to characterize BC composition. Overall, BCs were different among habitats with the littoral showing the highest variability and the hypolimnion the highest stability. The BC of rainy 2014 was distinct from the BCs of other years irrespective of the habitats considered. Seasonal differences in BCs were limited to spring, probably linked to meltwater inflow and mixing. Thus, temporal effects related to year and season were linked to the hydrological gradient of habitats. We suggest that despite potential within-lake dispersal of bacterioplankton by water flow and mixing, local environmental conditions played a major role in Lake Tovel, fostering distinct BCs in the three habitats.

  • 445.
    Obrador, Biel
    et al.
    Univ Barcelona, Dept Evolutionary Biol Ecol & Environm Sci, Av Diagonal 643, E-08028 Barcelona, Spain..
    von Schiller, Daniel
    Univ Girona, Catalan Inst Water Res ICRA, Sci & Technol Pk,Emili Grahit 101, Girona 17003, Spain.;Univ Basque Country, Fac Sci & Technol, Dept Plant Biol & Ecol, Apdo 644, Bilbao 48080, Spain..
    Marce, Rafael
    Univ Girona, Catalan Inst Water Res ICRA, Sci & Technol Pk,Emili Grahit 101, Girona 17003, Spain..
    Gomez-Gener, Lluis
    Univ Barcelona, Dept Evolutionary Biol Ecol & Environm Sci, Av Diagonal 643, E-08028 Barcelona, Spain.;Umea Univ, Dept Ecol & Environm Sci, Linnaeus Vag 6, S-90187 Umea, Sweden..
    Koschorreck, Matthias
    UFZ Helmholtz Ctr Environm Res, Dept Lake Res, Bruckstr 3a, D-39114 Magdeburg, Germany..
    Borrego, Carles
    Univ Girona, Catalan Inst Water Res ICRA, Sci & Technol Pk,Emili Grahit 101, Girona 17003, Spain.;Univ Girona, Inst Aquat Ecol, Grp Mol Microbial Ecol, Campus Montilivi, Girona 17071, Spain..
    Catalan, Nuria
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Univ Barcelona, Dept Evolutionary Biol Ecol & Environm Sci, Av Diagonal 643, E-08028 Barcelona, Spain.;Univ Girona, Catalan Inst Water Res ICRA, Sci & Technol Pk,Emili Grahit 101, Girona 17003, Spain..
    Dry habitats sustain high CO2 emissions from temporary ponds across seasons2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3015Article in journal (Refereed)
    Abstract [en]

    Despite the increasing understanding of the magnitude and drivers of carbon gas emissions from inland waters, the relevance of water fluctuation and associated drying on their dynamics is rarely addressed. Here, we quantified CO2 and CH4 fluxes from a set of temporary ponds across seasons. The ponds were in all occasion net CO2 emitters irrespective of the presence or absence of water. While the CO2 fluxes were in the upper range of emissions for freshwater lentic systems, CH4 fluxes were mostly undetectable. Dry habitats substantially contributed to these emissions and were always a source of CO2, whereas inundated habitats acted either as a source or a sink of atmospheric CO2 along the year. Higher concentrations of coloured and humic organic matter in water and sediment were linked to higher CO2 emissions. Composition of the sediment microbial community was related both to dissolved organic matter concentration and composition, but we did not find a direct link with CO2 fluxes. The presence of methanogenic archaea in most ponds suggested the potential for episodic CH4 production and emission. Our results highlight the need for spatially and temporally inclusive approaches that consider the dry phases and habitats to characterize carbon cycling in temporary systems.

