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  • 301.
    Kothawala, Dolly N.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    von Wachenfeldt, Eddie
    Swedish Species Information Centre, Swedish University of Agricultural Sciences.
    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.
    Selective loss and preservation of lake water dissolved organic matter fluorescenceduring long-term dark incubations2012Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 433, s. 238-246Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biogeochemical processing of dissolved organic matter (DOM) in inland waters is inherently related to its molecular structure and ecological function. Controlled bioassays are a valuable tool to analyze these relationships, but are seldom conducted and compared at temporal scales that typically prevail in natural inland waters. Here we incubated water from six boreal lakes in the dark and examined changes to the initial fluorescence and absorbance after 3.5 years. We identified five fluorescence components with parallel factor (PARAFAC) analysis (CC, CM, CA, CX and CT) and found a consistent change in the relative intensity of two dominant PARAFAC components (increase in CA:CC, corresponding to Peak A:Peak C), commonly found in lake water, that represent terrestrially-derived DOM. Surprisingly, we only found minor changes to specific absorbance (SUVA), and did not find any changes to other spectral indexes including the fluorescence index, humification index and freshness index. By incorporating lakes spanning a wide range of initial total organic carbon concentrations (3.7 to 32.5 mg L− 1), water residence times, and spectral characteristics (e.g. SUVA 1.13 to 3.77 L·mg C− 1·m− 1), we found that the relative intensities of two humic-like peaks were the most revealing of changes to DOM structure during dark incubations. We also verified that inner filter effects were adequately corrected within the concentration range of incubated samples. Thus, the processing of DOM under dark conditions, including microbial decomposition and flocculation, may have a greater influence on the humic-like peaks, particularly CC (Peak C), with negligible changes to more commonly used spectral indexes.

     

  • 302. Krause, Sascha
    et al.
    Le Roux, Xavier
    Niklaus, Pascal A.
    Van Bodegom, Peter M.
    Lennon, Jay T.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Grossart, Hans-Peter
    Philippot, Laurent
    Bodelier, Paul L. E.
    Trait-based approaches for understanding microbial biodiversity and ecosystem functioning2014Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 5, s. 251-Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    In ecology, biodiversity-ecosystem functioning (BEE) research has seen a shift in perspective from taxonomy to function in the last two decades, with successful application of trait-based approaches. This shift offers opportunities for a deeper mechanistic understanding of the role of biodiversity in maintaining multiple ecosystem processes and services. In this paper, we highlight studies that have focused on BEE of microbial communities with an emphasis on integrating trait-based approaches to microbial ecology. In doing so, we explore some of the inherent challenges and opportunities of understanding BEE using microbial systems. For example, microbial biologists characterize communities using gene phylogenies that are often unable to resolve functional traits. Additionally, experimental designs of existing microbial BEE studies are often inadequate to unravel BEE relationships. We argue that combining eco-physiological studies with contemporary molecular tools in a trait-based framework can reinforce our ability to link microbial diversity to ecosystem processes. We conclude that such trait-based approaches are a promising framework to increase the understanding of microbial BEE relationships and thus generating systematic principles in microbial ecology and more generally ecology.

  • 303.
    Krizsan, Sophie J
    et al.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Mateos-Rivera, Alejandro
    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.
    Felton, Annika
    Swedish University of Agricultural Sciences, Alnarp, Sweden.
    Anttila, Anne
    Helsinki University, Helsinki, Finland.
    Ramin, Mohammad
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Vaga, Merko
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Gidlund, Helena
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Huhtanen, Pekka
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    An in vitro evaluation of browser and grazer fermentation efficiency and microbiota using European moose spring and summer foods2018Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, s. 4183-4196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Evolutionary morphological and physiological differences between browsers and grazers contribute to species- specific digestion efficiency of food resources. Rumen microbial community structure of browsers is supposedly adapted to characteristic nutrient composition of the diet source. If this assumption is correct, domesticated ruminants, or grazers, are poor model animals for assessing the nutritional value of food consumed by browsing game species. In this study, typical spring and summer foods of the European moose (Alces alces) were combined with rumen fluid collected from both dairy cows (Bos taurus) and from moose, with the aim of comparing fer- mentation efficiency and microbial community composition. The nutritional value of the food resources was characterized by chemical analysis and advanced in vitro measurements. The study also addressed whether or not feed evaluation based on in vitro techniques with cattle rumen fluid as inoculum could be a practical alternative when evaluating the nutritional value of plants consumed by wild browsers. Our re- sults suggest that the fermentation characteristics of moose spring and summer food are partly host- specific and related to the contribution of the bacterial phyla Firmicutes and Bacteriodetes to the rumen microbial community. Host- specific adaptations of the ruminal microbial community structure could be explained from the evolutionary adaptations related to feeding habitats and morphophysiological differences be- tween browsers and grazers. However, the observed overall differences in microbial community structure could not be related to ruminal digestion parameters measured in vitro. The in vitro evaluation of digestion efficiency reveals that equal amounts of methane were produced across all feed samples regardless of whether the ruminal fluid was from moose or dairy cow. The results of this study suggested that the nutri- tional value of browsers’ spring and summer food can be predicted using rumen fluid from domesticated grazers as inoculum in in vitro assessments of extent of digestion when excluding samples of the white water lily root, but not of fermentation characteristics as indicated by the proportions of individual fermentation fatty acids to the total of volatile fatty acids.

  • 304.
    Kutser, Tiit
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    The possibility of using the Landsat image archive for monitoring long time trends in coloured dissolved organic matter concentration in lake waters2012Inngår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 123, s. 334-338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent studies indicate that lakes are regulators of carbon cycling and climate. Therefore, it is important to know how the lake carbon content has changed over the last decades. In situ long time data series about the amount of dissolved organic carbon (DOC) in lakes are rare. The only potential way to study retrospectively the changes in lake carbon over the last decades is by means of remote sensing data provided there are sensors that can provide data about coloured dissolved organic matter (CDOM) in lakes over long periods. Landsat data archive contains images from 1984 to nowadays and covers the whole Earth. Although the sensors were not designed for remote sensing of aquatic environments it is still tempting to utilise the long data series. Landsat 4, Landsat 5 and Landsat 7 imagery available in free Landsat image archive was compared with time series of CDOM in situ data from 19 sampling stations available in the Swedish University of Natural Sciences lake monitoring database. There was no correlation between the image and in situ data when all the above mentioned data were used. Low radiometric resolution of the sensor, small size of many lakes (= large adjacency effects) and high concentration of CDOM (negligible water leaving radiation) could be the reasons. The results were more promising (R-2 = 0.62) when Lake Malaren stations were analysed separately. The lake is sufficiently large and with variable, but not extremely high. CDOM content. The Lake Malaren in situ data showed very different trends in CDOM concentrations in different basins of the lake over the last 45 years. Although the correlation between the image and in situ data was a bit low for accurate daily estimation of CDOM concentrations from Landsat data it could allow detecting general trends in lake CDOM content. Unfortunately, there is currently a gap in Landsat archive (for our study sites) between 1988 and 1998 which makes calculations of long time trends unreasonable for the time being. (C) 2012 Elsevier Inc. All rights reserved.

  • 305.
    Kutser, Tiit
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Alikas, Krista
    Kothawala, Dolly N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kohler, Stephan J.
    Impact of iron associated to organic matter on remote sensing estimates of lake carbon content2015Inngår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 156, s. 109-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a strong need to develop remote sensing methods for mapping lake carbon content on regional to global scales. The use of in situ methods is impractical for monitoring lake water quality over large geographical areas, which is a fundamental requirement to understand the true role of lakes in the global carbon cycle. The coloured component of dissolved organic carbon (DOC), called CDOM, absorbs light strongly in the blue part of the visible spectrum and can be used as a proxy for mapping lake DOC with remote sensing. However, iron associated to organic matter can cause extra browning of waters. Consequently, the remote sensing signal we interpret as DOC may partially be attributed to the presence of iron associated to organic matter, potentially hampering our ability to estimate carbon concentrations. A thorough analysis of biogeochemical parameters was carried out on Lake Malaren on August 23, 2010, and a MERIS full resolution image was acquired simultaneously. MERIS standard, Case 2 Regional, and Boreal processors were used to calculate remote sensing products, which were compared with different lake water characteristics. The carbon to iron ratio was different from the rest of the lake in one of the basins. MERIS standard and Case 2 Regional processors were sensitive to this difference as the correlation between MERIS CDOM product and DOC was low (R-2 = 0.43) for all sampling stations and increased to 0.92 when the one basin was excluded. The Boreal Lakes processor results were less disturbed by the different carbon-iron ratios found in one basin and produced reasonably good results (R-2 = 0.65). We found MERIS products (e.g. total absorption) that provided good correlation (R-2 = 0.80) with DOC-specific absorbance at 254 nm, called SUVA, which is a metric commonly used to assess drinking water treatability. However, none of the MERIS products were suitable for mapping the total organic carbon in Lake Malaren.MERIS total suspended matter product was a good (R-2 = 0.73) proxy for particulate iron, meaning that the particulate iron content in Malaren can be mapped from space. (C) 2014 Elsevier Inc. All rights reserved.

