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  • 201.
    Grasset, Charlotte
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Laboratory of Aquatic Ecology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
    Abril, Gwenaël
    Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d'Histoire Naturelle, Paris cedex 05, France; Programa de Geoquímica, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil.
    Mendonca, Raquel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Laboratory of Aquatic Ecology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
    Roland, Fabio
    Laboratory of Aquatic Ecology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    The transformation of macrophyte-derived organic matter to methane relates to plant water and nutrient contents2019Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 64, nr 4, s. 1737-1749Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Macrophyte detritus is one of the main sources of organic carbon (OC) in inland waters, and it is potentially available for methane (CH4) production in anoxic bottom waters and sediments. However, the transformation of macrophyte‐derived OC into CH4 has not been studied systematically, thus its extent and relationship with macrophyte characteristics remains uncertain. We performed decomposition experiments of macrophyte detritus from 10 different species at anoxic conditions, in presence and absence of a freshwater sediment, in order to relate the extent and rate of CH4 production to the detritus water content, C/N and C/P ratios. A significant fraction of the macrophyte OC was transformed to CH4 (mean = 7.9%; range = 0–15.0%) during the 59‐d incubation, and the mean total C loss to CO2 and CH4 was 17.3% (range = 1.3–32.7%). The transformation efficiency of macrophyte OC to CH4 was significantly and positively related to the macrophyte water content, and negatively to its C/N and C/P ratios. The presence of sediment increased the transformation efficiency to CH4 from an average of 4.0% (without sediment) to 11.8%, possibly due to physicochemical conditions favorable for CH4 production (low redox potential, buffered pH) or because sediment particles facilitate biofilm formation. The relationship between macrophyte characteristics and CH4 production can be used by future studies to model CH4 emission in systems colonized by macrophytes. Furthermore, this study highlights that the extent to which macrophyte detritus is mixed with sediment also affects CH4 production.

  • 202.
    Grasset, Charlotte
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Delolme, Cécile
    Arthaud, Florent
    Bornette, Gudrun
    Carbon allocation in aquatic plants with contrasting strategies: The role of habitat nutrient content2015Inngår i: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 26, s. 946-955Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Questions: The link between the carbon composition of aquatic plants and (1) plant strategies and (2) habitat nutrient availability has received little attention. We tested whether three aquatic species belonging to the three adaptive strategies defined by Grime (ruderal, stress tolerant and competitive) had contrasting carbon allocation patterns, and if these patterns varied in the same way between populations distributed along a gradient of habitat nutrient content. Location: Wetlands in the northern Rhône River Basin, France. Methods: The three species were sampled in 17 wetlands along a gradient of nutrient content in the northern Rhône River Basin. In each population sampled, we measured plant water content, C/N ratio, structural compounds (lignin and structural polysaccharides) and storage compounds (free sugars and starch) in two seasons (spring and autumn 2012). Results: The stress-tolerant species had higher content of structural compounds than the competitive and ruderal species. The content of storage compounds was higher in the competitive and stress-tolerant species compared to the ruderal species. Allocation of carbon compounds varied with habitat nutrient content in different ways for the three species, suggesting contrasting plasticities, possibly linked to plant strategy. Conclusion: Plant strategies and habitat nutrient content are likely key drivers in plant carbon allocation and should be taken into account when studying interactions between habitat and plant quality.

  • 203.
    Grasset, Charlotte
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Laboratory of Aquatic Ecology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Brazil.
    Mendonça, Raquel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Federal University of Juiz de Fora, Juiz de Fora, Brazil.
    Villamor Saucedo, Gabriella
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Federal University of Juiz de Fora, Juiz de Fora, Brazil.
    Bastviken, David
    Department of Thematic Studies – Environmental Change, Linköping University, Linköping, Sweden.
    Roland, Fabio
    Federal University of Juiz de Fora, Juiz de Fora, Brazil.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Large but variable methane production in anoxic freshwater sediment upon addition of allochthonous and autochthonous organic matter2018Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, nr 4, s. 1488-1501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important question in the context of climate change is to understand how CH4 production is regulated in anoxic sediments of lakes and reservoirs. The type of organic carbon (OC) present in lakes is a key factor controlling CH4 production at anoxic conditions, but the studies investigating the methanogenic potential of the main OC types are fragmented. We incubated different types of allochthonous OC (alloOC; terrestrial plant leaves) and autochthonous OC (autoOC; phytoplankton and two aquatic plants species) in an anoxic sediment during 130 d. We tested if (1) the supply of fresh alloOC and autoOC to an anoxic refractory sediment would fuel CH4 production and if (2) autoOC would decompose faster than alloOC. The addition of fresh OC greatly increased CH4 production and the δ13C-CH4 partitioning indicated that CH4 originated exclusively from the fresh OC. The large CH4 production in an anoxic sediment fueled by alloOC is a new finding which indicates that all systems with anoxic conditions and high sedimentation rates have the potential to be CH4 emitters. The autoOC decomposed faster than alloOC, but the total CH4 production was not higher for all autoOC types, one aquatic plant species having values as low as the terrestrial leaves, and the other one having values as high as phytoplankton. Our study is the first to report such variability, suggesting that the extent to which C fixed by aquatic plants is emitted as greenhouse gases or buried as OC in sediment could more generally differ between aquatic vegetation types.

  • 204.
    Grasset, Charlotte
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Rodriguez, Célia
    Delolme, Cécile
    Marmonier, Pierre
    Bornette, Gudrun
    Can Soil Organic Carbon Fractions Be Used as Functional Indicators of Wetlands?2017Inngår i: Wetlands (Wilmington, N.C.), ISSN 0277-5212, E-ISSN 1943-6246, Vol. 37, nr 6, s. 1195-1205Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work aimed to determine whether the organic carbon in wetland soils correlated with physico-chemical characteristics of wetlands (e.g. nutrient content, pH) and differentiated wetlands according to their plant community composition definied by the CORINE Biotope nomenclature. 96 wetlands were sampled in southeastern France, belonging to 14 CORINE habitats grouped into 3 CORINE hydrological categories: wet meadows, peatlands and aquatic wetlands. The total organic carbon content, the carbon content of humic fractions (humic acid (CHA), fulvic acid (CFA) and Chumin), and water extractable organic carbon were measured in samples collected in the upper 20 cm soil layer. These soil organic carbon fractions correlated with pH and soil nutrient content but differed slightly among the 14 CORINE habitats. In contrast, soil organic carbon fractions greatly differed among the 3 CORINE hydrological categories. The CFA/CHA ratio was significantly lower for wet meadows and peatlands and the proportion of CHumin was significantly higher for peatlands and aquatic wetlands. These soil organic carbon fractions inform on the hydrological status of wetlands and may consequently be used as functional indicator in addition to a plant-based classification as the CORINE Biotope nomenclature.

  • 205.
    Groeneveld, Marloes M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Selective adsorption of terrestrial dissolved organic matter to inorganic surfaces along a boreal inland water continuum (data set)2020Dataset
    Abstract [en]

    Different processes contribute to the loss or transformation of dissolved organic matter (DOM) and change DOM concentration and composition systematically along the inland water continuum. Substantial efforts have been made to estimate the importance of microbial and photochemical degradation for DOM concentration and composition and, to some extent, also DOM losses by flocculation, whereas the significance of DOM adsorption to inorganic surfaces has received less attention. Hence, knowledge on the possible extent of adsorption, its effect on DOM loads and composition and on where along the aquatic continuum it might be important is currently limited or lacking altogether. Here, we experimentally determine DOM adsorption onto mineral particles in freshwater ecosystems covering a water residence time gradient in boreal landscape Sweden. We hypothesized that adsorption would gradually decrease with increasing water residence time, but actually found that DOM is highly susceptible to adsorption throughout the aquatic continuum. Mass spectrometry and fluorescence analysis on DOM suggest that freshly produced aquatic DOM is less susceptible to adsorption than more terrestrial material. Moreover, the percentage DOM adsorbed in the experiments greatly exceeds the actual adsorption taking place in boreal inland waters across all studied systems. These results illustrate the potential impact of mineral erosion, for example as a result of agriculture, mining or forestry practices, on the availability, transport and composition of organic carbon in inland waters. 

  • 206.
    Groeneveld, Marloes M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Natchimuthu, Sivakiruthika
    Linkoping Univ, Dept Themat Studies Environm Change, S-58183 Linkoping, Sweden.
    Koehler, Birgit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Photochemical mineralisation in a boreal brown water lake: considerable temporal variability and minor contribution to carbon dioxide production2016Inngår i: Biogeosciences Discussions, ISSN 1810-6277, E-ISSN 1810-6285, Vol. 13, nr 13, s. 3931-3943Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sunlight induces photochemical mineralisation of chromophoric dissolved organic matter (CDOM) to dissolved inorganic carbon (DIC) in inland waters, resulting in carbon dioxide (CO2) emissions to the atmosphere. Photochemical rate modelling is used to determine sunlight-induced CO2 emissions on large spatial and temporal scales. A sensitive model parameter is the wavelength-specific photochemical CDOM reactivity, the apparent quantum yield (AQY). The modelling studies so far assume that AQY spectra determined for single lakes and on single occasions represent larger spatial and temporal scales. Here, we studied a humic boreal lake in Sweden. We measured AQY spectra for photochemical DIC production monthly between June and November 2014 and parameterised a photochemical rate model. Photochemical reactivity increased slightly during the open water period, likely due to a high rainfall event with consecutive mixing in autumn that increased availability of highly photoreactive CDOM. However, the variability in AQY spectra over time was much smaller than previously reported variability in AQY spectra across lakes. Yet, using either the AQY spectrum from the least or from the most photoreactive water sample resulted in a 5-fold difference in simulated annual DIC photoproduction (2.0 ± 0.1 and 10.3 ± 0.7 g C m−2 yr−1, respectively). Using the monthly measured AQY spectrum to simulate DIC photoproduction for month-long time periods resulted in an apparent time lag between irradiance and DIC photoproduction. This suggested that temporal variability in AQY spectra occurs on shorter time scales. Therefore, we parameterised the model with the pooled AQY spectrum of six monthly measurements. Simulated DIC photoproduction for three years (2012–2014) averaged 4.5 ± 0.2 g C m−2 yr−1, which represented 3 % of the mean CO2 emissions from this lake. We conclude that (1) it may be recommendable to conduct repeated AQY measurements across the season for more accurate simulation of annual photochemical DIC production in lakes and (2), in agreement with previous studies, direct CDOM photomineralisation makes only a minor contribution to mean CO2 emissions from Swedish humic lakes.

  • 207.
    Grubisic, Lorena M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Eiler, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Heinrich, Friederike
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Brutemark, Andreas
    Tvarminne Zool Stn, Hango, Finland.;Novia Univ Appl Sci, ARONIA Coastal Zone Res Team, Ekenas, Finland.;Abo Akad Univ, Ekenas, Finland..
    Alonso-Sáez, Laura
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Andersson, Anders F.
    Uppsala universitet, Science for Life Laboratory, SciLifeLab. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. KTH Royal Inst Technol & Sci Life Lab, Sch Biotechnol, Stockholm, Sweden.
    Gantner, Stephan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. Leibniz Inst Sci & Math Educ, Dept Educ Sci Biol, Kiel, Germany..
    Riemann, Lasse
    Univ Copenhagen, Dept Biol, Marine Biol Sect, Helsingor, Denmark..
    Beier, Sara
    Uppsala universitet, Science for Life Laboratory, SciLifeLab. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz Inst Balt Sea Res Warnemunde IOW, Rostock, Germany..
    Lake bacterioplankton dynamics over diurnal timescales2017Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 62, nr 1, s. 191-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Planktonic bacterial community dynamics over short timescales can be of great importance for food webs and ecosystem functioning but are rarely described when microbial community and composition are assessed. To study the significance of such dynamics we sampled the surface water at the deepest point of a mesotrophic lake (Lake Erken, Sweden) every third hour over two days. 2. By combining 454 pyrosequencing of 16S rRNA genes with bromodeoxyuridine immunocapturing of DNA, replicating populations were identified and compared to the community retrieved from total DNA samples. This comparison revealed a significant difference between the actively replicating and total community. 3. The high-frequency diurnal sampling was compared to a year-long survey conducted in the same lake in order to compare the diurnal and seasonal variation in bacterioplankton community composition. At the diurnal-scale, the variation was significantly higher in the replicating than in the total community. However, variation in both active and total diurnal community was significantly lower than the variation in the seasonal total community. 4. Our analysis revealed pronounced short-term dynamics of individual bacterial populations uncoupled from the diurnal light cycle. For example, the proliferating fraction of the most abundant bacterial tribe (LD12) followed a cyclic pattern that covaried with viral abundance. This implies that environmental factors other than light may act as important drivers of microbial community composition, at least in mesotrophic Lake Erken.

