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  • 601.
    Weyhenmeyer, Gesa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Sonesten, L
    Klimat och vattenstånd under 20042005Report (Other academic)
  • 602.
    Wilken, Susanne
    et al.
    Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden.;Inst Marine Sci, ICM, CSIC, Barcelona, Spain.;Univ Amsterdam, IBED, FAME, Dept Freshwater & Marine Ecol, Amsterdam, Netherlands..
    Soares, Margarida
    Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden.;Monterey Bay Aquarium Res Inst, Moss Landing, CA 95039 USA.;Lund Univ, Dept Biol, Microbial Ecol, Lund, Sweden..
    Urrutia Cordero, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden.
    Ratcovich, Jens
    Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden.;Lansstyrelsen Kalmar Lan, Tillvaxt Och Miljo, Vattenenheten, Kalmar, Sweden..
    Ekvall, Mattias K.
    Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden..
    Van Donk, Ellen
    Netherlands Inst Ecol, NIOO, KNAW, Dept Aquat Ecol, Wageningen, Netherlands.;Univ Utrecht, Dept Ecol & Biodivers, Utrecht, Netherlands..
    Hansson, Lars-Anders
    Lund Univ, Dept Biol, Aquat Ecol, Lund, Sweden..
    Primary producers or consumers?: Increasing phytoplankton bacterivory along a gradient of lake warming and browning2018In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, no Suppl. 1, p. S142-S155Article in journal (Refereed)
    Abstract [en]

    Eukaryotic phytoplankton form the basis of aquatic food webs and play a key role in the global carbon cycle. Many of these evolutionarily diverse microalgae are also capable of feeding on other microbes, and hence simultaneously act both as primary producers and consumers. The net ecosystem impact of such mixotrophs depends on their nutritional strategy which is likely to alter with environmental change. Many temperate lakes are currently warming at unprecedented rates and are simultaneously increasing in water color (browning) due to increased run-off of humic substances. We hypothesized that the resulting reduction in light intensity and increased bacterial abundances would favor mixotrophic phytoplankton over obligate autotrophs, while higher temperatures might boost their rates of bacterivory. We tested these hypotheses in a mesocosm experiment simulating a gradient of increasing temperature and water color in temperate shallow lakes as expected to occur over the coming century. Mixotrophs showed a faster increase in abundance under the climate change scenario during spring, when they dominated the phytoplankton community. Furthermore, both bacterial abundances and rates of phytoplankton bacterivory increased under future climate conditions. Bacterivory contributed significantly to phytoplankton resource acquisition under future climate conditions, while remaining negligible throughout most of the season in treatments resembling today's conditions. Hence, to our knowledge, we here provide the first evidence for an increasing importance of bacterivory by phytoplankton in future temperate shallow lakes. Such a change in phytoplankton nutritional strategies will likely impact biogeochemical cycles and highlights the need to conceptually integrate mixotrophy into current ecosystem models.

  • 603. Willen, Eva
    et al.
    Ahlgren, Gunnel
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Tilahun, Girma
    Spoof, Lisa
    Neffling, Milla-Riina
    Meriluoto, Jussi
    Cyanotoxin production in seven Ethiopian Rift Valley lakes2011In: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 1, no 2, p. 81-91Article in journal (Refereed)
    Abstract [en]

    We hypothesized that unusual deaths and illnesses in wild and domestic animals in lake areas of the Rift Valley south of Addis Ababa were caused by toxic cyanobacteria. In the first cyanotoxic analyses conducted in samples from Ethiopia, we found lakes Chamo, Abaya, Awassa, Chitu, Langano, Ziway, and Koka all had concentrations of microcystins (MC) ranging from trace to hazardous, whereas only traces less than limits of detection (LOD) of cylindrospermopsin (CYN) were found. In the December 2006 dry season we sampled the lakes for analyses of MC, CYN, species structures, and calculations of cyanobacteria biomass. We used the Utermol technique to analyse cyanobacterial biomass and monitored MC toxins using HPLC-DAD, LC-ESI-MS-MRM, and ELISA-test and CYN with HPLC-DAD and ELISA. The various toxicity tests coincided well. In 4 of the lakes (Chamo, Langano, Ziway, and Koka), the inter-lake range of total MC concentration was 1.3-48 mu g L-1; in 3 (Abaya, Awassa, and Chitu), we found only traces of MC. Microcystis aeruginosa was the dominant species, with Microcystis panniformis, Anabaena spiroides, and Cylindrospermopsis spp. as subdominants. The MC concentration, especially in Lake Koka, exceeded levels for serious health hazards for humans, cattle, and wildlife.

  • 604.
    Williams, Clayton J.
    et al.
    Rubenstein School of Environment and Natural Resources, The University of Vermont, Burlington, VT 05405, USA.
    Conrad, Dan
    Buffalo Pound Water Treatment Plant, P.O. Box 1790, Regina, SK S4P 3C8, Canada.
    Kothawala, Dolly
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Baulch, Helen M.
    Univ Saskatchewan, Global Inst Water Secur, Sch Environm & Sustainabil, 11 Innovat Blvd, Saskatoon, SK S7N 3H5, Canada.
    Selective removal of dissolved organic matter affects the production and speciation of disinfection byproducts2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 652, p. 75-84Article in journal (Refereed)
    Abstract [en]

    The heterogeneity of dissolved organic matter (DOM) in natural and human impacted waters and the variety of drinking water treatment processes employed has made a mechanistic understanding of disinfection byproduct (DBP) formation challenging. In this study, we examined the formation of the regulated DBPs (Trichloromethanes, THM, and Haloacetic acids, HAA) during full-scale water treatment operations both with prechlorination treatment (normal operations for the drinking water plant) and without (altered operations); followed by coagulation, flocculation, filtration, and chlorination. The source water DOM concentration ranged 6.4 to 7.3 mg-C/L. DOM composition was moderately humic and degraded with a mix of microbial- and terrestrial-like characteristics. Removal of raw water prechlorination caused an average reduction in total THM and HAA concentrations of 52.7% and 40.0%, respectively, with the greater reduction noted for chlorinated-DBPs rather than brominated-DBPs. Prechlorination treatment resulted in a higher relative production of Cl3CH and BrCl2CH associated with aromatic, humic, and terrestrial-like DOM. Without prechlorination, the DBP pool had higher proportions of brominated-DBPs (Br3CH, Br2ClCH, Br2CHCOOH, BrClCHCOOH, and BrCH2COOH) associated with microbial-like, processed humic-like, and protein-like DOM. These observed patterns could not be explained by chloride demand and DOM concentration, indicating that DOM composition played an important role in DBP formation.

  • 605.
    Winterdahl, Mattias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Erlandsson, Martin
    Futter, Martyn N.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Intra-annual variability of organic carbon concentrations in running waters: Drivers along a climatic gradient2014In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 28, no 4, p. 451-464Article in journal (Refereed)
    Abstract [en]

    Trends in surface water dissolved organic carbon (DOC) concentrations have received considerable scientific interest during recent decades. However, intra-annual DOC variability is often orders of magnitude larger than long-term trends. Unraveling the controls on intra-annual DOC dynamics holds the key to a better understanding of long-term changes and their ecological significance. We quantified and characterized intra-annual DOC variability and compared it with long-term DOC trends in 136 streams and rivers, varying in size and geographical characteristics, across a 1400km latitudinal gradient during 2000-2010. Discharge, temperature, and month of the year were the most significant predictors of intra-annual DOC variability in a majority of the running waters. Relationships between DOC, discharge, and temperature were, however, different along a mean annual temperature (MAT) gradient. Running waters with low MAT generally displayed positive DOC-discharge correlations whereas the relationships in sites with higher MAT were more variable. This reflected contrasting relationships between temperature and discharge with discharge positively correlated with temperature in cold areas, while it was negatively correlated with temperature in catchments with higher MAT. Sites where flow, temperature, and month were poorly related to intra-annual DOC dynamics were large catchments or sites with extensive upstream lake cover. DOC trends were generally much smaller than intra-annual DOC variability and did not show any north-south gradient. Our findings suggest that DOC in running waters could respond to a changing climate in ways not predictable, or even discernible, from extrapolation of recent interannual trends. Key Points <list list-type="bulleted" id="gbc20160-list-0001"> <list-item id="gbc20160-li-0001">Large-scale characterization of intra-annual DOC dynamics in running waters <list-item id="gbc20160-li-0002">Discharge, temperature and month are significant predictors of DOC variability <list-item id="gbc20160-li-0003">Shifting patterns in DOC dynamics along a 1400 km climatic gradient

  • 606. Woolway, R. I.
    et al.
    Carrea, L.
    Merchant, J.
    Dokulil, M. T.
    de Eyto, E.
    DeGasper, C. L :
    Korhonen, J.
    Marszelewski, W.
    May, L.
    Paterson, A. M.
    Rimmer, A.
    Rusak, J. A.
    Schladow, S. G.
    Schmid, M.
    Shimaraeva, S. V.
    Silow, E.
    Timofeev, M. A.
    Verburg, P.
    Watanabe, S.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lake surface temperature [in €"State of the Climate in 2016"€]2017In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 98, no 8, p. S13-S14Article in journal (Other academic)
  • 607. Woolway, R. Iestyn
    et al.
    Jones, Ian D.
    Maberly, Stephen C.
    French, Jon R.
    Livingstone, David M.
    Monteith, Donald T.
    Simpson, Gavin L.
    Thackeray, Stephen J.
    Andersen, Mikkel R.
    Battarbee, Richard W.
    DeGasperi, Curtis L.
    Evans, Christopher D.
    de Eyto, Elvira
    Feuchtmayr, Heidrun
    Hamilton, David P.
    Kernan, Martin
    Krokowski, Jan
    Rimmer, Alon
    Rose, Kevin C.
    Rusak, James A.
    Ryves, David B.
    Scott, Daniel R.
    Shilland, Ewan M.
    Smyth, Robyn L.
    Staehr, Peter A.
    Thomas, Rhian
    Waldron, Susan
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Diel Surface Temperature Range Scales with Lake Size2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, article id e0152466Article in journal (Refereed)
    Abstract [en]

    Ecological and biogeochemical processes in lakes are strongly dependent upon water temperature. Long-term surface warming of many lakes is unequivocal, but little is known about the comparative magnitude of temperature variation at diel timescales, due to a lack of appropriately resolved data. Here we quantify the pattern and magnitude of diel temperature variability of surface waters using high-frequency data from 100 lakes. We show that the near-surface diel temperature range can be substantial in summer relative to long-term change and, for lakes smaller than 3 km(2), increases sharply and predictably with decreasing lake area. Most small lakes included in this study experience average summer diel ranges in their near-surface temperatures of between 4 and 7 degrees C. Large diel temperature fluctuations in the majority of lakes undoubtedly influence their structure, function and role in biogeochemical cycles, but the full implications remain largely unexplored.