  • 306.
    Kutser, Tiit
    et al.
    Univ Tartu, Estonian Marine Inst, Maealuse 14, EE-12618 Tallinn, Estonia.;Uppsala Univ, Evolutionary Biol Ctr, Limnol, Norbyvagen 18D, S-75236 Uppsala, Sweden..
    Paavel, Birgot
    Univ Tartu, Estonian Marine Inst, Maealuse 14, EE-12618 Tallinn, Estonia..
    Verpoorter, Charles
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ Lille Nord France, Lab Oceanol & Geosci, ULCO, 32 Ave Foch, F-62930 Wimereux, France..
    Ligi, Martin
    Tartu Observ, EE-61602 Toravere, Toravere, Estonia..
    Soomets, Tuuli
    Univ Tartu, Estonian Marine Inst, Maealuse 14, EE-12618 Tallinn, Estonia..
    Toming, Kaire
    Univ Tartu, Estonian Marine Inst, Maealuse 14, EE-12618 Tallinn, Estonia..
    Casal, Gema
    Univ Tartu, Estonian Marine Inst, Maealuse 14, EE-12618 Tallinn, Estonia..
    Remote Sensing of Black Lakes and Using 810 nm Reflectance Peak for Retrieving Water Quality Parameters of Optically Complex Waters2016Inngår i: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 8, nr 6, artikkel-id 497Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many lakes in boreal and arctic regions have high concentrations of CDOM (coloured dissolved organic matter). Remote sensing of such lakes is complicated due to very low water leaving signals. There are extreme (black) lakes where the water reflectance values are negligible in almost entire visible part of spectrum (400-700 nm) due to the absorption by CDOM. In these lakes, the only water-leaving signal detectable by remote sensing sensors occurs as two peaksnear 710 nm and 810 nm. The first peak has been widely used in remote sensing of eutrophic waters for more than two decades. We show on the example of field radiometry data collected in Estonian and Swedish lakes that the height of the 810 nm peak can also be used in retrieving water constituents from remote sensing data. This is important especially in black lakes where the height of the 710 nm peak is still affected by CDOM. We have shown that the 810 nm peak can be used also in remote sensing of a wide variety of lakes. The 810 nm peak is caused by combined effect of slight decrease in absorption by water molecules and backscattering from particulate material in the water. Phytoplankton was the dominant particulate material in most of the studied lakes. Therefore, the height of the 810 peak was in good correlation with all proxies of phytoplankton biomasschlorophyll-a (R-2 = 0.77), total suspended matter (R-2 = 0.70), and suspended particulate organic matter (R-2 = 0.68). There was no correlation between the peak height and the suspended particulate inorganic matter. Satellite sensors with sufficient spatial and radiometric resolution for mapping lake water quality (Landsat 8 OLI and Sentinel-2 MSI) were launched recently. In order to test whether these satellites can capture the 810 nm peak we simulated the spectral performance of these two satellites from field radiometry data. Actual satellite imagery from a black lake was also used to study whether these sensors can detect the peak despite their band configuration. Sentinel 2 MSI has a nearly perfectly positioned band at 705 nm to characterize the 700-720 nm peak. We found that the MSI 783 nm band can be used to detect the 810 nm peak despite the location of this band is not in perfect to capture the peak.

  • 307. Kutser, Tiit
    et al.
    Pierson, Donald C.
    Tranvik, L.J.
    Reinart, Anu
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Kallio, Kari Y.
    Using satellite remote sensing to estimate the colored dissolved organic matter absorption coefficient in lakes2005Inngår i: Ecosystems, Vol. 8, s. 709-720Artikkel i tidsskrift (Fagfellevurdert)
  • 308.
    Kutser, Tiit
    et al.
    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.
    Paavel, Birgot
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Estimating lake carbon fractions from remote sensing data2015Inngår i: Remote Sensing of Environment, ISSN 0034-4257, E-ISSN 1879-0704, Vol. 157, s. 138-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Issues like monitoring lake water quality, studying the role of lakes in the global carbon cycle or the response of lakes to global change require data more frequently and/or over much larger areas than the in situ water quality monitoring networks can provide. The aim of our study was to investigate whether it is feasible to estimate different lake carbon fractions (CDOM, DOC, TOC, DIC, TIC and pCO(2)) from space using sensors like OLCI on future Sentinel 3. In situ measurements were carried out in eight measuring stations in two Swedish lakes within 2 days of MERIS overpass. The results suggest that the MERIS CDOM product was not suitable for estimating CDOM in lakes Malaren and Tamnaren and was not a good proxy for mapping lake DOC and TOC from space. However, a simple green to red band ratio and some other MERIS products like the total absorption coefficient, turbidity index, suspended matter and chlorophyll-a were correlated with different carbon fractions and could potentially be used as proxies to map these lake carbon fractions (CDOM, DOC, TOC, DIC, TIC and pCO2) from space. (C) 2014 Elsevier Inc All rights reserved.

  • 309.
    Köhler, Birgit
    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.
    Reactivity continuum modeling of leaf, root, and wood decomposition across biomes2015Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 120, nr 7, s. 1196-1214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large carbon dioxide amounts are released to the atmosphere during organic matter decomposition. Yet the large-scale and long-term regulation of this critical process in global carbon cycling by litter chemistry and climate remains poorly understood. We used reactivity continuum (RC) modeling to analyze the decadal data set of the Long-term Intersite Decomposition Experiment, in which fine litter and wood decomposition was studied in eight biome types (224 time series). In 32 and 46% of all sites the litter content of the acid-unhydrolyzable residue (AUR, formerly referred to as lignin) and the AUR/nitrogen ratio, respectively, retarded initial decomposition rates. This initial rate-retarding effect generally disappeared within the first year of decomposition, and rate-stimulating effects of nutrients and a rate-retarding effect of the carbon/nitrogen ratio became more prevalent. For needles and leaves/grasses, the influence of climate on decomposition decreased over time. For fine roots, the climatic influence was initially smaller but increased toward later-stage decomposition. The climate decomposition index was the strongest climatic predictor of decomposition. The similar variability in initial decomposition rates across litter categories as across biome types suggested that future changes in decomposition may be dominated by warming-induced changes in plant community composition. In general, the RC model parameters successfully predicted independent decomposition data for the different litter-biome combinations (196 time series). We argue that parameterization of large-scale decomposition models with RC model parameters, as opposed to the currently common discrete multiexponential models, could significantly improve their mechanistic foundation and predictive accuracy across climate zones and litter categories.

  • 310.
    Köhler, Birgit
    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.
    Kothawala, Dolly
    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.
    Reactivity continuum of dissolved organic carbon decomposition in lake water2012Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 117, s. G01024-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We determined microbial decomposition of dissolved organic carbon (DOC) over 3.7-year long dark bioassays of six Swedish lake waters. The overall lost DOC fraction was similar in clearwater lakes (34.8 {plus minus} 2.4%) and brownwater lakes (37.8 {plus minus} 1.9%). Reactivity continuum modeling revealed that the most labile DOC fraction, degrading at rates >0.01 day-1, was larger in the clearwater (11.1 {plus minus} 1.2%) than the brownwater lakes (0.8 {plus minus} 0.1%). The initial apparent first-order decay coefficients k was fivefold larger in the clearwater (0.0043 {plus minus} 0.0012 day-1) than the brownwater lakes (0.0009 {plus minus} 0.0003 day-1). Over time, k decreased more steeply in the clearwater than the brownwater lakes, reaching the k of the brownwater lakes within five months. Finally, k averaged 0.0001 day-1 in both lake categories. In the brownwater lakes, CDOM absorption decayed with an initial k twice as large (0.0018 {plus minus} 0.0008 day-1) as that of DOC. The initial k was inversely correlated with initial specific UV absorption and colored dissolved organic matter (CDOM) absorption, and positively correlated with initial tryptophan-like fluorescence as proxy for autochthonous DOC. Exposure to simulated sunlight at the end of the incubations caused loss of color in the clearwater lakes and loss of DOC in the brownwater lakes, where subsequent mineralization was also stimulated. The DOC lost in the absence of photochemical processes fell below previously reported watershed-scale losses in Sweden by 25% at most. This suggests that a major part of the in situ DOC loss could potentially be attributed to dark reactions alone.

  • 311.
    Landbecker, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för biologisk grundutbildning.
    Utvärdering av Naturvårdsverkets bedömningsgrunder för makrofyter i sjöar2011Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [en]

    According to the Water Framework Directive of the European Union, macrophytes should be used as indicators in the ecological and environmental monitoring of lakes. In the member state Sweden the Environmental Protection Agency has elaborated assessment criteria for determining lake status based on macrophytes. The main focus of this thesis is to evaluate the efficiency of the assessment criteria for macrophytes. In addition the concordance between the ecological status classes of the four quality factors included was analysed.

    The assessment criteria for macrophytes are based on the total phosphorus preference of the respective species. The focus is thus mainly on the nutrient level of the investigated lakes and the environmental problem monitored is eutrophication. Macrophytes are one of the five biological quality factors used for lakes. The others are phytoplankton, diatoms, benthic fauna and fish. The two latter were included in this thesis. In addition to the biological factors the chemical factor, nutrients in lakes, i.e. the total phosphorus, was included. The macrophyte composition was investigated in two eutrophic Uppland lakes: Lake Trehörningen and Lake Edasjön. Since the assessment criteria were launched in 2007 there have been problems reported regarding the outcome of the methods. The results are sometimes inconclusive for eutrophicated lakes and especially for lakes with naturally high levels of nutrients. In this study the macrophyte species composition was compared with the nutrient level of different lakes. Some species were found in equal shares in oligotrophic lakes as in eutrophic, e.g. Nymphaea candida and Nuphar lutea. Hence they were considered less suitable as elements in the method evaluated. A couple of species were present in predominantly oligotrophic (e.g. Lobelia dortmanna) or eutrophic (e.g. Hydrocharis morsus-ranae) lakes, respectively. They were regarded as better indicators since they ”preferred” lakes either poor or rich in nutrients. It is important to point out that all the other biological quality factors used, except for macrophytes, are multimetric.