  • 208.
    Grubisic, Lorena M.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Brutemark, Andreas
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wikner, Johan
    Bamstedt, Ulf
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Effects of stratification depth and dissolved organic matter on brackish bacterioplankton communities2012Inngår i: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 453, s. 37-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bacterioplankton growth is often directly or indirectly controlled by external energy subsidies via organic matter inputs or solar radiation. We carried out a mesocosm experiment to assess how bacterioplankton communities responded to elevated levels of dissolved organic matter (DOM) and experimentally controlled stratification depth. The month-long experiment consisted of 2500 l mesocosms subjected to 4 experimental manipulations in triplicate: the stratification depth was set to either 1.5 or 3.5 m, with or without experimental addition of ambient levels of chromophoric DOM. DOM addition had a significant effect on bacterial community composition as assessed by terminal restriction fragment length polymorphism of amplified 16S rRNA genes. In contrast, there were no effects of the DOM amendment on bacterial biomass or production. Mixing depth and the coupled effective light climate in the photic zone also had a significant effect on bacterial community composition. Furthermore, shallow mixing depth was associated with enhanced primary production, whereas DOM addition had a negative effect on phyto plankton biomass and productivity. Our results suggest that bacterial community composition is coupled to primary production under the studied coastal nutrient regime, and point to a key role of DOM quality in controlling bacterioplankton communities.

  • 209.
    Gudasz, Cristian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Boreal Lake Sediments as Sources and Sinks of Carbon2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Inland waters process large amounts of organic carbon, contributing to CO2 and CH4 emissions, as well as storing organic carbon (OC) over geological timescales. Recently, it has been shown that the magnitude of these processes is of global significance. It is therefore important to understand what regulates OC cycling in inland waters and how is that affected by climate change. This thesis investigates the constraints on microbial processing of sediment OC, as a key factor of the carbon cycling in boreal lakes.

    Sediment bacterial metabolism was primarily controlled by temperature but also regulated by OC quality/origin. Temperature sensitivity of sediment OC mineralization was similar in contrasting lakes and over long-term. Allochthonous OC had a strong constraining effect on sediment bacterial metabolism and biomass, with increasingly allochthonous sediments supporting decreasing bacterial metabolism and biomass. The bacterial biomass followed the same pattern as bacterial activity and was largely regulated by similar factors. The rapid turnover of bacterial biomass as well as the positive correlation between sediment mineralization and bacterial biomass suggest a limited effect of bacterial grazing. Regardless of the OC source, the sediment microbial community was more similar within season than within lakes.

    A comparison of data from numerous soils as well as sediments on the temperature response of OC mineralization showed higher temperature sensitivity of the sediment mineralization. Furthermore, the low rates of areal OC mineralization in sediments compared to soils suggest that lakes sediments are hotspots of OC sequestration.

    Increased sediment mineralization due to increase in temperature in epilimnetic sediments can significantly reduce OC burial in boreal lakes. An increase of temperature, as predicted for Northern latitudes, under different climate warming scenarios by the end of the twenty-first century, resulted in 4–27% decrease in lake sediment OC burial for the entire boreal zone.

    Delarbeid
    1. Temperature-controlled organic carbon mineralization in lake sediments
    Åpne denne publikasjonen i ny fane eller vindu >>Temperature-controlled organic carbon mineralization in lake sediments
    Vise andre…
    2010 (engelsk)Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 466, nr 7305, s. 478-481Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Peatlands, soils and the ocean floor are well-recognized as sites of organic carbonaccumulation andrepresentimportant global carbon sinks(1,2). Although the annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments(3), these inland waters are components of the global carbon cycle that receive only limited attention(4-6). Of the organic carbon that is being deposited onto the sediments, a certain proportion will be mineralized and the remainder will be buried over geological timescales. Here we assess the relationship between sediment organic carbon mineralization and temperature in a cross-system survey of boreal lakes in Sweden, and with input froma compilation of published data from awide range of lakes that differ with respect to climate, productivity and organic carbon source. We find that the mineralization of organic carbon in lake sediments exhibits a strongly positive relationship with temperature, which suggests that warmer water temperatures lead to more mineralization and less organic carbon burial. Assuming that future organic carbon delivery to the lake sediments will be similar to that under present-day conditions, we estimate that temperature increases following the latest scenarios presented by the Intergovernmental Panel on Climate Change(7) could result in a 4-27 per cent (0.9-6.4 Tg Cyr(-1)) decrease in annual organic carbon burial in boreal lakes.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-135652 (URN)10.1038/nature09186 (DOI)000280141200033 ()
    Merknad

    Correction in Nature, vol. 466, issue 7310, doi 10.1038/nature09383

    Tilgjengelig fra: 2010-12-08 Laget: 2010-12-07 Sist oppdatert: 2020-01-28bibliografisk kontrollert
    2. Microbial biomass and community composition in boreal lake sediments
    Åpne denne publikasjonen i ny fane eller vindu >>Microbial biomass and community composition in boreal lake sediments
    Vise andre…
    2011 (engelsk)Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 56, nr 2, s. 725-733Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We used phospholipid fatty acids (PLFA) to determine microbial biomass and community structure in the sediments of eight boreal lakes with different loadings of allochthonous organic carbon and total phosphorus (TP) in the water during the course of a year. The total concentration of PLFA, an estimate of the microbial biomass, depended more on TP, a proxy for pelagic primary production, but not on dissolved organic carbon, a proxy for terrestrial organic carbon input. The composition of PLFAs varied considerably over time, demonstrating seasonal dynamics in microbial community composition. When PLFA profiles in all lakes andseasons are compared, community composition is more similar within season than within lakes.

     

    HSV kategori
    Forskningsprogram
    Limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-150710 (URN)10.4319/lo.2011.56.2.0725 (DOI)000290677800027 ()
    Tilgjengelig fra: 2011-04-04 Laget: 2011-04-04 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    3. Constrained microbial processing of allochthonous organic carbon in boreal lake sediments
    Åpne denne publikasjonen i ny fane eller vindu >>Constrained microbial processing of allochthonous organic carbon in boreal lake sediments
    Vise andre…
    2012 (engelsk)Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 57, nr 1, s. 163-175Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We investigated sediment bacterial metabolism in eight lakes with different inputs of allochthonous and autochthonous organic carbon in south-central Sweden. Sediment bacterial production, mineralization and biomass were measured on a seasonal basis and along a lake depth gradient together with different water and sediment characteristics. Sediment bacterial metabolism was primarily controlled by temperature but also regulated by organic carbon quality/origin. Metabolism was positively correlated to measures of autochthonous influence on the sediment organic carbon, but did not show a similar increase with increasing input of allochthonous organic carbon.  Hence, in contrast to what is currently known for the water column, increasing amounts of terrestrial organic carbon do not result in enhanced sediment bacterial metabolism.  Meio- and macrobenthic invertebrate biomass were at most weakly correlated to bacterial metabolism and biomass, suggesting limited control of sediment bacteria by grazing. We suggest that the bacterial metabolism in boreal lake sediments is constrained by low temperatures and by the recalcitrant nature of the dominant organic carbon, resulting in sediments being an effective sink of organic carbon.

    Emneord
    allochthonous organic carbon, microbial metabolism, lake sediments
    HSV kategori
    Forskningsprogram
    Limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-150712 (URN)10.4319/lo.2012.57.1.0163 (DOI)000298321300014 ()
    Tilgjengelig fra: 2011-04-04 Laget: 2011-04-04 Sist oppdatert: 2020-01-28bibliografisk kontrollert
    4. Mineralization of organic carbon in lake sediments: temperature sensitivity and a comparison to soils
    Åpne denne publikasjonen i ny fane eller vindu >>Mineralization of organic carbon in lake sediments: temperature sensitivity and a comparison to soils
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Temperature alone can explain a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that the temperature sensitivity is different for the decomposition of labile and recalcitrant OC, but lake sediments with different contributions of labile and recalcitrant components have been reported to show similar temperature sensitivities. Sediment mineralization is typically measured in short-term incubations. However, whether the mineralization of OC in sediments dominated by recalcitrant and labile OC have different temperature sensitivities at the longer term is not clear. Here we show that during 5 months of continuous incubation of contrasting boreal lake sediments, sediment mineralization was strongly dependent on temperature and OC quality/origin but temperature sensitivity was similar across lakes and over time. Sediment mineralization showed low overall rates in spite of low apparent activation energy (Ea) compared to published rates of soil and litter mineralization. The fraction of the total OC pool that was lost during 5 months varied between 0.4 and 14%. The non-buried sediment OC pool was lost slowly, with apparent turnover times between 2.5 and 32 years. At a large scale, lake sediments, by showing lower mineralization rates than soils are more effective as carbon sinks.

     

    Emneord
    lake sediment, mineralization, temperature sensitivity, organic carbon, turnover time
    HSV kategori
    Forskningsprogram
    Limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-150714 (URN)
    Tilgjengelig fra: 2011-04-04 Laget: 2011-04-04 Sist oppdatert: 2018-05-21
  • 210.
    Gudasz, Cristian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    The Department of Thematic Studies - Water and Environmental Studies Linköping university.
    Premke, Katrin
    Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, and Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany.
    Steger, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Constrained microbial processing of allochthonous organic carbon in boreal lake sediments2012Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 57, nr 1, s. 163-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated sediment bacterial metabolism in eight lakes with different inputs of allochthonous and autochthonous organic carbon in south-central Sweden. Sediment bacterial production, mineralization and biomass were measured on a seasonal basis and along a lake depth gradient together with different water and sediment characteristics. Sediment bacterial metabolism was primarily controlled by temperature but also regulated by organic carbon quality/origin. Metabolism was positively correlated to measures of autochthonous influence on the sediment organic carbon, but did not show a similar increase with increasing input of allochthonous organic carbon.  Hence, in contrast to what is currently known for the water column, increasing amounts of terrestrial organic carbon do not result in enhanced sediment bacterial metabolism.  Meio- and macrobenthic invertebrate biomass were at most weakly correlated to bacterial metabolism and biomass, suggesting limited control of sediment bacteria by grazing. We suggest that the bacterial metabolism in boreal lake sediments is constrained by low temperatures and by the recalcitrant nature of the dominant organic carbon, resulting in sediments being an effective sink of organic carbon.

  • 211.
    Gudasz, Cristian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Umea Univ, Dept Ecol & Environm Sci, CIRC, Umea, Sweden.
    Ruppenthal, Marc
    Eberhard Karls Univ Tuebingen, Forsch Bereich Geog, Tubingen, Germany.
    Kalbitz, Karsten
    Tech Univ Dresden, Inst Soil Sci & Site Ecol, Fac Environm Sci, Soil Resources & Land Use, Tharandt, Germany;Univ Amsterdam, IBED, Amsterdam, Netherlands.
    Cerli, Chiara
    Univ Amsterdam, IBED, Amsterdam, Netherlands.
    Fiedler, Sabine
    Johannes Gutenberg Univ Mainz, Inst Geog, Mainz, Germany.
    Oelmann, Yvonne
    Eberhard Karls Univ Tuebingen, Forsch Bereich Geog, Tubingen, Germany.
    Andersson, August
    Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, Stockholm, Sweden.
    Karlsson, Jan
    Umea Univ, Dept Ecol & Environm Sci, CIRC, Umea, Sweden.
    Contributions of terrestrial organic carbon to northern lake sediments2017Inngår i: LIMNOLOGY AND OCEANOGRAPHY LETTERS, ISSN 2378-2242, Vol. 2, nr 6, s. 218-227Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sediments of northern lakes sequester large amounts of organic carbon (OC), but direct evidence of the relative importance of their sources is lacking. We used stable isotope ratios of nonexchangeable hydrogen (delta H-2(n)) in topsoil, algae, and surface sediments in order to measure the relative contribution of terrestrial OC in surface sediments of 14 mountainous arctic and lowland boreal lakes in Sweden. The terrestrial contribution to the sediment OC pool was on average 66% (range 46-80) and similar between arctic and boreal lakes. Proxies for the supply of terrestrial and algal OC explained trends in the relative contribution of terrestrial OC across lakes. However, the data suggest divergent predominant sources for terrestrial OC of sediments in Swedish lakes, with dissolved matter dominating in lowland boreal lakes and particulate OC in mountainous arctic lakes.

  • 212.
    Gudasz, Cristian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    The Department of Thematic Studies - Water and Environmental Studies Linköping university.
    Koehler, Birgit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Mineralization of organic carbon in lake sediments: temperature sensitivity and a comparison to soilsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Temperature alone can explain a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that the temperature sensitivity is different for the decomposition of labile and recalcitrant OC, but lake sediments with different contributions of labile and recalcitrant components have been reported to show similar temperature sensitivities. Sediment mineralization is typically measured in short-term incubations. However, whether the mineralization of OC in sediments dominated by recalcitrant and labile OC have different temperature sensitivities at the longer term is not clear. Here we show that during 5 months of continuous incubation of contrasting boreal lake sediments, sediment mineralization was strongly dependent on temperature and OC quality/origin but temperature sensitivity was similar across lakes and over time. Sediment mineralization showed low overall rates in spite of low apparent activation energy (Ea) compared to published rates of soil and litter mineralization. The fraction of the total OC pool that was lost during 5 months varied between 0.4 and 14%. The non-buried sediment OC pool was lost slowly, with apparent turnover times between 2.5 and 32 years. At a large scale, lake sediments, by showing lower mineralization rates than soils are more effective as carbon sinks.

