DOCSLIB.ORG

Primary Production, Nitrogen Cycling and the Ecosystem Role Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Primary Production, Nitrogen Cycling and the Ecosystem Role Of PRIMARY PRODUCTION, NITROGEN CYCLING AND THE ECOSYSTEM ROLE OF MANGROVE MICROBIAL MATS ON TWIN CAYS, BELIZE by ROSALYNN Y. LEE (Under the Direction of Samantha B. Joye) ABSTRACT The seasonal variability of porewater nutrient concentrations, metabolism, nitrogen cycling (denitrification and nitrogen fixation), and primary production (oxygenic and anoxygenic photosynthesis and chemoautotrophy) was examined in benthic mangrove environments on Twin Cays, Belize. Twin Cays mangroves exhibit a tree-height gradient from tall seaward fringe trees, through a transition of intermediate tree heights to short dwarf trees surrounding interior ponds and lagoons. Detailed investigations of steady state porewater profiles of nutrients and terminal metabolic products in dwarf mangrove soils revealed strong seasonal differences in salinity, organic carbon and nitrogen inventories, redox conditions and reduced manganese concentrations. Substantial rates of organic matter remineralization were coupled primarily to sulfate reduction. Redox conditions contributed to variability in mat nitrogen fixation and denitrification response to nutrient addition, while dissolved organic carbon did not. Nitrogen fixation was controlled primarily by the sensitivity of nitrogenase to oxygen inhibition, whereas denitrification was limited by nitrate availability. Community composition of photosynthetic organisms appeared to be controlled by light fluctuations due to mangrove canopy light gaps and by differential tolerance to environmental stresses such as desiccation or nitrogen limitation. Dwarf mangrove cyanobacteria-dominated microbial mats achieved a high biomass of photopigments in well-illuminated soils. Transition and fringe soils were more shaded and contained diatoms and green algae and less cyanobacteria and anoxygenic photosynthetic bacteria than in dwarf soils. Oxygenic photosynthesis was the primary mode of carbon fixation (56%) in all habitats under full sun, with a lesser contribution by anoxygenic photosynthesis (32%) and chemoautotrophy (12%). In situ light conditions underscore the gradient from highest rates of carbon fixation in dwarf mangrove habitat mats (0.21 g C m-2 d-1) to diminished rates in shaded transition and fringe mangrove habitat mats (0.08 and 0.05 g C m-2 d-1, respectively). Well-lit mats associated with dwarf mangrove habitats fix 18-20% of the net primary productivity of Twin Cays’ dwarf mangrove trees and can supply 5- 28% of the nitrogen requirement of Twin Cays’ dwarf mangrove trees via nitrogen fixation. Light limitation restricts the fixation of carbon and nitrogen in transition and fringe mangrove habitat mats which account for only <0.3% of the net production and <2% of the nitrogen requirement of the respective mangrove trees. INDEX WORDS: Mangrove, microbial mat, cyanobacteria, porewater nutrients, benthic metabolism, primary production, respiration, carbon fixation, nitrogen fixation, denitrification, desiccation, oxygenic photosynthesis, anoxygenic photosynthesis, chemoautotrophy, natural abundance isotopic signatures PRIMARY PRODUCTION, NITROGEN CYCLING AND THE ECOSYSTEM ROLE OF MANGROVE MICROBIAL MATS ON TWIN CAYS, BELIZE by ROSALYNN Y. LEE B.A., University of Virginia, 1998 A Dissertation Submitted to the Graduate Faculty of the University of Georgia in Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY ATHENS, GEORGIA 2006 © 2006 Rosalynn Y. Lee All Rights Reserved PRIMARY PRODUCTION, NITROGEN CYCLING AND THE ECOSYSTEM ROLE OF MANGROVE MICROBIAL MATS ON TWIN CAYS, BELIZE by ROSALYNN Y. LEE Major Professor: Samantha B. Joye Committee: James T. Hollibaugh Robert J. Maier Scott Noakes Catherine M. Pringle Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia December 2005 ACKNOWLEDGEMENTS I thank the National Science Foundation Biocomplexity in the Environment Program (DEB-0002796) and the University of Georgia’s University-Wide Fellowship Program for funding this work. I thank my dissertation committee, Mandy Joye, Tim Hollibaugh, Rob Maier, Scott Noakes, and Cathy Pringle, as well as Joe Montoya, for ensuring the quality of my philosophical development in the sciences. I also thank the members of the Joye lab who have helped me in the field and laboratory, especially Steve Carini, Bill Porubsky, and Nat Weston. Thanks to everyone who has supported me in this defining stage of my life, both intellectually and emotionally, especially my mentors Mandy Joye and Sybil Seitzinger, my friends Steve Carini, Leigh McCallister, Donna Falk, and Jason Sylvan, my aunt Winnie and my mother Wendy. