DOCSLIB.ORG

Interactions Among Sulfate-Reducing and Purple Sulfur Bacteria in the Chemocline of Meromictic Lake Cadagno, Switzerland

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Interactions Among Sulfate-Reducing and Purple Sulfur Bacteria in the Chemocline of Meromictic Lake Cadagno, Switzerland Diss. ETH No. 15015 Interactions among sulfate-reducing and purple sulfur bacteria in the chemocline of meromictic Lake Cadagno, Switzerland A dissertation submitted to the SWISS FEDERAL INSTITUTE OF TECHNOLOGY ZURICH for the degree of DOCTOR OF NATURAL SCIENCES presented by SANDRO PEDUZZI Ing. dipl. EPFL born on October 15, 1973 from Airolo (Ticino) accepted on the recommendation of Prof. Dr. Alexander J.B. Zehnder, examiner Prof. Dr. Dittmar Hahn, co-examiner Dr. Mauro Tonolla, co-examiner 2003 Contents Summary....................................................................................................................................7 Résumé.......................................................................................................................................9 Chapter 1 13 Introduction 13 1.1 Stratified lakes........................................................................................................................... 14 1.2 Lake Cadagno............................................................................................................................ 17 1.3 The sulfur cycle......................................................................................................................... 20 1.3.1 Sulfate-reduction............................................................................................................... 24 1.3.2 Sulfur disproportionation .................................................................................................. 25 1.3.3 Anoxygenic photosynthesis .............................................................................................. 26 1.3.4 Sulfate-reducing and phototropic sulfur bacteria in Lake Cadagno.................................. 29 1.3 Aim of the thesis ....................................................................................................................... 32 1.4 References................................................................................................................................. 34 Chapter 2 45 In situ analysis of sulfate-reducing bacteria related to Desulfocapsa thiozymogenes in the chemocline of meromictic Lake Cadagno (Switzerland) 45 Abstract ........................................................................................................................................... 46 References....................................................................................................................................... 53 Chapter 3 57 Spatio-temporal distribution of phototrophic sulfur bacteria in the chemocline of meromictic Lake Cadagno (Switzerland) 57 3.1 Abstract ..................................................................................................................................... 58 3.2 Introduction............................................................................................................................... 58 3.3. Material and Methods............................................................................................................... 59 3.3.1. Site description, physical analyses and sampling............................................................. 59 3.3.2. Chemical analysis ............................................................................................................ 60 3.3.3. Microbial analysis............................................................................................................ 60 3.4 Results....................................................................................................................................... 62 3.4.1. Analysis of physico-chemical conditions......................................................................... 62 3.4.2. Microbial analysis............................................................................................................ 64 3.5 Discussion ................................................................................................................................. 68 3.6 References................................................................................................................................. 71 Chapter 4 77 Vertical distribution of sulfate-reducing bacteria in the chemocline of Lake Cadagno, Switzerland, over an annual cycle 77 Abstract ........................................................................................................................................... 78 References....................................................................................................................................... 89 Chapter 5 93 Isolation and characterization of aggregate-forming sulfate-reducing and purple sulfur bacteria from the chemocline of meromictic Lake Cadagno, Switzerland 93 5.1 Abstract ..................................................................................................................................... 94 5.2 Introduction............................................................................................................................... 94 5.3 Material and methods................................................................................................................ 96 5.3.1 Enrichment and isolation ..................................................................................................96 5.3.2 Identification and characterization.................................................................................... 97 5.3.3 Mixed culture study .......................................................................................................... 98 5.4 Results..................................................................................................................................... 100 5.4.1 Isolation and characterization of the sulfate-reducing bacterium, isolate Cad626.......... 100 5.4.2 Isolation and characterization of the phototrophic sulfur bacterium, isolate Cad16....... 101 5.4.3 Mixed culture study ........................................................................................................ 105 5.5 Discussion ............................................................................................................................... 106 5.6 References............................................................................................................................... 