     

  • 213.
    Gudasz, Cristian
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    Köhler, Birgit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Temperature sensitivity of organic carbon mineralization in contrasting lake sediments2015Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 7, s. 1215-1225Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21 degrees C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (E-a). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.

  • 214.
    Guillemette, Francois
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    von Wachenfeldt, Eddie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Swedish Univ Agr Sci, Swedish Species Informat Ctr, Uppsala, Sweden..
    Kothawala, Dolly
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bastviken, David
    Linkoping Univ, Dept Themat Studies Environm Change, Linkoping, Sweden..
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Preferential sequestration of terrestrial organic matter in boreal lake sediments2017Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 122, nr 4, s. 863-874Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molecular composition and origin has recently been demonstrated to play a critical role in the persistence of organic matter in lake water, but it is unclear to what degree chemical attributes and sources may also control settling and burial of organic matter in lake sediments. Here we compared the annual contribution of allochthonous and autochthonous sources to the organic matter settling in the water column and present in the sediments of 12 boreal lakes. We used the fluorescence properties and elemental composition of the organic matter to trace its origin and found a consistent pattern of increasing contribution of terrestrial compounds in the sediments as compared to the settling matter, with an annual average allochthony of similar to 87% and similar to 57%, respectively. Seasonal data revealed a predominance of in-lake-produced compounds sinking in the water column in summer. Yet only a slight concurrent decrease in the contribution of terrestrial C to lake sediments was observed during the same period, and sediment allochthony increased again to high levels in autumn. Our results reveal a preferential preservation of allochthonous matter in the sediments and highlight the role of lakes as sequesters of organic carbon primarily originating from the surrounding landscape.

  • 215.
    Guillemette, François
    et al.
    Research Center for Watershed - Aquatic Ecosystem Interactions (RIVE), Université du Québec à Trois-Rivières, Québec, Canada.
    Mostovaya, Alina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Seasonal variability in dissolved organic carbon degradation in boreal lakes: links to composition, sources, and baseline metabolismManuskript (preprint) (Annet vitenskapelig)
  • 216.
    Guinea Barrientos, Héctor Estuardo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Swain, Ashok
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Uppsala centrum för hållbar utveckling, CSD Uppsala.
    Wallin, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Nyberg, Lars
    Disaster Management Cooperation in Central America: The Case of Rainfall-induced Natural Disasters2015Inngår i: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 97, nr 1, s. 85-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rainfall-induced natural disasters rank first among all natural disasters in Central America. Due to the geographical conditions of the Central American region, it is common that two or more countries are struck by the same rainfall event, for example Hurricane Mitch in 1998 affected the entire Central American region, killing more than 18 000 people. As a consequence, Central American countries have started to promote regional policies and programs that aim for better preparation and response to these events, including disaster management cooperation. However, cooperation poses several challenges that may hinder its goals. In order to analyse these challenges, we present analysis in this paper of the current policy and legal institutions as well as the main challenges that may hinder international disaster management cooperation in Central America.

  • 217. Gurnell, Angela M.
    et al.
    O'Hare, Matthew T.
    O'Hare, Judith M.
    Scarlett, Peter
    Liffen, Thomas M. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    The geomorphological context and impact of the linear emergent macrophyte, Sparganium erectum L.: a statistical analysis of observations from British rivers2013Inngår i: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 38, nr 15, s. 1869-1880Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper explores the geomorphological context and impact of the widely-occurring, linear emergent macrophyte, Sparganium erectum. Forty-seven sites across Britain were selected for field investigation, spanning the range of environmental conditions within which Sparganium erectum had been found to be present in previous analyses of national data sets. A combination of descriptive graphs and statistics, principal components analysis, and Kruskal-Wallis tests were used to explore the large multivariate data set collected at the 47 sites. The analyses showed that Sparganium erectum is present in significant quantities in relatively narrow and shallow (< 18m wide and<0.9m deep to the limit of terrestrial vegetation), low gradient (maximum 0.004) channels of varying bed sediment calibre (cobble to silt). Within these environments, S. erectum stands (features) were associated with fine sediment retention, aggradation and submerged landform construction, leading to bench development and so, potentially, to adjustments in channel form and position. Sediment retention and landform construction within S. erectum features was most strongly apparent within reaches with a relatively high S. erectum cover and the presence of large area S. erectum features. It was also associated more weakly with S. erectum features that were comprised of relatively higher densities of plants with relatively smaller inter-plant spacing and fewer leaves. The sediment retained in S. erectum features and associated bench and bank toe deposits showed larger numbers and species of viable seeds, indicating the potential for colonization and growth of other species on S. erectum features once they aggrade above the low flow water level and are no longer a suitable habitat for S. erectum.

  • 218. Guy-Haim, Tamar
    et al.
    Alexander, Harriet
    Bell, Tom W.
    Bier, Raven L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bortolotti, Lauren E.
    Briseño-Avena, Christian
    Dong, Xiaoli
    Flanagan, Alison M.
    Grosse, Julia
    Grossmann, Lars
    Hasnain, Sarah
    Hovel, Rachel
    Johnston, Cora A.
    Miller, Dan R.
    Muscarella, Mario
    Noto, Akana E.
    Reisinger, Alexander J.
    Smith, Heidi J.
    Stamieszkin, Karen
    What are the type, direction, and strength of species, community, and ecosystem responses to warming in aquatic mesocosm studies and their dependency on experimental characteristics?: A systematic review protocol2017Inngår i: Environmental Evidence, ISSN 2047-2382, E-ISSN 2047-2382, Vol. 6, nr 1, artikkel-id 6Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Mesocosm experiments have become increasingly popular in climate change research as they bridge the gap between small-scale, less realistic, microcosm experiments, and large-scale, more complex, natural systems. Characteristics of aquatic mesocosm designs (e.g., mesocosm volume, study duration, and replication) vary widely, potentially affecting the magnitude and direction of effect sizes measured in experiments. In this global systematic review we aim to identify the type, direction and strength of climate warming effects on aquatic species, communities and ecosystems in mesocosm experiments. Furthermore, we will investigate the context-dependency of the observed effects on several a priori determined effect moderators (ecological and methodological). Our conclusions will provide recommendations for aquatic scientists designing mesocosm experiments, as well as guidelines for interpretation of experimental results by scientists, policy-makers and the general public. Methods: We will conduct a systematic search using multiple online databases to gather evidence from the scientific literature on the effects of warming experimentally tested in aquatic mesocosms. Data from relevant studies will be extracted and used in a random effects meta-analysis to estimate the overall effect sizes of warming experiments on species performance, biodiversity and ecosystem functions. Experimental characteristics (e.g., mesocosm size and shape, replication-level, experimental duration and design, biogeographic region, community type, crossed manipulation) will be further analysed using subgroup analyses.

  • 219.
    Gómez-Gener, Lluís
    et al.
    Department of Ecology, University of Barcelona.
    Obrador, Biel
    Department of Ecology, University of Barcelona.
    von Schiller, Daniel
    Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country.
    Marcé, Rafael
    Catalan Institute for Water Research, Scientific and Technological Park of the University of Girona.
    Casas-Ruiz, Joan Pere
    Catalan Institute for Water Research, Scientific and Technological Park of the University of Girona.
    Proia, Lorenzo
    Catalan Institute for Water Research, Scientific and Technological Park of the University of Girona.
    Acuña, Vicenç
    Catalan Institute for Water Research, Scientific and Technological Park of the University of Girona.
    Catalán, Núria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Muñoz, Isabel
    Department of Ecology, University of Barcelona.
    Koschorreck, Matthias
    Department Lake Research, Helmholtz Centre for Environmental Research.
    Hot spots for carbon emissions from Mediterranean fluvial networks during summer drought2015Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 125, nr 3, s. 409-426Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During summer drought, Mediterranean fluvial networks are transformed into highly heterogeneous landscapes characterized by different environments (i.e., running and impounded waters, isolated river pools and dry beds). This hydrological setting defines novel biogeochemically active areas that could potentially increase the rates of carbon emissions from the fluvial network to the atmosphere. Using chamber methods, we aimed to identify hot spots for carbon dioxide (CO2) and methane (CH4) emissions from two typical Mediterranean fluvial networks during summer drought. The CO2 efflux from dry beds (mean ± SE = 209 ± 10 mmol CO2 m−2 d−1) was comparable to that from running waters (120 ± 33 mmol m−2 d−1) and significantly higher than from impounded waters (36.6 ± 8.5 mmol m−2 d−1) and isolated pools (17.2 ± 0.9 mmol m−2 d−1). In contrast, the CH4 efflux did not significantly differ among environments, although the CH4 efflux was notable in some impounded waters (13.9 ± 10.1 mmol CH4 m−2 d−1) and almost negligible in the remaining environments (mean <0.3 mmol m−2 d−1). Diffusion was the only mechanism driving CO2 efflux in all environments and was most likely responsible for CH4 efflux in running waters, isolated pools and dry beds. In contrast, the CH4 efflux in impounded waters was primarily ebullition-based. Using a simple heuristic approach to simulate potential changes in carbon emissions from Mediterranean fluvial networks under future hydrological scenarios, we show that an extreme drying out (i.e., a four-fold increase of the surface area of dry beds) would double the CO2 efflux from the fluvial network. Correspondingly, an extreme transformation of running waters into impounded waters (i.e., a twofold increase of the surface area of impounded waters) would triple the CH4 efflux. Thus, carbon emissions from dry beds and impounded waters should be explicitly considered in carbon assessments of fluvial networks, particularly under predicted global change scenarios, which are expected to increase the spatial and temporal extent of these environments.

  • 220.
    Habiba, G.
    et al.
    Univ Addis Ababa, Ethiopian Inst Water Resources, Addis Ababa, Ethiopia.
    Abebe, G.
    Univ Addis Ababa, Dept Zool Sci, Addis Ababa, Ethiopia.
    Bravo, Andrea G.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Ermias, D.
    Hawassa Univ, Addis Ababa, Ethiopia.
    Staffan, Ǻ.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Bishop, Kevin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Mercury Human Exposure in Populations Living Around Lake Tana (Ethiopia)2017Inngår i: Biological Trace Element Research, ISSN 0163-4984, E-ISSN 1559-0720, Vol. 175, nr 2, s. 237-243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A survey carried out in Lake Tana in 2015 found that Hg levels in some fish species exceeded internationally accepted safe levels for fish consumption. The current study assesses human exposure to Hg through fish consumption around the Lake Tana. Of particular interest was that a dietary intake of fishes is currently a health risk for Bihar Dar residents and anglers. Hair samples were collected from three different groups: anglers, college students and teachers, and daily laborers. A questionary includes gender, age, weight, activity. Frequency of fish consumption and origin of the eaten fish were completed by each participant. Mercury concentrations in hair were significantly higher (P value <0.05) for anglers (mean ± standard deviation 0.120 ± 0.199 μg/g) than college students (mean ± standard deviation 0.018 ± 0.039 μg/g) or daily workers (mean ± standard deviation 16 ± 9.5 ng/g). Anglers consumed fish more often than daily workers and college group. Moreover, there was also a strong correlation (P value <0.05) between the logarithms of total mercury and age associated with mercury concentration in scalp hair. Mercury concentrations in the hair of men were on average twice the value of the women. Also, users of skin lightening soap on a daily basis had 2.5 times greater mercury in scalp hair than non-users. Despite the different sources of mercury exposure mentioned above, the mercury concentrations of the scalp hair of participants of this study were below levels deemed to pose a threat to health.

  • 221.
    Hamilton, Joshua J.
    et al.
    University of Wisconsin—Madison, Madison, USA.
    Garcia, Sarahi L.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Brown, Brittany S.
    University of Wisconsin—Madison, Madison, USA.
    Oyserman, Ben O.
    University of Wisconsin—Madison, Madison, USA.
    Moya-Flores, Francisco
    University of Wisconsin—Madison, Madison, USA.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Malmstrom, Rex R.
    United States Department of Energy Joint Genome Institute, Walnut Creek, USA.
    Forest, Katrina T.
    University of Wisconsin—Madison, Madison, USA.
    McMahon, Katherine D.
    University of Wisconsin—Madison, Madison, USA.
    Metabolic Network Analysis and Metatranscriptomics Reveal Auxotrophies and Nutrient Sources of the Cosmopolitan Freshwater Microbial Lineage acI2017Inngår i: mSystems, E-ISSN 2379-5077, Vol. 2, nr 4, artikkel-id e00091-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An explosion in the number of available genome sequences obtained through metagenomics and single-cell genomics has enabled a new view of the diversity of microbial life, yet we know surprisingly little about how microbes interact with each other or their environment. In fact, the majority of microbial species remain uncultivated, while our perception of their ecological niches is based on reconstruction of their metabolic potential. In this work, we demonstrate how the “seed set framework,” which computes the set of compounds that an organism must acquire from its environment (E. Borenstein, M. Kupiec, M. W. Feldman, and E. Ruppin, Proc Natl Acad Sci U S A 105:14482–14487, 2008, https://doi.org/10.1073/pnas.0806162105 ), enables computational analysis of metabolic reconstructions while providing new insights into a microbe’s metabolic capabilities, such as nutrient use and auxotrophies. We apply this framework to members of the ubiquitous freshwater actinobacterial lineage acI, confirming and extending previous experimental and genomic observations implying that acI bacteria are heterotrophs reliant on peptides and saccharides. We also present the first metatranscriptomic study of the acI lineage, revealing high expression of transport proteins and the light-harvesting protein actinorhodopsin. Putative transport proteins complement predictions of nutrients and essential metabolites while providing additional support of the hypothesis that members of the acI are photoheterotrophs.