    I conclude that more parameters are needed for evaluation of macrophytes in lakes. Tentatively, the degree of coverage of the plants and algae, the presence and degree of coverage of invasive nonnative species, lake lowerings and the consequent composition and abundance change, all should be tested as additional parameters.  A high level of concordance was verified for the status classifications of the four quality factors in lakes of oligotrophy as well as in lakes of eutrophy, i.e. no particular  pattern based on trophy level was found. The macrophyte inventories of the two Uppland lakes both resulted in a moderate ecological status for macrophytes.

  • 312.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Berga, Mercé
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Populationsbiologi och naturvårdsbiologi.
    Székely, Anna J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Temporal variation of beta-diversity and assembly mechanisms in a bacterial metacommunity2012Inngår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 6, nr 6, s. 1107-1114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The turnover of community composition across space, beta-diversity, is influenced by different assembly mechanisms, which place varying weight on local habitat factors, such as environmental conditions and species interactions, and regional factors such as dispersal and history. Several assembly mechanisms may function simultaneously; however, little is known about how their importance changes over time and why. Here, we implemented a field survey where we sampled a bacterial metacommunity consisting of 17 rock pools located at the Swedish Baltic Sea coast at 11 occasions during 1 year. We determined to which extent communities were structured by different assembly mechanisms using variation partitioning and studied changes in beta-diversity across environmental gradients over time. beta-Diversity was highest at times of high overall productivity and environmental heterogeneity in the metacommunity, at least partly due to species sorting, that is, selection of taxa by the prevailing environmental conditions. In contrast, dispersal-driven assembly mechanisms were primarily detected at times when beta-diversity was relatively low. There were no indications for strong and persistent differences in community composition or beta-diversity between permanent and temporary pools, indicating that the physical disturbance regime is of relatively minor importance. In summary, our study clearly suggests that there are temporal differences in the relative importance of different assembly mechanisms related to abiotic factors and shows that the temporal variability of those factors is important for a more complete understanding of bacterial metacommunity dynamics.

  • 313.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bulling, Mark T.
    Prosser, James I.
    Solan, Martin
    Role of functionally dominant species in varying environmental regimes: evidence for the performance-enhancing effect of biodiversity2012Inngår i: BMC Ecology, ISSN 1472-6785, E-ISSN 1472-6785, Vol. 12, s. 14-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Theory suggests that biodiversity can act as a buffer against disturbances and environmental variability via two major mechanisms: Firstly, a stabilising effect by decreasing the temporal variance in ecosystem functioning due to compensatory processes; and secondly, a performance enhancing effect by raising the level of community response through the selection of better performing species. Empirical evidence for the stabilizing effect of biodiversity is readily available, whereas experimental confirmation of the performance-enhancing effect of biodiversity is sparse. Results: Here, we test the effect of different environmental regimes (constant versus fluctuating temperature) on bacterial biodiversity-ecosystem functioning relations. We show that positive effects of species richness on ecosystem functioning are enhanced by stronger temperature fluctuations due to the increased performance of individual species. Conclusions: Our results provide evidence for the performance enhancing effect and suggest that selection towards functionally dominant species is likely to benefit the maintenance of ecosystem functioning under more variable conditions.

  • 314.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bulling, Mark T.
    Solan, Martin
    Prosser, James I.
    Bacterial biodiversity-ecosystem function relations are modified by environmental complexity2010Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 5, nr 5, s. e10834-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background

    With the recognition that environmental change resulting from anthropogenic activities is causing a global decline in biodiversity, much attention has been devoted to understanding how changes in biodiversity may alter levels of ecosystem functioning. Although environmental complexity has long been recognised as a major driving force in evolutionary processes, it has only recently been incorporated into biodiversity-ecosystem functioning investigations. Environmental complexity is expected to strengthen the positive effect of species richness on ecosystem functioning, mainly because it leads to stronger complementarity effects, such as resource partitioning and facilitative interactions among species when the number of available resource increases.

    Methodology/Principal Findings

    Here we implemented an experiment to test the combined effect of species richness and environmental complexity, more specifically, resource richness on ecosystem functioning over time. We show, using all possible combinations of species within a bacterial community consisting of six species, and all possible combinations of three substrates, that diversity-functioning (metabolic activity) relationships change over time from linear to saturated. This was probably caused by a combination of limited complementarity effects and negative interactions among competing species as the experiment progressed. Even though species richness and resource richness both enhanced ecosystem functioning, they did so independently from each other. Instead there were complex interactions between particular species and substrate combinations.

    Conclusions/Significance

    Our study shows clearly that both species richness and environmental complexity increase ecosystem functioning. The finding that there was no direct interaction between these two factors, but that instead rather complex interactions between combinations of certain species and resources underlie positive biodiversity ecosystem functioning relationships, suggests that detailed knowledge of how individual species interact with complex natural environments will be required in order to make reliable predictions about how altered levels of biodiversity will most likely affect ecosystem functioning.

  • 315.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Comte, Jérôme
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ Laval, Ctr Etud Nord, UMI Takuvik, Dept Biol IBIS, Pavillon Charles Eugene Marchand,1030 Ave Med, Quebec City, PQ G1V 0A6, Canada.
    Zha, Yinghua
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Samad, Md Sainur
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Univ Otago, Dept Microbiol & Immunol, 720 Cumberland St North Dunedin, Dunedin 9016, New Zealand.
    Sinclair, Lucas
    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.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Remnants of marine bacterial communities can be retrieved from deep sediments in lakes of marine origin2016Inngår i: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 8, nr 4, s. 479-485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some bacteria can be preserved over time in deep sediments where they persist either in dormant or slow-growing vegetative stages. Here, we hypothesized that such cells can be revived when exposed to environmental conditions similar to those before they were buried in the sediments. To test this hypothesis, we collected bacteria from sediment samples of different ages (140–8500 calibrated years before present, cal BP) from three lakes that differed in the timing of their physical isolation from the Baltic Sea following postglacial uplift. After these bacterial communities were grown in sterile water from the Baltic Sea, we determined the proportion of 16S rRNA sequence reads associated with marine habitats by extracting the environment descriptive terms of homologous sequences retrieved from public databases. We found that the proportion of reads associated with marine descriptive term was significantly higher in cultures inoculated with sediment layers formed under Baltic conditions and where salinities were expected to be similar to current levels. Moreover, a similar pattern was found in the original sediment layers. Our study, therefore, suggests that remnants of marine bacterial communities can be preserved in sediments over thousands of years and can be revived from deep sediments in lakes of marine origin.

  • 316.
    Langenheder, Silke
    et al.
    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.
    Factors influencing aquatic and terrestrial bacterial community assembly2019Inngår i: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 11, nr 3, s. 306-315Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    During recent years, many studies have shown that different processes including drift, environmental selection and dispersal can be important for the assembly of bacterial communities in aquatic and terrestrial ecosystems. However, we lack a conceptual overview about the ecological context and factors that influence the relative importance of the different assembly mechanisms and determine their dynamics in time and space. Focusing on free-living, i.e., nonhost associated, bacterial communities, this minireview, therefore, summarizes and conceptualizes findings from empirical studies about how (i) environmental factors, such as environmental heterogeneity, disturbances, productivity and trophic interactions; (ii) connectivity and dispersal rates (iii) spatial scale, (iv) community properties and traits and (v) the use of taxonomic/phylogenetic or functional metrics influence the relative importance of different community assembly processes. We find that there is to-date little consistency among studies and suggest that future studies should now address how (i)-(v) differ between habitats and organisms and how this, in turn, influences the temporal and spatial-scale dependency of community assembly processes in microorganisms.

  • 317.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Szekely, Anna J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Species sorting and neutral processes are both important during the initial assembly of bacterial communities2011Inngår i: The ISME Journal, ISSN 1751-7362, Vol. 5, nr 7, s. 1086-1094Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many studies have shown that species sorting, that is, the selection by local environmental conditions is important for the composition and assembly of bacterial communities. On the other hand, there are other studies that could show that bacterial communities are neutrally assembled. In this study, we implemented a microcosm experiment with the aim to determine, at the same time, the importance of species sorting and neutral processes for bacterial community assembly during the colonisation of new, that is, sterile, habitats, by atmospheric bacteria. For this we used outdoor microcosms, which contained sterile medium from three different rock pools representing different environmental conditions, which were seeded by rainwater bacteria. We found some evidence for neutral assembly processes, as almost every 4th taxon growing in the microcosms was also detectable in the rainwater sample irrespective of the medium. Most of these taxa belonged to widespread families with opportunistic growth strategies, such as the Pseudomonadaceae and Comamonadaceae, indicating that neutrally assembled taxa may primarily be generalists. On the other hand, we also found evidence for species sorting, as one out of three media selected a differently composed bacterial community. Species sorting effects were relatively weak and established themselves via differences in relative abundance of generalists among the different media, as well as media-specific occurrences of a few specific taxa. In summary, our results suggest that neutral and species sorting processes interact during the assembly of bacterial communities and that their importance may differ depending on how many generalists and specialists are present in a community.

