DOCSLIB.ORG

Turner-2015-Fecal-Pellet-Review.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Turner-2015-Fecal-Pellet-Review.Pdf Progress in Oceanography 130 (2015) 205–248 Contents lists available at ScienceDirect Progress in Oceanography journal homepage: www.elsevier.com/locate/pocean Review Zooplankton fecal pellets, marine snow, phytodetritus and the ocean’s biological pump ⇑ Jefferson T. Turner Biology Department, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA School for Marine Science and Technology, University of Massachusetts Dartmouth, 706 South Rodney French Boulevard, New Bedford, MA 02744, USA article info abstract Article history: The ‘‘biological pump’’ is the process by which photosynthetically-produced organic matter in the ocean Received 17 August 2013 descends from the surface layer to depth by a combination of sinking particles, advection or vertical mix- Received in revised form 7 August 2014 ing of dissolved organic matter, and transport by animals. Particulate organic matter that is exported Accepted 8 August 2014 downward from the euphotic zone is composed of combinations of fecal pellets from zooplankton and Available online 27 August 2014 fish, organic aggregates known as ‘‘marine snow’’ and phytodetritus from sinking phytoplankton. Previ- ous reviews by Turner and Ferrante (1979) and Turner (2002) focused on publications that appeared through late 2001. Since that time, studies of the biological pump have continued, and there have been >300 papers on vertical export flux using sediment traps, large-volume filtration systems and other tech- niques from throughout the global ocean. This review will focus primarily on recent studies that have appeared since 2001. Major topics covered in this review are (1) an overview of the biological pump, and its efficiency and variability, and the role of dissolved organic carbon in the biological pump; (2) zoo- plankton fecal pellets, including the contribution of zooplankton fecal pellets to export flux, epipelagic retention of zooplankton fecal pellets due to zooplankton activities, zooplankton vertical migration and fecal pellet repackaging, microbial ecology of fecal pellets, sinking velocities of fecal pellets and aggregates, ballasting of sinking particles by mineral contents, phytoplankton cysts, intact cells and harmful algae toxins in fecal pellets, importance of fecal pellets from various types of zooplankton, and the role of zooplankton fecal pellets in picoplankton export; (3) marine snow, including the origins, abundance, and distributions of marine snow, particles and organisms associated with marine snow, con- sumption and fragmentation of marine snow by animals, pathogens associated with marine snow; (4) phytodetritus, including pulsed export of phytodetritus, phytodetritus from Phaeocystis spp., picoplank- ton in phytodetritus, the summer export pulse (SEP) of phytodetritus in the subtropical North Pacific, benthic community responses to phytodetritus; (5) other components of the biological pump, including fish fecal pellets and fish-mediated export, sinking carcasses of animals and macrophytes, feces from marine mammals, transparent exopolymer particles (TEP); (6) the biological pump and climate, including origins of the biological pump, the biological pump and glacial/interglacial cycles, the biological pump and contemporary climate variations, and the biological pump and anthropogenic climate change. The review concludes with potential future modifications in the biological pump due to climate change. Ó 2014 Elsevier Ltd. All rights reserved. Contents Introduction. ...................................................................................................... 206 The ocean’s biological pump ......................................................................................... 206 Recent studies of the export flux of particulate organic carbon (POC) . ...................................................... 208 Dissolved organic carbon (DOC). ......................................................................... 212 Zooplankton fecal pellets . ................................................................................... 213 Contribution of zooplankton fecal pellets to export flux . ...................................................... 213 Epipelagic retention of zooplankton fecal pellets due to zooplankton activities . ................................... 213 ⇑ Addresses: Biology Department, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA, School for Marine Science and Technology, University of Massachusetts Dartmouth, 706 South Rodney French Boulevard, New Bedford, MA 02744, USA. E-mail address: [email protected] http://dx.doi.org/10.1016/j.pocean.2014.08.005 0079-6611/Ó 2014 Elsevier Ltd. All rights reserved. 206 J.T. Turner / Progress in Oceanography 130 (2015) 205–248 Zooplankton vertical migration and fecal pellet repackaging. ............................................................ 215 Microbial ecology of fecal pellets. ............................................................................ 217 Sinking velocity of fecal pellets and aggregates, and ballasting by mineral contents. ......................................... 218 Phytoplankton cysts, intact cells and harmful algae toxins in fecal pellets and sediment traps . ...................... 219 Importance of fecal pellets from various types of zooplankton . ............................................................ 219 Zooplankton fecal pellets and picoplankton export . ............................................................ 220 Marine snow . ......................................................................................................... 