  • 608.
    Woolway, R. Iestyn
    et al.
    Univ Reading, Dept Meteorol, Reading, Berks, England.
    Verburg, Piet
    Natl Inst Water & Atmospher Res, Hamilton, New Zealand.
    Lenters, John D.
    Univ Wisconsin, Ctr Limnol, Madison, WI 53706 USA.
    Merchant, Christopher J.
    Univ Reading, Dept Meteorol, Reading, Berks, England;Univ Reading, Natl Ctr Earth Observat, Reading, Berks, England.
    Hamilton, David P.
    Griffith Univ, Australian Rivers Inst, Brisbane, Qld, Australia.
    Brookes, Justin
    Univ Adelaide, Inst Environm, Sch Biol Sci, Adelaide, SA, Australia.
    de Eyto, Elvira
    Marine Inst, Newport, Mayo, Ireland.
    Kelly, Sean
    Marine Inst, Newport, Mayo, Ireland;Natl Univ Ireland Galway, Sch Nat Sci, Earth & Ocean Sci, Galway, Ireland.
    Healey, Nathan C.
    CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA.
    Hook, Simon
    CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA.
    Laas, Alo
    Estonian Univ Life Sci, Inst Agr & Environm Sci, Chair Hydrobiol & Fishery, Tartu, Estonia.
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Rusak, James A.
    Ontario Minist Environm & Climate Change, Dorset Environm Sci Ctr, Dorset, ON, Canada.
    Kuha, Jonna
    Univ Jyvaskyla, Dept Biol & Environm Sci, Jyvaskyla, Finland.
    Karjalainen, Juha
    Univ Jyvaskyla, Dept Biol & Environm Sci, Jyvaskyla, Finland.
    Kallio, Kari
    Finnish Environm Inst, Ctr Marine Res, Helsinki, Finland.
    Lepistoe, Ahti
    Finnish Environm Inst, Freshwater Ctr, Helsinki, Finland.
    Jones, Ian D.
    Lancaster Environm Ctr, Ctr Ecol & Hydrol, Lancaster, England.
    Geographic and temporal variations in turbulent heat loss from lakes: A global analysis across 45 lakes2018In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, no 6, p. 2436-2449Article in journal (Refereed)
    Abstract [en]

    Heat fluxes at the lake surface play an integral part in determining the energy budget and thermal structure in lakes, including regulating how lakes respond to climate change. We explore patterns in turbulent heat fluxes, which vary across temporal and spatial scales, using in situ high-frequency monitoring data from 45 globally distributed lakes. Our analysis demonstrates that some of the lakes studied follow a marked seasonal cycle in their turbulent surface fluxes and that turbulent heat loss is highest in larger lakes and those situated at low latitude. The Bowen ratio, which is the ratio of mean sensible to mean latent heat fluxes, is smaller at low latitudes and, in turn, the relative contribution of evaporative to total turbulent heat loss increases toward the tropics. Latent heat transfer ranged from similar to 60% to > 90% of total turbulent heat loss in the examined lakes. The Bowen ratio ranged from 0.04 to 0.69 and correlated significantly with latitude. The relative contributions to total turbulent heat loss therefore differ among lakes, and these contributions are influenced greatly by lake location. Our findings have implications for understanding the role of lakes in the climate system, effects on the lake water balance, and temperature-dependent processes in lakes.

  • 609.
    Woolway, R. Iestyn
    et al.
    Univ Reading, Dept Meteorol, Reading, Berks, England..
    Verburg, Piet
    Natl Inst Water & Atmospher Res, Hamilton, New Zealand..
    Merchant, Christopher J.
    Univ Reading, Dept Meteorol, Reading, Berks, England..
    Lenters, John D.
    Univ Wisconsin, Ctr Limnol, Madison, WI 53706 USA..
    Hamilton, David P.
    Griffith Univ, Australian Rivers Inst, Brisbane, Qld, Australia..
    Brookes, Justin
    Univ Adelaide, Sch Biol Sci, Environm Inst, Adelaide, SA, Australia..
    Kelly, Sean
    Marine Inst, Newport, Ireland.;Natl Univ Ireland Galway, Sch Nat Sci, Earth & Ocean Sci, Galway, Ireland..
    Hook, Simon
    CALTECH, Jet Prop Lab, Pasadena, CA USA..
    Laas, Alo
    Estonian Univ Life Sci, Inst Agr & Environm Sci, Ctr Limnol, Tartu, Estonia..
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Rimmer, Alon
    Israel Oceanog & Limnol Res, Yigal Allon Kinneret Limnol Lab, Migdal, Israel..
    Rusak, James A.
    Ontario Minist Environm & Climate Change, Dorset Environm Sci Ctr, Dorset, ON, Canada..
    Jones, Ian D.
    Lancaster Environm Ctr, Ctr Ecol & Hydrol, Lancaster, England..
    Latitude and lake size are important predictors of over-lake atmospheric stability2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 17, p. 8875-8883Article in journal (Refereed)
    Abstract [en]

    Turbulent fluxes across the air-water interface are integral to determining lake heat budgets, evaporation, and carbon emissions from lakes. The stability of the atmospheric boundary layer (ABL) influences the exchange of turbulent energy. We explore the differences in over-lake ABL stability using data from 39 globally distributed lakes. The frequency of unstable ABL conditions varied between lakes from 71 to 100% of the time, with average air temperatures typically several degrees below the average lake surface temperature. This difference increased with decreasing latitude, resulting in a more frequently unstable ABL and a more efficient energy transfer to and from the atmosphere, toward the tropics. In addition, during summer the frequency of unstable ABL conditions decreased with increasing lake surface area. The dependency of ABL stability on latitude and lake size has implications for heat loss and carbon fluxes from lakes, the hydrologic cycle, and climate change effects.

  • 610.
    Woolway, R. Iestyn
    et al.
    Univ Reading, Dept Meteorol, Reading, Berks, England;Dundalk Inst Technol, Dundalk, Louth, Ireland.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Schmid, Martin
    Eawag Swiss Fed Inst Aquat Sci & Technol, Surface Waters Res & Management, Kastanienbaum, Switzerland.
    Dokulil, Martin T.
    Univ Innsbruck, Res Dept Limnol, Mondsee, Austria.
    de Eyto, Elvira
    Marine Inst, Furnace, Newport, Ireland.
    Maberly, Stephen C.
    Ctr Ecol & Hydrol, Lancaster, England.
    May, Linda
    Ctr Ecol & Hydrol, Edinburgh, Midlothian, Scotland.
    Merchant, Christopher J.
    Univ Reading, Dept Meteorol, Reading, Berks, England;Univ Reading, Natl Ctr Earth Observat, Reading, Berks, England.
    Substantial increase in minimum lake surface temperatures under climate change2019In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 155, no 1, p. 81-94Article in journal (Refereed)
    Abstract [en]

    The annual minimum of lake surface water temperature influences ecological and biogeochemical processes, but variability and change in this extreme have not been investigated. Here, we analysed observational data from eight European lakes and investigated the changes in annual minimum surface water temperature. We found that between 1973 and 2014, the annual minimum lake surface temperature has increased at an average rate of + 0.35 degrees Cdecade(-1), comparable to the rate of summer average lake surface temperature change during the same period (+ 0.32 degrees C decade(-1)). Coherent responses to climatic warming are observed between the increase in annual minimum lake surface temperature and the increase in winter air temperature variations. As a result of the rapid warming of annual minimum lake surface temperatures, some of the studied lakes no longer reach important minimum surface temperature thresholds that occur in winter, with complex and significant potential implications for lakes and the ecosystem services that they provide.

  • 611. Woolway, R.I.
    et al.
    Carrea, L
    Merchant, C.J.
    Dokulil, M.T.
    de Eyto, E.
    DeGasperi, C.L.
    Korhonen, J.
    Marszelewski, W
    May, L
    Paterson, A.M.
    Rimmer, A.
    Rusak, J.A.
    Schladow, S.G.
    Schmid, M
    Shimaraeva, S.V.
    Silow, E.A.
    Timofeyev, M.A.
    Verburg, P.
    Watanabe, S.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lake surface temperature [in “State of the Climate in 2017”]2018In: Bulletin of the American Meteorological Society, Vol. 99, no 8, p. S13-15Article in journal (Refereed)
  • 612. Woolway, R.I
    et al.
    Weyhenmeyer, Gesa
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lake surface temperatures2016In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 97, no 8, p. S17-S18Article in journal (Refereed)
  • 613.
    Wu, Pianpian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Beneficial yet Risky: Evaluate Risks of Fish Diet of Mercury Exposure to Consumers in Sweden2012Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

                For a long time, fish is regarded as an important food source beneficial for human health. But there’s nowadays an increasing concern of fish consumption for increasing existence of mercury (Hg) and methylmercury (MeHg), which can be accumulated upon fish intake and pose health threats to human.  It is suggested that children and pregnant women are more vulnerable to effects due to accumulation of Hg. There have been continuous efforts done by governments and researchers all over the world, e.g. publishing national and regional advisories on fish consumption, in order to inform public related risks aroused by excess fish consumption. Sweden, as one of the earliest countries abandons the use of Hg (Regeringskansliet, http://www.sweden.gov.se), has published a national advisory on fish consumption for pregnant and breastfeeding women (Swedish National Food Agency, SLV, http://www.slv.se/). Hg level in edible fish organs is also limited for safe consumption.  In order to picture a better image of this, we investigated existed databases in Sweden on Hg levels in fish, fishery statistics, consumption data, and observed Hg level in human in recent decades for human exposure to Hg in Sweden. Though mercury emission decreased, the exposure to mercury via fish consumption is still high. We believe there’s a potential risk for Swedish inhabitants, especially pregnant women and women in breastfeeding, as well as young children. It is strongly recommended a safer limit of Hg in fish products for consumption in Sweden.

                We hope for more synthesized knowledge of safe fish consumption that benefit for the public and promote regional/national policy in having an up-to-date fish consumption advisory in Sweden.

  • 614.
    Wu, Pianpian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Risks of Cadmium Nanoparticles on Estuarine Organisms: Ecotoxicological Effects of Engineered Cadmium Nanoparticles through Biochemical and Behavioral Responses in Two Marine Invertebrates, Nereis diversicolor and Scrobicularia plana2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There is an increasing concern over the safety of engineered nanoparticles (ENPs) to humans and the environment. It is important that the environmental risks of these particles to be tested under research and regulatory schemes, e.g. Nano Risks to the environment & Human Health (NanoReTox) under Seventh Framework Programme (FP7) in EU. Due to their unique properties and the fact that their detection and characterization in complex matrices is challenging, classic analytical methods and test approaches for assessing environmental risk may not be appropriate for ENPs. In this paper I present the challenges associated with ENPs exposure to the estuarine environment and the testing of a chosen ENPs to generate data on ecotoxicity in the test estuarine organisms for further consideration of risk assessment of marine environment. Careful consideration was given to the selection of the test materials (benthic organisms Nereis diversicolor and Scrobicularia plana), the test system and the test exposure conditions (CdS ENPs and aqueous CdS added to filtered natural seawater with a concentration of 10 µg L-1). Evaluation of the exposure effects was carried out by behavioral tests (burrowing kinetics and feeding rate) and biochemical responses (quantification of biomarkers). Multispecies Freshwater Biomonitor®  (MFB) tests and GST analysis results show significant differences in between control group and CdS NPs exposure one, indicating that CdS NPs are potential to cause sublethal effects in test organisms. Our knowledge in environmental risk assessment of ENPs is still limited. Coordinated research is required to gain a better understanding of the factors and processes affecting ENP fate and effects in the environment as well as to develop more usable, robust and sensitive methods for characterization and detection of ENPs in environmental systems.