  • 446.
    Onuţ-Brännström, Ioana
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Benjamin, Mitchell
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Scofield, Douglas G.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Evolutionary Biology.
    Starri, Heiðmarsson
    Icelandic Institute of Natural History, Borgir Nordurslod, Iceland.
    Andersson, Martin G.I.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lindström, Eva S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Johannesson, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Sharing of photobionts in sympatric populations of Thamnolia and Cetraria lichens: evidence from high-throughput sequencing2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 4406Article in journal (Refereed)
    Abstract [en]

    In this study, we explored the diversity of green algal symbionts (photobionts) in sympatric populations of the cosmopolitan lichen-forming fungi Thamnolia and Cetraria. We sequenced with both Sanger and Ion Torrent High-Throughput Sequencing technologies the photobiont ITS-region of 30 lichen thalli from two islands: Iceland and Öland. While Sanger recovered just one photobiont genotype from each thallus, the Ion Torrent data recovered 10–18 OTUs for each pool of 5 lichen thalli, suggesting that individual lichens can contain heterogeneous photobiont populations. Both methods showed evidence for photobiont sharing between Thamnolia and Cetraria on Iceland. In contrast, our data suggest that on Öland the two mycobionts associate with distinct photobiont communities, with few shared OTUs revealed by Ion Torrent sequencing. Furthermore, by comparing our sequences with public data, we identified closely related photobionts from geographically distant localities. Taken together, we suggest that the photobiont composition in Thamnolia and Cetraria results from both photobiont-mycobiont codispersal and local acquisition during mycobiont establishment and/or lichen growth. We hypothesize that this is a successful strategy for lichens to be flexible in the use of the most adapted photobiont for the environment.

  • 447. O’Reilly, Catherine M.
    et al.
    Sharma, Sapna
    Gray, Derek K.
    Hampton, Stephanie E.
    Read, Jordan S.
    Rowley, Rex J.
    Schneider, Philipp
    Lenters, John D.
    McIntyre, Peter B.
    Kraemer, Benjamin M.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Straile, Dietmar
    Dong, Bo
    Adrian, Rita
    Allan, Mathew G.
    Anneville, Orlane
    Arvola, Lauri
    Austin, Jay
    Bailey, John L.
    Baron, Jill S.
    Brookes, Justin D.
    de Eyto, Elvira
    Dokulil, Martin T.
    Hamilton, David P.
    Havens, Karl
    Hetherington, Amy L.
    Higgins, Scott N.
    Hook, Simon
    Izmest’eva, Lyubov R.
    Joehnk, Klaus D.
    Kangur, Kulli
    Kasprzak, Peter
    Kumagai, Michio
    Kuusisto, Esko
    Leshkevich, George
    Livingstone, David M.
    MacIntyre, Sally
    May, Linda
    Melack, John M.
    Mueller-Navarra, Doerthe C.
    Naumenko, Mikhail
    Noges, Peeter
    Noges, Tiina
    North, Ryan P.
    Plisnier, Pierre-Denis
    Rigosi, Anna
    Rimmer, Alon
    Rogora, Michela
    Rudstam, Lars G.
    Rusak, James A.
    Salmaso, Nico
    Samal, Nihar R.
    Schindler, Daniel E.
    Schladow, S. Geoffrey
    Schmid, Martin
    Schmidt, Silke R.
    Silow, Eugene
    Soylu, M. Evren
    Teubner, Katrin
    Verburg, Piet
    Voutilainen, Ari
    Watkinson, Andrew
    Williamson, Craig E.
    Zhang, Guoqing
    Rapid and highly variable warming of lake surface waters around the globe2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 24Article in journal (Refereed)
    Abstract [en]

    In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade−1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade−1) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53°C decade−1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.

  • 448.
    Osman, Omneya Ahmed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Isolation And Characterization Of Surface Active Compounds Produced By Halophilic Bacteria2012In: Book of Proceedings: 5th International Symposium on Biosorption and Bioremediation / [ed] Petra Lovecká, Martina Nováková, Petra Prouzová, Ondrej Uhlik, Prague: ICT Press , 2012, p. 164-168Conference paper (Other academic)
    Abstract [en]