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS........................................................................................................... iv CHAPTER 1 INTRODUCTION .........................................................................................................1 2 POREWATER BIOGEOCHEMISTRY AND SOIL METABOLISM IN STUNTED RED MANGROVE HABITATS (TWIN CAYS, BELIZE)...................................10 3 PATTERNS OF NET AND GROSS PRIMARY PRODUCTION IN MANGROVE SOILS, TWIN CAYS, BELIZE: FIELD RESULTS AND MODELING ..............51 4 SEASONAL PATTERNS OF NITROGEN FIXATION AND DENITRIFICATION IN OCEANIC MANGROVE HABITATS .............................................................83 5 ECOSYSTEM ROLE OF BENTHIC MICROBIAL MATS IN CARBON FIXATION AND NITROGEN DYNAMICS ON OCEANIC MANGROVE ISLANDS .............................................................................................................124 6 CONCLUSIONS........................................................................................................149 v CHAPTER 1 INTRODUCTION Mangrove ecosystems dominate tropical coastlines, covering 18 million hectares worldwide (Spalding et al. 1997), and serve important economic and ecological functions acting as nurseries for commercially important aquatic organisms that contribute to coastal, estuarine and deep-sea fisheries (Ronnback 1999, Mumby et al. 2004), as habitat for resident and migratory birds, as nutrient and particulate filters from upland sources, and as protection from physical damage of shoreline due to tidal waves, erosion, hurricanes, and tsunamis (Mitch & Gosselink 1993). More than half of the world’s original mangrove habitats have been destroyed (Kelleher et al. 1995, Spalding et al. 1997), with about 70% of that loss occurring in the last 20 years (Valiela et al. 2001). Anthropogenic pressures leading to the destruction of mangrove habitat include over-harvesting for timber and fuel-wood (Hussein 1995), clearing for aquaculture and salt-pond construction (Terchunian et al. 1986, Primavera 1997), mining, and pollution and damming of rivers which alter salinity levels in the mangrove (Wolanski 1992). Mangrove habitats in terrestrial-riverine coasts and oceanic islands vary from 10.5 m tall (on average, Lugo 1990), dense, seaward fringe trees adjacent to the shore, to sparser ≤1.5 m tall “stunted” trees located away from the shoreline (Lugo & Snedaker 1974, Koltes et al. 1998, Feller et al. 2003). In this dissertation, these “stunted” mangrove habitats will be referred to as “dwarf” mangrove habitats for consistency with the published manuscript from this dissertation (Lee & Joye 2006, Ch. 4). The perception of dwarf mangrove habitats as unproductive “stunted” 1 or “scrub” forests (Pool et al. 1977) has been used to justify the devaluation and subsequent destruction of these habitats for shrimp aquaculture; this type of habitat accounts for 20-50% of mangrove destruction worldwide (Primavera 1997). Mangrove soils are typically nutrient-deficient (Alongi & Sasekumar 1992) despite being rich in organic matter, suggesting highly efficient recycling of nutrients which are regenerated by mangrove litter decomposition (Holguin et al. 2001). Mangroves must also adapt to the stresses of intertidal environments, including high salinity and reducing soil conditions (Kathiresan & Bingham 2001). Seasonal monsoonal rains affect porewater salinity, redox potential, pH, and soil biogeochemical processes (Alongi et al. 1999, Alongi et al. 2004). Numerous studies investigating benthic metabolism and nutrient transformations in fringe mangrove soils have demonstrated the relationship between organic matter availability and sulfate reduction with mangrove density and speciation (Nedwell et al. 1994, Sherman et al. 1998), however data from dwarf mangrove zones is lacking. In CHAPTER 2, I characterize the seasonal variability of porewater nutrients and metabolic end products in dwarf mangrove soils from Twin Cays, Belize (Fig. 1.1), to identify spatial and temporal patterns of benthic metabolism and nutrient dynamics. Studies of benthic productivity in