221 Origins, abundance, and distributions of marine snow . ............................................................ 221 Particles and organisms associated with marine snow. ............................................................ 221 Consumption and fragmentation of marine snow by animals . ............................................................ 221 Pathogens associated with marine snow. ............................................................................ 221 Phytodetritus . ......................................................................................................... 222 Pulsed export of phytodetritus. ............................................................................ 222 Aggregation and disaggregation of phytodetritus and other particles. ......................................... 222 Transparent exopolymer particles (TEP) . ............................................................................ 222 Phytodetritus from Phaeocystis spp. ............................................................................ 223 Picoplankton in phytodetritus . ............................................................................ 224 The summer export pulse (SEP) of phytodetritus in the subtropical north pacific. ......................................... 224 Benthic community responses to phytodetritus . ............................................................ 224 Other components of the biological pump . ...................................................................... 225 Fish fecal pellets and fish-mediated export. ............................................................................ 225 Sinking carcasses of animals and macrophytes. ............................................................ 225 Feces from marine mammals . ............................................................................ 226 The biological pump and climate. ......................................................................................... 226 Origins of the biological pump. ............................................................................ 226 The biological pump and glacial/interglacial cycles . ............................................................ 227 The biological pump and contemporary climate variations . ............................................................ 228 The biological pump and anthropogenic climate change . ............................................................ 229 Conclusions . ......................................................................................................... 232 Acknowledgements . ......................................................................................... 232 References . ......................................................................................................... 232 Introduction polar waters (Buesseler, 1998). Usually only <3% of net primary production reaches bathypelagic depths (>1000 m) in the deep The ocean’s biological pump sea (De La Rocha and Passow, 2007, and references therein). Such variability in export to depth is partly due to variability in the The ‘‘biological pump’’ is the process through which photosyn- planktonic food webs in overlying epipelagic waters (Legendre thetically-produced organic matter in the ocean is exported from and Rivkin, 2002). The >97% of net primary production that does the surface layer to depth by a combination of sinking particles, not reach the deep sea is consumed or respired in the water advection or vertical mixing of dissolved organic matter, and trans- column, with approximately 15% being processed by bacteria port by animals. (Ducklow, 2000), 30–70% by microzooplankton 20–200 lm in size Together with the ‘‘solubility pump’’ (Volk and Hoffert, 1985), (Calbet and Landry, 2004) and 20–35% by the >200 lm mesozoo- whereby the solubility of CO2 increases with depth due to
Load more

Recommended publications
  • Marine Ecology Progress Series 600:21
    Vol. 600: 21–39, 2018 MARINE ECOLOGY PROGRESS SERIES Published July 30 https://doi.org/10.3354/meps12663 Mar Ecol Prog Ser OPENPEN ACCESSCCESS Short-term processing of ice algal- and phytoplankton- derived carbon by Arctic benthic communities revealed through isotope labelling experiments Anni Mäkelä1,*, Ursula Witte1, Philippe Archambault2 1School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU, UK 2Département de biologie, Québec Océan, Université Laval, Québec, QC G1V 0A6, Canada ABSTRACT: Benthic ecosystems play a significant role in the carbon (C) cycle through remineral- ization of organic matter reaching the seafloor. Ice algae and phytoplankton are major C sources for Arctic benthic consumers, but climate change-mediated loss of summer sea ice is predicted to change Arctic marine primary production by increasing phytoplankton and reducing ice algal contributions. To investigate the impact of changing algal C sources on benthic C processing, 2 isotope tracing experiments on 13C-labelled ice algae and phytoplankton were conducted in the North Water Polynya (NOW; 709 m depth) and Lancaster Sound (LS; 794 m) in the Canadian Arc- tic, during which the fate of ice algal (CIA) and phytoplankton (CPP) C added to sediment cores was traced over 4 d. No difference in sediment community oxygen consumption (SCOC, indicative of total C turnover) between the background measurements and ice algal or phytoplankton cores was found at either site. Most of the processed algal C was respired, with significantly more CPP than CIA being released as dissolved inorganic C at both sites. Macroinfaunal uptake of algal C was minor, but bacterial assimilation accounted for 33−44% of total algal C processing, with no differences in bacterial uptake of CPP and CIA found at either site.