109 Chapter 6 115 Discussion 115 6.1 Aggregate formation ............................................................................................................... 116 6.2 Interactions among organisms involved in the sulfur cycle .................................................... 120 6.3 Interactions between sulfate-reducing and small-celled purple sulfur bacteria ...................... 124 6.4 Future perspectives.................................................................................................................. 131 6.5 References............................................................................................................................... 133 Curriculum vitae......................................................................................................................141 Aknowledgements...................................................................................................................143 Summary 7 Summary Permanently stratified lakes represent optimal model systems for the study of aquatic microorganisms since defined and stable vertical gradients of environmental conditions such as light intensity and quality, oxygen availability, or the presence of sulfide support the development of diverse populations of microorganisms adapted to defined ecological niches. Lake Cadagno is a meromictic lake located 1923 m above sea level in the Southern Alps of Switzerland (46°33'N, 8°43'E), in the catchment area of a dolomite vein rich in gypsum (Piora-Mulde). A permanent chemocline at a depth between 9 and 14 meters is stabilized by density differences of salt-rich water constantly supplied by subaquatic springs to the monimolimnion and of electrolyte-poor surface water feeding the mixolimnion. High concentrations of sulfate and steep sulfide gradients in the chemocline support the growth of large numbers of bacteria (up to 107 cells ml-1) indicating that a bacterial community making use of these gradients is present. Molecular techniques that were used to analyze microbial community structure unaffected by the limitations of culturability showed that almost all bacteria in the chemocline of Lake Cadagno belonged to the Proteobacteria with numbers for the -, -, - and -subdivision of Proteobacteria accounting for 23, 17, 45 and 15% of the total number of bacteria, respectively. Most prominent numerically (ca. 35% of all bacteria) were large- and small-celled phototrophic purple sulfur bacteria. The large-celled phototrophic sulfur bacteria were identified as Chromatium okenii, while small- celled phototrophic sulfur bacteria consisted of four major populations forming a tight cluster with Lamprocystis purpurea (former Amoebobacter purpureus and Pfennigia purpurea) and L. roseopersicina. The numerically most important phototrophic sulfur bacteria in the chemocline were small-celled purple sulfur bacteria of two yet uncultured populations designated D and F. Other small-celled purple sulfur bacteria (L. purpurea and L. roseopersicina) were found in numbers about one order of magnitude lower. These numbers were similar to those of the large-celled purple sulfur bacteria (C. okenii) and green
Load more

Recommended publications
  • Thureborn Et Al 2013
    http://www.diva-portal.org This is the published version of a paper published in PLoS ONE. Citation for the original published paper (version of record): Thureborn, P., Lundin, D., Plathan, J., Poole, A., Sjöberg, B. et al. (2013) A Metagenomics Transect into the Deepest Point of the Baltic Sea Reveals Clear Stratification of Microbial Functional Capacities. PLoS ONE, 8(9): e74983 http://dx.doi.org/10.1371/journal.pone.0074983 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Permanent link to this version: http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-20021 A Metagenomics Transect into the Deepest Point of the Baltic Sea Reveals Clear Stratification of Microbial Functional Capacities Petter Thureborn1,2*., Daniel Lundin1,3,4., Josefin Plathan2., Anthony M. Poole2,5, Britt-Marie Sjo¨ berg2,4, Sara Sjo¨ ling1 1 School of Natural Sciences and Environmental Studies, So¨derto¨rn University, Huddinge, Sweden, 2 Department of Molecular Biology and Functional Genomics, Stockholm University, Stockholm, Sweden, 3 Science for Life Laboratories, Royal Institute of Technology, Solna, Sweden, 4 Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden, 5 School of Biological Sciences, University of Canterbury, Christchurch, New Zealand Abstract The Baltic Sea is characterized by hyposaline surface waters, hypoxic and anoxic deep waters and sediments. These conditions, which in turn lead to a steep oxygen gradient, are particularly evident at Landsort Deep in the Baltic Proper. Given these substantial differences in environmental parameters at Landsort Deep, we performed a metagenomic census spanning surface to sediment to establish whether the microbial communities at this site are as stratified as the physical environment.
    [Show full text]
  • A Dolomitization Event at the Oceanic Chemocline During the Permian-Triassic Transition Mingtao Li1, Haijun Song1*, Thomas J
    https://doi.org/10.1130/G45479.1 Manuscript received 11 August 2018 Revised manuscript received 4 October 2018 Manuscript accepted 5 October 2018 © 2018 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 23 October 2018 A dolomitization event at the oceanic chemocline during the Permian-Triassic transition Mingtao Li1, Haijun Song1*, Thomas J. Algeo1,2,3, Paul B. Wignall4, Xu Dai1, and Adam D. Woods5 1State Key Laboratory of Biogeology and Environmental Geology, School of Earth Science, China University of Geosciences, Wuhan 430074, China 2State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science, China University of Geosciences, Wuhan 430074, China 3Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, USA 4School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK 5Department of Geological Sciences, California State University, Fullerton, California 92834-6850, USA ABSTRACT in dolomite in the uppermost Permian–lowermost Triassic was first noted The Permian-Triassic boundary (PTB) crisis caused major short- by Wignall and Twitchett (2002) and has been attributed to an increased term perturbations in ocean chemistry, as recorded by the precipita- weathering flux of Mg-bearing clays to the ocean (Algeo et al., 2011). tion of anachronistic carbonates. Here, we document for the first time Here, we examine the distribution of dolomite in 22 PTB sections, docu- a global dolomitization event during the Permian-Triassic transition menting a global dolomitization event and identifying additional controls based on Mg/(Mg + Ca) data from 22 sections with a global distri- on its formation during the Permian-Triassic transition.