    Biosurfactants or bioemulsifiers produced by microorganisms is considered an essential step in hydrocarbon biodegradation in the marine environment. Four bacterial strains isolated from Maruit lake, Egypt displayed hemolytic activity when grown on blood agar. 16S rRNA sequencing revealed that these strains were affiliated to Halomonas, Chromohalobacter and Halobacillus. Bacterial adhesion to benzene, xylene and lubricant motor oil ranged between 60-80 % indicating the presence of surface active compounds. The 4 strains had the capacity to produce surface active compounds when grown with 1% of motor oil, rapeseed oil and olive oil as sole carbon source and in the presence of different NaCl concentrations (0.0, 0.5 and 1.0 M). Most of the strains showed enhanced growth in the presence of 0.5 and 1.0 M NaCl, emphasizing the importance of NaCl in controlling the growth of halophilic bacteria. Drop collapse test was positive in all strains. Surface tension measurements ranged between 72-58 mN/m for motor oil, olive oil and rapeseed oil. All the isolates exhibit emusification stability of 69-100% with the tested oils. Resultant emulsion found stable without any phase separation. We concluded that these strains have a potential application as a bioemulsifiers which can grow in different types of oils.

  • 449.
    Osman, Omneya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Gudasz, Cristian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Diversity and abundance of aromatic catabolic genes in lake sediments in response to temperature change2014In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 88, no 3, p. 468-481Article in journal (Refereed)
    Abstract [en]

    The abundance and composition of genes involved in the catabolism of aromatic compounds provide important information on the biodegradation potential of organic pollutants and naturally occurring compounds in the environment. We studied catechol 2, 3 dioxygenase (C23O) and benzylsuccinate synthase (bssA) genes coding for key enzymes of aerobic and anaerobic degradation of aromatic compounds in experimental incubations with sediments from two contrasting lakes; humic lake Svarttjärn and eutrophic Vallentunasjön, respectively. Sediment cores from both lakes were incubated continuously for 5 months at constant temperatures ranging from 1.0 to 21.0 °C. The difference in C23O gene composition of the sediment analyzed at the end of the experiment was larger between lakes, than among temperature treatments within each lake. The abundance of C23O gene copies and measured respiration was positively correlated with temperature in Vallentunasjön, whereas putative C23O genes were present in lower concentrations in Svarttjärn sediments. Putative bssA genes were only detected in Svarttjärn. For both lakes, the two catabolic genes were most abundant in the surface sediment. The results emphasize the important role of temperature and nutrient availability in controlling the functional potential of sediment microorganisms and reveal differences between systems with contrasting trophic status. A better understanding of catabolic pathways and enzymes will enable more accurate forecasting of the functional properties of ecosystems under various scenarios of environmental change.

  • 450.
    PAPAZACHARIOU, VASILIKI
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Coral Fungia fungites- associated microbial communities and their shifts upon anthropogenic disturbances2019Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    One of the main focus of coral reef ecology has been to shed light on the importance of all microbial members of coral holobiont and how their interactions contribute to the coral’s resilience. However, knowledge is lacking about the composition of microbial communities inhabiting the surface mucus layer of corals including Fungia fungites, a species that lives under stressful conditions close to fish farms in Vietnam. I investigated the prokaryotic communities that are thriving in Fungia fungites surface mucus layer (SML) in the wild and how they were affected upon antibiotics and nitrogen stress using 16S rRNA gene-based techniques. Firstly, I observed a significant alteration in the composition of microbial communities due to antibiotics effect, with exposed communities featuring lower richness and α-diversity in contrast to the controls. Further, mucosal microbial communities were found to be mostly dominated by Proteobacteria (especially of the classes of Alphaproteobacteria and Gammaproteobacteria) and less by Bacteroidetes (Flavobacteriia). Results from this study suggest a developed antibiotic resistance of Alteromonadales and Campylobacterales indicated by their increased abundance upon antibiotics effect. Moving forward, future studies should focus on exploring also the contribution of non-prokaryotic microbial members of Fungia fungites holobiont and how antibiotic resistance can potentially influence coral’s health. The results support that Fungia fungites SML microbial communities are strongly affected by antibiotics exposure and call for future research to focus on the function of these microbial communities and how they can contribute to the coral’s resilience.

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