  • 318.
    Langenheder, Silke
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Wang, Jianjun
    Department of Geosciences and Geography, University of Helsinki, Helsinki FIN-00014, Finland; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academic of Sciences, Nanjing 210008, China.
    Karjalainen, Satu Maaria
    Finnish Environment Institute, Freshwater Centre, FI-90570 Oolu, Finland.
    Laamanen, Tiina M.
    Finnish Environment Institute, Freshwater Centre, FI-90570 Oolu, Finland.
    Tolonen, Kimmo T.
    Finnish Environment Institute, Natural Environment Centre, Biodiversity, FI-90570 Oulu, Finland.
    Vilmi, Annika
    Finnish Environment Institute, Natural Environment Centre, Biodiversity, FI-90570 Oulu, Finland.
    Heino, Jani
    Finnish Environment Institute, Natural Environment Centre, Biodiversity, FI-90570 Oulu, Finland.
    Bacterial metacommunity organization in a highly connected aquatic system2017Inngår i: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 93, nr 4, artikkel-id fiw225Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The spatial structure and underlying assembly mechanisms of bacterial communities have been studied widely across aquatic systems, focusing primarily on isolated sites, such as different lakes, ponds and streams. Here, our main aim was to determine the underlying mechanisms for bacterial biofilm assembly within a large, highly connected lake system in Northern Finland using associative methods based on taxonomic and phylogenetic alpha- and beta-diversity and a large number of abiotic and biotic variables. Furthermore, null model approaches were used to quantify the relative importance of different community assembly processes. We found that spatial variation in bacterial communities within the lake was structured by different assembly processes, including stochasticity, species sorting and potentially even dispersal limitation. Species sorting by abiotic environmental conditions explained more of the taxonomic and particularly phylogenetic turnover in community composition compared with that by biotic variables. Finally, we observed clear differences in alpha diversity (species richness and phylogenetic diversity), which were to a stronger extent determined by abiotic compared with biotic factors, but also by dispersal effects. In summary, our study shows that the biodiversity of bacterial biofilm communities within a lake ecosystem is driven by within-habitat gradients in abiotic conditions and by stochastic and deterministic dispersal processes.

  • 319. Lapierre, J.F.
    et al.
    Guillemette, Francois
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Berggren, M.
    del Giorgio, P.A.
    Increases in terrestrially derived carbon stimulate organic carbon processing and CO2 emissions in boreal aquatic ecosystems2013Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 4Artikkel i tidsskrift (Fagfellevurdert)
  • 320.
    Larson, Daniel
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Ahlgren, Gunnel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Willén, Eva
    Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment.
    Bioaccumulation of microcystins in the food web: a field study of four Swedish lakes2014Inngår i: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 4, nr 1, s. 91-104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The transfer of microcystins (MC) up the food chain was measured in 4 lakes in central Sweden; Ekoln, Lilla Ullfjärden, Valloxen, and Storsjön. In lakes Ekoln and Valloxen, Microcystis aeruginosa was the dominant cyanobacterium, while the oscillatorian species Planktothrix prolifica form dense blooms in Lake Lilla Ullfjärden. The cyanobacterial composition in Lake Storsjön was more diverse with several Microcystis andDolichospermum species. All dominant taxa are well-known producers of hepatotoxic MC. The highest recorded MC in the water samples from Lake Lilla Ullfjärden was measured in the bloom of Pprolifica (35 µg L−1). The highest MC content was measured in invertebrates; however, the MC concentration was usually low in fish. Maximum levels were 9 µg g−1 dry weight (dw) in zooplankton, 10 µg g−1 dw in benthos, and 2.7 µg g−1 dw in fish (smelt) liver. In fish muscle the highest recorded levels were 0.10–0.18 µg g−1 dw in bleak and smelt from Lake Lilla Ullfjärden and in pike-perch and roach from Lake Storsjön. Based on the World Health Organization’s tolerable daily intake value of 0.04 µg kg−1 body weight, we conclude that any risk related to MC from human consumption of fish from these lakes is minimal.

  • 321.
    Lavonen, E. E.
    et al.
    Swedish Univ Agr Sci SLU, Dept Aquat Sci & Assessment, S-75007 Uppsala, Sweden..
    Kothawala, Dolly. N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Swedish Univ Agr Sci SLU, Dept Aquat Sci & Assessment, S-75007 Uppsala, Sweden..
    Tranvik, Lars. J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Gonsior, M.
    Linkoping Univ, Unit Environm Change, Dept Themat Studies, S-58183 Linkoping, Sweden.;Univ Maryland, Ctr Environm Sci, Chesapeake Biol Lab, Solomons, MD 20688 USA..
    Schmitt-Kopplin, P.
    Helmholtz Zentrum Munchen, German Res Ctr Environm Hlth, Analyt BioGeoChem, D-85764 Neuherberg, Germany.;Tech Univ Munich, Analyt Food Chem, D-85354 Freising Weihenstephan, Germany..
    Kohler, S. J.
    Swedish Univ Agr Sci SLU, Dept Aquat Sci & Assessment, S-75007 Uppsala, Sweden..
    Tracking changes in the optical properties and molecular composition of dissolved organic matter during drinking water production2015Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 85, s. 286-294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Absorbance, 3D fluorescence and ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) were used to explain patterns in the removal of chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) at the molecular level during drinking water production at four large drinking water treatment plants in Sweden. When dissolved organic carbon (DOC) removal was low, shifts in the dissolved organic matter (DOM) composition could not be detected with commonly used DOG-normalized parameters (e.g. specific UV254 absorbance SUVA), but was clearly observed by using differential absorbance and fluorescence or ESI-FT-ICR-MS. In addition, we took a novel approach by identifying how optical parameters were correlated to the elemental composition of DOM by using rank correlation to connect optical properties to chemical formulas assigned to mass peaks from FT-ICR-MS analyses. Coagulation treatment selectively removed FDOM at longer emission wavelengths (450-600 nm), which significantly correlated with chemical formulas containing oxidized carbon (average carbon oxidation state >= 0), low hydrogen to carbon ratios (H/C: average +/- SD = 0.83 +/- 0.13), and abundant oxygen-containing functional groups (O/C = 0.62 +/- 0.10). Slow sand filtration was less efficient in removing DOM, yet selectively targeted FDOM at shorter emission wavelengths (between 300 and 450 nm), which commonly represents algal rather than terrestrial sources. This shorter wavelength FDOM correlated with chemical formulas containing reduced carbon (average carbon oxidation state <= 0), with relatively few carbon-carbon double bonds (H/C = 1.32 +/- 0.16) and less oxygen per carbon (O/C = 0.43 +/- 0.10) than those removed during coagulation. By coupling optical approaches with FT-ICR-MS to characterize DOM, we were for the first time able to confirm the molecular composition of absorbing and fluorescing DOM selectively targeted during drinking water treatment.

  • 322. Lavonen, Elin E.
    et al.
    Gonsior, Michael
    Tranvik, Lars J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Schmitt-Kopplin, Philippe
    Kohler, Stephan J.
    Selective Chlorination of Natural Organic Matter: Identification of Previously Unknown Disinfection Byproducts2013Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 47, nr 5, s. 2264-2271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Natural organic matter (NOM) serve as precursors for disinfection byproducts (DBPs) in drinking water production making NOM removal essential in predisinfection treatment processes. We identified molecular formulas of chlorinated DBPs after chlorination and chloramination in four Swedish surface water treatment plants (WTPs) using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chlorine-containing formulas were detected before and after disinfection and were therefore classified to identify DBPs. In total, 499 DBPs were detected, of which 230 have not been reported earlier. The byproducts had, as a group, significantly lower ratio of hydrogen to carbon (H/C) and significantly higher average carbon oxidation state (Cos), double bond equivalents per carbon (DBE/C) and ratio of oxygen to carbon (O/C) compared to Cl-containing components present before disinfection and CHO formulas in samples taken both before and after disinfection. Electrophilic substitution, the proposed most significant reaction pathway for chlorination of NOM, results in carbon oxidation and decreased H/C while O/C and DBE/C is left unchanged. Because the identified DBPs had significantly higher DBE/C and O/C than the CHO formulas we concluded that chlorination of NOM during disinfection is selective toward components with relatively high double bond equivalency and number of oxygen atoms per carbon. Furthermore, choice of disinfectant, dose, and predisinfection treatment at the different WTPs resulted in distinct patterns in the occurrence of DBP formulas.

  • 323. Leavitt, Peter R.
    et al.
    Fritz, S. C.
    Anderson, N. J.
    Baker, P. A.
    Blenckner, Thorsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bunting, L.
    Catalan, J.
    Conley, D. J.
    Hobbs, W. O.
    Jeppesen, E.
    Korhola, A.
    McGowan, S.
    Ruehland, K.
    Rusak, J. A.
    Simpson, G. L.
    Solovieva, N.
    Werne, J.
    Paleolimnological evidence of the effects on lakes of energy and mass transfer from climate and humans2009Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 54, nr 6, s. 2330-2348Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The premise of this article is that climate effects on lakes can be quantified most effectively by the integration of process-oriented limnological studies with paleolimnological research, particularly when both disciplines operate within a common conceptual framework. To this end, the energy (E)-mass (m) flux framework (Em flux) is developed and applied to selected retrospective studies to demonstrate that climate variability regulates lake structure and function over diverse temporal and spatial scales through four main pathways: rapid direct transfer of E to the lake surface by irradiance, heat, and wind; slow indirect effects of E via changes in terrestrial development and subsequent m subsidies to lakes; direct influx of m as precipitation, particles, and solutes from the atmosphere; and indirect influx of water, suspended particles, and dissolved substances from the catchment. Sedimentary analyses are used to illustrate the unique effects of each pathway on lakes but suggest that interactions among mechanisms are complex and depend on the landscape position of lakes, catchment characteristics, the range of temporal variation of individual pathways, ontogenetic changes in lake basins, and the selective effects of humans on m transfers. In particular, preliminary synthesis suggests that m influx can overwhelm the direct effects of E transfer to lakes, especially when anthropogenic activities alter m subsidies from catchments.