mangroves are limited and typically demonstrate low photosynthetic biomass and activity. The primary producers in mangrove soils and sediments include eukaryotic microalgae and cyanobacteria. Light intensity is commonly described as the primary factor limiting benthic primary production due to mangrove canopy shading (Alongi 1988, Kristensen et al. 1988, Alongi & Sasekumar 1992, Alongi 1994), although a variety of other controls have also been proposed. Nutrients (both nitrogen and phosphorus) can significantly limit mangrove benthic primary production and microalgal growth (Kristensen et al. 1988, Alongi et al. 1993). Inhibition by physical factors other than low light may include high 2 temperatures, wide salinity variations, and surficial erosion by hydrological processes such as rainstorms
Load more

Recommended publications
  • A Study on the Phototrophic Microbial Mat Communities of Sulphur Mountain Thermal Springs and Their Association with the Endangered, Endemic Snail Physella Johnsoni
    A Study on the Phototrophic Microbial Mat Communities of Sulphur Mountain Thermal Springs and their Association with the Endangered, Endemic Snail Physella johnsoni By Michael Bilyj A thesis submitted to the Faculty of Graduate Studies in partial fulfillment of the requirements for the degree of Master of Science Department of Microbiology Faculty of Science University of Manitoba Winnipeg, Manitoba October 2011 © Copyright 2011, Michael A. Bilyj 1 Abstract The seasonal population fluctuation of anoxygenic phototrophs and the diversity of cyanobacteria at the Sulphur Mountain thermal springs of Banff, Canada were investigated and compared to the drastic population changes of the endangered snail Physella johnsoni. A new species and two strains of Rhodomicrobium were taxonomically characterized in addition to new species of Rhodobacter and Erythromicrobium. Major mat-forming organisms included Thiothrix-like species, oxygenic phototrophs of genera Spirulina, Oscillatoria, and Phormidium and purple nonsulfur bacteria Rhodobacter, Rhodopseudomonas and Rhodomicrobium. Aerobic anoxygenic phototrophs comprised upwards of 9.6 x 104 CFU/cm2 of mat or 18.9% of total aerobic heterotrophic bacterial isolates at certain sites, while maximal purple nonsulfur and purple sulfur bacteria were quantified at 3.2 x 105 and 2.0 x 106 CFU/cm2 of mat, respectively. Photosynthetic activity measurements revealed incredibly productive carbon fixation rates averaging 40.5 mg C/cm2/24 h. A temporal mismatch was observed for mat area and prokaryote-based organics to P. johnsoni population flux in a ―tracking inertia‖ manner. 2 Acknowledgements It is difficult to express sufficient gratitude to my supervisor Dr. Vladimir Yurkov for his unfaltering patience, generosity and motivation throughout this entire degree.
    [Show full text]
  • Thermophilic Lithotrophy and Phototrophy in an Intertidal, Iron-Rich, Geothermal Spring 2 3 Lewis M
    bioRxiv preprint doi: https://doi.org/10.1101/428698; this version posted September 27, 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 Thermophilic Lithotrophy and Phototrophy in an Intertidal, Iron-rich, Geothermal Spring 2 3 Lewis M. Ward1,2,3*, Airi Idei4, Mayuko Nakagawa2,5, Yuichiro Ueno2,5,6, Woodward W. 4 Fischer3, Shawn E. McGlynn2* 5 6 1. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 USA 7 2. Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8550, Japan 8 3. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 9 91125 USA 10 4. Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, 11 Japan 12 5. Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo, 13 152-8551, Japan 14 6. Department of Subsurface Geobiological Analysis and Research, Japan Agency for Marine-Earth 15 Science and Technology, Natsushima-cho, Yokosuka 237-0061, Japan 16 Correspondence: [email protected] or [email protected] 17 18 Abstract 19 Hydrothermal systems, including terrestrial hot springs, contain diverse and systematic 20 arrays of geochemical conditions that vary over short spatial scales due to progressive interaction 21 between the reducing hydrothermal fluids, the oxygenated atmosphere, and in some cases 22 seawater. At Jinata Onsen, on Shikinejima Island, Japan, an intertidal, anoxic, iron- and 23 hydrogen-rich hot spring mixes with the oxygenated atmosphere and sulfate-rich seawater over 24 short spatial scales, creating an enormous range of redox environments over a distance ~10 m.