  • 222. Hampton, Stephanie E.
    et al.
    Galloway, Aaron W. E.
    Powers, Stephen M.
    Ozersky, Ted
    Woo, Kara H.
    Batt, Ryan D.
    Labou, Stephanie G.
    O’Reilly, Catherine M.
    Sharma, Sapna
    Lottig, Noah R.
    Stanley, Emily H.
    North, Rebecca L.
    Stockwell, Jason D.
    Adrian, Rita
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Arvola, Lauri
    Baulch, Helen M.
    Bertani, Isabella
    Bowman, Larry L.
    Carey, Cayelan C.
    Catalan, Jordi
    Colom-Montero, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Domine, Leah M.
    Felip, Marisol
    Granados, Ignacio
    Gries, Corinna
    Grossart, Hans-Peter
    Haberman, Juta
    Haldna, Marina
    Hayden, Brian
    Higgins, Scott N.
    Jolley, Jeff C.
    Kahilainen, Kimmo K.
    Kaup, Enn
    Kehoe, Michael J.
    MacIntyre, Sally
    Mackay, Anson W.
    Mariash, Heather L.
    McKay, Robert M.
    Nixdorf, Brigitte
    Nõges, Peeter
    Nõges, Tiina
    Palmer, Michelle
    Pierson, Don C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Post, David M.
    Pruett, Matthew J.
    Rautio, Milla
    Read, Jordan S.
    Roberts, Sarah L.
    Rücker, Jacqueline
    Sadro, Steven
    Silow, Eugene A.
    Smith, Derek E.
    Sterner, Robert W.
    Swann, George E. A.
    Timofeyev, Maxim A.
    Toro, Manuel
    Twiss, Michael R.
    Vogt, Richard J.
    Watson, Susan B.
    Whiteford, Erika J.
    Xenopoulos, Marguerite A.
    Ecology under lake ice2017Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 20, nr 1, s. 98-111Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

  • 223. Harrison, John A.
    et al.
    Barros, Nathan
    Bastviken, David
    Deemer, Bridget
    Evans, Christopher
    Grinham, Alistair
    Harby, Atle
    Lovelock, Catherine
    Peacock, Michael
    Prairie, Yves
    Sherman, Bradford
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Dams: weigh pros and cons case by case2019Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 568, nr 7751, s. 171-171Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 224. Hastie, Adam
    et al.
    Lauerwald, Ronny
    Weyhenmeyer, Gesa A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Verpoorter, Charles
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ Lille, Univ Littoral Cole Opale, CNRS, LOG,UMR 8187, Wimereux, France.
    Regnier, Pierre
    CO2 evasion from boreal lakes: Revised estimate, drivers of spatial variability, and future projections2018Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, nr 2, s. 711-728Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lakes (including reservoirs) are an important component of the global carbon (C) cycle, as acknowledged by the 5th assessment report of the IPCC. In the context of lakes, the boreal region is disproportionately important contributing to 27% of the worldwide lake area, despite representing just 14% of global land surface area. In this study, we used a statistical approach to derive a prediction equation for the partial pressure of CO2 (pCO2) in lakes as a function of lake area, terrestrial net primary productivity (NPP) and precipitation (r2 = 0.56), and to create the first high resolution, circumboreal map (0.5) of lake pCO2. The map of pCO2 was combined with lake area from the recently published GLOWABO database and three different estimates of the gas transfer velocity k to produce a resulting map of CO2 evasion (FCO2). For the boreal region we estimate an average, lake area weighted,pCO2 of 966 (678- 1325) μatm and a total FCO2 of 189 (74-347) Tg C yr−1, and evaluate the corresponding uncertainties based on Monte Carlo simulation. Our estimate of FCO2 is approximately twofold greater than previous estimates, as a result of methodological and data source differences. We use our results along with published estimates of the other C fluxes through inland waters to derive a C budget for the boreal region, and find that FCO2 from lakes is the most significant flux of the land-ocean aquatic continuum, and of a similar magnitude as emissions from forest fires. Using the model and applying it to spatially resolved projections of terrestrial NPP and precipitation while keeping everything else constant, we predict a 107% increase in boreal lake FCO2 under emission scenario RCP8.5 by 2100. Our projections are largely driven by increases in terrestrial NPP over the same period, showing the very close connection between the terrestrial and aquatic C cycle.

  • 225.
    Hawkes, Jeffrey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Dittmar, Thorsten
    Carl von Ossietzky Univ Oldenburg, Inst Chem & Biol Marine Environm, Res Grp Marine Geochem, D-26129 Oldenburg, Germany..
    Patriarca, Claudia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Evaluation of the Orbitrap Mass Spectrometer for the Molecular Fingerprinting Analysis of Natural Dissolved Organic Matter2016Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 88, nr 15, s. 7698-7704Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the application of the LTQ-Orbitrap mass spectrometer (LTQ-Velos Pro, Thermo Fisher) for resolving complex mixtures of natural aquatic dissolved organic matter (DOM) and compared this technique to the more established state-of-the-art technique, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS, Bruker Daltonics), in terms of the distribution of molecular masses detected and the reproducibility of the results collected. The Orbitrap was capable of excellent reproducibility: Bray-Curtis dissimilarity between duplicate measurements was 2.85 +/- 0.42% (mean +/- standard deviation). The Orbitrap was also capable of the detection of most major ionizable organic molecules in typical aquatic mixtures, with the exception of most sulfur and phosphorus containing masses. This result signifies that the Orbitrap is an appropriate technique for the investigation of very subtle biogeochemical processing of bulk DOM. The lower costs (purchase and maintenance) and wider availability of Orbitrap mass spectrometers in university departments means that the tools necessary for research into DOM processing at the molecular level should be accessible to a much wider group of scientists than before. The main disadvantage of the technique is that substantially fewer molecular formulas can be resolved from a complex mixture (roughly one third as many), meaning some loss of information. In balance, most biogeochemical studies that aim at molecularly fingerprinting the source of natural DOM could be satisfactorily carried out with Orbitrap mass spectrometry. For more targeted metabolomic studies where individual compounds are traced through natural systems, FTICR-MS remains advantageous.

  • 226.
    Hawkes, Jeffrey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Patriarca, Claudia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Sjöberg, Per J. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Extreme isomeric complexity of dissolved organic matter found across aquatic environments2018Inngår i: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 3, nr 2, s. 21-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The natural aquatic environment contains an enormous pool of dissolved reduced carbon, present as ultra‐complex mixtures that are constituted by an unknown number of compounds at vanishingly small concentrations. We attempted to separate individual structural isomers from several samples using online reversed‐phase chromatography with selected ion monitoring/tandem mass spectrometry, but found that isomeric complexity still presented a boundary to investigation even after chromatographic simplification of the samples. However, it was possible to determine that the structural complexity differed among samples. Our results also suggest that extreme structural complexity was a ubiquitous feature of dissolved organic matter (DOM) in all aquatic systems, meaning that this diversity may play similar roles for recalcitrance and degradation of DOM in all tested environments.

  • 227.
    Hawkes, Jeffrey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Radoman, Nikola
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi. Stockholm Univ, Dept Environm Sci & Analyt Chem, Stockholm, Sweden.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Wallin, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Löfgren, Stefan
    Swedish Univ Agr Sci SLU, Dept Aquat Sci & Assessment, Sect Geochem & Hydrol, Uppsala, Sweden.
    Regional diversity of complex dissolved organic matter across forested hemiboreal headwater streams2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, nr 1, artikkel-id 16060Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dissolved organic matter (DOM) from soils enters the aquatic environment via headwater streams. Thereafter, it is gradually transformed, removed by sedimentation, and mineralised. Due to the proximity to the terrestrial source and short water residence time, the extent of transformation is minimal in headwaters. DOM has variable composition across inland waters, but the amount of variability in the terrestrial end member is unknown. This gap in knowledge is crucial considering the potential impact large variability would have on modelling DOM degradation. Here, we used a novel liquid chromatography –mass spectrometry method to characterise DOM in 74 randomly selected, forested headwater streams in an 87,000 km2 region of southeast Sweden. We found a large degree of sample similarity across this region, with Bray-Curtis dissimilarity values averaging 8.4 ± 3.0% (mean ± SD). The identified variability could be reduced to two principle coordinates, correlating to varying groundwater flow-paths and regional mean temperature. Our results indicate that despite reproducible effects of groundwater geochemistry and climate, the composition of DOM is remarkably similar across catchments already as it leaves the terrestrial environment, rather than becoming homogeneous as different headwaters and sub-catchments mix.

  • 228.
    Hawkes, Jeffrey A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Sjöberg, Per J. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Analytisk kemi.
    Tranvik, Lars
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Complexity of dissolved organic matter in the molecular size dimension: insights from coupled size exclusion chromatography electrospray ionisation mass spectrometry2019Inngår i: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 218, s. 52-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper investigates the relationship between apparent size distribution and molecular complexity of dissolved organic matter from the natural environment. We used a high pressure size exclusion chromatography (HPSEC) method coupled to UV-Vis diode array detection (UV-DAD) and electrospray ionisation mass spectrometry (ESI-MS) in order to compare the apparent size of natural organic matter, determined by HPSEC-UV and the molecular mass determined online by ESI-MS. We found that there was a clear discrepancy between the two methods, and found evidence for an important pool of organic matter that has a strong UV absorbance and no ESI-MS signal. Contrary to some previous research, we found no evidence that apparently high molecular weight organic matter is constituted by aggregates of low molecular weight (<1000 Da) material. Furthermore, our results suggest that the majority of apparent size variability within the ESI ionisable pool of organic matter is due to secondary interaction and exclusion effects on the HPSEC column, and not true differences in hydrodynamic size or intermolecular aggregation.

  • 229. He, Shaomei
    et al.
    Ivanova, Natalia
    Kirton, Edward
    Allgaier, Martin
    Bergin, Claudia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Scheffrahn, Rudolf H.
    Kyrpides, Nikos C.
    Warnecke, Falk
    Tringe, Susannah G.
    Hugenholtz, Philip
    Comparative Metagenomic and Metatranscriptomic Analysis of Hindgut Paunch Microbiota in Wood- and Dung-Feeding Higher Termites2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 4, s. e61126-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Termites effectively feed on many types of lignocellulose assisted by their gut microbial symbionts. To better understand the microbial decomposition of biomass with varied chemical profiles, it is important to determine whether termites harbor different microbial symbionts with specialized functionalities geared toward different feeding regimens. In this study, we compared the microbiota in the hindgut paunch of Amitermes wheeleri collected from cow dung and Nasutitermes corniger feeding on sound wood by 16S rRNA pyrotag, comparative metagenomic and metatranscriptomic analyses. We found that Firmicutes and Spirochaetes were the most abundant phyla in A. wheeleri, in contrast to N. corniger where Spirochaetes and Fibrobacteres dominated. Despite this community divergence, a convergence was observed for functions essential to termite biology including hydrolytic enzymes, homoacetogenesis and cell motility and chemotaxis. Overrepresented functions in A. wheeleri relative to N. corniger microbiota included hemicellulose breakdown and fixed-nitrogen utilization. By contrast, glycoside hydrolases attacking celluloses and nitrogen fixation genes were overrepresented in N. corniger microbiota. These observations are consistent with dietary differences in carbohydrate composition and nutrient contents, but may also reflect the phylogenetic difference between the hosts.