  • 324. Leblond, Jeffrey D.
    et al.
    Lasiter, Andrew D.
    Li, Cen
    Logares, Ramiro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Rengefors, Karin
    Evens, Terence J.
    A data mining approach to dinoflagellate clustering according to sterol composition: correlations with evolutionary history2010Inngår i: International journal of data mining and bioinformatics, ISSN 1748-5673, Vol. 4, nr 4, s. 431-451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study examined the sterol compositions of 102 dinoflagellates using clustering and cluster validation techniques, as a means of determining the relatedness of the organisms. In addition, dinoflagellate sterol-based relationships were compared statistically to 18S rDNA-based phylogenetic relationships using the Mantel test. Our results indicated that the examined dinoflagellates formed six clusters based on sterol composition and that several, but not all, dinoflagellate genera, which formed discrete clusters in the 18S rDNA-based phylogeny, shared similar sterol compositions. This and other correspondences suggest that the sterol compositions of dinoflagellates are explained, to a certain extent, by the evolutionary history of this lineage.

  • 325.
    Lebret, Karen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Colinas, Noemi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Swedish Univ Agr Sci, Dept Aquat Resources, Öregrund, Sweden.
    Lindström, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Increased water colour affects freshwater plankton communities in a mesocosm study2018Inngår i: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 81, nr 1, s. 1-17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increases in water colour (brownification) have been observed in aquatic systems in the Northern Hemisphere, partly caused by increased loading of organic carbon from terrestrial origins. We investigated the effect of increase in water colour on the composition, structure and function of lake plankton communities (bacteria, phytoplankton and zooplankton) conducting a mesocosm experiment in 3 medium-coloured lakes (average absorbance at 420 nm: 0.034 cm(-1)), with different nutrient concentrations and phytoplankton community composition. To simulate an increase in water colour, we added humic substances (HuminFeed) at 3 different concentrations. The additions significantly affected the water colour of the mesocosms, but had no measurable effect on total organic carbon concentration, thus change in light conditions was the main effect of our treatment on the plankton communities. The increase in water colour did not significantly affect the measured functions (productivity, respiration) and biomass of the plankton communities (bacteria, phytoplankton and zooplankton), but led to changes in the relative abundance of some phytoplankton taxa and, to a lesser extent, the bacterial community (differences in relative abundance). The treatments had no significant effect on zooplankton biomass or composition. Our study suggests that increases in water colour favour low-light-adapted phytoplankton species, which in turn also can affect bacterial composition, whereas the change in light climate had no clear impact on the functioning of plankton communities in weakly humic lakes.

  • 326.
    Lebret, Karen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Marine Biol Assoc UK, Citadel Hill, Plymouth, Devon, England.
    Schroeder, Joanna
    Marine Biol Assoc UK, Citadel Hill, Plymouth, Devon, England.
    Balestreri, Cecilia
    Marine Biol Assoc UK, Citadel Hill, Plymouth, Devon, England.
    Highfield, Andrea
    Marine Biol Assoc UK, Citadel Hill, Plymouth, Devon, England.
    Cummings, Denise
    Plymouth Marine Lab, Prospect Pl, Plymouth, Devon, England.
    Smyth, Tim
    Plymouth Marine Lab, Prospect Pl, Plymouth, Devon, England.
    Schroeder, Declan
    Marine Biol Assoc UK, Citadel Hill, Plymouth, Devon, England.
    Choice of molecular barcode will affect species prevalence but not bacterial community composition2016Inngår i: Marine Genomics, ISSN 1874-7787, E-ISSN 1876-7478, Vol. 29, s. 39-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract The rapid advancement of next generation sequencing protocols in recent years has led to the diversification in the methods used to study microbial communities; however, how comparable the data generated from these different methods are, remains unclear. In this study we compared the taxonomic composition and seasonal dynamics of the bacterial community determined by two distinct 16s amplicon sequencing protocols: sequencing of the V6 region of the 16s rRNA gene using 454 pyrosequencing vs the V4 region of the 16s rRNA gene using the Illumina Hiseq 2500 platform. Significant differences between relative abundances at all taxonomic levels were observed; however, their seasonal dynamics between phyla were largely consistent between methods. This study highlights that care must be taken when comparing datasets generated from different methods.

  • 327.
    Lebret, Karen
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Centre for Ecology and Evolution in Microbial model Systems - EEMiS, Department of Biology and Environmental Science, Linnæus University, SE-391 82, Kalmar, Sweden.
    Östman, Örjan
    Department of Aquatic Resources, Swedish University of Agricultural Sciences, Skolgatan 6, SE-742 42, Öregrund, Sweden.
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Drakare, Stina
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences - SLU, PO Box 7050, SE-750 07, Uppsala, Sweden.
    Guillemette, François
    Research Center on Watershed – Aquatic Ecosystem Interactions (RIVE), Department of Environmental Sciences, Université du Québec à Trois-Rivières, Québec, Canada.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    High abundances of the nuisance raphidophyte Gonyostomum semen in brown water lakes are associated with high concentrations of iron2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, nr 1, artikkel-id 13463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Algal blooms occur frequently in lakes and oceans and the causes and consequences of those are often studied. In this study, we focus on a less well known type of algal bloom by the freshwater raphidophyte Gonyostomum semen. This species’ abundance and occurrence is increasing, especially in brown water lakes, the most abundant lake type in the boreal zone. The aim of the study was to investigate which environmental factors are associated with G. semen by statistical evaluation of field data of 95 Swedish lakes over five years. Although we found G. semen to be associated with dark waters it was, contrary to our expectations, mainly high concentrations of iron, and only to a lesser extent high TOC (total organic carbon) concentrations, that were associated with blooms of G. semen. In addition, high phosphorus concentrations and low pH also appear to facilitate G. semen blooms. We suggest that browning of lakes caused by increased iron concentrations may decrease net heterotrophy by fostering heavy algal blooms, i.e. the opposite to commonly assumed effects of increased DOM (dissolved organic matter).

  • 328.
    Ledesma, J. L. J.
    et al.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Kothawala, Dolly N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Bastviken, P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper. Geol Survey Sweden, Uppsala, Sweden.
    Maehder, S.
    BIOS Gutachten Okol Bestandsaufnahmen Bewertungen, Osterholz Scharmbeck, Germany; Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Grabs, Thomas J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Futter, M. N.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Stream Dissolved Organic Matter Composition Reflects the Riparian Zone, Not Upslope Soils in Boreal Forest Headwaters2018Inngår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 54, nr 6, s. 3896-3912Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite the strong quantitative evidence that riparian zones (RZs) are the dominant source of dissolved organic carbon (DOC) to boreal streams, there is still a debate about the potential contribution of upslope areas to fluvial carbon export. To shed new light into this debate, we investigated the molecular composition of dissolved organic matter (DOM) in four upslope-riparian-stream transects in a Northern Swedish forest catchment using absorbance (A(254)/A(365) and SUVA(254)) and fluorescence (fluorescence and freshness indices) metrics. Based on these metrics, our results indicate that stream water DOM molecular composition resembles that of RZs and significantly differs from that of upslope areas. The resemblance between stream and riparian DOM was most apparent for the Dominant Source Layer (DSL), a narrow RZ stratum that, theoretically, contributes the most to solute and water fluxes to streams. Spectroscopic characterization based on traditional interpretations of the metrics suggested that mineral upslope (podzol) DOM is less aromatic, more microbially derived, and more recently produced than organic riparian (histosol) and stream DOM. We conclude that RZs, and specifically DSLs, are the main sources of DOC to boreal headwater streams and potentially to other streams located in low-gradient, organic matter-rich catchments. Plain Language Summary Understanding carbon cycling in natural ecosystems is critical because ongoing climate change can promote the release of previously stored carbon in forest soils to streams and rivers, with the potential to form carbon dioxide, the main greenhouse gas. This is particularly important in boreal ecosystems, which are the largest stores of terrestrial carbon in the world. In this study, we identify the near-stream area, the so-called riparian zone, as the main source of carbon from boreal forest soils to streams. We provide qualitative data to support this, which together with previous quantitative analyses, make up enough evidence to support that the riparian zone is the main source of carbon to streams. As there is still a debate about the potential contribution of other areas in the ecosystem to the fluvial carbon export, our study importantly highlights that the riparian zone should be the focus of scientific assessments and management strategies in relation to carbon exports in surface waters.