    [Show full text]
  • Aerobic Respiration
    Life is based on redox • All energy generation in biological systems is due to redox (reduction-oxidation) reactions Aerobic Respiration: + - C6H12O6 + 6 H2O ==> 6 CO2 + 24 H +24 e oxidation electron donor (aka energy source) + - (O2+ 4H + 4e ==> 2H2O) x6 reduction electron acceptor --------------------------------------- C6H12O6 + 6 O2 ==> 6 CO2 + 6 H2O overall reaction (24 electrons) Types of bacterial metabolisms • While eukaryotes only reduce O2 and oxidize organic compounds, prokaryotes can use a variety of electron donors and acceptors, organic and inorganic. - • Aerobic respiration: e acceptor is O2 - • Anaerobic respiration: e acceptor is not O2 • Fermentation: e- donor and acceptor are organic molecules • Chemolithotrophy: e- donor and acceptor are inorganic molecules • Phototrophy: e- donor is light and e- acceptor is either organic or inorganic all microorganisms energy source? chemical light chemotroph phototroph carbon source? carbon source? organic organic CO CO compound 2 compound 2 chemoheterotroph chemoautotroph photoheterotroph photoautotroph e- acceptor? Nitrifying and sulfur- use H O to reduce CO ? oxidizing bacteria 2 2 green non-sulfur and O Other than O 2 2 purple non-sulfur bacteria anoxygenic oxygenic photosynthesis: photosynthesis: green sulfur and most bacteria Organic Inorganic cyanobacteria compound compound purple sulfur bacteria fermentative organism anaerobic respiration: nitrate, sulfate, Fe(III) Aerobic or anaerobic respiration Chemolithotrophy Important molecules Redox Electron Carrier: for example the
    [Show full text]
  • The Vulnerability of Microbial Ecosystems in a Changing Climate: Potential Impact in Shark Bay
    life Review The Vulnerability of Microbial Ecosystems in a Changing Climate: Potential Impact in Shark Bay Max Reinold 1,2, Hon Lun Wong 1,2, Fraser I. MacLeod 1,2, Julia Meltzer 1,2, April Thompson 1,2 and Brendan P. Burns 1,2,* 1 School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia 2 Australian Centre for Astrobiology, The University of New South Wales, Sydney 2052, Australia * Correspondence: [email protected]; Tel.: +612-9385-3659; Fax: +612-9385-1591 Received: 30 July 2019; Accepted: 28 August 2019; Published: 2 September 2019 Abstract: The potential impact of climate change on eukaryotes, including humans, has been relatively well described. In contrast, the contribution and susceptibility of microorganisms to a changing climate have, until recently, received relatively less attention. In this review, the importance of microorganisms in the climate change discourse is highlighted. Microorganisms are responsible for approximately half of all primary production on earth, support all forms of macroscopic life whether directly or indirectly, and often persist in “extreme” environments where most other life are excluded. In short, microorganisms are the life support system of the biosphere and therefore must be included in decision making regarding climate change. Any effects climate change will have on microorganisms will inevitably impact higher eukaryotes and the activity of microbial communities in turn can contribute to or alleviate the severity of the changing climate. It is of vital importance that unique, fragile, microbial ecosystems are a focus of research efforts so that their resilience to extreme weather events and climate change are thoroughly understood and that conservation efforts can be implemented as a response.