  • 615.
    Wu, Pianpian
    et al.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Kainz, Martin J.
    Interuniv Ctr Aquat Ecosyst Res, WasserCluster Biol Stn Lunz, Lunz, Austria.
    Bravo, Andrea Garcia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Åkerblom, Staffan
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Sonesten, Lars
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Bishop, Kevin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    The importance of bioconcentration into the pelagic food web base for methylmercury biomagnification: A meta-analysis2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 646, p. 357-367Article, review/survey (Refereed)
    Abstract [en]

    Methylmercury (MeHg) transfer from water into the base of the food web (bioconcentration) and subsequent biomagnification in the aquatic food web leads to most of the MeHg in fish. But how important is bioconcentration compared to biomagnification in predicting MeHg in fish? To answer this question we reviewed articles in which MeHg concentrations in water, plankton (seston and/or zooplankton), as well as fish (planktivorous and small omnivorous fish) were reported. This yielded 32 journal articles with data from 59 aquatic ecosystems at 22 sites around the world. Although there are many case studies of particular aquatic habitats and specific geographic areas that have examined MeHg bioconcentration and biomagnification, we performed a meta-analysis of such studies. Aqueous MeHg was not a significant predictor of MeHg in fish, but MeHg in seston i.e., the base of the aquatic food web, predicted 63% of the variability in fish MeHg. The MeHg bioconcentration factors (i.e., transfer of MeHg from water to seston; BCFw-s) varied from 3 to 7 orders of magnitude across sites and correlated significantly with MeHg in fish. The MeHg biomagnification factors from zooplankton to fish varied much less (logBMFz-f, 0.75 ± 0.31), and did not significantly correlate with fish MeHg, suggesting that zooplanktivory is not as important as bioconcentration in the biomagnification of fish MeHg across the range of ecosystems represented in our meta-analysis. Partial least square (PLS) and linear regression analyses identified several environmental factors associated with increased BCF, including low dissolved organic carbon, low pH, and oligotrophy. Our study reveals the widespread importance of MeHg bioconcentration into the base of the aquatic food web for MeHg at higher trophic levels in aquatic food webs, as well as the major influences on the variability in this bioconcentration.

  • 616.
    Wu, Pianpian
    et al.
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Kainz, Martin
    Interuniv Ctr Aquat Ecosyst Res, WasserCluster Biol Stn Lunz, Lunz Am See, Austria.
    Åkerblom, Staffan
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden;Stat Sweden, Stockholm, Sweden.
    Bravo, Andrea Garcia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab. Spanish Natl Res Council, Madrid, Spain.
    Sonesten, Lars
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Branfireun, Brian
    Western Univ, Dept Biol, London, ON, Canada;Western Univ, Ctr Environm & Sustainabil, London, ON, Canada.
    Deininger, Anne
    Univ Agder, Dept Nat Sci, Kristiansand, Norway;Norwegian Inst Water Res NIVA, Grimstad, Norway.
    Bergström, Ann-Kristin
    Umea Univ, Dept Ecol & Environm Sci, Umea, Sweden.
    Bishop, Kevin
    Swedish Univ Agr Sci, Dept Aquat Sci & Assessment, Uppsala, Sweden.
    Terrestrial diet influences mercury bioaccumulation in zooplankton and macroinvertebrates in lakes with differing dissolved organic carbon concentrations2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 669, p. 821-832Article in journal (Refereed)
    Abstract [en]

    Dietary uptake is a key step in conveying both toxic mercury (Hg; particularly as highly bioavailable methylmercury, MeHg) and essential dietary biochemicals, such as polyunsaturated fatty acids (PUFA), across trophic levels within aquatic food webs. Using stable isotopes and fatty acids we evaluated the role of food sources in size-fractioned plankton and littoral macroinvertebrates for the bioaccumulation of total Hg and MeHg in six oligotrophic and one mesotrophic Swedish lakes with differing concentrations of dissolved organic carbon (DOC). We found that the consumption of both algal and terrestrial diets (assessed by PUFA and long-chain saturated fatty acids, respectively) predicted >66% of the Hg concentration variability in meso- (100-500 mu m) and macrozooplankton (>500 mu m) in oligotrophic lakes. In the mesotrophic lake, total Hg bioaccumulation in higher trophic level biota, carnivorous macroinvertebrates was also significantly related to terrestrial diet sources (R-2 = 0.65, p < 0.01). However, lake pH and DOC correlated to total Hg bioaccumulation and bioconcentration across all lakes, suggesting the consumption of different diet sources is mediated by the influence of lake characteristics. This field study reveals that using dietary biomarkers (stable isotopes and fatty acids) together with the physico-chemical lake parameters pH and nutrients together improve our ability to predict Hg bioaccumulation in aquatic food webs. Fatty acids used as dietary biomarkers provide correlative evidence of specific diet source retention in consumers and their effect on Hg bioaccumulation, while pH and nutrients are the underlying physico-chemical lake parameters controlling differences in Hg bioaccumulation between lakes.

  • 617. Wu, Xiaofen
    et al.
    Holmfeldt, Karin
    Hubalek, Valerie
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Lundin, Daniel
    Åström, Mats
    Bertilsson, Stefan
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Dopson, Mark
    Microbial metagenomes from three aquifers in the Fennoscandian shield terrestrial deep biosphere reveal metabolic partitioning among populations2016In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 10, no 5, p. 1192-1203Article in journal (Refereed)
    Abstract [en]

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

  • 618.
    Wu, Xiaofen
    et al.
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMIS, S-39182 Kalmar, Sweden..
    Pedersen, Karsten
    Microbial Analyt Sweden AB, Molnlycke, Sweden..
    Edlund, Johanna
    Microbial Analyt Sweden AB, Molnlycke, Sweden..
    Eriksson, Lena
    Microbial Analyt Sweden AB, Molnlycke, Sweden..
    Astrom, Mats
    Linnaeus Univ, Dept Biol & Environm Sci, Kalmar, Sweden..
    Andersson, Anders F.
    KTH Royal Inst Technol, Sch Biotechnol, Sci Life Lab, Stockholm, Sweden..
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Dopson, Mark
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMIS, S-39182 Kalmar, Sweden..
    Potential for hydrogen-oxidizing chemolithoautotrophic and diazotrophic populations to initiate biofilm formation in oligotrophic, deep terrestrial subsurface waters2017In: Microbiome, ISSN 0026-2633, E-ISSN 2049-2618, Vol. 5, article id 37Article in journal (Refereed)
    Abstract [en]

    Background: Deep terrestrial biosphere waters are separated from the light-driven surface by the time required to percolate to the subsurface. Despite biofilms being the dominant form of microbial life in many natural environments, they have received little attention in the oligotrophic and anaerobic waters found in deep bedrock fractures. This study is the first to use community DNA sequencing to describe biofilm formation under in situ conditions in the deep terrestrial biosphere. Results: In this study, flow cells were attached to boreholes containing either "modern marine" or "old saline" waters of different origin and degree of isolation from the light-driven surface of the earth. Using 16S rRNA gene sequencing, we showed that planktonic and attached populations were dissimilar while gene frequencies in the metagenomes suggested that hydrogen-fed, carbon dioxide-and nitrogen-fixing populations were responsible for biofilm formation across the two aquifers. Metagenome analyses further suggested that only a subset of the populations were able to attach and produce an extracellular polysaccharide matrix. Initial biofilm formation is thus likely to be mediated by a few bacterial populations which were similar to Epsilonproteobacteria, Deltaproteobacteria, Betaproteobacteria, Verrucomicrobia, and unclassified bacteria. Conclusions: Populations potentially capable of attaching to a surface and to produce extracellular polysaccharide matrix for attachment were identified in the terrestrial deep biosphere. Our results suggest that the biofilm populations were taxonomically distinct from the planktonic community and were enriched in populations with a chemolithoautotrophic and diazotrophic metabolism coupling hydrogen oxidation to energy conservation under oligotrophic conditions.

  • 619. Wurzbacher, Christian
    et al.
    Attermeyer, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany.
    Kettner, Maria Therese
    Flintrop, Clara
    Warthmann, Norman
    Hilt, Sabine
    Grossart, Hans-Peter
    Monaghan, Michael T.
    DNA metabarcoding of unfractionated water samples relates phyto-, zoo- and bacterioplankton dynamics and reveals a single-taxon bacterial bloom2017In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 9, no 4, p. 383-388Article in journal (Refereed)
    Abstract [en]

    Most studies of aquatic plankton focus on either macroscopic or microbial communities, and on either eukaryotes or prokaryotes. This separation is primarily for methodological reasons, but can overlook potential interactions among groups. We tested whether DNA metabarcoding of unfractionated water samples with universal primers could be used to qualitatively and quantitatively study the temporal dynamics of the total plankton community in a shallow temperate lake. We found significant changes in the relative proportions of normalized sequence reads of eukaryotic and prokaryotic plankton communities over a three-month period in spring. Patterns followed the same trend as plankton estimates measured using traditional microscopic methods. We characterized the bloom of a conditionally rare bacterial taxon belonging to Arcicella, which rapidly came to dominate the whole lake ecosystem and would have remained unnoticed without metabarcoding. Our data demonstrate the potential of universal DNA metabarcoding applied to unfractionated samples for providing a more holistic view of plankton communities.

  • 620.
    Wurzbacher, Christian
    et al.
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany; Berlin Center for Genomics in Biodiversity Research, Germany; Department of Biological and Environmental Sciences, University of Gothenburg, Sweden.
    Fuchs, Andrea
    Carl-von-Ossietzky University Oldenburg, Germany; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany.
    Attermeyer, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Leibniz-InsLeibniz-Institute of Freshwater Ecology and Inland Fisheries, Germanytitute of Freshwater Ecology and Inland Fisheries, Alte Fischerhütte 2, 16775 Stechlin, Germany.
    Frindte, Katharina
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, 16775 Stechlin, Germany; Institute of Crop Science and Resource Conservation – Molecular Biology of the Rhizosphere, Bonn University, Germany.
    Grossart, Hans-Peter
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany; Institute for Biochemistry and Biology, Potsdam University, Germany.
    Hupfer, Michael
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany.
    Casper, Peter
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany.
    Monaghan, Michael T.
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Germany; Berlin Center for Genomics in Biodiversity Research, Germany.
    Shifts among Eukaryota, Bacteria, and Archaea define the vertical organization of a lake sediment2017In: Microbiome, ISSN 0026-2633, E-ISSN 2049-2618, Vol. 5, article id 41Article in journal (Refereed)
    Abstract [en]

    Background: Lake sediments harbor diverse microbial communities that cycle carbon and nutrients while being constantly colonized and potentially buried by organic matter sinking from the water column. The interaction of activity and burial remained largely unexplored in aquatic sediments. We aimed to relate taxonomic composition to sediment biogeochemical parameters, test whether community turnover with depth resulted from taxonomic replacement or from richness effects, and to provide a basic model for the vertical community structure in sediments.

    Methods: We analyzed four replicate sediment cores taken from 30-m depth in oligo-mesotrophic Lake Stechlin in northern Germany. Each 30-cm core spanned ca. 170 years of sediment accumulation according to 137Cs dating and was sectioned into layers 1–4 cm thick. We examined a full suite of biogeochemical parameters and used DNA metabarcoding to examine community composition of microbial Archaea, Bacteria, and Eukaryota.

    Results: Community β-diversity indicated nearly complete turnover within the uppermost 30 cm. We observed a pronounced shift from Eukaryota- and Bacteria-dominated upper layers (<5 cm) to Bacteria-dominated intermediate layers (5–14 cm) and to deep layers (>14 cm) dominated by enigmatic Archaea that typically occur in deep-sea sediments. Taxonomic replacement was the prevalent mechanism in structuring the community composition and was linked to parameters indicative of microbial activity (e.g., CO2 and CH4 concentration, bacterial protein production). Richness loss played a lesser role but was linked to conservative parameters (e.g., C, N, P) indicative of past conditions.