    [Show full text]
  • Methane Cold Seeps As Biological Oases in the High‐
    LIMNOLOGY and Limnol. Oceanogr. 00, 2017, 00–00 VC 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. OCEANOGRAPHY on behalf of Association for the Sciences of Limnology and Oceanography doi: 10.1002/lno.10732 Methane cold seeps as biological oases in the high-Arctic deep sea Emmelie K. L. A˚ strom€ ,1* Michael L. Carroll,1,2 William G. Ambrose, Jr.,1,2,3,4 Arunima Sen,1 Anna Silyakova,1 JoLynn Carroll1,2 1CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT The Arctic University of Norway, Tromsø, Norway 2Akvaplan-niva, FRAM – High North Research Centre for Climate and the Environment, Tromsø, Norway 3Division of Polar Programs, National Science Foundation, Arlington, Virginia 4Department of Biology, Bates College, Lewiston, Maine Abstract Cold seeps can support unique faunal communities via chemosynthetic interactions fueled by seabed emissions of hydrocarbons. Additionally, cold seeps can enhance habitat complexity at the deep seafloor through the accretion of methane derived authigenic carbonates (MDAC). We examined infaunal and mega- faunal community structure at high-Arctic cold seeps through analyses of benthic samples and seafloor pho- tographs from pockmarks exhibiting highly elevated methane concentrations in sediments and the water column at Vestnesa Ridge (VR), Svalbard (798 N). Infaunal biomass and abundance were five times higher, species richness was 2.5 times higher and diversity was 1.5 times higher at methane-rich Vestnesa compared to a nearby control region. Seabed photos reveal different faunal associations inside, at the edge, and outside Vestnesa pockmarks. Brittle stars were the most common megafauna occurring on the soft bottom plains out- side pockmarks.
    [Show full text]
  • Carbon Dynamics of Subtropical Wetland Communities in South Florida DISSERTATION Presented in Partial Fulfillment of the Require
    Carbon Dynamics of Subtropical Wetland Communities in South Florida DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Jorge Andres Villa Betancur Graduate Program in Environmental Science The Ohio State University 2014 Dissertation Committee: William J. Mitsch, Co-advisor Gil Bohrer, Co-advisor James Bauer Jay Martin Copyrighted by Jorge Andres Villa Betancur 2014 Abstract Emission and uptake of greenhouse gases and the production and transport of dissolved organic matter in different wetland plant communities are key wetland functions determining two important ecosystem services, climate regulation and nutrient cycling. The objective of this dissertation was to study the variation of methane emissions, carbon sequestration and exports of dissolved organic carbon in wetland plant communities of a subtropical climate in south Florida. The plant communities selected for the study of methane emissions and carbon sequestration were located in a natural wetland landscape and corresponded to a gradient of inundation duration. Going from the wettest to the driest conditions, the communities were designated as: deep slough, bald cypress, wet prairie, pond cypress and hydric pine flatwood. In the first methane emissions study, non-steady-state rigid chambers were deployed at each community sequentially at three different times of the day during a 24- month period. Methane fluxes from the different communities did not show a discernible daily pattern, in contrast to a marked increase in seasonal emissions during inundation. All communities acted at times as temporary sinks for methane, but overall were net -2 -1 sources. Median and mean + standard error fluxes in g CH4-C.m .d were higher in the deep slough (11 and 56.2 + 22.1), followed by the wet prairie (9.01 and 53.3 + 26.6), bald cypress (3.31 and 5.54 + 2.51) and pond cypress (1.49, 4.55 + 3.35) communities.