    [Show full text]
  • The Mysterious Microbial Mats
    Submarine Ring of Fire 2012: NE Lau Basin Expedition The Mysterious Microbial Mats Focus Ecological role of microbial mats in hydrothermal vent ecosystems Grade Level 5-6 (Life Science) Focus Question What is the role of microbial mats in hydrothermal vent ecosystems? Learning Objectives n Students will plan an investigation using a model ecosystem to explain some of the components of an anaerobic ecosystem. n Students will construct explanations for the potential role of microbial mats in hydrothermal vent ecosystems. Materials For each student group: q Directions for setting up Winogradsky columns from http:// quest.arc.nasa.gov/projects/astrobiology/fieldwork/lessons/ Winogradsky_5_8.pdf q Two 2-liter plastic soda bottles q Black mud from a local river, lake, or estuary, approximately 2.5 l q 2.5 l of water from each mud/sand location used q 1 small bucket q 250 ml graduated cylinder or 1 cup measure q 1 paint stirrer or large spoon q 1 sheet of newspaper q 1 tablespoon powdered chalk q One hard boiled egg yolk or one tablespoon calcium sulfate q 1 set measuring spoons q Aluminum foil or plastic wrap and rubber band q Masking tape and markers for labeling columns q (Optional) Pencil sharpener for crushing chalk q (Optional) Mortar and pestle for making egg yolk powder q (Optional) 1 lamp with 40- to 60-watt light bulb q (Optional) Microscopes and materials for making wet mounts Image captions/credits on Page 2. Audio-Visual Materials q (Optional) Interactive whiteboard 1 www.oceanexplorer.noaa.gov Submarine Ring of Fire 2012: NE Lau
    [Show full text]
  • Obecné Znaky Metabolismu + Bioenergetika
    Metabolism • General concept of metabolism + Bioenergetics • Cellular respiration (glykolysis + CKC + oxidative phosphorylation) • Sacharide metabolism + photosynthesis • Lipid metabolism • Metabolism of nitrous compounds Obecné znaky metabolismu + bioenergetika BUNĚČNÁ TEORIE Robert Hook (1667) "buňka" 1. Buňky tvoří veškerou živou hmotu (x viry). 2. Veškeré buňky pocházejí z jiných buněk (x samoplození). 3. Informace se předávají z generace na generaci. 4. V buňkách látky podléhají chemickým přeměnám. 5. Buňky reagují na vnější podněty. Otevřené systémy: tok látek, energie a informací dovnitř a ven dynamická rovnováha → ustálený stav Pravá rovnováha → smrt organismu Metabolic types (trofika, trofé = výživa): Energy source: light→ phototroph chemical reaction(redox) → chemotrophs Proton/electron donor acceptor Anorganic Organic Oxygen Other lithotrophs organotrophs aerobic anaerobic (líthos = stone) Fermentace: „disproporcionace“ Např.: C6H12O6 2 CH3-CH(OH)-COOH C6H12O6 2 CH3-CH2-OH + 2CO2 To be continued…….. Carbon source: anorganic → autotrophs organic → heterotrophs Common metabolic types METABOLISM Carbon source Proton source Proton example acceptor photolithotrophs CO2 H2O CO2 Green parts of (autotrophic) plant photolithotrophs Organic comp H2O (CO2) Some (heterotrophic) photosynthetic bacteria Photoorganotrophs Organic comp. Organic comp CO2 Some algae nad (heterotrophic) bacteria chemoorganotrophs Organic comp Organic comp O2 Animals, aerobic aerobic MO 2- Chemoorganotrophs Organic comp Organic comp SO4 Soil anaerobic - Anaerobic
    [Show full text]
  • “How to Make a Microbial Mat”
    Science Lesson Plan: How to Make a Microbial Mat Brad Bebout, Allison Pfeifer, Erich Fleming, Adrienne Frisbee, Jan Winter NASA Ames Research Center Background Microbes have shaped the atmosphere and climate of Earth over geologic time. Microbes may be important in the search for life both within our solar system and on extrasolar planets. Some of the earliest and most widespread evidence of life on Earth were in the form of microbial mats. Microbial mats are complex, usually layered collections of microorganisms that can be observed in a number of aquatic ecosystems. They are complete ecosystems in miniature. In this activity, students create living versions of the microbial mats that have existed on earth for 3.5 billion years. Living microbial mats constructed in plastic boxes. Main Concepts Photosynthetic microbial mats are complex ecosystems that generally exhibit vertical gradients in light, and chemical compounds. These gradients are established by photosynthesis at the top of the mat and control the functioning of the intact ecosystem. Scientific Question What factors contribute to the vertical structure of microbial mats in the field? Objectives 1. The students will create their own microbial mat. 2. The microbial mat will be available for later experimentation and/or observation. Abstract of Lesson Microbial mats are defined as layered communities of microorganisms that are only a few millimeters thick. Many biogeochemical processes are conducted by the organisms in the mat to sustain life. For example, the mats perform photosynthesis, and respiration, and can acquire nitrogen through the process of nitrogen fixation. The mat community is a fully functioning ecosystem containing both producers and consumers or organic carbon.