    Conclusions: By including all three domains, we were able to directly link the exponential decay of eukaryotes with the active sediment microbial community. The dominance of Archaea in deeper layers confirms earlier findings from marine systems and establishes freshwater sediments as a potential low-energy environment, similar to deep sea sediments. We propose a general model of sediment structure and function based on microbial characteristics and burial processes. An upper “replacement horizon” is dominated by rapid taxonomic turnover with depth, high microbial activity, and biotic interactions. A lower “depauperate horizon” is characterized by low taxonomic richness, more stable “low-energy” conditions, and a dominance of enigmatic Archaea.

  • 621.
    Wurzbacher, Christian
    et al.
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden.;Gothenburg Global Biodivers Ctr, Gothenburg, Sweden..
    Nilsson, R. Henrik
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden.;Gothenburg Global Biodivers Ctr, Gothenburg, Sweden..
    Rautio, Milla
    Univ Quebec Chicoutimi, Dept Sci Fondamentales, Chicoutimi, PQ, Canada.;Univ Quebec Chicoutimi, Ctr Northern Studies CEN, Chicoutimi, PQ, Canada..
    Peura, Sari
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular epidemiology. Swedish Univ Agr Sci, Dept Forest Mycol & Plant Pathol, Sci Life Lab, Uppsala, Sweden..
    Poorly known microbial taxa dominate the microbiome of permafrost thaw ponds2017In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 11, no 8, p. 1938-1941Article in journal (Refereed)
    Abstract [en]

    In the transition zone of the shifting permafrost border, thaw ponds emerge as hotspots of microbial activity, processing the ancient carbon freed from the permafrost. We analyzed the microbial succession across a gradient of recently emerged to older ponds using three molecular markers: one universal, one bacterial and one fungal. Age was a major modulator of the microbial community of the thaw ponds. Surprisingly, typical freshwater taxa comprised only a small fraction of the community. Instead, thaw ponds of all age classes were dominated by enigmatic bacterial and fungal phyla. Our results on permafrost thaw ponds lead to a revised perception of the thaw pond ecosystem and their microbes, with potential implications for carbon and nutrient cycling in this increasingly important class of freshwaters.

  • 622.
    Wurzbacher, Christian
    et al.
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Ecosyst Res, Berlin, Germany.;Berlin Ctr Genom Biodivers Res, Berlin, Germany.;Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Expt Limnol, Stechlin, Germany.;Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Warthmann, Norman
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Ecosyst Res, Berlin, Germany.;Berlin Ctr Genom Biodivers Res, Berlin, Germany.;Australian Natl Univ, Res Sch Biol, Div Plant Sci, Canberra, ACT, Australia..
    Bourne, Elizabeth C.
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Ecosyst Res, Berlin, Germany.;Berlin Ctr Genom Biodivers Res, Berlin, Germany..
    Attermeyer, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Expt Limnol, Stechlin, Germany.
    Allgaier, Martin
    Berlin Ctr Genom Biodivers Res, Berlin, Germany.;Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Expt Limnol, Stechlin, Germany..
    Powell, Jeff R.
    Univ Western Sydney, Hawkesbury Inst Environm, Penrith, NSW, Australia..
    Detering, Harald
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Ecosyst Res, Berlin, Germany.;Berlin Ctr Genom Biodivers Res, Berlin, Germany.;Univ Vigo, Dept Biochem Genet & Immunol, Vigo, Spain..
    Mbedi, Susan
    Berlin Ctr Genom Biodivers Res, Berlin, Germany.;Leibniz Inst Evolut & Biodivers Sci, Museum Nat Kunde, Berlin, Germany..
    Grossart, Hans-Peter
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Expt Limnol, Stechlin, Germany.;Univ Potsdam, Inst Biochem & Biol, Potsdam, Germany..
    Monaghan, Michael T.
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Dept Ecosyst Res, Berlin, Germany.;Berlin Ctr Genom Biodivers Res, Berlin, Germany..
    High habitat-specificity in fungal communities in oligo-mesotrophic, temperate Lake Stechlin (North-East Germany)2016In: MycoKeys, ISSN 1314-4057, E-ISSN 1314-4049, no 16, p. 17-44Article in journal (Refereed)
    Abstract [en]

    Freshwater fungi are a poorly studied ecological group that includes a high taxonomic diversity. Most studies on aquatic fungal diversity have focused on single habitats, thus the linkage between habitat heterogeneity and fungal diversity remains largely unexplored. We took 216 samples from 54 locations representing eight different habitats in the meso-oligotrophic, temperate Lake Stechlin in North-East Germany. These included the pelagic and littoral water column, sediments, and biotic substrates. We performed high throughput sequencing using the Roche 454 platform, employing a universal eukaryotic marker region within the large ribosomal subunit (LSU) to compare fungal diversity, community structure, and species turnover among habitats. Our analysis recovered 1027 fungal OTUs (97% sequence similarity). Richness estimates were highest in the sediment, biofilms, and benthic samples (189-231 OTUs), intermediate in water samples (42-85 OTUs), and lowest in plankton samples (8 OTUs). NMDS grouped the eight studied habitats into six clusters, indicating that community composition was strongly influenced by turnover among habitats. Fungal communities exhibited changes at the phylum and order levels along three different substrate categories from littoral to pelagic habitats. The large majority of OTUs (> 75%) could not be classified below the order level due to the lack of aquatic fungal entries in public sequence databases. Our study provides a first estimate of lake-wide fungal diversity and highlights the important contribution of habitat heterogeneity to overall diversity and community composition. Habitat diversity should be considered in any sampling strategy aiming to assess the fungal diversity of a water body.

  • 623.
    Wünsch, Urban J.
    et al.
    Tech Univ Denmark, Natl Inst Aquat Resources, Sect Oceans & Arctic, Lyngby, Denmark..
    Stedmon, Colin A.
    Tech Univ Denmark, Natl Inst Aquat Resources, Sect Oceans & Arctic, Lyngby, Denmark..
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Guillemette, Francois
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Univ Quebec Trois Rivieres, Res Ctr Watershed Aquat Ecosyst Interact RIVE, Trois Rivieres, PQ, Canada..
    Unraveling the size-dependent optical properties of dissolved organic matter2018In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, no 2, p. 588-601Article in journal (Refereed)
    Abstract [en]

    The size-dependent optical properties of dissolved organic matter (DOM) from four Swedish lakes were investigated using High Performance Size Exclusion Chromatography (HPSEC) in conjunction with online characterization of absorbance (240-600 nm) and fluorescence (excitation: 275 nm, emission: 300-600 nm). The molecular size of chromophoric DOM (CDOM) was consistently higher than that of fluorescent DOM (FDOM), with an average difference of 0.37 kDa. The relative abundance of FDOM vs. CDOM ranged from 0.3 to 0.7 across lakes, and increased with decreasing average molecular size. Across sites, the CDOM spectral slopes of the large molecular size fraction were highly similar while the low molecular size fraction differed and contributed to different bulk spectral slopes. Our results indicate structural congruence of high molecular size DOM across systems while lake trophic status determined the characteristics of the low size range. Furthermore, the combination of HPSEC and parallel factor analysis (HPSEC-PARAFAC2) allowed the decomposition of DOM fluorescence chromatograms. Three humic-like components and one protein-like component with broadly overlapping molecular size distributions were identified. This overlap provides further evidence for the supramolecular assembly hypothesis since fluorophores, as revealed by PARAFAC2, occur in aggregates of overlapping molecular size. Our results further suggest a link between the molecular size of these fluorophores and the associated supramolecular assemblies. This study demonstrates the potential for HPSEC and novel mathematical approaches to provide unprecedented insights into the relationship between optical and chemical properties of DOM in aquatic systems.

  • 624.
    Xu, Jingying
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Remediation of mercury contaminated soil and biological mercury methylation in the landscape2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Accumulation of mercury (Hg) in soil originating from both natural and anthropogenic sources poses a major hazard to environmental and human health. Inorganic Hg(II) in soil can be transformed to highly toxic methylmercury (MeHg) mainly via methylating microorganisms. Although MeHg constitutes less than 2% of total Hg in soil, it enters aquatic systems through runoff and can be subsequently bioaccumulated along the food chain, thereby causing severe harm to humans.

    Current major remediation techniques to control soil Hg contamination were reviewed. Organic matter, clay/minerals and complexation ligands within soil are principal factors influencing Hg mobility that is crucial for evaluating and optimising remedial techniques. The potential of soil washing to treat soil Hg contamination was evaluated. The studied soil was fractionated from fine to coarse particles to assess the effectiveness of physical separation. Batch leaching and pH-static titration tests were performed using (1) water, (2) EDTA, (3) NaOH, (4) HCl, (5) acidic leachates from biodegradable wastes, and (6) alkaline leachates from fly/bottom ashes, to estimate the efficiency of chemical extraction. Less than 1.5% of the total Hg could be mobilised after combined treatments, implying very tight binding of Hg to soil particles, thereby hampering soil washing as a strategy for the studied soil.

    Hg(II) methylation in boreal soils and lake sediments can have major consequences for MeHg inputs to downstream aquatic systems. It is therefore important to understand the biogeochemical mechanisms involved in MeHg formation in these landscapes. The microbes involved in Hg(II) methylation in sediments and boreal forests and wetlands were investigated by high-throughput 16S rRNA and hgcA sequencing with molecular barcoding. In all three environments, hgcA sequences were distributed among Proteobacteria, Firmicutes and Euryarchaeota, and Deltaproteobacteria, particularly Geobacteraceae, appeared to play a predominant role. Ruminococcaceae were also abundant Hg(II) methylators in soils from one forest and all the wetlands. The boreal forest survey provided some first insights about the possible link between MeHg formation and non-Hg(II) methylating bacterial communities that likely support the growth and activity of Hg(II) methylating members. Results from wetlands pointed out nutrient status as an important factor shaping Hg(II) methylating communities across the four wetlands, and highlighted a significant role of water content and iron in controlling the distribution of Hg(II) methylators within individual wetlands. Furthermore, the interactions between Hg(II) methylating groups revealed that the more anaerobic and productive conditions seemed to favour the activity of Methanoregulaceae and hamper the growth of Ruminococcaceae. Results from lake sediments supported that Geobacteraceae have an important role in Hg(II) methylation under ferruginous geochemical conditions. Our findings provide a better understanding of Hg(II) methylating communities in the landscape.