    [Show full text]
  • Article Is Available Gen Availability
    Hydrol. Earth Syst. Sci., 23, 1763–1777, 2019 https://doi.org/10.5194/hess-23-1763-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Oxycline oscillations induced by internal waves in deep Lake Iseo Giulia Valerio1, Marco Pilotti1,4, Maximilian Peter Lau2,3, and Michael Hupfer2 1DICATAM, Università degli Studi di Brescia, via Branze 43, 25123 Brescia, Italy 2Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany 3Université du Quebec à Montréal (UQAM), Department of Biological Sciences, Montréal, QC H2X 3Y7, Canada 4Civil & Environmental Engineering Department, Tufts University, Medford, MA 02155, USA Correspondence: Giulia Valerio ([email protected]) Received: 22 October 2018 – Discussion started: 23 October 2018 Revised: 20 February 2019 – Accepted: 12 March 2019 – Published: 2 April 2019 Abstract. Lake Iseo is undergoing a dramatic deoxygena- 1 Introduction tion of the hypolimnion, representing an emblematic exam- ple among the deep lakes of the pre-alpine area that are, to a different extent, undergoing reduced deep-water mixing. In Physical processes occurring at the sediment–water inter- the anoxic deep waters, the release and accumulation of re- face of lakes crucially control the fluxes of chemical com- duced substances and phosphorus from the sediments are a pounds across this boundary (Imboden and Wuest, 1995) major concern. Because the hydrodynamics of this lake was with severe implications for water quality. In stratified shown to be dominated by internal waves, in this study we in- lakes, the boundary-layer turbulence is primarily caused by vestigated, for the first time, the role of these oscillatory mo- wind-driven internal wave motions (Imberger, 1998).
    [Show full text]
  • A Primer on Limnology, Second Edition
    BIOLOGICAL PHYSICAL lake zones formation food webs variability primary producers light chlorophyll density stratification algal succession watersheds consumers and decomposers CHEMICAL general lake chemistry trophic status eutrophication dissolved oxygen nutrients ecoregions biological differences The following overview is taken from LAKE ECOLOGY OVERVIEW (Chapter 1, Horne, A.J. and C.R. Goldman. 1994. Limnology. 2nd edition. McGraw-Hill Co., New York, New York, USA.) Limnology is the study of fresh or saline waters contained within continental boundaries. Limnology and the closely related science of oceanography together cover all aquatic ecosystems. Although many limnologists are freshwater ecologists, physical, chemical, and engineering limnologists all participate in this branch of science. Limnology covers lakes, ponds, reservoirs, streams, rivers, wetlands, and estuaries, while oceanography covers the open sea. Limnology evolved into a distinct science only in the past two centuries, when improvements in microscopes, the invention of the silk plankton net, and improvements in the thermometer combined to show that lakes are complex ecological systems with distinct structures. Today, limnology plays a major role in water use and distribution as well as in wildlife habitat protection. Limnologists work on lake and reservoir management, water pollution control, and stream and river protection, artificial wetland construction, and fish and wildlife enhancement. An important goal of education in limnology is to increase the number of people who, although not full-time limnologists, can understand and apply its general concepts to a broad range of related disciplines. A primary goal of Water on the Web is to use these beautiful aquatic ecosystems to assist in the teaching of core physical, chemical, biological, and mathematical principles, as well as modern computer technology, while also improving our students' general understanding of water - the most fundamental substance necessary for sustaining life on our planet.