  • 230.
    He, Shaomei
    et al.
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA.;Univ Wisconsin, Dept Geosci, Madison, WI USA..
    Stevens, Sarah L. R.
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA..
    Chan, Leong-Keat
    DOE Joint Genome Inst, Walnut Creek, CA USA..
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    del Rio, Tijana Glavina
    DOE Joint Genome Inst, Walnut Creek, CA USA..
    Tringe, Susannah G.
    DOE Joint Genome Inst, Walnut Creek, CA USA..
    Malmstrom, Rex R.
    DOE Joint Genome Inst, Walnut Creek, CA USA..
    McMahon, Katherine D.
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA.;Univ Wisconsin, Dept Civil & Environm Engn, Madison, WI 53706 USA..
    Ecophysiology of Freshwater Verrucomicrobia Inferred from Metagenome-Assembled Genomes2017Inngår i: MSPHERE, ISSN 2379-5042, Vol. 2, nr 5, artikkel-id e00277-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microbes are critical in carbon and nutrient cycling in freshwater ecosystems. Members of the Verrucomicrobia are ubiquitous in such systems, and yet their roles and ecophysiology are not well understood. In this study, we recovered 19 Verrucomicrobia draft genomes by sequencing 184 time-series metagenomes from a eutrophic lake and a humic bog that differ in carbon source and nutrient availabilities. These genomes span four of the seven previously defined Verrucomicrobia subdivisions and greatly expand knowledge of the genomic diversity of freshwater Verrucomicrobia. Genome analysis revealed their potential role as (poly) saccharide degraders in freshwater, uncovered interesting genomic features for this lifestyle, and suggested their adaptation to nutrient availabilities in their environments. Verrucomicrobia populations differ significantly between the two lakes in glycoside hydrolase gene abundance and functional profiles, reflecting the autochthonous and terrestrially derived allochthonous carbon sources of the two ecosystems, respectively. Interestingly, a number of genomes recovered from the bog contained gene clusters that potentially encode a novel porin-multiheme cytochrome c complex and might be involved in extracellular electron transfer in the anoxic humus-rich environment. Notably, most epilimnion genomes have large numbers of so-called "Planctomycete-specific" cytochrome c-encoding genes, which exhibited distribution patterns nearly opposite to those seen with glycoside hydrolase genes, probably associated with the different levels of environmental oxygen availability and carbohydrate complexity between lakes/layers. Overall, the recovered genomes represent a major step toward understanding the role, ecophysiology, and distribution of Verrucomicrobia in freshwater. IMPORTANCE Freshwater Verrucomicrobia spp. are cosmopolitan in lakes and rivers, and yet their roles and ecophysiology are not well understood, as cultured freshwater Verrucomicrobia spp. are restricted to one subdivision of this phylum. Here, we greatly expanded the known genomic diversity of this freshwater lineage by recovering 19 Verrucomicrobia draft genomes from 184 metagenomes collected from a eutrophic lake and a humic bog across multiple years. Most of these genomes represent the first freshwater representatives of several Verrucomicrobia subdivisions. Genomic analysis revealed Verrucomicrobia to be potential (poly) saccharide degraders and suggested their adaptation to carbon sources of different origins in the two contrasting ecosystems. We identified putative extracellular electron transfer genes and so-called " Planctomycete-specific" cytochrome c-encoding genes and identified their distinct distribution patterns between the lakes/layers. Overall, our analysis greatly advances the understanding of the function, ecophysiology, and distribution of freshwater Verrucomicrobia, while highlighting their potential role in freshwater carbon cycling.

  • 231.
    Heinrich, Friederike
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Abundance and diveristy of Alphaproteobacteria in the Southern Ocean: the dark side of SAR11Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Alphaproteobacteria represented by lineages such as SAR11 and Roseobacter are ubiquitous and often dominant in marine bacterioplankton communities. The Southern Ocean is no exception even if annual extremes in light regime and autochthonous inputs of organic substrates present an environment that are in many ways very different from other oceanic regions. Using population mapping and community analysis of bacterioplankton during the highly dynamic summer season within the Ross and Amundsen Seas, in combination with experimental incubations under contrasting light regimes, we studied the impact of solar radiation and other environmental factors on individual lineages and populations within class Alphaproteobacteria. Quantitative population tracking by fluorescence in-situ hybridization was combined with pyrosequencing-derived 16S rRNA gene inventories to resolve the community beyond class and abundant lineages. Both experiments and depth-resolved distribution patterns confirm SAR11 as a major component of the bacterial community regardless of water mass and depth. However, the experiments revealed that SAR11 as a lineage was less competitive under solar-exposed conditions whereas the opposite response was observed for Roseobacter. Resolving the SAR11 linage into subclades, clear partitioning of groups between the different water masses and light regimes was observed. Also the diversity within the SAR11 lineage varied with significantly higher richness in the deeper, permanently dark water masses. Using this abundant marine bacterial lineage as a model, we could demonstrate clear separation of closely related bacterial populations between water masses and along environmental gradients of light exposure, oxygen availability, phytoplankton and nutrients. It is evident that such ecologically coherent populations can only be tracked at high phylogenetic resolution and that ecological and evolutionary mechanisms underpinning the observed phylogeographic patterns differ between water masses in the Southern Ocean. 

  • 232.
    Heinrich, Friederike
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Alteration of lake bacterioplankton diversity and community composition during lake stratification and gradual oxygen depletionManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Hypolimnetic waters of many stratifying lakes experience gradual oxygen depletion and seasonal hypoxia as organic matter is degraded with oxygen as terminal electron acceptor. Such changes are known to have dramatic effects on larger organisms, but also resident microbiota are likely to be affected by altered availability of oxygen, nutrients and other chemical constituents. We explored how such seasonal shifts in water mass characteristics influenced the resident bacterioplankton in a mesotrophic temperate lake by tracing the temporal dynamics of bacterial communities and populations at different phylogenetic resolution across the entire period of summer stratification. Compared to the epilimnion, bacterial richness was significantly higher in the hypolimnion where varying hypoxia was also reflected in higher beta diversity. Many abundant groups of freshwater bacteria, such as Actinobacteria acI, Polynucleobacter and freshwater SAR11 (LD12), were abundant in both the epi- and hypolimnion, with distinct temporal and vertical population shifts observed at the 97% population identity level. The mechanisms that lead to closely related populations partitioning into ecotypes are not well understood, but are probably due to fine-tuned physiological adaptions towards oxygen and nutrient concentrations in the lake. The existence of ecotypes partitioned by oxygen availability and the seasonal succession in hypolimnetic bacteria driven by gradual oxygen depletion and associated changes in water chemistry merits further studies on their implications for biogeochemical cycles.

  • 233.
    Heinrich, Friederike
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Drivers of Population Dynamics in Bacterioplankton: Spotlight on Alphaproteobacteria and its dominant SAR11 Lineage2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Bacteria are mediators of biogeochemical cycles and are in this way vital for maintaining life on earth. Their distribution, abundance and functioning are driven by environmental heterogeneity and dynamic change in abiotic and biotic factors. Both, freshwater lakes and oceans play central roles in the global carbon cycle and bacteria in these systems perform many services for the ecosystems, such as the transfer of organic carbon from primary producers to higher trophic levels. With estimated relative abundances up to 50% of the total bacterioplankton, the Alphaproteobacteria lineage SAR11 is the most abundant group of aquatic bacteria. It is globally distributed and can be partitioned into multiple sub-clades, one of which is exclusive to freshwaters. Until recently, the distribution, abundance and ecological role of this freshwater SAR11 named LD12 was unknown. The aim of the thesis was to study the drivers and mechanisms that influence the dynamics of aquatic bacterial communities in general and the SAR11 and LD12 groups in particular. The thesis consists of environmental surveys of a mesotrophic Lake Erken and the western Southern Ocean, an experiment and a data-mining exercise to reveal the phylogenetic structure of the SAR11 lineage on various temporal and spatial scales. The analysis of a long-term bacterioplankton community survey in lake Erken provided insights about the dynamics of the entire bacterial community and the LD12 population over an annual cycle. The results demonstrate that LD12 can be an equally abundant member of freshwater communities as marine SAR11 in oceans. LD12 featured strong seasonality and was positively coupled to environmental conditions indicative for an oligotrophic lifestyle. LD12 as well as other dominant lake bacterioplankton also maintained stable populations throughout spatial and temporal varying environments, but at high phylogenetic resolution, habitat preferences were revealed, particularly in response to oxygen concentrations. The later was not the case in LD12 as a single ribotype dominated. This is in stark contrast to the habitat partitioning with light availability, depth and water masses observed for marine SAR11 subclades in the Southern Ocean. The global data-mining corroborated that LD12 as a group was much less diverse than SAR11 furthermore, suggesting that the marine-freshwater barrier acted as a population bottleneck. My work shows that bacterial populations can respond in very different ways to environmental drivers, highlight the importance of highly resolved temporal and spatial scales as well as the need for high phylogenetic resolutions to target ecologically coherent populations.

    Delarbeid
    1. Infrequent Transitions between Saline and Fresh Waters in One of the Most Abundant Microbial Lineages (SAR11)
    Åpne denne publikasjonen i ny fane eller vindu >>Infrequent Transitions between Saline and Fresh Waters in One of the Most Abundant Microbial Lineages (SAR11)
    Vise andre…
    2010 (engelsk)Inngår i: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 27, nr 2, s. 347-357Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The aquatic bacterial group SAR11 is one of the most abundant organisms on Earth, with an estimated global population size of 2.4 x 10(28) cells in the oceans. Members of SAR11 have also been detected in brackish and fresh waters, but the evolutionary relationships between the species present in the different environments have been ambiguous. In particular, it was not clear how frequently this lineage has crossed the saline-freshwater boundary during its evolutionary diversification. Due to the huge population size of SAR11 and the potential of microbes for long-distance dispersal, we hypothesized that environmental transitions could have occurred repeatedly during the evolutionary diversification of this group. Here, we have constructed extensive 16S rDNA-based molecular phylogenies and undertaken metagenomic data analyses to assess the frequency of saline-freshwater transitions in SAR11 and to investigate the evolutionary implications of this process. Our analyses indicated that very few saline-freshwater transitions occurred during the evolutionary diversification of SAR11, generating genetically distinct saline and freshwater lineages that do not appear to exchange genes extensively via horizontal gene transfer. In contrast to lineages from saline environments, extant freshwater taxa from diverse, and sometimes distant, geographic locations were very closely related. This points to a rapid diversification and dispersal in fresh waters or to slower evolutionary rates in fresh water SAR11 when compared with marine counterparts. In addition, the colonization of both saline and fresh waters appears to have occurred early in the evolution of SAR11. We conclude that the different biogeochemical conditions that prevail in saline and fresh waters have likely prevented the environmental transitions in SAR11, promoting the evolution of clearly distinct lineages in each environment.

    Emneord
    environmental transitions, prokaryotes, saline, freshwater, SAR11, 16S rDNA
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-137815 (URN)10.1093/molbev/msp239 (DOI)000273704400013 ()
    Tilgjengelig fra: 2010-12-17 Laget: 2010-12-16 Sist oppdatert: 2017-12-11bibliografisk kontrollert
    2. Abundance and diveristy of Alphaproteobacteria in the Southern Ocean: the dark side of SAR11
    Åpne denne publikasjonen i ny fane eller vindu >>Abundance and diveristy of Alphaproteobacteria in the Southern Ocean: the dark side of SAR11
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Alphaproteobacteria represented by lineages such as SAR11 and Roseobacter are ubiquitous and often dominant in marine bacterioplankton communities. The Southern Ocean is no exception even if annual extremes in light regime and autochthonous inputs of organic substrates present an environment that are in many ways very different from other oceanic regions. Using population mapping and community analysis of bacterioplankton during the highly dynamic summer season within the Ross and Amundsen Seas, in combination with experimental incubations under contrasting light regimes, we studied the impact of solar radiation and other environmental factors on individual lineages and populations within class Alphaproteobacteria. Quantitative population tracking by fluorescence in-situ hybridization was combined with pyrosequencing-derived 16S rRNA gene inventories to resolve the community beyond class and abundant lineages. Both experiments and depth-resolved distribution patterns confirm SAR11 as a major component of the bacterial community regardless of water mass and depth. However, the experiments revealed that SAR11 as a lineage was less competitive under solar-exposed conditions whereas the opposite response was observed for Roseobacter. Resolving the SAR11 linage into subclades, clear partitioning of groups between the different water masses and light regimes was observed. Also the diversity within the SAR11 lineage varied with significantly higher richness in the deeper, permanently dark water masses. Using this abundant marine bacterial lineage as a model, we could demonstrate clear separation of closely related bacterial populations between water masses and along environmental gradients of light exposure, oxygen availability, phytoplankton and nutrients. It is evident that such ecologically coherent populations can only be tracked at high phylogenetic resolution and that ecological and evolutionary mechanisms underpinning the observed phylogeographic patterns differ between water masses in the Southern Ocean. 