    List of papers
    1. Sources and remediation techniques for mercury contaminated soil
    Open this publication in new window or tab >>Sources and remediation techniques for mercury contaminated soil
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    2015 (English)In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 74, p. 42-53Article, review/survey (Refereed) Published
    Abstract [en]

    Mercury (Hg) in soils has increased by a factor of 3 to 10 in recent times mainly due to combustion of fossil fuels combined with long-range atmospheric transport processes. Other sources as chlor-alkali plants, gold mining and cement production can also be significant, at least locally. This paper summarizes the natural and anthropogenic sources that have contributed to the increase of Hg concentration in soil and reviews major remediation techniques and their applications to control soil Hg contamination. The focus is on soil washing, stabilisation/solidification, thermal treatment and biological techniques; but also the factors that influence Hg mobilisation in soil and therefore are crucial for evaluating and optimizing remediation techniques are discussed. Further research on bioremediation is encouraged and future study should focus on the implementation of different remediation techniques under field conditions.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Mercury contaminated soil, Mobility, Remediation, Soil washing, Stabilisation/solidification
    National Category
    Earth and Related Environmental Sciences
    Identifiers
    urn:nbn:se:uu:diva-242480 (URN)10.1016/j.envint.2014.09.007 (DOI)000346681700006 ()
    Funder
    Swedish Research Council, D0697801
    Available from: 2015-01-26 Created: 2015-01-26 Last updated: 2018-03-15Bibliographically approved
    2. Influence of particle size distribution, organic carbon, pH and chlorides on washing of mercury contaminated soil
    Open this publication in new window or tab >>Influence of particle size distribution, organic carbon, pH and chlorides on washing of mercury contaminated soil
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    2014 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 109, p. 99-105Article in journal (Refereed) Published
    Abstract [en]

    Feasibility of soil washing to remediate Hg contaminated soil was studied. Dry sieving was performed to evaluate Hg distribution in soil particle size fractions. The influence of dissolved organic matter and chlo- rides on Hg dissolution was assessed by batch leaching tests. Mercury mobilization in the pH range of 3– 11 was studied by pH-static titration. Results showed infeasibility of physical separation via dry sieving, as the least contaminated fraction exceeded the Swedish generic guideline value for Hg in soils. Soluble Hg did not correlate with dissolved organic carbon in the water leachate. The highest Hg dissolution was achieved at pH 5 and 11, reaching up to 0.3% of the total Hg. The pH adjustment was therefore not suf- ficient for the Hg removal to acceptable levels. Chlorides did not facilitate Hg mobilization under acidic pH either. Mercury was firmly bound in the studied soil thus soil washing might be insufficient method to treat the studied soil. 

    Keywords
    Organic matter, Mobilization pH-dependent, dissolution, Soil remediation
    National Category
    Environmental Sciences
    Identifiers
    urn:nbn:se:uu:diva-224367 (URN)10.1016/j.chemosphere.2014.02.058 (DOI)
    Available from: 2014-05-09 Created: 2014-05-09 Last updated: 2018-03-15Bibliographically approved
    3. Mercury methylating microbial communities of boreal forest soils
    Open this publication in new window or tab >>Mercury methylating microbial communities of boreal forest soils
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    2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 518Article in journal (Refereed) Published
    Abstract [en]

    The formation of the potent neurotoxic methylmercury (MeHg) is a microbially mediated process that has raised much concern because MeHg poses threats to wildlife and human health. Since boreal forest soils can be a source of MeHg in aquatic networks, it is crucial to understand the biogeochemical processes involved in the formation of this pollutant. High-throughput sequencing of 16S rRNA and the mercury methyltransferase, hgcA, combined with geochemical characterisation of soils, were used to determine the microbial populations contributing to MeHg formation in forest soils across Sweden. The hgcA sequences obtained were distributed among diverse clades, including Proteobacteria, Firmicutes, and Methanomicrobia, with Deltaproteobacteria, particularly Geobacteraceae, dominating the libraries across all soils examined. Our results also suggest that MeHg formation is linked to the composition of also non-mercury methylating bacterial communities, likely providing growth substrate (e.g. acetate) for the hgcA-carrying microorganisms responsible for the actual methylation process. While previous research focused on mercury methylating microbial communities of wetlands, this study provides some first insights into the diversity of mercury methylating microorganisms in boreal forest soils.

    National Category
    Forest Science
    Research subject
    Biology with specialization in Limnology
    Identifiers
    urn:nbn:se:uu:diva-346175 (URN)10.1038/s41598-018-37383-z (DOI)000456553400083 ()
    Funder
    Swedish Research Council, 2011-7192Swedish Research Council, 2012-3892Swedish Research Council, 2013-6978Swedish Energy Agency, 36155-1
    Available from: 2018-03-15 Created: 2018-03-15 Last updated: 2019-02-18Bibliographically approved
    4. Mercury methylating microbial communities in boreal wetlands
    Open this publication in new window or tab >>Mercury methylating microbial communities in boreal wetlands
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    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Understanding the formation of the potent neurotoxic methylmercury (MeHg) is a major concern due to its threats to wildlife and human health. As boreal wetlands play a crucial role for Hg cycling on a global scale, it is crucial to understand the biogeochemical processes involved in MeHg formation in this landscape. A strategy combining high-throughput hgcA amplicon sequencing with molecular barcoding was used to revealed diverse clades of Hg(II) methylators in a wide range of wetland soils. Our results confirms a predominant role of Deltaproteobacteria, and in particular Geobacteraceae, as important Hg(II) methylators in boreal wetland soils. Firmicutes, and in particular Ruminococcaceae, were also abundant members of the Hg(II) methylating microbial communities. Our survey highlight the importance of nutrient status for the shaping of Hg(II) methylating communities across the four wetlands and reveal that water content and prevailing redox states are key factors determining the local variation in Hg(II) methylating community composition within individual wetlands. Also, our study suggests that high nutrient levels linked to low redox potential seemed to favour Hg(II) methylating methanogens within the Methanoregulaceae. Our findings expand the current knowledge on the Hg(II) methylating microbial community composition in wetland soils and the geochemical factors underpinning spatial heterogeity in such communities.  

    Keywords
    Wetlands, Methylmercury, Mercury methylation, hgcA, Community composition, Bacteria
    National Category
    Genetics
    Research subject
    Biology with specialization in Limnology
    Identifiers
    urn:nbn:se:uu:diva-346177 (URN)
    Available from: 2018-03-15 Created: 2018-03-15 Last updated: 2018-03-15Bibliographically approved
    5. Geobacteraceae are important members of mercury-methylating microbial communities of sediments impacted by wastewater releases
    Open this publication in new window or tab >>Geobacteraceae are important members of mercury-methylating microbial communities of sediments impacted by wastewater releases
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    (English)In: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370Article in journal (Refereed) Accepted
    National Category
    Earth and Related Environmental Sciences
    Identifiers
    urn:nbn:se:uu:diva-335005 (URN)
    Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2018-03-15
  • 625.
    Xu, Jingying
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Lulea Univ Technol, Dept Civil Environm & Nat gesources Engn, S-97187 Lulea, Sweden.
    Bravo, Andrea Garcia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lagerkvist, Anders
    Lulea Univ Technol, Dept Civil Environm & Nat gesources Engn, S-97187 Lulea, Sweden.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Sjöblom, Rolf
    Lulea Univ Technol, Dept Civil Environm & Nat gesources Engn, S-97187 Lulea, Sweden.
    Kumpiene, Jurate
    Lulea Univ Technol, Dept Civil Environm & Nat gesources Engn, S-97187 Lulea, Sweden.
    Sources and remediation techniques for mercury contaminated soil2015In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 74, p. 42-53Article, review/survey (Refereed)
    Abstract [en]

    Mercury (Hg) in soils has increased by a factor of 3 to 10 in recent times mainly due to combustion of fossil fuels combined with long-range atmospheric transport processes. Other sources as chlor-alkali plants, gold mining and cement production can also be significant, at least locally. This paper summarizes the natural and anthropogenic sources that have contributed to the increase of Hg concentration in soil and reviews major remediation techniques and their applications to control soil Hg contamination. The focus is on soil washing, stabilisation/solidification, thermal treatment and biological techniques; but also the factors that influence Hg mobilisation in soil and therefore are crucial for evaluating and optimizing remediation techniques are discussed. Further research on bioremediation is encouraged and future study should focus on the implementation of different remediation techniques under field conditions.

  • 626. Yager, Patricia L.
    et al.
    Sherrell, R. M.
    Stammerjohn, S. E.
    Ducklow, H. W.
    Schofield, O. M E.
    Ingall, E. D.
    Wilson, S. E.
    Lowry, K. E.
    Williams, C. M.
    Riemann, Lasse
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Alderkamp, A-C
    Dinasquet, J.
    Logares, R.
    Richert, Inga
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Sipler, R.E.
    Melara, A.J.
    Mu, L.
    Newstead, R.G.
    Post, A.F.
    Swalethorp, R.
    van Dijken, G.L.
    A carbon budget for the Amundsen Sea Polynya, Antarctica: estimating net community production and export in a highly productive polar ecosystem2016In: Elementa: Science of the Anthropocene, ISSN 2325-1026, Vol. 4, article id 000140Article in journal (Refereed)
    Abstract [en]

    Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP) is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 µg L−1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010–11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozooplankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (ΔDIN; 0.027–0.74 mol N m−2), changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m−2) and gas exchange (0–1.7 mol C m−2) were combined to estimate early season net community production (sNCP; 0.2–5.9 mol C m−2) and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to ~60%) of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2–3 days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3–6%) of the export from ~100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.

  • 627. Yager, Patricia L.
    et al.
    Sherrell, Robert M.
    Stammerjohn, Sharon E.
    Alderkamp, Anne-Carlijn
    Schofield, Oscar
    Abrahamsen, E. Povl
    Arrigo, Kevin R.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Garay, D. Lollie
    Guerrero, Raul
    Lowry, Kate E.
    Moksnes, Per-Olav
    Ndungu, Kuria
    Post, Anton F.
    Randall-Goodwin, Evan
    Riemann, Lasse
    Severmann, Silke
    Thatje, Sven
    van Dijken, Gert L.
    Wilson, Stephanie
    ASPIRE The Amundsen Sea Polynya International Research Expedition2012In: Oceanography, ISSN 1042-8275, Vol. 25, no 3, p. 40-53Article in journal (Refereed)
    Abstract [en]

    In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010-2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment.

  • 628.
    Yang, Yang
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Phytoplankton and Physical Disturbance: Seasonal dynamics in temperate Lake Erken, Sweden2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Phytoplankton mirrors changes in the environment and plays an important role in biogeochemical processes. Phytoplankton dynamics is the outcome of both autogenic succession and external disturbances. This thesis focused on the seasonal variation of water column stability and its effects on phytoplankton, particularly considering the influence of mixing events on phytoplankton development. Lake Erken is a dimictic lake with weak and often interrupted summer stratification, which represents an intermediate case between a polymictic lake and a lake with strong summer stratification.

    There are two diatom phases annually. The spring bloom is caused by pioneer centric diatoms, and the autumn diatom phase is dominated by meroplanktonic diatoms induced by turnover. A summer Cyanobacteria bloom – mainly Gloeotrichia echinulata, depended on the length and stability of stratification.

    Winter and spring air temperature is found to play an important role in the annual succession of phytoplankton by initiating changes in ice/snow-cover and lake thermal stability and setting the basic status. Instead of starting from zero, the vernal phytoplankton piles up on the overwintering community, this trans-annual ecological memory influences both the composition and diversity and taxonomic distinctness of spring phytoplankton.

    Water column stability during summer in Lake Erken is mainly influenced by wind-induced turbulence and internal seiches. As thermal stratification develops from early until late summer, variations in stability and gradual deepening of the thermocline depth influence phytoplankton dynamics directly by changing its distribution, and also indirectly by altering the nutrient and light availability. A new disturbance index (DI) was defined to quantify environmental stability/disturbance and tested well to indicate phytoplankton equilibrium status in two summer stratification periods. The concept of species and functional groups was generally used in this study. However, a next generation sequencing based approach was also tested and proved to provide an excellent candidate for revealing distribution patterns of phytoplankton in inland waters.