  • 329.
    Leith, Fraser Leith
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Dinsmore, Kerry
    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.
    Billett, Michael
    Heal, Kate
    Laudon, Hjalmar
    Öquist, Mats
    Bishop, Kevin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Carbon dioxide transport across the hillslope–riparian–stream continuum in a boreal headwater catchment2015Inngår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 12, s. 1881-1892Artikkel i tidsskrift (Fagfellevurdert)
  • 330.
    Lim, Hwanmi
    et al.
    Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, S-10691 Stockholm, Sweden..
    Ahmed, Trifa M.
    Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, S-10691 Stockholm, Sweden.;Livsmedelsverket, Box 622, S-75126 Uppsala, Sweden..
    Bergvall, Christoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, S-10691 Stockholm, Sweden..
    Westerholm, Roger
    Stockholm Univ, Dept Environm Sci & Analyt Chem ACES, S-10691 Stockholm, Sweden..
    Automated clean-up, separation and detection of polycyclic aromatic hydrocarbons in particulate matter extracts using a 2D-LC/2D-GC system: a method translation from two FIDs to two MS detectors2017Inngår i: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 409, nr 24, s. 5619-5629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An online two-dimensional (2D) liquid chromatography/2D gas chromatography system with two mass-selective detectors has been developed on the basis of a previous system with two flame ionization detectors. The method translation involved the change of carrier gas from hydrogen to helium, column dimension and detectors. The 2D system with two mass-selective detectors was validated with use of polycyclic aromatic hydrocarbon (PAH) standards and two standard reference materials from air and diesel exhaust. Furthermore, the system was applied to a real sample, wood smoke particulates. The PAH values determined correlated well with the previous data and those from the National Institute of Standards and Technology. The system enhanced the benefits of the previous system, which were limited by the low detectability and lack of mass selectivity. This study shows an automated 2D system that is valid for PAH analysis of complex environmental samples directly from crude extracts.

  • 331. Lindenmayer, D. B.
    et al.
    Likens, Gene E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Andersen, A.
    Bowman, D.
    Bull, C. M.
    Burns, E.
    Dickman, C. R.
    Hoffmann, A. A.
    Keith, D. A.
    Liddell, M. J.
    Lowe, A. J.
    Metcalfe, D. J.
    Phinn, S. R.
    Russell-Smith, J.
    Thurgate, N.
    Wardle, G. M.
    Value of long-term ecological studies2012Inngår i: Austral ecology (Print), ISSN 1442-9985, E-ISSN 1442-9993, Vol. 37, nr 7, s. 745-757Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Long-term ecological studies are critical for providing key insights in ecology, environmental change, natural resource management and biodiversity conservation. In this paper, we briefly discuss five key values of such studies. These are: (1) quantifying ecological responses to drivers of ecosystem change; (2) understanding complex ecosystem processes that occur over prolonged periods; (3) providing core ecological data that may be used to develop theoretical ecological models and to parameterize and validate simulation models; (4) acting as platforms for collaborative studies, thus promoting multidisciplinary research; and (5) providing data and understanding at scales relevant to management, and hence critically supporting evidence-based policy, decision making and the management of ecosystems. We suggest that the ecological research community needs to put higher priority on communicating the benefits of long-term ecological studies to resource managers, policy makers and the general public. Long-term research will be especially important for tackling large-scale emerging problems confronting humanity such as resource management for a rapidly increasing human population, mass species extinction, and climate change detection, mitigation and adaptation. While some ecologically relevant, long-term data sets are now becoming more generally available, these are exceptions. This deficiency occurs because ecological studies can be difficult to maintain for long periods as they exceed the length of government administrations and funding cycles. We argue that the ecological research community will need to coordinate ongoing efforts in an open and collaborative way, to ensure that discoverable long-term ecological studies do not become a long-term deficiency. It is important to maintain publishing outlets for empirical field-based ecology, while simultaneously developing new systems of recognition that reward ecologists for the use and collaborative sharing of their long-term data sets. Funding schemes must be re-crafted to emphasize collaborative partnerships between field-based ecologists, theoreticians and modellers, and to provide financial support that is committed over commensurate time frames.

  • 332. Lindenmayer, David B.
    et al.
    Laurance, William F.
    Franklin, Jerry F.
    Likens, Gene E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Banks, Sam C.
    Blanchard, Wade
    Gibbons, Philip
    Ikin, Karen
    Blair, David
    McBurney, Lachlan
    Manning, Adrian D.
    Stein, John A. R.
    New Policies for Old Trees: Averting a Global Crisis in a Keystone Ecological Structure2014Inngår i: Conservation Letters, ISSN 1755-263X, E-ISSN 1755-263X, Vol. 7, nr 1, s. 61-69Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large old trees are critical organisms and ecological structures in forests, woodlands, savannas, and agricultural and urban environments. They play many essential ecological roles ranging from the storage of large amounts of carbon to the provision of key habitats for wildlife. Some of these roles cannot be replaced by other structures. Large old trees are disproportionately vulnerable to loss in many ecosystems worldwide as a result of accelerated rates of mortality, impaired recruitment, or both. Drivers of loss, such as the combined impacts of fire and browsing by domestic or native herbivores, chemical spray drift in agricultural environments, and postdisturbance salvage logging, are often unique to large old trees but also represent ecosystem-specific threats. Here, we argue that new policies and practices are urgently needed to conserve existing large old trees and restore ecologically effective and viable populations of such trees by managing trees and forests on much longer time scales than is currently practiced, and by protecting places where they are most likely to develop. Without these steps, large old trees will vanish from many ecosystems, and associated biota and ecosystem functions will be severely diminished or lost.

  • 333.
    Lindström, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Bacterial Diversity in Freshwater2017Inngår i: Oxford Bibliographies in Ecology / [ed] David Gibson, New York: Oxford University Press, 2017Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 334.
    Lindström, Eva
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Increased water colour affects freshwater plankton communities but not ecosystem functions in a mesocosm study2017Dataset
  • 335.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    High abundances of Gonyostomum semen in brown water lakes are associated with high concentrations of iron: Fluorescence and abosrbance data2018Dataset
  • 336.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Repeated disturbances affect functional but not compositional resistance and resilience in aquatic bacterioplankton communities - supporting data2017Dataset
  • 337.
    Lindström, Eva S.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Supporting data version 22017Dataset
  • 338.
    Lindström, Eva S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Andersson, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Effects of sterilization on composition and bacterial utilization of dissolved organic carbon2017Dataset
  • 339.
    Lindström, Eva S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Andersson, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Effects of sterilization on composition and bacterial utilization of dissolved organic carbon2017Dataset
  • 340.
    Lindström, Eva S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    del Giorgio, Paul A.
    Départment des sciences biologiques, Université du Québec à Montréal (UQÀM), Montréal, QC H3C 3P8, Canada .
    Progress and perspectives in aquatic microbial ecology: highlights of the SAME 14, Uppsala, Sweden, 20152017Inngår i: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 80, s. 101-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The presentations and discussion during the Symposium of Aquatic Microbial Ecology (SAME) in Uppsala, Sweden, in August 2015 highlighted new directions and challenges in the study of aquatic microbial communities. In this virtual Special Issue, plenary speakers and meeting awardees explore these challenges. The contributions cover a wide range of topics from the use of molecular analyses of microbial communities to cultivation and stoichiometric analyses. The virtual Special also includes theoretical developments on the concept of rarity to community assembly. A common theme for the Special is, however, the importance of a combination of different approaches in order to deepen our understanding of the ecology of microbial communities.

    Fulltekst tilgjengelig fra 2022-11-24 14:31
  • 341.
    Lindström, Eva S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Langenheder, Silke
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Local and regional factors influencing bacterial community assembly2012Inngår i: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 4, nr 1, s. 1-9Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The classical view states that microbial biogeography is not affected by dispersal barriers or historical events, but only influenced by the local contemporary habitat conditions (species sorting). This has been challenged during recent years by studies suggesting that also regional factors such as mass effect, dispersal limitation and neutral assembly are important for the composition of local bacterial communities. Here we summarize results from biogeography studies in different environments, i.e. in marine, freshwater and soil as well in human hosts. Species sorting appears to be the most important mechanism. However, this result might be biased since this is the mechanism that is easiest to measure, detect and interpret. Hence, the importance of regional factors may have been underestimated. Moreover, our survey indicates that different assembly mechanisms might be important for different parts of the total community, differing, for example, between generalists and specialists, and between taxa of different dispersal ability and motility. We conclude that there is a clear need for experimental studies, first, to clearly separate regional and local factors in order to study their relative importance, and second, to test whether there are differences in assembly mechanisms depending on different taxonomic or functional groups.

  • 342.
    Lindström, Eva S.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Östman, Örjan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Populationsbiologi och naturvårdsbiologi.
    The Importance of Dispersal for Bacterial Community Composition and Functioning2011Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, nr 10, s. e25883-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We conducted a metacommunity experiment to investigate the role of dispersal for bacterial community composition (BCC) and function of freshwater bacteria. Bacteria were dispersed from a common source pool into three different lake communities in their natural lake water. The experiment was conducted in dialysis bags to enable a decoupling between a change in the local environment and dispersal. BCC was determined by terminal restriction fragment length polymorphism (tRFLP) of the 16S rRNA gene. We show that the greatest changes in BCC occurred between 10% and 43% of dispersal of standing stock per day. Functioning, measured as growth rate, was also affected by dispersal in all three communities but the qualitative pattern differed between communities, sometimes showing a hump-shaped relationship to dispersal and sometimes decreasing with increasing dispersal. In all waters, functioning was related to BCC. Our results show that dispersal does affect BCC and functioning but that high dispersal rates are needed. Further, the effect of dispersal on BCC and function seem to depend on the quality of the habitat to which bacteria disperse into.