    [Show full text]
  • Microbial Lithification in Marine Stromatolites and Hypersaline Mats
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by RERO DOC Digital Library Published in Trends in Microbiology 13,9 : 429-438, 2005, 1 which should be used for any reference to this work Microbial lithification in marine stromatolites and hypersaline mats Christophe Dupraz1 and Pieter T. Visscher2 1Institut de Ge´ ologie, Universite´ de Neuchaˆ tel, Rue Emile-Argand 11, CP 2, CH-2007 Neuchaˆ tel, Switzerland 2Center for Integrative Geosciences, Department of Marine Sciences, University of Connecticut, 1080 Shennecossett Road, Groton, Connecticut, 06340, USA Lithification in microbial ecosystems occurs when pre- crucial role in regulating sedimentation and global bio- cipitation of minerals outweighs dissolution. Although geochemical cycles. the formation of various minerals can result from After the decline of stromatolites in the late Proterozoic microbial metabolism, carbonate precipitation is pos- (ca. 543 million years before present), microbially induced sibly the most important process that impacts global and/or controlled precipitation continued throughout the carbon cycling. Recent investigations have produced geological record as an active and essential player in most models for stromatolite formation in open marine aquatic ecosystems [9,10]. Although less abundant than in environments and lithification in shallow hypersaline the Precambrian, microbial precipitation is observed in a lakes, which could be highly relevant for interpreting the multitude of semi-confined (physically or chemically)
    [Show full text]
  • MIXOTROPHY in FRESHWATER FOOD WEBS a Dissertation
    MIXOTROPHY IN FRESHWATER FOOD WEBS A Dissertation Submitted to the Temple University Graduate Board In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY by Sarah B. DeVaul May 2016 Examining Committee Members: Robert W. Sanders, Advisory Chair, Biology Erik E. Cordes, Biology Amy Freestone, Biology Dale Holen, External Member, Penn State Worthington Scranton © Copyright 2016 by Sarah B. DeVaul All Rights Reserved ii ABSTRACT Environmental heterogeneity in both space and time has significant repercussions for community structure and ecosystem processes. Dimictic lakes provide examples of vertically structured ecosystems that oscillate between stable and mixed thermal layers on a seasonal basis. Vertical patterns in abiotic conditions vary during both states, but with differing degrees of variation. For example, during summer thermal stratification there is high spatial heterogeneity in temperature, nutrients, dissolved oxygen and photosynthetically active radiation. The breakdown of stratification and subsequent mixing of the water column in fall greatly reduces the stability of the water column to a vertical gradient in light. Nutrients and biomass that were otherwise constrained to the depths are also suspended, leading to a boom in productivity. Freshwater lakes are teeming with microbial diversity that responds to the dynamic environment in a seemingly predictable manner. Although such patterns have been well studied for nanoplanktonic phototrophic and heterotrophic populations, less work has been done to integrate the influence of mixotrophic nutrition to the protistan assemblage. Phagotrophy by phytoplankton increases the complexity of nutrient and energy flow due to their dual functioning as producers and consumers. The role of mixotrophs in freshwater planktonic communities also varies depending on the relative balance between taxon-specific utilization of carbon and energy sources that ranges widely between phototrophy and heterotrophy.
    [Show full text]
  • Evolution of Oxygenic Photosynthesis
    EA44CH24-Fischer ARI 17 May 2016 19:44 ANNUAL REVIEWS Further Click here to view this article's online features: • Download figures as PPT slides • Navigate linked references • Download citations Evolution of Oxygenic • Explore related articles • Search keywords Photosynthesis Woodward W. Fischer, James Hemp, and Jena E. Johnson Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125; email: wfi[email protected] Annu. Rev. Earth Planet. Sci. 2016. 44:647–83 Keywords First published online as a Review in Advance on Great Oxidation Event, photosystem II, chlorophyll, oxygen evolving May 11, 2016 complex, molecular evolution, Precambrian The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract This article’s doi: The origin of oxygenic photosynthesis was the most important metabolic 10.1146/annurev-earth-060313-054810 innovation in Earth history. It allowed life to generate energy and reducing Copyright c 2016 by Annual Reviews. power directly from sunlight and water, freeing it from the limited resources All rights reserved of geochemically derived reductants. This greatly increased global primary productivity and restructured ecosystems. The release of O2 as an end prod- Access provided by California Institute of Technology on 07/14/16. For personal use only. Annu. Rev. Earth Planet. Sci. 2016.44:647-683. Downloaded from www.annualreviews.org uct of water oxidation led to the rise of oxygen, which dramatically altered the redox state of Earth’s atmosphere and oceans and permanently changed all major biogeochemical cycles. Furthermore, the biological availability of O2 allowed for the evolution of aerobic respiration and novel biosynthetic pathways, facilitating much of the richness we associate with modern biology, including complex multicellularity.