    List of papers
    1. Unveiling Distribution Patterns of Freshwater Phytoplankton by a Next Generation Sequencing Based Approach
    Open this publication in new window or tab >>Unveiling Distribution Patterns of Freshwater Phytoplankton by a Next Generation Sequencing Based Approach
    Show others...
    2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 1, p. e53516-Article in journal (Refereed) Published
    Abstract [en]

    The recognition and discrimination of phytoplankton species is one of the foundations of freshwater biodiversity research and environmental monitoring. This step is frequently a bottleneck in the analytical chain from sampling to data analysis and subsequent environmental status evaluation. Here we present phytoplankton diversity data from 49 lakes including three seasonal surveys assessed by next generation sequencing (NGS) of 16S ribosomal RNA chloroplast and cyanobacterial gene amplicons and also compare part of these datasets with identification based on morphology. Direct comparison of NGS to microscopic data from three time-series showed that NGS was able to capture the seasonality in phytoplankton succession as observed by microscopy. Still, the PCR-based approach was only semi-quantitative, and detailed NGS and microscopy taxa lists had only low taxonomic correspondence. This is probably due to, both, methodological constraints and current discrepancies in taxonomic frameworks. Discrepancies included Euglenophyta and Heterokonta that were scarce in the NGS but frequently detected by microscopy and Cyanobacteria that were in general more abundant and classified with high resolution by NGS. A deep-branching taxonomically unclassified cluster was frequently detected by NGS but could not be linked to any group identified by microscopy. NGS derived phytoplankton composition differed significantly among lakes with different trophic status, showing that our approach can resolve phytoplankton communities at a level relevant for ecosystem management. The high reproducibility and potential for standardization and parallelization makes our NGS approach an excellent candidate for simultaneous monitoring of prokaryotic and eukaryotic phytoplankton in inland waters.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-194906 (URN)10.1371/journal.pone.0053516 (DOI)000314019100023 ()
    Available from: 2013-02-20 Created: 2013-02-19 Last updated: 2017-12-06Bibliographically approved
    2. Repetitive baselines of phytoplankton succession in an unstably stratified temperate lake (Lake Erken, Sweden): a long-term analysis
    Open this publication in new window or tab >>Repetitive baselines of phytoplankton succession in an unstably stratified temperate lake (Lake Erken, Sweden): a long-term analysis
    2016 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 764, no 1, p. 211-227Article in journal (Refereed) Published
    Abstract [en]

    The seasonal development of phytoplankton is a sequence of consecutive events with waxes and wanes of biomass and compositional shifts. This study analyzed 16 years data in Lake Erken, Sweden and revealed four baselines of phytoplankton succession with their underlying drivers. Results showed that there were two diatom-dominated phases annually. The vernal community was dominated by centric diatoms larger than 15 A mu m (functional groups B and C) which were fast-growing diatoms being highly efficient in the use of nutrients. The autumn community was comprised mainly meroplanktonic mixing-dependent Aulacoseira granulata and Fragilaria sp. (MP and P) or/and large centric diatoms (B). Between the two mixing-phases with diatoms, a Gloeotrichia echinulata (H 2) bloom occurred due to its preference for a stratified water column with elevated water temperatures and high light availability. The summer stratification in Lake Erken was weak and short, thus, favoring meroplanktonic diatoms to peak once the lake turned over in early autumn. Lake Erken represents an intermediate case between a highly mixed polymictic lake and a lake with strong summer stratification, where the observed stratification patterns allowed the development of an autumn diatom phase similar, by extent, to the vernal one and mainly dominated by meroplanktonic diatoms.

    National Category
    Ecology
    Identifiers
    urn:nbn:se:uu:diva-262459 (URN)10.1007/s10750-015-2314-1 (DOI)000365727500017 ()
    Available from: 2015-09-15 Created: 2015-09-15 Last updated: 2017-12-04Bibliographically approved
    3. Water column stability and summer phytoplankton dynamics in a temperate lake (Lake Erken, Sweden)
    Open this publication in new window or tab >>Water column stability and summer phytoplankton dynamics in a temperate lake (Lake Erken, Sweden)
    2016 (English)In: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 6, no 4, p. 499-508Article in journal (Refereed) Published
    Abstract [en]

    Phytoplankton development in aquatic ecosystems is caused by interactions among multiple environmental factors. Physical processes, particularly development of thermal stratification, have been proposed to be important factors for regulating phytoplankton composition and abundance during summer. This study examined the temporal pattern of thermal stratification during summer in Lake Erken, Sweden, based on 21 years of historical data spanning 23 years and investigated the role played by water stability on phytoplankton development. Water column stability indexes were calculated from high frequency measurements during periods of summer thermal stratification. Clustering and ordination analyzed the dissimilarities between communities during different periods and extracted the significant environmental gradients controlling phytoplankton succession. Wind introduced the major external disturbance to Lake Erken during summer and played an important role for the progression of thermocline depth. Species-specific thermal stability preference or tolerance determined the response of individual species to the stratification and constitutes a mechanism of species selection in phytoplankton dynamics. Lake Erken is an unstably stratified lake during summer, caused by wind-induced turbulence and internal seiches. Adaptation to these unstable conditions is the major determinant of phytoplankton dynamics. Hydrodynamic variability, characterized by different stability indexes in early, mid, and late summer, was the key factor regulating phytoplankton dynamics, directly by changing phytoplankton distribution and indirectly by altering both the light and nutrient availability in the epilimnion.

    Keywords
    Gloeotrichia echinulata, hydrodynamics, Lake Analyzer, phytoplankton dynamics, succession, thermal stratification and mixing
    National Category
    Ecology
    Identifiers
    urn:nbn:se:uu:diva-262451 (URN)10.5268/IW-6.4.874 (DOI)000388608700003 ()
    Available from: 2015-09-15 Created: 2015-09-15 Last updated: 2017-12-04Bibliographically approved
    4. Development of a disturbance index based on high frequency temperature measurements and its test on phytoplankton assemblage equilibrium during summer stratification in Lake Erken
    Open this publication in new window or tab >>Development of a disturbance index based on high frequency temperature measurements and its test on phytoplankton assemblage equilibrium during summer stratification in Lake Erken
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology
    Identifiers
    urn:nbn:se:uu:diva-262454 (URN)
    Available from: 2015-09-15 Created: 2015-09-15 Last updated: 2015-10-12
    5. Effects of physical factors on spring phytoplankton in a temperate lake (Lake Erken, Sweden)
    Open this publication in new window or tab >>Effects of physical factors on spring phytoplankton in a temperate lake (Lake Erken, Sweden)
    (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117Article in journal (Other academic) Submitted
    National Category
    Ecology
    Identifiers
    urn:nbn:se:uu:diva-262455 (URN)
    Available from: 2015-09-15 Created: 2015-09-15 Last updated: 2017-12-04
  • 629.
    Yang, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Colom-Montero, William
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Water column stability and summer phytoplankton dynamics in a temperate lake (Lake Erken, Sweden)2016In: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 6, no 4, p. 499-508Article in journal (Refereed)
    Abstract [en]

    Phytoplankton development in aquatic ecosystems is caused by interactions among multiple environmental factors. Physical processes, particularly development of thermal stratification, have been proposed to be important factors for regulating phytoplankton composition and abundance during summer. This study examined the temporal pattern of thermal stratification during summer in Lake Erken, Sweden, based on 21 years of historical data spanning 23 years and investigated the role played by water stability on phytoplankton development. Water column stability indexes were calculated from high frequency measurements during periods of summer thermal stratification. Clustering and ordination analyzed the dissimilarities between communities during different periods and extracted the significant environmental gradients controlling phytoplankton succession. Wind introduced the major external disturbance to Lake Erken during summer and played an important role for the progression of thermocline depth. Species-specific thermal stability preference or tolerance determined the response of individual species to the stratification and constitutes a mechanism of species selection in phytoplankton dynamics. Lake Erken is an unstably stratified lake during summer, caused by wind-induced turbulence and internal seiches. Adaptation to these unstable conditions is the major determinant of phytoplankton dynamics. Hydrodynamic variability, characterized by different stability indexes in early, mid, and late summer, was the key factor regulating phytoplankton dynamics, directly by changing phytoplankton distribution and indirectly by altering both the light and nutrient availability in the epilimnion.

  • 630.
    Yeo, Sara K.
    et al.
    University of Hawaii.
    Huggett, Megan J.
    University of Hawaii.
    Eiler, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Rappé, Michael S.
    University of Hawaii.
    Coastal Bacterioplankton Community Dynamics in Response to a Natural Disturbance2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 2, p. e56207-Article in journal (Refereed)
    Abstract [en]

    In order to characterize how disturbances to microbial communities are propagated over temporal and spatial scales in aquatic environments, the dynamics of bacterial assemblages throughout a subtropical coastal embayment were investigated via SSU rRNA gene analyses over an 8-month period, which encompassed a large storm event. During non-perturbed conditions, sampling sites clustered into three groups based on their microbial community composition: an offshore oceanic group, a freshwater group, and a distinct and persistent coastal group. Significant differences in measured environmental parameters or in the bacterial community due to the storm event were found only within the coastal cluster of sampling sites, and only at 5 of 12 locations; three of these sites showed a significant response in both environmental and bacterial community characteristics. These responses were most pronounced at sites close to the shoreline. During the storm event, otherwise common bacterioplankton community members such as marine Synechococcus sp. and members of the SAR11 clade of Alphaproteobacteria decreased in relative abundance in the affected coastal zone, whereas several lineages of GammaproteobacteriaBetaproteobacteria, and members of the Roseobacter clade of Alphaproteobacteria increased. The complex spatial patterns in both environmental conditions and microbial community structure related to freshwater runoff and wind convection during the perturbation event leads us to conclude that spatial heterogeneity was an important factor influencing both the dynamics and the resistance of the bacterioplankton communities to disturbances throughout this complex subtropical coastal system. This heterogeneity may play a role in facilitating a rapid rebound of regions harboring distinctly coastal bacterioplankton communities to their pre-disturbed taxonomic composition.

  • 631. Ylla, Irene
    et al.
    Peter, Hannes
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Romani, Anna M.
    Tranvik, Lars J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Different diversity-functioning relationship in lake and stream bacterial communities2013In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 85, no 1, p. 95-103Article in journal (Refereed)
    Abstract [en]

    Biodiversity patterns have been successfully linked to many ecosystem functions, and microbial communities have been suspected to harbour a large amount of functionally redundant taxa. We manipulated the diversity of stream and lake water column bacterial communities and investigated how the reduction in diversity affects the activities of extracellular enzymes involved in dissolved organic carbon degradation. Dissimilar communities established in cultures inoculated with stream or lake bacteria and utilized different organic matter compounds as indicated by the different extracellular enzyme activities. Stream bacterial communities preferentially used plant-derived organic material such as cellulose and hemicellulose. Communities obtained from the lake, where the longer residence time might permit the organic matter to age, efficiently degraded lignin-like material and also showed higher peptide degradation capacities. The results highlight a stronger negative effect of decreasing diversity on ecosystem multifunctionality for stream than for lake bacterial communities. We found a relatively higher multifunctional redundancy in the lake as compared to the stream-derived cultures and suggest that community assembly might shape diversity-functioning relationships in freshwater bacterial communities.