    Emneord
    Southern Ocean, Alphaproteobacteria, SAR11, Roseobacter, community composition, solar radiation
    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot evolutionär genetik
    Identifikatorer
    urn:nbn:se:uu:diva-245066 (URN)
    Tilgjengelig fra: 2015-02-24 Laget: 2015-02-24 Sist oppdatert: 2015-04-17
    3. Seasonality and environmental control of freshwater SAR11 (LD12) in a temperate lake (Lake Erken, Sweden)
    Åpne denne publikasjonen i ny fane eller vindu >>Seasonality and environmental control of freshwater SAR11 (LD12) in a temperate lake (Lake Erken, Sweden)
    2013 (engelsk)Inngår i: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 70, nr 1, s. 33-44Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    THE SAR11 clade is ubiquitous and abundant in planktonic environments. In freshwater lakes, the clade is represented by tribe LD12 which is phylogenetically distinct from the marine SAR11. We studied the ecology of LD12 in a temperate dimictic lake (Lake Erken, Sweden), by analyzing its seasonal dynamics with quantitative PCR, CARD-FISH and 454 pyrosequencing of the 16S rRNA gene. Results showed that LD12 can be as numerous in freshwater bacterioplankton as their marine SAR11 siblings. They exhibited strong seasonality and made up from 1.8 to 40% of the total bacterial 16S rRNA pool (mean 14%) with pronounced peaks in summer and late fall. Except in spring, LD12 was the dominant Alphaproteobacteria, contributing on average 72% of the 16S rRNA within this class. The LD12 population was dominated by a single persistent ribotype, suggesting low local divergence, at least at the phylogenetic resolution accessed with rRNA genes. The relative abundance of LD12 was positively correlated to nutrient concentrations (phosphate, ammonia, nitrate, and silica) and water transparency whereas the relative abundance was lower during periods characterized by high phytoplankton biomass. Based on these observations we propose that LD12 are poor competitors during periods of high phytoplankton productivity and associated release of labile organic compounds, but thrive when availability of inorganic nutrients is high. Similar to the marine SAR11 sibling group, local LD12 populations appear to respond in contrasting ways to nutrient availability in different lakes, pointing to either ecological divergence within the tribe or variations in the interplay between environmental driver variables.

    Emneord
    LD12, Freshwater SAR11, Alphaproteobacteria, Seasonal dynamics, Quantitative PCR, 454 Pyrosequencing, CARD-FISH, 16S rRNA
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-207118 (URN)10.3354/ame01637 (DOI)000322999500003 ()
    Tilgjengelig fra: 2013-09-10 Laget: 2013-09-09 Sist oppdatert: 2017-12-06bibliografisk kontrollert
    4. Alteration of lake bacterioplankton diversity and community composition during lake stratification and gradual oxygen depletion
    Åpne denne publikasjonen i ny fane eller vindu >>Alteration of lake bacterioplankton diversity and community composition during lake stratification and gradual oxygen depletion
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Hypolimnetic waters of many stratifying lakes experience gradual oxygen depletion and seasonal hypoxia as organic matter is degraded with oxygen as terminal electron acceptor. Such changes are known to have dramatic effects on larger organisms, but also resident microbiota are likely to be affected by altered availability of oxygen, nutrients and other chemical constituents. We explored how such seasonal shifts in water mass characteristics influenced the resident bacterioplankton in a mesotrophic temperate lake by tracing the temporal dynamics of bacterial communities and populations at different phylogenetic resolution across the entire period of summer stratification. Compared to the epilimnion, bacterial richness was significantly higher in the hypolimnion where varying hypoxia was also reflected in higher beta diversity. Many abundant groups of freshwater bacteria, such as Actinobacteria acI, Polynucleobacter and freshwater SAR11 (LD12), were abundant in both the epi- and hypolimnion, with distinct temporal and vertical population shifts observed at the 97% population identity level. The mechanisms that lead to closely related populations partitioning into ecotypes are not well understood, but are probably due to fine-tuned physiological adaptions towards oxygen and nutrient concentrations in the lake. The existence of ecotypes partitioned by oxygen availability and the seasonal succession in hypolimnetic bacteria driven by gradual oxygen depletion and associated changes in water chemistry merits further studies on their implications for biogeochemical cycles.

    Emneord
    hypolimnion, Bacteria, Community Composition, Diversity, Hypoxia, Dynamics, Indicator, Habitat
    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot evolutionär genetik; Biologi med inriktning mot limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-245068 (URN)
    Tilgjengelig fra: 2015-02-24 Laget: 2015-02-24 Sist oppdatert: 2015-04-17
    5. Coherent dynamics and association networks among lake bacterioplankton taxa
    Åpne denne publikasjonen i ny fane eller vindu >>Coherent dynamics and association networks among lake bacterioplankton taxa
    2012 (engelsk)Inngår i: The ISME Journal: multidisciplinary journal of microbial ecology, ISSN 1751-7362, Vol. 6, nr 2, s. 330-342Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Bacteria have important roles in freshwater food webs and in the cycling of elements in the ecosystem. Yet specific ecological features of individual phylogenetic groups and interactions among these are largely unknown. We used 454 pyrosequencing of 16S rRNA genes to study associations of different bacterioplankton groups to environmental characteristics and their co-occurrence patterns over an annual cycle in a dimictic lake. Clear seasonal succession of the bacterioplankton community was observed. After binning of sequences into previously described and highly resolved phylogenetic groups (tribes), their temporal dynamics revealed extensive synchrony and associations with seasonal events such as ice coverage, ice-off, mixing and phytoplankton blooms. Coupling between closely and distantly related tribes was resolved by time-dependent rank correlations, suggesting ecological coherence that was often dependent on taxonomic relatedness. Association networks with the abundant freshwater Actinobacteria and Proteobacteria in focus revealed complex interdependencies within bacterioplankton communities and contrasting linkages to environmental conditions. Accordingly, unique ecological features can be inferred for each tribe and reveal the natural history of abundant cultured and uncultured freshwater bacteria.

    Emneord
    freshwater, 454 pyrosequencing, 16S rRNA, phylogenetic tribes, bacteria
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-171679 (URN)10.1038/ismej.2011.113 (DOI)000300984200011 ()
    Tilgjengelig fra: 2012-03-26 Laget: 2012-03-25 Sist oppdatert: 2016-04-22bibliografisk kontrollert
  • 234.
    Heinrich, Friederike
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eiler, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Seasonality and environmental control of freshwater SAR11 (LD12) in a temperate lake (Lake Erken, Sweden)2013Inngår i: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 70, nr 1, s. 33-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    THE SAR11 clade is ubiquitous and abundant in planktonic environments. In freshwater lakes, the clade is represented by tribe LD12 which is phylogenetically distinct from the marine SAR11. We studied the ecology of LD12 in a temperate dimictic lake (Lake Erken, Sweden), by analyzing its seasonal dynamics with quantitative PCR, CARD-FISH and 454 pyrosequencing of the 16S rRNA gene. Results showed that LD12 can be as numerous in freshwater bacterioplankton as their marine SAR11 siblings. They exhibited strong seasonality and made up from 1.8 to 40% of the total bacterial 16S rRNA pool (mean 14%) with pronounced peaks in summer and late fall. Except in spring, LD12 was the dominant Alphaproteobacteria, contributing on average 72% of the 16S rRNA within this class. The LD12 population was dominated by a single persistent ribotype, suggesting low local divergence, at least at the phylogenetic resolution accessed with rRNA genes. The relative abundance of LD12 was positively correlated to nutrient concentrations (phosphate, ammonia, nitrate, and silica) and water transparency whereas the relative abundance was lower during periods characterized by high phytoplankton biomass. Based on these observations we propose that LD12 are poor competitors during periods of high phytoplankton productivity and associated release of labile organic compounds, but thrive when availability of inorganic nutrients is high. Similar to the marine SAR11 sibling group, local LD12 populations appear to respond in contrasting ways to nutrient availability in different lakes, pointing to either ecological divergence within the tribe or variations in the interplay between environmental driver variables.

  • 235.
    Heinrich, Kristina
    et al.
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, Sci Life Lab, Stockholm, Sweden.
    Leslie, David J.
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, Sci Life Lab, Stockholm, Sweden.
    Morlock, Michaela
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, Sci Life Lab, Stockholm, Sweden.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Jonas, Kristina
    Stockholm Univ, Wenner Gren Inst, Dept Mol Biosci, Sci Life Lab, Stockholm, Sweden.
    Molecular Basis and Ecological Relevance of Caulobacter Cell Filamentation in Freshwater Habitats2019Inngår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 10, nr 4, artikkel-id e01557-19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    All living cells are characterized by certain cell shapes and sizes. Many bacteria can change these properties depending on the growth conditions. The underlying mechanisms and the ecological relevance of changing cell shape and size remain unclear in most cases. One bacterium that undergoes extensive shape-shifting in response to changing growth conditions is the freshwater bacterium Caulobacter crescentus. When incubated for an extended time in stationary phase, a subpopulation of C. crescentus forms viable filamentous cells with a helical shape. Here, we demonstrated that this stationary-phase-induced filamentation results from downregulation of most critical cell cycle regulators and a consequent block of DNA replication and cell division while cell growth and metabolism continue. Our data indicate that this response is triggered by a combination of three stresses caused by prolonged growth in complex medium, namely, the depletion of phosphate, alkaline pH, and an excess of ammonium. We found that these conditions are experienced in the summer months during algal blooms near the surface in freshwater lakes, a natural habitat of C. crescentus, suggesting that filamentous growth is a common response of C. crescentus to its environment. Finally, we demonstrate that when grown in a biofilm, the filamentous cells can reach beyond the surface of the biofilm and potentially access nutrients or release progeny. Altogether, our work highlights the ability of bacteria to alter their morphology and suggests how this behavior might enable adaptation to changing environments.

    IMPORTANCE Many bacteria drastically change their cell size and morphology in response to changing environmental conditions. Here, we demonstrate that the freshwater bacterium Caulobacter crescentus and related species transform into filamentous cells in response to conditions that commonly occur in their natural habitat as a result of algal blooms during the warm summer months. These filamentous cells may be better able to scavenge nutrients when they grow in biofilms and to escape from protist predation during planktonic growth. Our findings suggest that seasonal changes and variations in the microbial composition of the natural habitat can have profound impact on the cell biology of individual organisms. Furthermore, our work highlights that bacteria exist in morphological and physiological states in nature that can strongly differ from those commonly studied in the laboratory.

  • 236. Henche, Anna-Lena
    et al.
    Ghosh, Abhrajyoti
    Yu, Xiong
    Jeske, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Egelman, Edward
    Albers, Sonja-Verena
    Structure and function of the adhesive type IV pilus of Sulfolobus acidocaldarius2012Inngår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 14, nr 12, s. 3188-3202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Archaea display a variety of type IV pili on their surface and employ them in different physiological functions. In the crenarchaeon Sulfolobus acidocaldarius the most abundant surface structure is the aap pilus (archaeal adhesive pilus). The construction of in frame deletions of the aap genes revealed that all the five genes (aapA, aapX, aapE, aapF, aapB) are indispensible for assembly of the pilus and an impact on surface motility and biofilm formation was observed. Our analyses revealed that there exists a regulatory cross-talk between the expression of aap genes and archaella (formerly archaeal flagella) genes during different growth phases. The structure of the aap pilus is entirely different from the known bacterial type IV pili as well as other archaeal type IV pili. An aap pilus displayed 3 stranded helices where there is a rotation per subunit of ∼ 138° and a rise per subunit of ∼ 5.7 Å. The filaments have a diameter of ∼ 110 Å and the resolution was judged to be ∼ 9 Å. We concluded that small changes in sequence might be amplified by large changes in higher-order packing. Our finding of an extraordinary stability of aap pili possibly represents an adaptation to harsh environments that S. acidocaldarius encounters.

  • 237. Herlemann, Daniel P. R.
    et al.
    Labrenz, Matthias
    Juergens, Klaus
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Waniek, Joanna J.
    Andersson, Anders F.
    Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea2011Inngår i: The ISME Journal, ISSN 1751-7362, Vol. 5, nr 10, s. 1571-1579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater-freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.

  • 238.
    Herrero Ortega, Sonia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. Leibniz Inst Freshwater Ecol & Inland Fisheries I, Dept Expt Limnol, Stechlin, Germany.
    Catalán, Núria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab. Catalan Inst Water Res ICRA, Girona, Spain.
    Björn, Erik
    Gröntoft, Hannes
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Hilmarsson, Torfi Geir
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Wu, Pianpian
    Bishop, Kevin
    Levanoni, Oded
    Bravo, Andrea Garcia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    High methylmercury formation in ponds fueled by fresh humic and algal derived organic matter2018Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, nr S1, s. S44-S53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neurotoxic methylmercury causes adverse effects to ecosystem viability and human health. Previous studies have revealed that ponding alters natural organic matter (NOM) composition and increase methylmercury concentrations in rivers, especially in the first years after flooding. Here, we investigate the influence of NOM composition (i.e., sources and degradation status) on mercury methylation rate constants in nine boreal beaver ponds of different ages across Sweden.We show that increased methylmercury concentrations in surface waters is a consequence of enhanced mercury methylation in the pond sediments. Moreover, our results reveal that during the first years after the initial flooding, mercury methylation rates are fueled by the amount of fresh humic substances released from the flooded soils and by an increased production of algal-derived NOM triggered by enhanced nutrient availability. Our findings indicate that impoundment-induced changes in NOM composition control mercury methylation processes, causing the raise in MeHg levels in ponds.