    [Show full text]
  • Chapter 4: PROKARYOTIC DIVERSITY
    Chapter 4: PROKARYOTIC DIVERSITY 1. Prokaryote Habitats, Relationships & Biomes 2. Proteobacteria 3. Gram-negative and Phototropic Non-Proteobacteria 4. Gram-Positive Bacteria 5. Deeply Branching Bacteria 6. Archaea 1. Prokaryote Habitats, Relationships & Biomes Important Metabolic Terminology Oxygen tolerance/usage: aerobic – requires or can use oxygen (O2) anaerobic – does not require or cannot tolerate O2 Energy usage: phototroph – uses light as an energy source • all photosynthetic organisms chemotroph – acquires energy from organic or inorganic molecules • organotrophs – get energy from organic molecules • lithotrophs – get energy from inorganic molecules …more Important Terminology Carbon Source: autotroph – uses CO2 as a carbon source • e.g., photoautotrophs or chemoautotrophs heterotroph – requires an organic carbon source • e.g., chemoheterotroph – gets energy & carbon from organic molecules Oligotrophs require few nutrients, the opposite of eutrophs or copiotrophs Facultative vs Obligate (or Strict): facultative – “able to, but not requiring” • e.g., facultative anaerobes can survive w/ or w/o O2 obligate – “absolutely requires” • e.g., obligate anaerobes cannot survive in O2 Symbiotic Relationships Symbiotic relationships (close, direct interactions) between different organisms in nature are of several types: • e.g., humans have beneficial bacteria in their digestive tracts that also benefit from the food we eat (mutualism) Microbiomes All the microorganisms that inhabit a particular organism or environment (e.g., human or
    [Show full text]
  • 7.014 Lectures 16 &17: the Biosphere & Carbon and Energy Metabolism
    MIT Department of Biology 7.014 Introductory Biology, Spring 2005 7.014 Lectures 16 &17: The Biosphere & Carbon and Energy Metabolism Simplified Summary of Microbial Metabolism The metabolism of different types of organisms drives the biogeochemical cycles of the biosphere. Balanced oxidation and reduction reactions keep the system from “running down”. All living organisms can be ordered into two groups1, autotrophs and heterotrophs, according to what they use as their carbon source. Within these groups the metabolism of organisms can be further classified according to their source of energy and electrons. Autotrophs: Those organisms get their energy from light (photoautotrophs) or reduced inorganic compounds (chemoautotrophs), and their carbon from CO2 through one of the following processes: Photosynthesis (aerobic) — Light energy used to reduce CO2 to organic carbon using H2O as a source of electrons. O2 evolved from splitting H2O. (Plants, algae, cyanobacteria) Bacterial Photosynthesis (anaerobic) — Light energy used to reduce CO2 to organic carbon (same as photosynthesis). H2S is used as the electron donor instead of H2O. (e.g. purple sulfur bacteria) Chemosynthesis (aerobic) — Energy from the oxidation of inorganic molecules is used to reduce CO2 to organic carbon (bacteria only). -2 e.g. sulfur oxidizing bacteria H2S → S → SO4 + - • nitrifying bacteria NH4 → NO2 → NO3 iron oxidizing bacteria Fe+2 → Fe+3 methane oxidizing bacteria (methanotrophs) CH4 → CO2 Heterotrophs: These organisms get their energy and carbon from organic compounds (supplied by autotrophs through the food web) through one or more of the following processes: Aerobic Respiration (aerobic) ⎯ Oxidation of organic compounds to CO2 and H2O, yielding energy for biological work.
    [Show full text]