    [Show full text]
  • Dark Aerobic Sulfide Oxidation by Anoxygenic Phototrophs in the Anoxic Waters 2 of Lake Cadagno 3 4 Jasmine S
    bioRxiv preprint doi: https://doi.org/10.1101/487272; this version posted December 6, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 Dark aerobic sulfide oxidation by anoxygenic phototrophs in the anoxic waters 2 of Lake Cadagno 3 4 Jasmine S. Berg1,2*, Petra Pjevac3, Tobias Sommer4, Caroline R.T. Buckner1, Miriam Philippi1, Philipp F. 5 Hach1, Manuel Liebeke5, Moritz Holtappels6, Francesco Danza7,8, Mauro Tonolla7,8, Anupam Sengupta9, , 6 Carsten J. Schubert4, Jana Milucka1, Marcel M.M. Kuypers1 7 8 1Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany 9 2Institut de Minéralogie, Physique des Matériaux et Cosmochimie, Université Pierre et Marie Curie, CNRS UMR 10 7590, 4 Place Jussieu, 75252 Paris Cedex 05, France 11 3Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, 1090 12 Vienna, Austria 13 4Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland 14 5Department of Symbiosis, Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany 15 6Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Alten Hafen 26, 27568 16 Bremerhaven, Germany 17 7Laboratory of Applied Microbiology (LMA), Department for Environmental Constructions and Design (DACD), 18 University of Applied Sciences and Arts of Southern Switzerland (SUPSI), via Mirasole 22a, 6500 Bellinzona, 19 Switzerland 20 8Microbiology Unit, Department of Botany and Plant Biology, University of Geneva, 1211 Geneva, Switzerland 21 9Institute for Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH 22 Zurich, 8093 Zurich, Switzerland.
    [Show full text]
  • Spatio-Temporal Distribution of Phototrophic Sulfur Bacteria in the Chemocline of Meromictic Lake Cadagno (Switzerland)
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by RERO DOC Digital Library FEMS Microbiology Ecology 43 (2003) 89^98 www.fems-microbiology.org Spatio-temporal distribution of phototrophic sulfur bacteria in the chemocline of meromictic Lake Cadagno (Switzerland) Mauro Tonolla a, Sandro Peduzzi a;b, Dittmar Hahn b;Ã, Ra¡aele Peduzzi a a Cantonal Institute of Microbiology, Microbial Ecology (University of Geneva), Via Giuseppe Bu⁄ 6, CH-6904 Lugano, Switzerland b Department of Chemical Engineering, New Jersey Institute of Technology (NJIT), and Department of Biological Sciences, Rutgers University, 101 Warren Street, Smith Hall 135, Newark, NJ 07102-1811, USA Received 24 May 2002; received in revised form 26 July 2002; accepted 30 July 2002 First published online 4 September 2002 Abstract In situ hybridization was used to study the spatio-temporal distribution of phototrophic sulfur bacteria in the permanent chemocline of meromictic Lake Cadagno, Switzerland. At all four sampling times during the year the numerically most important phototrophic sulfur bacteria in the chemocline were small-celled purple sulfur bacteria of two yet uncultured populations designated Dand F. Other small- celled purple sulfur bacteria (Amoebobacter purpureus and Lamprocystis roseopersicina) were found in numbers about one order of magnitude lower. These numbers were similar to those of large-celled purple sulfur bacteria (Chromatium okenii) and green sulfur bacteria that almost entirely consisted of Chlorobium phaeobacteroides. In March and June when low light intensities reached the chemocline, cell densities of all populations, with the exception of L. roseopersicina, were about one order of magnitude lower than in August and October when light intensities were much higher.
    [Show full text]
  • The Dynamics of Nutrient Enrichment and Primary Production Related to the Recent Changes in the Ecosystem of the Black Sea
    IAEA-SM-354/29 XA9951900 THE DYNAMICS OF NUTRIENT ENRICHMENT AND PRIMARY PRODUCTION RELATED TO THE RECENT CHANGES IN THE ECOSYSTEM OF THE BLACK SEA YILMAZ A., YAYLA M., and SALlHOGLU I., Middle East Technical University, Institute of Marine Sciences, P.CBox 28, 33731, Erdemli-icel, Turkey E. MORKOg, Turkish Scientific and Technological Research Council (TUBITAK), Marmara Research Center, P.O.Box 21, 41470, Gebze-Kocaeli, Turkey Abstract During the spring period of 1998, light penetrated into the upper 25-35m, with an attenuation coefficient varying between 0.1 and 0.5 m"1. The chlorophyll-a (Chl-a) concentrations for the euphotic zone ranged from 0.2 to 1.4 ug I"1. Coherent sub-surface Chl-a maxima were formed near the base of the euphotic zone and a secondary one was located at very low level of light in the Rim Current region. Production rates varied between 450 and 690 mgC/m2/d in this period. The chemocline boundaries and the distinct chemical features of the oxic/anoxic transition layer (the so-called suboxic zone) are all located at specific density surfaces; however, they exhibited remarkable spatial variations both in their position and in their magnitude. Bioassay experiments (using extra NO3, NH4, PO4 and Si) performed during Spring 1998 cruise showed that under optimum light conditions the phytoplankton population is nitrate limited in the open waters. Phosphate seems to control the growth in the Rim Current regions of the southern Black Sea. Si concentration also influenced the phytoplankton growth since the majority of the population was determined as diatom.