  • 343.
    Linkhorst, Annika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Greenhouse gas emission from tropical reservoirs: Spatial and temporal dynamics2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The emission of methane (CH4) and carbon dioxide (CO2) from reservoirs has been estimated to make up for about 1.3% of the global anthropogenic greenhouse gas emission. The impoundment of a river leads to the accumulation of sediment that is brought in from inflowing rivers, and the sediment organic matter is degraded to CH4 and CO2. CH4 is of particular concern as its global warming potential is 34 times stronger than that of CO2. In the tropics, high temperatures and high availability of fresh organic matter from high net primary production fuel CH4 and CO2 production. As the construction of hydropower plants is currently undergoing a boom, especially in the tropics, reservoir emission is probably bound to increase.

    The emission of CH4 and CO2 from reservoir surfaces is, however, highly variable, which makes current estimates uncertain. This thesis is built on the hypothesis that the spatial and temporal variability of greenhouse gas emission in tropical reservoirs, particularly of CH4 ebullition (the emission via gas bubbles), is so large that the sampling strategy affects whole-system estimates of greenhouse gas emission.

    This thesis shows that greenhouse gas emission from the four studied tropical reservoirs in Brazil varied greatly at different timescales – over 24 hours, between days and between seasons. Seasonal variability was identified as the most important temporal scale to be covered for CH4 ebullition inventories. In addition, the spatial variability of gas emission was large for all pathways. The variability of CH4 ebullition across space, for example, was estimated to be almost as large as its variability between seasons, and patterns of spatial variability in diffusive CH4 and CO2 emission differed between seasons. For both ebullition and diffusion, river inflow areas were prone to elevated greenhouse gas emission.

    This thesis shows that for retrieving solid emission estimates, there is no alternative to time-consuming measurements in the field. Measurements should be repeated at least once during each hydrological season (i.e. falling and rising water level). The seasonal surveys should cover space at a high resolution, including areas with and without river inflows, and different water column depths. CH4 ebullition made up for 60–99% of the total CO2-equivalent emission from the whole water surface of the studied reservoirs, with the highest contribution in the most productive reservoir. The most variable greenhouse gas emission pathway is therefore the most important one to be measured at appropriate resolution, particularly in productive reservoirs.

    Delarbeid
    1. Deconstructing carbon emission pathways of a diel cycle from four tropical reservoirs
    Åpne denne publikasjonen i ny fane eller vindu >>Deconstructing carbon emission pathways of a diel cycle from four tropical reservoirs
    Vise andre…
    (engelsk)Inngår i: Artikkel i tidsskrift (Fagfellevurdert) Submitted
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-393436 (URN)
    Tilgjengelig fra: 2019-09-22 Laget: 2019-09-22 Sist oppdatert: 2019-09-30
    2. Comparing methane ebullition variability across space and time in a Brazilian reservoir
    Åpne denne publikasjonen i ny fane eller vindu >>Comparing methane ebullition variability across space and time in a Brazilian reservoir
    Vise andre…
    (engelsk)Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Abstract [en]

    The potent greenhouse gas methane (CH4) is readily emitted from tropical reservoirs, often via ebullition (bubbles). This highly stochastic emission pathway varies in space and time, however, hampering efforts to accurately assess total CH4emissions from water bodies. We systematically studied both the spatial and temporal scales of ebullition variability in a river inflow bay of a tropical Brazilian reservoir. We conducted multiple highly resolved spatial surveys of CH4 ebullition using a hydroacoustic approach supplemented with bubble traps over a 12‐month and a 2‐week timescale to evaluate which scale of variation was more important. To quantify the spatial and temporal variability of CH4 ebullition, we used the quartile coefficients of dispersion at each point in space and time and compared their frequency distributions across the various temporal and spatial scales. We found that CH4 ebullition varied more temporally than spatially and that the intra‐annual variability was stronger than daily variability within 2 weeks. We also found that CH4 ebullition was positively related to water temperature increase and pressure decrease, but no consistent relationship with water column depth or sediment characteristics was found, further highlighting that temporal drivers of emissions were stronger than spatial drivers. Annual estimates of CH4ebullition from our study area may vary by 75–174% if ebullition is not resolved in time and space, but at a minimum we recommend conducting spatially resolved measurements at least once during each major hydrologic season in tropical regions (i.e., in dry and rainy season when water levels are falling and rising, respectively).

    Emneord
    CH4, carbon cycle, lake, biogeochemistry, spatial, temporal scale
    HSV kategori
    Forskningsprogram
    Biologi med inriktning mot limnologi
    Identifikatorer
    urn:nbn:se:uu:diva-393435 (URN)10.1002/lno.11410 (DOI)
    Tilgjengelig fra: 2019-09-22 Laget: 2019-09-22 Sist oppdatert: 2020-02-04
    3. Spatially Resolved Measurements of CO2 and CH4 Concentration and Gas-Exchange Velocity Highly Influence Carbon-Emission Estimates of Reservoirs
    Åpne denne publikasjonen i ny fane eller vindu >>Spatially Resolved Measurements of CO2 and CH4 Concentration and Gas-Exchange Velocity Highly Influence Carbon-Emission Estimates of Reservoirs
    Vise andre…
    2018 (engelsk)Inngår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, nr 2, s. 607-615Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The magnitude of diffusive carbon dioxide (CO2) and methane (CH4) emission from man-made reservoirs is uncertain because the spatial variability generally is not well-represented. Here, we examine the spatial variability and its drivers for partial pressure, gas-exchange velocity (k), and diffusive flux of CO2 and CH4 in three tropical reservoirs using spatially resolved measurements of both gas concentrations and k. We observed high spatial variability in CO2 and CH4 concentrations and flux within all three reservoirs, with river inflow areas generally displaying elevated CH4 concentrations. Conversely, areas close to the dam are generally characterized by low concentrations and are therefore not likely to be representative for the whole system. A large share (44–83%) of the within-reservoir variability of gas concentration was explained by dissolved oxygen, pH, chlorophyll, water depth, and within-reservoir location. High spatial variability in k was observed, and kCH4 was persistently higher (on average, 2.5 times more) than kCO2. Not accounting for the within-reservoir variability in concentrations and k may lead to up to 80% underestimation of whole-system diffusive emission of CO2 and CH4. Our findings provide valuable information on how to develop field-sampling strategies to reliably capture the spatial heterogeneity of diffusive carbon fluxes from reservoirs.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-337400 (URN)10.1021/acs.est.7b05138 (DOI)000423012200025 ()29257874 (PubMedID)
    Forskningsfinansiär
    EU, European Research Council, 336642
    Tilgjengelig fra: 2017-12-25 Laget: 2017-12-25 Sist oppdatert: 2019-09-22bibliografisk kontrollert
    4. Upscaling spatially-resolved methane ebullition measurements in two contrasting tropical reservoirs
    Åpne denne publikasjonen i ny fane eller vindu >>Upscaling spatially-resolved methane ebullition measurements in two contrasting tropical reservoirs
    Vise andre…
    (engelsk)Manuskript (preprint) (Annet vitenskapelig)
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-393434 (URN)
    Tilgjengelig fra: 2019-09-22 Laget: 2019-09-22 Sist oppdatert: 2019-09-30
    5. Spatial heterogeneity of diffusive CO2 and CH4 emission varies seasonally in four tropical reservoirs
    Åpne denne publikasjonen i ny fane eller vindu >>Spatial heterogeneity of diffusive CO2 and CH4 emission varies seasonally in four tropical reservoirs
    Vise andre…
    (engelsk)Inngår i: Artikkel i tidsskrift (Fagfellevurdert) Submitted
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-393437 (URN)
    Tilgjengelig fra: 2019-09-22 Laget: 2019-09-22 Sist oppdatert: 2019-09-30
  • 344.
    Linkhorst, Annika
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hiller, Carolin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    DelSontro, Tonya
    Aquatic Physics Group, Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Geneva, Switzerland.
    Millen Azevedo, Guilherme
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Juiz de Fora, Brazil .
    Barros, Nathan
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Juiz de Fora, Brazil .
    Mendonça, Raquel
    Department of Biology, Institute of Biological Sciences, 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.
    Comparing methane ebullition variability across space and time in a Brazilian reservoirInngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The potent greenhouse gas methane (CH4) is readily emitted from tropical reservoirs, often via ebullition (bubbles). This highly stochastic emission pathway varies in space and time, however, hampering efforts to accurately assess total CH4emissions from water bodies. We systematically studied both the spatial and temporal scales of ebullition variability in a river inflow bay of a tropical Brazilian reservoir. We conducted multiple highly resolved spatial surveys of CH4 ebullition using a hydroacoustic approach supplemented with bubble traps over a 12‐month and a 2‐week timescale to evaluate which scale of variation was more important. To quantify the spatial and temporal variability of CH4 ebullition, we used the quartile coefficients of dispersion at each point in space and time and compared their frequency distributions across the various temporal and spatial scales. We found that CH4 ebullition varied more temporally than spatially and that the intra‐annual variability was stronger than daily variability within 2 weeks. We also found that CH4 ebullition was positively related to water temperature increase and pressure decrease, but no consistent relationship with water column depth or sediment characteristics was found, further highlighting that temporal drivers of emissions were stronger than spatial drivers. Annual estimates of CH4ebullition from our study area may vary by 75–174% if ebullition is not resolved in time and space, but at a minimum we recommend conducting spatially resolved measurements at least once during each major hydrologic season in tropical regions (i.e., in dry and rainy season when water levels are falling and rising, respectively).