  • 239. Hillebrand, Helmut
    et al.
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Lebret, Karen
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Striebel, Maren
    Decomposing multiple dimensions of stability in global change experiments2018Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, nr 1, s. 21-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ecological stability is the central framework to understand an ecosystem's ability to absorb or recover from environmental change. Recent modelling and conceptual work suggests that stability is a multidimensional construct comprising different response aspects. Using two freshwater mesocosm experiments as case studies, we show how the response to single perturbations can be decomposed in different stability aspects (resistance, resilience, recovery, temporal stability) for both ecosystem functions and community composition. We find that extended community recovery is tightly connected to a nearly complete recovery of the function (biomass production), whereas systems with incomplete recovery of the species composition ranged widely in their biomass compared to controls. Moreover, recovery was most complete when either resistance or resilience was high, the latter associated with low temporal stability around the recovery trend. In summary, no single aspect of stability was sufficient to reflect the overall stability of the system.

  • 240. Hilt, Sabine
    et al.
    Wanke, Thomas
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Brauns, Mario
    Syväranta, Jari
    Brothers, Soren
    Gaedke, Ursula
    Köhler, Jan
    Lischke, Betty
    Mehner, Thomas
    Contrasting response of two shallow eutrophic cold temperate lakes to a partial winterkill of fish2015Inngår i: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 749, nr 1, s. 31-42Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Food-web effects of winterkill are difficult to predict as the enhanced mortality of planktivorous fish may be counterbalanced by an even higher mortality of piscivores. We hypothesised that a winterkill in a clear and a turbid shallow lake would equalise their fish community composition, but seasonal plankton successions would differ between lakes. After a partial winterkill, we observed a reduction of fish biomass by 16 and 43% in a clear-water and a turbid small temperate lake, respectively. Fish biomass and piscivore shares (5% of fish biomass) were similar in both lakes after this winterkill, but young-of-the-year (YOY) abundances were higher in the turbid lake. Top-down control by crustaceans was only partly responsible for low phytoplankton biomass at the end of May following the winterkill in both lakes. Summer phytoplankton biomass remained low in the clear-water lake despite high abundances of YOY fish (mainly roach). In contrast, the crustacean biomass of the turbid lake was reduced in summer by a high YOY abundance (sunbleak and roach), leading to a strong increase in phytoplankton biomass. The YOY abundance of fish in shallow eutrophic lakes may thus be more important for their summer phytoplankton development after winterkill than the relative abundance of piscivores.

  • 241. Hinrichsen, H. -H
    et al.
    Petereit, C
    von Dewitz, B
    Haslob, H
    Ustups, D
    Florin, A. -B
    Nissling, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Biophysical modeling of survival and dispersal of Central and Eastern Baltic Sea flounder (Platichthys flesus) larvae2018Inngår i: Journal of Sea Research, ISSN 1385-1101, Vol. 142, s. 11-20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The period of larval drift into a suitable nursery area is considered to be of great significance for recruitment variability in flatfish. Here, a hydrodynamic model coupled with a Lagrangian particle tracking technique was utilized to study the drift from the first feeding larval stage until time of settlement of Central and Eastern Baltic flounder (Platichthys flesus), originating from spawning in the Baltic Sea deep basins, the Arkona- and Bornholm basin (central Baltic Sea), and the Gdansk deep and Gotland basin (eastern Baltic Sea). We examined the spatio-temporal dynamics of the probability to settle in preferred nursery habitat by detailed drift model simulations. The study suggests that the majority of larvae (89% and 74% for Central- and Eastern Baltic flounder, respectively) drift towards coastal areas and settle at metamorphosis ≤20 km from a sandy habitat enabling further migration to a preferred nursery area, i.e. larval drift seems not to be a major bottleneck in recruitment of flounder spawning in the Baltic Sea deep basins. The drift model results suggest that Central Baltic flounder utilize nursery areas mainly in the central and western Baltic, and in the Kattegat, whereas Eastern Baltic flounder mainly utilize the coast in the central and eastern Baltic. Thus, the two stock components seem to use different nursery areas following settlement. Further, in accordance with the “nursery size hypothesis”, the model demonstrates that larvae from the Bornholm basin, utilizing areas with extensive distribution of preferred nursery habitat, display the highest relative successful transport to nursery grounds until settling (72% of successfully settled larvae), suggesting that spawning in the Bornholm Basin is of great importance for stock recruitment of deep basin spawning Baltic flounder.

  • 242.
    Hinrichsen, Hans-Harald
    et al.
    GEOMAR Helmholtz Ctr Ocean Res Kiel, Dusternbrooker Weg 20, D-24105 Kiel, Germany..
    Petereit, Christoph
    GEOMAR Helmholtz Ctr Ocean Res Kiel, Dusternbrooker Weg 20, D-24105 Kiel, Germany..
    Nissling, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wallin, Isa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik.
    Ustups, Didzis
    Inst Food Safety Anim Hlth & Environm BIOR, Daugavgrivas Str 8, LV-1048 Riga, Latvia..
    Florin, Ann-Britt
    Swedish Univ Agr Sci, Dept Aquat Resources, Inst Coastal Res, Skolgatan 6, S-74242 Oregrund, Sweden..
    Survival and dispersal variability of pelagic eggs and yolk-sac larvae of central and eastern baltic flounder (Platichthys flesus): application of biophysical models2017Inngår i: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 74, nr 1, s. 41-55Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hydrodynamic model coupled with a Lagrangian particle tracking technique was utilized to simulate spatially and temporally resolved long-term environmentally related (i) size of habitat suitable for reproduction, (ii) egg/yolk-sac larval survival, (iii) separation of causes of mortality, and (iv) connectivity between spawning areas of Baltic flounder with pelagiceggs. Information on reproduction habitat requirements and mortality sources were obtained from field or laboratory studies. In our modelling study we only quantified physical processes generating heterogeneity in spatial distribution of eggs and yolk-sac larvae, as e.g. predation is not accounted for. The spatial extent of eggs and larvae represented as modelled particles is primarily determined by oxygen and salinity conditions. The reproduction habitat most suitable was determined for the Gdansk Deep, followed by the Bornholm Basin. Relatively low habitat suitability was obtained for the Arkona Basin and the Gotland Basin. The model runs also showed yolk-sac larval survival to be to a large extent affected by sedimentation. Eggs initially released in the Arkona Basin and Bornholm Basin are strongly affected by sedimentation compared with those released in the Gdansk Deep and Gotland Basin. Highest relative survival of eggs occurred in the Gdansk Deep and in the Bornholm Basin. Relatively low survival rates in the Gotland Basin were attributable to oxygen-dependent mortality. Oxygen content had almost no impact on survival in the Arkona Basin. For all spawning areas mortality caused by lethally low temperatures was only evident after severe winters. Buoyancy of eggs and yolk-sac larvae in relation to topographic features appear as a barrier for the transport of eggs and yolk-sac larvae and potentially limits the connectivity of early life stages between the different spawning areas.

  • 243.
    Hirsch, Philipp E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Phenotypic Processes Triggered by Biological Invasions2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Individuals within a single population can vary widely in their phenotype e.g. in their body shape. These differences are an important source of biodiversity and they can precede evolutionary divergence within a population.

    In this thesis we use the biological invasion of the zebra mussels into Swedish lakes to investigate which processes create or maintain phenotypic diversity within populations of the two native fish species perch and roach and the mussel itself. Both fishes have specially adapted body shapes that depend on whether they feed in the near-shore or open-water habitat of lakes. This habitat-specific divergence was more pronounced in lakes with zebra mussels, probably because resources in both habitats were in higher supply due to the mussels’ effects on the lakes. Divergence in perch body shapes between habitats was also higher in lakes with a higher water clarity, suggesting that visual conditions can affect the resource use and thus also the expression of a habitat-specific body shape.

    When investigating the diversity of body shapes in the mussel itself we found that mussels from one lake changed their shell shape when exposed to different predators: fish predators induced a more elongated shell shape while crayfish predators induced a rounder shell. These specific shell shapes probably serve as two alternative predator defenses protecting the mussel from predation.

    We conclude that the availability and use of distinct resources is an important source of diversity within populations. Abiotic conditions can play a previously underappreciated role by promoting or impairing the use of the distinct resources thus affecting the divergence. The diversity of shell shapes we found in the zebra mussels complements our study by demonstrating that not only consumer responses to resources but also resources’ responses to predators can generate phenotypic diversity.

    Delarbeid
    1. Different venues, different menus: causes and consequences of disruptive selection in natural populations
    Åpne denne publikasjonen i ny fane eller vindu >>Different venues, different menus: causes and consequences of disruptive selection in natural populations
    2011 (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Forskningsprogram
    Biologi
    Identifikatorer
    urn:nbn:se:uu:diva-158670 (URN)
    Tilgjengelig fra: 2011-09-13 Laget: 2011-09-13 Sist oppdatert: 2013-06-12
    2. Indirect trophic interactions with an invasive species affect phenotypic divergence in a top consumer
    Åpne denne publikasjonen i ny fane eller vindu >>Indirect trophic interactions with an invasive species affect phenotypic divergence in a top consumer
    2013 (engelsk)Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 172, nr 1, s. 245-256Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    While phenotypic responses to direct species interactions are well studied, we know little about the consequences of indirect interactions for phenotypic divergence.In this study we used lakes with and without the zebra mussel to investigate effects ofindirect trophic interactions on phenotypic divergence between littoral and pelagic perch. We found a greater phenotypic divergence between littoral and pelagic individuals inlakes with zebra mussels and propose a mussel-mediated increase in pelagic and benthic resource availability as a major factor underlying this divergence. Lakes withzebra mussels contained higher densities of large plankton taxa and large invertebrates. We suggest that this augmented resource availability improved perch foraging opportunities in both the littoral and pelagic zones. Perch in both habitats could hence express a more specialized foraging morphology, leading to an increased divergence of perch forms in lakes with zebra mussels. As perch do not prey on mussels directly, we conclude that the increased divergence results from indirect interactions with the mussels. Our results hence suggest that species at lower food web levels can indirectlyaffect phenotypic divergence in species at the top of the food chain.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-158687 (URN)10.1007/s00442-013-2611-1 (DOI)000317686800022 ()
    Tilgjengelig fra: 2011-09-13 Laget: 2011-09-13 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    3. Replicated divergence in two consumer species affected by resource availability
    Åpne denne publikasjonen i ny fane eller vindu >>Replicated divergence in two consumer species affected by resource availability
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    Emneord
    food web, resource polymorphisms, adaptive foraging, morphological divergence, Rutilus rutilus, Perca fluviatilis
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-158685 (URN)
    Tilgjengelig fra: 2011-09-13 Laget: 2011-09-13 Sist oppdatert: 2013-02-11
    4. Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)
    Åpne denne publikasjonen i ny fane eller vindu >>Water transparency drives intra-population divergence in Eurasian perch (Perca fluviatilis)
    2012 (engelsk)Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 8, s. e43641-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Trait combinations that lead to a higher efficiency in resource utilization are important drivers of divergent natural selection and adaptive radiation. However, variation in environmental features might constrain foraging in complex ways and therefore impede the exploitation of critical resources. We tested the effect of water transparency on intra-population divergence in morphology of Eurasian perch (Perca fluviatilis) across seven lakes in central Sweden. Morphological divergence between near-shore littoral and open-water pelagic perch substantially increased with increasing water transparency. Reliance on littoral resources increased strongly with increasing water transparency in littoral populations, whereas littoral reliance was not affected by water transparency in pelagic populations. Despite the similar reliance on pelagic resources in pelagic populations along the water transparency gradient, the utilization of particular pelagic prey items differed with variation in water transparency in pelagic populations. Pelagic perch utilized cladocerans in lakes with high water transparency and copepods in lakes with low water transparency. We suggest that under impaired visual conditions low utilization of littoral resources by littoral perch and utilization of evasive copepods by pelagic perch may lead to changes in morphology. Our findings indicate that visual conditions can affect population divergence in predator populations through their effects on resource utilization.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-158689 (URN)10.1371/journal.pone.0043641 (DOI)000308063700123 ()
    Tilgjengelig fra: 2011-09-13 Laget: 2011-09-13 Sist oppdatert: 2017-12-08bibliografisk kontrollert
    5. Plastic Responses of a Sessile Prey to Multiple Predators: A Field and Experimental Study
    Åpne denne publikasjonen i ny fane eller vindu >>Plastic Responses of a Sessile Prey to Multiple Predators: A Field and Experimental Study
    2014 (engelsk)Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 12, s. e115192-Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Background: Theory predicts that prey facing a combination of predators with different feeding modes have two options: to express a response against the feeding mode of the most dangerous predator, or to express an intermediate response. Intermediate phenotypes protect equally well against several feeding modes, rather than providing specific protection against a single predator. Anti-predator traits that protect against a common feeding mode displayed by all predators should be expressed regardless of predator combination, as there is no need for trade-offs. Principal Findings: We studied phenotypic anti-predator responses of zebra mussels to predation threat from a handling-time-limited (crayfish) and a gape-size-limited (roach) predator. Both predators dislodge mussels from the substrate but diverge in their further feeding modes. Mussels increased expression of a nonspecific defense trait (attachment strength) against all combinations of predators relative to a control. In response to roach alone, mussels showed a tendency to develop a weaker and more elongated shell. In response to crayfish, mussels developed a harder and rounder shell. When exposed to either a combination of predators or no predator, mussels developed an intermediate phenotype. Mussel growth rate was positively correlated with an elongated weaker shell and negatively correlated with a round strong shell, indicating a trade-off between anti-predator responses. Field observations of prey phenotypes revealed the presence of both anti-predator phenotypes and the trade-off with growth, but intra-specific population density and bottom substrate had a greater influence than predator density. Conclusions: Our results show that two different predators can exert both functionally equivalent and inverse selection pressures on a single prey. Our field study suggests that abiotic factors and prey population density should be considered when attempting to explain phenotypic diversity in the wild.