    [Show full text]
  • Geochemical Features of Redox-Sensitive Trace Metals in Sediments Under Oxygen-Depleted Marine Environments
    minerals Article Geochemical Features of Redox-Sensitive Trace Metals in Sediments under Oxygen-Depleted Marine Environments Moei Yano 1,2, Kazutaka Yasukawa 1,2,3 , Kentaro Nakamura 3, Minoru Ikehara 4 and Yasuhiro Kato 1,2,3,5,* 1 Ocean Resources Research Center for Next Generation, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan; [email protected] (M.Y.); [email protected] (K.Y.) 2 Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan 3 Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; [email protected] 4 Center for Advanced Marine Core Research, Kochi University, B200 Monobe, Nankoku, Kochi 783-8502, Japan; [email protected] 5 Submarine Resources Research Center, Research Institute for Marine Resources Utilization, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan * Correspondence: [email protected]; Tel.: +81-3-5841-7022 Received: 13 September 2020; Accepted: 13 November 2020; Published: 17 November 2020 Abstract: Organic- and sulfide-rich sediments have formed in oxygen-depleted environments throughout Earth’s history. The fact that they are generally enriched in redox-sensitive elements reflects the sedimentary environment at the time of deposition. Although the modern ocean is well oxidized, oxygen depletion occurs in certain areas such as restricted basins and high-productivity zones.
    [Show full text]
  • The Behavior of Molybdenum and Its Isotopes Across the Chemocline and in the Sediments of Sulfidic Lake Cadagno, Switzerland
    Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 74 (2010) 144–163 www.elsevier.com/locate/gca The behavior of molybdenum and its isotopes across the chemocline and in the sediments of sulfidic Lake Cadagno, Switzerland Tais W. Dahl a,*, Ariel D. Anbar b, Gwyneth W. Gordon b, Minik T. Rosing a, Robert Frei c, Donald E. Canfield d a Nordic Center for Earth Evolution (NordCEE) and Geological Museum, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark b School of Earth and Space Exploration, Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA c Nordic Center for Earth Evolution (NordCEE) and Institute for Geography and Geology, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark d Nordic Center for Earth Evolution (NordCEE) and Biological Institute, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark Received 16 March 2009; accepted in revised form 15 September 2009; available online 22 September 2009 Abstract Molybdenum (Mo) isotope studies in black shales can provide information about the redox evolution of the Earth’s oceans, provided the isotopic consequences of Mo burial into its major sinks are well understood. Previous applications of the Mo isotope paleo-ocean redox proxy assumed quantitative scavenging of Mo when buried into sulfidic sediments. This paper contains the first complete suite of Mo isotope fractionation observations in a sulfidic water column and sediment sys- tem, the meromictic Lake Cadagno, Switzerland, a small alpine lake with a pronounced oxygen–sulfide transition reaching up 2À À 2À to H2S 200 lM in the bottom waters (or about 300 lM total sulfide: RS =H2S+HS +S ).
    [Show full text]
  • Geophysical and Geochemical Signatures of Gulf of Mexico Seafloor Brines
    Biogeosciences, 2, 295–309, 2005 www.biogeosciences.net/bg/2/295/ Biogeosciences SRef-ID: 1726-4189/bg/2005-2-295 European Geosciences Union Geophysical and geochemical signatures of Gulf of Mexico seafloor brines S. B. Joye1, I. R. MacDonald2, J. P. Montoya3, and M. Peccini2 1Department of Marine Sciences, University of Georgia, Athens, Georgia 30602, USA 2School of Physical and Life Sciences, Texas A&M University, Corpus Christi, Texas, USA 3School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA Received: 21 April 2005 – Published in Biogeosciences Discussions: 31 May 2005 Revised: 30 August 2005 – Accepted: 23 September 2005 – Published: 28 October 2005 Abstract. Geophysical, temperature, and discrete depth- 1 Introduction stratified geochemical data illustrate differences between an actively venting mud volcano and a relatively quiescent brine Submarine mud volcanoes are conspicuous examples of fo- pool in the Gulf of Mexico along the continental slope. Geo- cused flow regimes in sedimentary settings (Carson and Scre- physical data, including laser-line scan mosaics and sub- aton, 1998) and have been associated with high thermal gra- bottom profiles, document the dynamic nature of both envi- dients (Henry et al., 1996), shallow gas hydrates (Ginsburg ronments. Temperature profiles, obtained by lowering a CTD et al., 1999), and an abundance of high-molecular weight hy- into the brine fluid, show that the venting brine was at least drocarbons (Roberts and Carney, 1997). Mud volcanoes are 10◦C warmer than the bottom water. At the brine pool, ther- common seafloor features along continental shelves, conti- mal stratification was observed and only small differences in nental slopes, and in the deeper portions of inland seas (e.g., stratification were documented between three sampling times the Caspian Sea, Milkov, 2000) along both active and pas- (1991, 1997 and 1998).