  • 632. Yvon-Durocher, Gabriel
    et al.
    Allen, Andrew P.
    Bastviken, David
    Conrad, Ralf
    Gudasz, Cristian
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    St-Pierre, Annick
    Thanh-Duc, Nguyen
    del Giorgio, Paul A.
    Methane fluxes show consistent temperature dependence across microbial to ecosystem scales2014In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 507, no 7493, p. 488-491Article in journal (Refereed)
    Abstract [en]

    Methane (CH4) is an important greenhouse gas because it has 25 times the global warming potential of carbon dioxide (CO2) by mass over a century(1). Recent calculations suggest that atmospheric CH4 emissions have been responsible for approximately 20% of Earth's warming since pre-industrial times(2). Understanding how CH4 emissions from ecosystems will respond to expected increases in global temperature is therefore fundamental to predicting whether the carbon cycle will mitigate or accelerate climate change. Methanogenesis is the terminal step in the remineralization of organic matter and is carried out by strictly anaerobic Archaea(3). Like most other forms of metabolism, methanogenesis is temperature-dependent(4,5). However, it is not yet known how this physiological response combines with other biotic processes (for example, methanotrophy(6), substrate supply(3,7), microbial community composition(8)) and abiotic processes (for example, water-table depth(9,10)) to determine the temperature dependence of ecosystem-level CH4 emissions. It is also not known whether CH4 emissions at the ecosystem level have a fundamentally different temperature dependence than other key fluxes in the carbon cycle, such as photosynthesis and respiration. Here we use meta-analyses to show that seasonal variations in CH4 emissions from a wide range of ecosystems exhibit an average temperature dependence similar to that of CH4 production derived from pure cultures of methanogens and anaerobic microbial communities. This average temperature dependence (0.96 electron volts (eV)), which corresponds to a 57-fold increase between 0 and 30 degrees C, is considerably higher than previously observed for respiration (approximately 0.65 eV)(11) and photosynthesis (approximately 0.3 eV)(12). As a result, we show that both the emission of CH4 and the ratio of CH4 to CO2 emissions increase markedly with seasonal increases in temperature. Our findings suggest that global warming may have a large impact on the relative contributions of CO2 and CH4 to total greenhouse gas emissions from aquatic ecosystems, terrestrial wetlands and rice paddies.

  • 633.
    Zaremba-Niedzwiedzka, Katarzyna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Viklund, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Zhao, Weizhou
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Ast, Jennifer
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Languages, Department of Scandinavian Languages.
    Sczyrba, Alexander
    Woyke, Tanja
    McMahon, Katherina
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Stepanauskas, Ramunas
    Andersson, Siv
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Single cell genomics reveals low recombination frequencies in freshwater bacteria of the SAR11 clade2013In: Genome Biology, ISSN 1465-6906, E-ISSN 1474-760X, Vol. 14, no 11, article id R130Article in journal (Refereed)
    Abstract [en]

    Background: The SAR11 group of Alphaproteobacteria is highly abundant in the oceans. It contains a recently diverged freshwater clade, which offers the opportunity to compare adaptations to salt-and freshwaters in a monophyletic bacterial group. However, there are no cultivated members of the freshwater SAR11 group and no genomes have been sequenced yet. Results: We isolated ten single SAR11 cells from three freshwater lakes and sequenced and assembled their genomes. A phylogeny based on 57 proteins indicates that the cells are organized into distinct microclusters. We show that the freshwater genomes have evolved primarily by the accumulation of nucleotide substitutions and that they have among the lowest ratio of recombination to mutation estimated for bacteria. In contrast, members of the marine SAR11 clade have one of the highest ratios. Additional metagenome reads from six lakes confirm low recombination frequencies for the genome overall and reveal lake-specific variations in microcluster abundances. We identify hypervariable regions with gene contents broadly similar to those in the hypervariable regions of the marine isolates, containing genes putatively coding for cell surface molecules. Conclusions: We conclude that recombination rates differ dramatically in phylogenetic sister groups of the SAR11 clade adapted to freshwater and marine ecosystems. The results suggest that the transition from marine to freshwater systems has purged diversity and resulted in reduced opportunities for recombination with divergent members of the clade. The low recombination frequencies of the LD12 clade resemble the low genetic divergence of host-restricted pathogens that have recently shifted to a new host.

  • 634.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Assembly of Gut Microbial Communities in Freshwater Fish and Their Roles in Fish Condition2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Animal hosts provide associated microorganisms with suitable ecological niches in their intestines. Microbes help their hosts to digest food, protect against pathogens, and influence the host’s metabolisms. Compositional variation of gut microbial communities is common among hosts, and may affect the health status of hosts. Diet and genetic factors are well known to influence the assembly of gut microbial communities. This thesis focuses on disentangling the contributions of factors including host genetics (sex), diet, environment, and other ecological processes to the assembly of gut microbial communities in freshwater fish. The association between gut microbial communities and fish condition is also evaluated in this thesis.

    Applying metacommunity theory, we found environmental factors including fish habitat, fish species, their diet, dispersal factors including microbes from fish diet, and ecological drift contributed to the assembly of fish gut microbial communities. The proportion of their contribution varied between fish species, where ecological drift explained more in perch than in roach.

    Under natural conditions fish populations face the risk of predation, which can induce competition and impose predation stress within prey individuals. This can therefore lead to changes in their diet qualities and quantities. In this thesis, it was shown that fish diet in terms of qualities and quantities significantly influenced the overall gut microbial composition, and this influence was dependent on fish sex, a host genetic factor. Predation stress was also suggested to significantly decrease the species richness. Furthermore, when fish were experiencing a diet shift, we showed that different bacterial phyla from novel food had different colonization success in the intestine, and this colonization success was positively influenced by predation stress. Fish condition was suggested in this thesis to be affected by gut microbial composition, especially by the contributions of the bacterial phyla Tenericutes and Actinobacteria.

    List of papers
    1. Contributions of environment and ecological processes to gut microbial communities in freshwater fish
    Open this publication in new window or tab >>Contributions of environment and ecological processes to gut microbial communities in freshwater fish
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology Microbiology
    Identifiers
    urn:nbn:se:uu:diva-314231 (URN)
    Available from: 2017-01-31 Created: 2017-01-31 Last updated: 2017-02-01
    2. Stress responses in intestinal microbiota and host condition depend on gender and diet in a vertebrate
    Open this publication in new window or tab >>Stress responses in intestinal microbiota and host condition depend on gender and diet in a vertebrate
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology Microbiology
    Identifiers
    urn:nbn:se:uu:diva-314232 (URN)
    Available from: 2017-01-31 Created: 2017-01-31 Last updated: 2017-01-31
    3. Effects of food ration and predation stress on perch gut microbial communities
    Open this publication in new window or tab >>Effects of food ration and predation stress on perch gut microbial communities
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology Microbiology
    Identifiers
    urn:nbn:se:uu:diva-314233 (URN)
    Available from: 2017-01-31 Created: 2017-01-31 Last updated: 2017-01-31
    4. Colonization and extinction probabilities in fish gut microbial communities under diet switch and predation stress
    Open this publication in new window or tab >>Colonization and extinction probabilities in fish gut microbial communities under diet switch and predation stress
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology Microbiology
    Identifiers
    urn:nbn:se:uu:diva-314234 (URN)
    Available from: 2017-01-31 Created: 2017-01-31 Last updated: 2017-01-31
  • 635.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Effects of diversity and dispersal on the response of bacterial community to starvation perturbation2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Bacterial diversity and ecosystem functioning (BEF) relationships have received considerable attention during the last three decades and tend to be positive in most cases. However, most studies were done in closed systems and largely ignored the importance of placing local communities into the metacommunity context, in which dispersal can be a crucial factor modifying community diversity and composition and ecosystem functioning.

    The aim of this study was to investigate the effects of both diversity and dispersal on the responses of bacterial community to a starvation perturbation. To achieve this, we implemented a batch culture experiment using the dilution-to-extinction approach to create a diversity gradient of local bacterial community richness. Different dispersal rates were manipulated by transferring cells in different quantities from a regional source to the cultures, and they were then exposed to a perturbation by transferring them into water from another lake which differed in organic carbon content and quality. We evaluated the BEF relationship by measuring the bacterial community composition using t-RFLP and multiple ecosystem functions. Generally, our results demonstrated that diversity and dispersal have an interactive and positive effect on ecosystem functioning. In particular, dispersal had a stronger and more pronounced effect on ecosystem functioning when bacterial diversity was low. When evaluating the responses of bacterial community respiration, no significant difference was observed among different treatments, however, there were clear differences in substrate utilization patterns, implying that specific functions, such as decomposing certain substrates, are more sensitive to a perturbation than general functions, such as respiration. Therefore it is important to include multiple functional parameters when studying BEF relationships and, in particular, when applying our knowledge to the conservation of natural environments.

  • 636.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Alexander, Eiler
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.; eDNA Solut Ltd, Molndal, Sweden..
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Effects of predation stress and food ration on perch gut microbiota2018In: Microbiome, ISSN 0026-2633, E-ISSN 2049-2618, Vol. 6, article id 28Article in journal (Refereed)
    Abstract [en]

    Background: Gut microbiota provide functions of importance to influence hosts' food digestion, metabolism, and protection against pathogens. Factors that affect the composition and functions of gut microbial communities are well studied in humans and other animals; however, we have limited knowledge of how natural food web factors such as stress from predators and food resource rations could affect hosts' gut microbiota and how it interacts with host sex. In this study, we designed a two-factorial experiment exposing perch (Perca fluviatilis) to a predator (pike, Esox lucius), and different food ratios, to examine the compositional and functional changes of perch gut microbiota based on 16S rRNA amplicon sequencing. We also investigated if those changes are host sex dependent.

    Results: We showed that overall gut microbiota composition among individual perch significantly responded to food ration and predator presence. We found that species richness decreased with predator presence, and we identified 23 taxa from a diverse set of phyla that were over-represented when a predator was present. For example, Fusobacteria increased both at the lowest food ration and at predation stress conditions, suggesting that Fusobacteria are favored by stressful situations for the host. In concordance, both food ration and predation stress seemed to influence the metabolic repertoire of the gut microbiota, such as biosynthesis of other secondary metabolites, metabolism of cofactors, and vitamins. In addition, the identified interaction between food ration and sex emphasizes sex-specific responses to diet quantity in gut microbiota.

    Conclusions: Collectively, our findings emphasize an alternative state in gut microbiota with responses to changes in natural food webs depending on host sex. The obtained knowledge from this study provided us with an important perspective on gut microbiota in a food web context.

  • 637.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Berga, Mercè
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Comte, Jérôme
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Langenheder, Silke
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Effects of Dispersal and Initial Diversity on the Composition and Functional Performance of Bacterial Communities2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 5, article id e0155239Article in journal (Refereed)
    Abstract [en]

    Natural communities are open systems and consequently dispersal can play an important role for the diversity, composition and functioning of communities at the local scale. It is, however, still unclear how effects of dispersal differ depending on the initial diversity of local communities. Here we implemented an experiment where we manipulated the initial diversity of natural freshwater bacterioplankton communities using a dilution-to-extinction approach as well as dispersal from a regional species pool. The aim was further to test whether dispersal effects on bacterial abundance and functional parameters (average community growth rates, respiration rates, substrate utilisation ability) differ in dependence of the initial diversity of the communities. First of all, we found that both initial diversity and dispersal rates had an effect on the recruitment of taxa from a regional source, which was higher in communities with low initial diversity and at higher rates of dispersal. Higher initial diversity and dispersal also promoted higher levels of richness and evenness in local communities and affected, both, separately or interactively, the functional performance of communities. Our study therefore suggests that dispersal can influence the diversity, composition and functioning of bacterial communities and that this effect may be enhanced if the initial diversity of communities is depleted.