  • 345.
    Linkhorst, Annika
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Paranaíba, José
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil.
    Barros, Nathan
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil.
    DelSontro, Tonya
    Aquatic Physics Group, Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Switzerland.
    Mendonça, Raquel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil.
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Deconstructing carbon emission pathways of a diel cycle from four tropical reservoirsInngår i: Artikkel i tidsskrift (Fagfellevurdert)
  • 346.
    Linkhorst, Annika
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Paranaíba, José
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil .
    Mendonça, Raquel
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil .
    Rudberg, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    DelSontro, Tonya
    Aquatic Physics Group, Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Switzerland.
    Barros, Nathan
    Department of Biology, Institute of Biological Sciences, Federal University of Juiz de Fora, Brazil .
    Sobek, Sebastian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Upscaling spatially-resolved methane ebullition measurements in two contrasting tropical reservoirsManuskript (preprint) (Annet vitenskapelig)
  • 347.
    Linz, Alexandra M.
    et al.
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA.
    He, Shaomei
    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.
    Anantharaman, Karthik
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA.
    Rohwer, Robin R.
    Univ Wisconsin, Environm Chem & Technol Program, Madison, WI USA.
    Malmstrom, Rex R.
    Joint Genome Inst, Dept Energy, 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.
    McMahon, Katherine D.
    Univ Wisconsin, Dept Bacteriol, Madison, WI 53706 USA;Univ Wisconsin, Dept Civil & Environm Engn, Madison, WI 53706 USA.
    Freshwater carbon and nutrient cycles revealed through reconstructed population genomes2018Inngår i: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 6, artikkel-id e6075Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although microbes mediate much of the biogeochemical cycling in freshwater, the categories of carbon and nutrients currently used in models of freshwater biogeochemical cycling are too broad to be relevant on a microbial scale. One way to improve these models is to incorporate microbial data. Here, we analyze both genes and genomes from three metagenomic time series and propose specific roles for microbial taxa in freshwater biogeochemical cycles. Our metagenomic time series span multiple years and originate from a eutrophic lake (Lake Mendota) and a humic lake (Trout Bog Lake) with contrasting water chemistry. Our analysis highlights the role of polyamines in the nitrogen cycle, the diversity of diazotrophs between lake types, the balance of assimilatory vs. dissimilatory sulfate reduction in freshwater, the various associations between types of phototrophy and carbon fixation, and the density and diversity of glycoside hydrolases in freshwater microbes. We also investigated aspects of central metabolism such as hydrogen metabolism, oxidative phosphorylation, methylotrophy, and sugar degradation. Finally, by analyzing the dynamics over time in nitrogen fixation genes and Cyanobacteria genomes, we show that the potential for nitrogen fixation is linked to specific populations in Lake Mendota. This work represents an important step towards incorporating microbial data into ecosystem models and provides a better understanding of how microbes may participate in freshwater biogeochemical cycling.

  • 348. Lischke, Betty
    et al.
    Mehner, Thomas
    Hilt, Sabine
    Attermeyer, Katrin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz Inst Freshwater Ecol & Inland Fisheries, Stechlin, Germany.
    Brauns, Mario
    Brothers, Soren
    Grossart, Hans Peter
    Köhler, Jan
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany.
    Gaedke, Ursula
    Benthic carbon is inefficiently transferred in the food webs of two eutrophic shallow lakes2017Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 62, nr 10, s. 1693-1706Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. The sum of benthic autotrophic and bacterial production often exceeds the sum of pelagic autotrophic and bacterial production, and hence may contribute sub- stantially to whole-lake carbon fluxes, especially in shallow lakes. Furthermore, both benthic and pelagic autotrophic and bacterial production are highly edible and of sufficient nutritional quality for animal consumers. We thus hypothesised that pelagic and benthic transfer efficiencies (ratios of production at adjacent trophic levels) in shallow lakes should be similar. 2. We performed whole ecosystem studies in two shallow lakes (3.5 ha, mean depth 2 m), one with and one without submerged macrophytes, and quantified pelagic and benthic biomass, production and transfer efficiencies for bacteria, phytoplank- ton, epipelon, epiphyton, macrophytes, zooplankton, macrozoobenthos and fish. We expected higher transfer efficiencies in the lake with macrophytes, because these provide shelter and food for macrozoobenthos and may thus enable a more efficient conversion of basal production to consumer production. 3. In both lakes, the majority of the whole-lake autotrophic and bacterial produc- tion was provided by benthic organisms, but whole-lake primary consumer pro- duction mostly relied on pelagic autotrophic and bacterial production. Consequently, transfer efficiency of benthic autotrophic and bacterial production to macrozoobenthos production was an order of magnitude lower than the transfer efficiency of pelagic autotrophic and bacterial production to rotifer and crustacean production. Between-lake differences in transfer efficiencies were minor. 4. We discuss several aspects potentially causing the unexpectedly low benthic transfer efficiencies, such as the food quality of producers, pelagic–benthic links, oxygen concentrations in the deeper lake areas and additional unaccounted con- sumer production by pelagic and benthic protozoa and meiobenthos at interme- diate or top trophic levels. None of these processes convincingly explain the large differences between benthic and pelagic transfer efficiencies. 5. Our data indicate that shallow eutrophic lakes, even with a major share of auto- trophic and bacterial production in the benthic zone, can function as pelagic sys- tems with respect to primary consumer production. We suggest that the benthic autotrophic production was mostly transferred to benthic bacterial production, which remained in the sediments, potentially cycling internally in a similar way to what has previously been described for the microbial loop in pelagic habitats. Understanding the energetics of whole-lake food webs, including the fate of the substantial benthic bacterial production, which is either mineralised at the sedi- ment surface or permanently buried, has important implications for regional and global carbon cycling

  • 349. Lischke, Betty
    et al.
    Weithoff, Guntram
    Wickham, Stephen
    Attermeyer, Katrin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Grossart, Hans-Peter
    Scharnweber, Kristin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Hilt, Sabine
    Gaedke, Ursula
    Large biomass of small feeders: Ciliates may dominate herbivory in eutrophic lakes2016Inngår i: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 38, nr 1, s. 2-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The importance of ciliates as herbivores and in biogeochemical cycles is increasingly recognized. An opportunity to observe the potential consequences of zooplankton dominated by ciliates arose when winter fish kills resulted in strong suppression of crustaceans by young planktivorous fish in two shallow lakes. On an annual average, ciliates made up 38-76% of the total zooplankton biomass in both lakes during two subsequent years. Consequently, ciliate biomass and their estimated grazing potential were extremely high compared with other lakes of various trophic states and depths. Grazing estimates based on abundance and size suggest that ciliates should have cleared the water column of small (<5 mu m) and intermediate (5-50 mu m) sized phytoplankton more than once a day. Especially, small feeders within the ciliates were important, likely exerting a strong top-down control on small phytoplankton. Particle-attached bacteria were presumably strongly suppressed by intermediate-sized ciliate feeders. In contrast to other lakes, large phytoplankton was proportionately very abundant. The phytoplankton community had a high evenness, which may be attributed to the feeding by numerous fast growing and selective ciliate species. Our study highlights ciliates as an important trophic link and adds to the growing awareness of the role of winter processes for plankton dynamics.

  • 350.
    Liu, Haoyu
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Waldén, Tomas
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Ahl, David
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Nyman, Margareta
    Lund Univ, Dept Food Technol Engn & Nutr, S-22100 Lund, Sweden.
    Bertilsson, Stefan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Uppsala universitet, Science for Life Laboratory, SciLifeLab.
    Phillipson, Mia
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    Holm, Lena
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk cellbiologi.
    High-Fat Diet Enriched with Bilberry Modifies Colonic Mucus Dynamics and Restores Marked Alterations of Gut Microbiome in Rats2019Inngår i: Molecular Nutrition & Food Research, ISSN 1613-4125, E-ISSN 1613-4133, Vol. 63, nr 20, artikkel-id 1900117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Scope Emerging evidence suggests that high-fat diet (HFD) is associated with gut microbiome dysbiosis and related disorders. Bilberry is a prebiotic food component with known health benefits. Herein, the dynamics of the colonic mucus layer and microbiome during HFD and bilberry supplementation are addressed. Methods and results The effects on colonic mucus thickness in vivo and gut microbiota composition (Illumina sequencing, quantitative real-time PCR) are investigated in young rats fed a low-fat diet or HFD with or without bilberries for 8 weeks (n = 8). HFD induced significant local colonic effects, despite no observed weight gain or systemic inflammation, as HFD causes epithelial upregulation of inducible nitric oxide synthase, which is counteracted by bilberry. The firmly adherent mucus layer becomes thicker and the mRNA levels of Muc2 and Tff3 are increased by HFD with or without bilberry. In parallel, HFD reduced the colonic abundance of mucolytic bacterial species Akkermansia muciniphila and Bacteroides spp. Finally, bilberry prevents HFD-induced microbiota dysbiosis, including expansion of pathobionts, for example, Enterobacteriaceae. Conclusion HFD expand firmly adherent mucus thickness and reduce mucus-foraging bacteria populations in the colon prior to obesity. Enriching HFD with bilberry protects against intestinal inflammation and marked microbiota encroachment.

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