    [Show full text]
  • Photoferrotrophs Thrive in an Archean Ocean Analogue
    Photoferrotrophs thrive in an Archean Ocean analogue Sean A. Crowe*, CarriAyne Jones†, Sergei Katsev*‡,Ce´ dric Magen*, Andrew H. O’Neill§, Arne Sturm¶, Donald E. Canfield†, G. Douglas Haffner§, Alfonso Mucci*, Bjørn Sundby*ʈ, and David A. Fowle¶** *Earth and Planetary Sciences, McGill University, Montre´al, QC, Canada H3A 2A7; †Institute of Biology, Nordic Center for Earth Evolution, University of Southern Denmark, 5230 Odense, Denmark; ‡Large Lakes Observatory and Department of Physics, University of Minnesota, Duluth, MN 55812; §Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada N9B 3P4; ¶Department of Geology, University of Kansas, Lawrence, KS 66047; and ʈInstitut des Sciences de la Mer de Rimouski, Universite´du Que´bec, Rimouski, QC, Canada G5L 3A1 Edited by Andrew H. Knoll, Harvard University, Cambridge, MA, and approved August 27, 2008 (received for review May 31, 2008) Considerable discussion surrounds the potential role of anoxygenic low oxygen partial pressure is much faster, and this chemoau- phototrophic Fe(II)-oxidizing bacteria in both the genesis of totrophic metabolism (see review in ref. 1) is well known to occur Banded Iron Formations (BIFs) and early marine productivity. How- in modern microaerophilic environments. Provided an adequate ever, anoxygenic phototrophs have yet to be identified in modern supply of O2, chemolithoautotrophy could have been an impor- environments with comparable chemistry and physical structure to tant source of oxidized Fe to BIFs. the ancient Fe(II)-rich (ferruginous) oceans from which BIFs depos- UV photolysis, however, would not have required oxygen. The ited. Lake Matano, Indonesia, the eighth deepest lake in the world, UV oxidation of Fe(II) has been demonstrated in the laboratory ,is such an environment.
    [Show full text]
  • Impact from the Deep
    C REDI T 64 SCIENTIFIC AMERICAN OCTOBER 2006 COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. GREEN AND PURPLE sulfur bacteria colonizing a hot spring thrive in water depleted of oxygen but rich in hydrogen sulfi de. Widespread ocean blooms of these organisms during ancient periods of mass extinction suggest similar conditions prevailed at those times. IMPACTFROMFROM THEDEEP Strangling heat and gases emanating from the earth and sea, not asteroids, most likely caused several ancient mass extinctions. Could the same killer-greenhouse conditions build once again? By Peter D. Ward hilosopher and historian Thomas S. Kuhn has suggest- extinctions underwent a Kuhnian revolution when a team at ed that scientifi c disciplines act a lot like living organ- the University of California, Berkeley, led by geologist Walter isms: instead of evolving slowly but continuously, they Alvarez proposed that the famous dinosaur-killing extinction enjoy long stretches of stability punctuated by infre- 65 million years ago occurred swiftly, in the ecosystem catas- P quent revolutions with the appearance of a new species—or in trophe that followed an asteroid collision. Over the ensuing the case of science, a new theory. This description is particu- two decades, the idea that a bolide from space could smite larly apt for my own area of study, the causes and consequenc- a signifi cant segment of life on the earth was widely em- es of mass extinctions—those periodic biological upheavals braced—and many researchers eventually came to believe that when a large proportion of the planet’s living creatures died cosmic detritus probably caused at least three more of the fi ve off and afterward nothing was ever the same again.
    [Show full text]