  • 638.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eiler, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Colonization and extinction probabilities in fish gut microbial communities under diet switch and predation stressManuscript (preprint) (Other academic)
  • 639.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eiler, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Effects of food ration and predation stress on perch gut microbial communitiesManuscript (preprint) (Other academic)
  • 640.
    Zha, Yinghua
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lindström, Eva S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eiler, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Svanbäck, Richard
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Contributions of environment and ecological processes to gut microbial communities in freshwater fishManuscript (preprint) (Other academic)
  • 641.
    Zhang, Huan
    et al.
    Chinese Acad Sci, Inst Hydrobiol, Wuhan, Hubei, Peoples R China;Lund Univ, Dept Biol, Aquat Ecol, SE-22362 Lund, Sweden.
    Urrutia Cordero, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Lund Univ, Dept Biol, Aquat Ecol, SE-22362 Lund, Sweden.
    He, Liang
    Nanchang Univ, Minist Educ, Key Lab Poyang Lake Environm & Resource Utilizat, Nanchang, Jiangxi, Peoples R China.
    Geng, Hong
    South Cent Univ Nationalities, Coll Life Sci, Wuhan, Hubei, Peoples R China.
    Chaguaceda, Fernando
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Lund Univ, Dept Biol, Aquat Ecol, SE-22362 Lund, Sweden.
    Xu, Jun
    Chinese Acad Sci, Inst Hydrobiol, Wuhan, Hubei, Peoples R China.
    Hansson, Lars-Anders
    Lund Univ, Dept Biol, Aquat Ecol, SE-22362 Lund, Sweden.
    Life-history traits buffer against heat wave effects on predator-prey dynamics in zooplankton2018In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 10, p. 4747-4757Article in journal (Refereed)
    Abstract [en]

    In addition to an increase in mean temperature, extreme climatic events, such as heat waves, are predicted to increase in frequency and intensity with climate change, which are likely to affect organism interactions, seasonal succession, and resting stage recruitment patterns in terrestrial as well as in aquatic ecosystems. For example, freshwater zooplankton with different life-history strategies, such as sexual or parthenogenetic reproduction, may respond differently to increased mean temperatures and rapid temperature fluctuations. Therefore, we conducted a long-term (18months) mesocosm experiment where we evaluated the effects of increased mean temperature (4 degrees C) and an identical energy input but delivered through temperature fluctuations, i.e., as heat waves. We show that different rotifer prey species have specific temperature requirements and use limited and species-specific temperature windows for recruiting from the sediment. On the contrary, co-occurring predatory cyclopoid copepods recruit from adult or subadult resting stages and are therefore able to respond to short-term temperature fluctuations. Hence, these different life-history strategies affect the interactions between cyclopoid copepods and rotifers by reducing the risk of a temporal mismatch in predator-prey dynamics in a climate change scenario. Thus, we conclude that predatory cyclopoid copepods with long generation time are likely to benefit from heat waves since they rapidly wake up even at short temperature elevations and thereby suppress fast reproducing prey populations, such as rotifers. In a broader perspective, our findings suggest that differences in life-history traits will affect predator-prey interactions, and thereby alter community dynamics, in a future climate change scenario.

  • 642.
    Zhang, Jiazhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Isolation and Characterization of Uncultured Freshwater Bacterioplankton from Lake Ekoln and Lake Erken through Dilution-to-Extinction Approach and Molecular Analysis Tools2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Not many of the abundant freshwater bacterial groups have a representative cultured isolate. In this master thesis project, some abundant bacterioplankton from two lakes (Lake Ekoln and Lake Erken) could be isolated by a dilution-to-extinction approach. Sterilized lake water which was obtained through an ultrafiltration system was used resembling a natural medium. Specific fragments of 16s rRNA of the isolates were amplified by universal bacterial primers (27f and 1492r, 341f and 805r.) for genotyping against a freshwater sequence database and RDP training set (Version 7). A total of 33 isolates from the two lakes were taxonomically classified and revealed the isolation of typical and abundant freshwater bacteria. Original bacterial community of Lake Ekoln was also analyzed by 16S rRNA clone library construction for diversity study. Phylogenetic trees were built through neighbor-joining method by Mega (Version 5) to reveal the evolutionary relationships among database entries, obtained isolates and clones. 

  • 643.
    Zhao, Weizhou
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Buck, Moritz
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Garcia, Sarahi L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Andersson, Siv G.E.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Rapid diversification of functional homologs in replacement genomic islands of freshwater ActinobacteriaManuscript (preprint) (Other academic)
  • 644.
    Zhao, Weizhou
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Garcia, Sarahi L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Andersson, Siv
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Evolution of subclass Candidatus Actinomarinidae inferred from single-cell amplified genomes of saltwater ActinobacteriaManuscript (preprint) (Other academic)
  • 645.
    Zhao, Weizhou
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution.
    Garcia, Sarahi L
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Grossart, Hans-Peter
    Leibniz Institute for Freshwater Ecology and Inland Fisheries.
    Wannicke, Nicola
    Leib­niz In­sti­tu­te for Plas­ma Sci­ence and Tech­no­lo­gy.
    McMahon, Katherine D
    Departments of Civil and Environmental Engineering and Bacteriology, University of Wisconsin, Madison.
    Andersson, Siv
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Evolution. Uppsala University, Science for Life Laboratory, SciLifeLab.
    A phylometagenomic study based on single-cell amplified genomes from Actinobacteria in the brackish waters of the Baltic SeaManuscript (preprint) (Other academic)
  • 646. Zheng, Zongli
    et al.
    Andersson, Anders F.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Ye, Weimin
    Nyrén, Olof
    Normark, Staffan
    Engstrand, Lars
    Metagenomic study of Helicobacter pylori microdissected from archived formalin-fixed paraffin-embedded biopsy sections2010In: Genome Biology, ISSN 1474-760X, Vol. 11, p. P42-Article in journal (Other academic)
  • 647.
    Zink, Eren
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Cultural Anthropology and Ethnology.
    Elvander, Marianne
    Lindberg, Ann
    Järhult, Josef D.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Infectious Diseases. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Biochemistry and Microbiology.
    Målqvist, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, International Maternal and Child Health (IMCH), International Child Health and Nutrition.
    Boqvist, Sofia
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Magnusson, Ulf
    Chandler, Rebecca
    Hur ska vi klara de nya epidemierna?2017Other (Other (popular science, discussion, etc.))
  • 648.
    Åberg, Jan
    et al.
    Department of Ecology and Environmental Science, Umeå University.
    Wallin, Marcus B.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Evaluating a fast headspace method for measuring DIC and subsequent calculation of pCO2 in freshwater systems2014In: Inland Waters, ISSN 2044-2041, EISSN 2044-205X, Vol. 4, no 2, p. 157-166Article in journal (Refereed)
    Abstract [en]

    A variety of different sampling and analysis methods are found in the literature for determining carbon dioxide (CO2) in freshwaters, methods that rarely have been evaluated or compared. Here we present an evaluation of an acidified headspace method (AHS) in which the dissolved inorganic carbon (DIC) is measured from an acidified sample and the partial pressure (pCO2) is calculated from DIC using pH and water temperature. We include information on practical sampling, accuracy, and precision of the DIC/pCO2 determination and a storage test of samples. The pCO2 determined from the AHS method is compared to that obtained from the more widely used direct headspace method (DHS) in which CO2 is equilibrated between the water and gas phases at ambient pH. The method was tested under both controlled laboratory conditions as well as wintertime field sampling. The accuracy of the DIC detection was on average 99% based on prepared standard solutions. The pCO2 determination in lab, using the DHS method as a reference, showed no significant difference, although the discrepancy between the methods was larger in samples with <1000 µatm. The precision of the pCO2 determination was on average ±4.3%, which was slightly better than the DHS method (±6.7%). In the field, the AHS method determined on average 10% higher pCO2 than the DHS method, which was explained by the extreme winter conditions (below −20 °C) at sampling that affected the sampling procedure of the DHS method. Although samples were acidified to pH 2, respiration processes were still occurring (at a low rate), and we recommend that analyses are conducted within 3 days from sampling. The AHS method was found to be a robust method to determine DIC and pCO2 in acidic to pH-neutral freshwater systems. The simple and quick sampling procedure makes the method suitable for time-limited sampling campaigns and sampling in cold climate.

  • 649.
    Öquist, Mats G.
    et al.
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU).
    Bishop, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Uppsala Centre for Sustainable Development, CSD Uppsala.
    Grelle, Achim
    Department of Ecology, Swedish University of Agricultural Sciences (SLU).
    Klemedtsson, Leif
    Department of Earth Sciences, Gothenburg University.
    Köhler, Stephan J.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU).
    Laudon, Hjalmar
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU).
    Lindroth, Anders
    Department of Physical Geography and Ecosystem Analysis, Lund University.
    Ottosson Löfvenius, Mikaell
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU).
    Wallin, Marcus B.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Nilsson, Mats B.
    Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU).
    The full annual carbon balance of boreal forestsis highly sensitive to precipitation2014In: Environmental Science and Technology Letters, ISSN 2328-8930, Vol. 1, no 7, p. 315-319Article in journal (Refereed)
    Abstract [en]

    The boreal forest carbon balance is predicted to be particularly sensitive to climate change. Carbon balance estimates of these biomes stem mainly from eddy-covariance measurements of net ecosystem exchange (NEE). However, a full net ecosystem carbon balance (NECB) must include the lateral carbon export (LCE) through discharge. We show that annual LCE at a boreal forest site ranged from 4 to 28%, averaging 11% (standard deviation of 8%), of annual NEE over 13 years. Annual LCE and NEE are strongly anticorrelated; years with weak NEE coincide with high LCE. The decreased NEE in response to increased precipitation is caused by a reduction in the amount of incoming radiation caused by clouds. If our finding is also valid for other sites, it implies that increased precipitation at high latitudes may shift forest NECB in large areas of the boreal biome. Our results call for future analysis of this dual effect of precipitation on NEE and LCE.

  • 650.
    Östman, Örjan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Population and Conservation Biology.
    Drakare, Stina
    Kritzberg, Emma S.
    Langenheder, Silke
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Logue, Jürg B.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Lindström, Eva S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Importance of space and the local environment for linking local and regional abundances of microbes2012In: Aquatic Microbial Ecology, ISSN 0948-3055, E-ISSN 1616-1564, Vol. 67, no 1, p. 35-45Article in journal (Refereed)
    Abstract [en]

    It is frequently observed that the local relative abundances of aquatic microbial taxa are correlated with their average relative abundance at the regional scale, which results in the composition of different communities being more similar than expected by chance or invariant. The degree to which communities within a region match the regional average community is variable and likely depends on several different mechanisms that control the process of microbial community assembly. Here, we show that environmental variables were associated with the community specific degree of regional invariance in 9 of 10 datasets of microbial communities in aquatic systems, being the main set of variables explaining differences in regional invariance in 5 of them. This indicates that variation in local environmental conditions across a region reduces the degree of regional invariance amongst communities. Spatial distances between communities were not related to the degrees of regional invariance, but in 7 of the datasets, regional invariance differed among different parts of the regions, particularly for phytoplankton communities. This suggests an influence of spatial or historical processes on the community specific degree of regional invariance. We conclude that both local environmental conditions and spatial/historical processes cause between-site differences in the degree of invariance between local and regional abundances in aquatic microbial metacommunities. We argue that studies of regional invariance can be an important complement to other statistical methods due to its propensity to detect variation in stochastic processes along gradients.

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