    Emneord
    trade-off, multiple predators, inducible defenses, Dreissena polymorpha, Rutilus rutilus, Pacifastacus leniusculus
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-158690 (URN)10.1371/journal.pone.0115192 (DOI)000347215600054 ()
    Tilgjengelig fra: 2011-09-13 Laget: 2011-09-13 Sist oppdatert: 2017-12-08bibliografisk kontrollert
  • 244.
    Hirsch, Philipp E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Cayon, Diaz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Plastic Responses of a Sessile Prey to Multiple Predators: A Field and Experimental Study2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 12, s. e115192-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Theory predicts that prey facing a combination of predators with different feeding modes have two options: to express a response against the feeding mode of the most dangerous predator, or to express an intermediate response. Intermediate phenotypes protect equally well against several feeding modes, rather than providing specific protection against a single predator. Anti-predator traits that protect against a common feeding mode displayed by all predators should be expressed regardless of predator combination, as there is no need for trade-offs. Principal Findings: We studied phenotypic anti-predator responses of zebra mussels to predation threat from a handling-time-limited (crayfish) and a gape-size-limited (roach) predator. Both predators dislodge mussels from the substrate but diverge in their further feeding modes. Mussels increased expression of a nonspecific defense trait (attachment strength) against all combinations of predators relative to a control. In response to roach alone, mussels showed a tendency to develop a weaker and more elongated shell. In response to crayfish, mussels developed a harder and rounder shell. When exposed to either a combination of predators or no predator, mussels developed an intermediate phenotype. Mussel growth rate was positively correlated with an elongated weaker shell and negatively correlated with a round strong shell, indicating a trade-off between anti-predator responses. Field observations of prey phenotypes revealed the presence of both anti-predator phenotypes and the trade-off with growth, but intra-specific population density and bottom substrate had a greater influence than predator density. Conclusions: Our results show that two different predators can exert both functionally equivalent and inverse selection pressures on a single prey. Our field study suggests that abiotic factors and prey population density should be considered when attempting to explain phenotypic diversity in the wild.

  • 245.
    Hirsch, Philipp E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Reyes, Martha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Quevedo, Mario
    Cantabrian Institute of Biodiversity (ICAB), Oviedo University, Departmento Biología Organismos y Sistemas, Campus del Cristo, 33006 Oviedo, Spain.
    Fransson, Rebecca
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Replicated divergence in two consumer species affected by resource availabilityManuskript (preprint) (Annet vitenskapelig)
  • 246.
    Hirsch, Philipp E
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Eklöv, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Svanbäck, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Indirect trophic interactions with an invasive species affect phenotypic divergence in a top consumer2013Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 172, nr 1, s. 245-256Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    While phenotypic responses to direct species interactions are well studied, we know little about the consequences of indirect interactions for phenotypic divergence.In this study we used lakes with and without the zebra mussel to investigate effects ofindirect trophic interactions on phenotypic divergence between littoral and pelagic perch. We found a greater phenotypic divergence between littoral and pelagic individuals inlakes with zebra mussels and propose a mussel-mediated increase in pelagic and benthic resource availability as a major factor underlying this divergence. Lakes withzebra mussels contained higher densities of large plankton taxa and large invertebrates. We suggest that this augmented resource availability improved perch foraging opportunities in both the littoral and pelagic zones. Perch in both habitats could hence express a more specialized foraging morphology, leading to an increased divergence of perch forms in lakes with zebra mussels. As perch do not prey on mussels directly, we conclude that the increased divergence results from indirect interactions with the mussels. Our results hence suggest that species at lower food web levels can indirectlyaffect phenotypic divergence in species at the top of the food chain.

  • 247. Ho, Lionel
    et al.
    Hoefel, Daniel
    Grasset, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Palazot, Sebastien
    Newcombe, Gayle
    Saint, Christopher P.
    Brookes, Justin D.
    Removal of cyanobacterial metabolites through wastewater treatment plant filters2012Inngår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 65, nr 7, s. 1244-1251Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wastewaters have the potential to proliferate excessive numbers of cyanobacteria due to high nutrient levels. This could translate to the production of metabolites, such as the saxitoxins, geosmin and 2-methylisoborneol (MIB), which can impair the quality of wastewater destined for re-use. Biological sand filtration was assessed for its ability to remove these metabolites from a wastewater. Results indicated that the sand filter was incapable of effectively removing the saxitoxins and in some instances, the effluent of the sand filter displayed greater toxicity than the influent. Conversely, the sand filter was able to effectively remove geosmin and MIB, with removal attributed to biodegradation. Granular activated carbon was employed as an alternative filter medium to remove the saxitoxins. Results showed similar removals to previous drinking water studies, where efficient removals were initially observed, followed by a decrease in the removal; a consequence of the presence of competing organics which reduced adsorption of the saxitoxins.

  • 248.
    Hoarfrost, Adrienne
    et al.
    Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA;Rutgers State Univ, Dept Biochem & Microbiol, New Brunswick, NJ 08901 USA.
    Balmonte, John Paul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA.
    Ghobrial, Sherif
    Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA.
    Ziervogel, Kai
    Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.
    Bane, John
    Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA.
    Gawarkiewicz, Glen
    Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA.
    Arnosti, Carol
    Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27515 USA.
    Gulf Stream Ring Water Intrusion on the Mid-Atlantic Bight Continental Shelf Break Affects Microbially Driven Carbon Cycling2019Inngår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 6, artikkel-id 394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Warm core, anticyclonic rings that spin off from the Gulf Stream circulate through the region directly offshore of the Mid-Atlantic Bight. If a warm core ring reaches the continental shelf break, its warm, highly saline water may subduct under cooler, fresher continental shelf surface water, resulting in subsurface waters at the shelf break and over the upper continental slope with high temperatures and salinities and distinct physical and chemical properties characteristic of Gulf Stream water. Such intruding water may also have microbial communities with distinct functional capacities, which may in turn affect the rate and nature of carbon cycling in this coastal/shelf environment. However, the functional capabilities of microbial communities within ring intrusion waters relative to surrounding continental shelf waters are largely unexplored. We investigated microbial community capacity to initiate organic matter remineralization by measuring hydrolysis of a suite of polysaccharide, peptide, and glucose substrates along a transect oriented across the Mid-Atlantic Bight shelf, shelf break, and upper slope. At the outermost sampling site, warm and salty water derived from a Gulf Stream warm core ring was present in the lower portion of the water column. This water exhibited hydrolytic capacities distinct from other sampling sites, and exhibited lower heterotrophic bacterial productivity overall. Warm core rings adjacent to the Mid-Atlantic Bight shelf have increased in frequency and duration in recent years. As the influence of warm core rings on the continental shelf and slope increases in the future, the rate and nature of organic matter remineralization on the continental shelf may also shift.

  • 249.
    Hubalek, Valerie
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Exposing the Dark Microbial Biosphere2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Dark biosphere research has been widely neglected, although by volume this biome comprises the lion’s share of habitats on our planet. In these systems the main metabolic strategies are of chemotrophic nature, leading to gradual depletion of redox gradients essential for sustaining life. Thus these environments are regarded more or less close to chemical equilibrium.

    Here, we use sequence data of whole community metagenomes and taxonomic marker approaches to study the ecology of environments close to the thermodynamic limit: deep terrestrial aquifers and aphotic systems impacted by petroleum- derived products. We show that these systems select for individuals with reduced genomes and cell sizes, likely as a mode to save energy. Due to genome reduction, these so called “streamlined” cells are reduced in the number of genes and metabolic pathways. This loss has led to community members sharing the metabolic burden of synthesizing in particular energy costly metabolites, creating tight interdependencies between the community members, as a consequence. In addition, we propose that cells scavenging anabolic products derived from detrital biomass and intermediate fermentation products are equally important in these systems. Hence, life at the thermodynamic limit involves a much more complex biological system than previously shown, that goes beyond traditionally described electron- and intermediate metabolite-transfer dependencies.

    This thesis furthermore includes ecological implications, demonstrating how species diversity and community metabolism are shaped by redox gradients and dispersal potential in the deep biosphere and contaminated sediments. This research is also relevant from a practical point of view, as it pinpoints new opportunities for enhanced bioremediation through metabolite additions in order to raise the efficiency of degradation processes.

    Delarbeid
    1. Microbial metagenomes from three aquifers in the Fennoscandian shield terrestrial deep biosphere reveal metabolic partitioning among populations
    Åpne denne publikasjonen i ny fane eller vindu >>Microbial metagenomes from three aquifers in the Fennoscandian shield terrestrial deep biosphere reveal metabolic partitioning among populations
    Vise andre…
    2016 (engelsk)Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 10, nr 5, s. 1192-1203Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Microorganisms in the terrestrial deep biosphere host up to 20% of the earth's biomass and are suggested to be sustained by the gases hydrogen and carbon dioxide. A metagenome analysis of three deep subsurface water types of contrasting age (from <20 to several thousand years) and depth (171 to 448 m) revealed phylogenetically distinct microbial community subsets that either passed or were retained by a 0.22 mu m filter. Such cells of <0.22 mu m would have been overlooked in previous studies relying on membrane capture. Metagenomes from the three water types were used for reconstruction of 69 distinct microbial genomes, each with >86% coverage. The populations were dominated by Proteobacteria, Candidate divisions, unclassified archaea and unclassified bacteria. The estimated genome sizes of the <0.22 mu m populations were generally smaller than their phylogenetically closest relatives, suggesting that small dimensions along with a reduced genome size may be adaptations to oligotrophy. Shallow 'modern marine' water showed community members with a predominantly heterotrophic lifestyle. In contrast, the deeper, 'old saline' water adhered more closely to the current paradigm of a hydrogen-driven deep biosphere. The data were finally used to create a combined metabolic model of the deep terrestrial biosphere microbial community.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-264125 (URN)10.1038/ismej.2015.185 (DOI)000374377200016 ()26484735 (PubMedID)
    Forskningsfinansiär
    Swedish Research Council, 621-2014-4398Swedish Research Council, 2012-3892The Crafoord Foundation, 20130557
    Merknad

    Supplementary information available for this article at http://www.nature.com/ismej/journal/v10/n5/suppinfo/ismej2015185s1.html

    Tilgjengelig fra: 2015-10-06 Laget: 2015-10-06 Sist oppdatert: 2017-12-01bibliografisk kontrollert
    2. Connectivity driven bacterial diversity patterns and functional potential in three deep aquifers of the Fennoscandian shield
    Åpne denne publikasjonen i ny fane eller vindu >>Connectivity driven bacterial diversity patterns and functional potential in three deep aquifers of the Fennoscandian shield
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-264126 (URN)
    Tilgjengelig fra: 2015-10-06 Laget: 2015-10-06 Sist oppdatert: 2015-11-10
    3. Metabolic partitioning in an alkane degrading bioreactor operating under methanogenic condition
    Åpne denne publikasjonen i ny fane eller vindu >>Metabolic partitioning in an alkane degrading bioreactor operating under methanogenic condition
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-264127 (URN)
    Tilgjengelig fra: 2015-10-06 Laget: 2015-10-06 Sist oppdatert: 2015-11-10
    4. Functional potential of microbial communities in freshwater sediments affected by century-long tar-contamination
    Åpne denne publikasjonen i ny fane eller vindu >>Functional potential of microbial communities in freshwater sediments affected by century-long tar-contamination
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-264128 (URN)
    Tilgjengelig fra: 2015-10-06 Laget: 2015-10-06 Sist oppdatert: 2015-11-10
  • 250.
    Hubalek, Valerie
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Buck, Moritz
    Tan, BoonFei
    Foght, Julia
    Wendeberg, Annelie
    Berry, David
    Bertilsson, Stefan
    Eiler, Alexander
    Metabolic partitioning in an alkane degrading bioreactor operating under methanogenic conditionManuskript (preprint) (Annet vitenskapelig)
2345678 201 - 250 of 685
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