    [Show full text]
  • Net Ecosystem Production: a Comprehensive Measure of Net Carbon Accumulation by Ecosystems
    Ecological Applications, 12(4), 2002, pp. 937±947 q 2002 by the Ecological Society of America NET ECOSYSTEM PRODUCTION: A COMPREHENSIVE MEASURE OF NET CARBON ACCUMULATION BY ECOSYSTEMS J. T. RANDERSON,1,6 F. S . C HAPIN, III,2 J. W. HARDEN,3 J. C. NEFF,4 AND M. E. HARMON5 1Divisions of Engineering and Applied Science and Geological and Planetary Sciences, California Institute of Technology, Mail Stop 100-23, Pasadena, California 91125 USA 2Institute for Arctic Biology, 311 Irvine 1 Building, University of Alaska, Fairbanks, Fairbanks, Alaska, 99775 USA 3U.S. Geological Survey, Mail Stop 962, 345 Middle®eld Road, Menlo Park, California 94025 USA 4U.S. Geological Survey, Mail Stop 980, Denver Federal Center, Denver, Colorado 80225 USA 5Department of Forest Science, Oregon State University, Corvallis, Oregon 97331-57521 USA Abstract. The conceptual framework used by ecologists and biogeochemists must allow for accurate and clearly de®ned comparisons of carbon ¯uxes made with disparate tech- niques across a spectrum of temporal and spatial scales. Consistent with usage over the past four decades, we de®ne ``net ecosystem production'' (NEP) as the net carbon accu- mulation by ecosystems. Past use of this term has been ambiguous, because it has been used conceptually as a measure of carbon accumulation by ecosystems, but it has often been calculated considering only the balance between gross primary production (GPP) and ecosystem respiration. This calculation ignores other carbon ¯uxes from ecosystems (e.g., leaching of dissolved carbon and losses associated with disturbance). To avoid conceptual ambiguities, we argue that NEP be de®ned, as in the past, as the net carbon accumulation by ecosystems and that it explicitly incorporate all the carbon ¯uxes from an ecosystem, including autotrophic respiration, heterotrophic respiration, losses associated with distur- bance, dissolved and particulate carbon losses, volatile organic compound emissions, and lateral transfers among ecosystems.
    [Show full text]
  • Toxicity Equivalence Factors for Marine Biotoxins Associated with Bivalve Molluscs TECHNICAL PAPER
    JOINT FAO/WHO Toxicity Equivalency Factors for Marine Biotoxins Associated with Bivalve Molluscs TECHNICAL PAPER Cover photograph: © FAOemergencies JOINT FAO/WHO Toxicity equivalence factors for marine biotoxins associated with bivalve molluscs TECHNICAL PAPER FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS WORLD HEALTH ORGANIZATION ROME, 2016 Recommended citation: FAO/WHO. 2016. Technical paper on Toxicity Equivalency Factors for Marine Biotoxins Associated with Bivalve Molluscs. Rome. 108 pp. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) or of the World Health Organization (WHO) concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or products of manufacturers, whether or not these have been patented, does not imply that these are or have been endorsed or recommended by FAO or WHO in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. All reasonable precautions have been taken by FAO and WHO to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall FAO and WHO be liable for damages arising from its use.
    [Show full text]
  • CO2-Fixing One-Carbon Metabolism in a Cellulose-Degrading Bacterium
    CO2-fixing one-carbon metabolism in a cellulose- degrading bacterium Clostridium thermocellum Wei Xionga, Paul P. Linb, Lauren Magnussona, Lisa Warnerc, James C. Liaob,d, Pin-Ching Manessa,1, and Katherine J. Choua,1 aBiosciences Center, National Renewable Energy Laboratory, Golden, CO 80401; bDepartment of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095; cNational Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401; and dAcademia Sinica, Taipei City, Taiwan 115 Edited by Lonnie O. Ingram, University of Florida, Gainesville, FL, and approved September 23, 2016 (received for review April 6, 2016) Clostridium thermocellum can ferment cellulosic biomass to for- proposed pathway involving CO2 utilization in C. thermocellum is mate and other end products, including CO2. This organism lacks the malate shunt and its variant pathway (7, 14), in which CO2 is formate dehydrogenase (Fdh), which catalyzes the reduction of first incorporated by phosphoenolpyruvate carboxykinase (PEPCK) 13 CO2 to formate. However, feeding the bacterium C-bicarbonate to form oxaloacetate and then is released either by malic enzyme or and cellobiose followed by NMR analysis showed the production via oxaloacetate decarboxylase complex, yielding pyruvate. How- of 13C-formate in C. thermocellum culture, indicating the presence ever, other pathways capable of carbon fixation may also exist but of an uncharacterized pathway capable of converting CO2 to for- remain uncharacterized. mate. Combining genomic and experimental data, we demon- In recent years, isotopic tracer experiments followed by mass strated that the conversion of CO2 to formate serves as a CO2 spectrometry (MS) (15, 16) or NMR measurements (17) have entry point into the reductive one-carbon (C1) metabolism, and emerged as powerful tools for metabolic analysis.
    [Show full text]
  • Phytoplankton As Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate
    sustainability Review Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate Samarpita Basu * ID and Katherine R. M. Mackey Earth System Science, University of California Irvine, Irvine, CA 92697, USA; [email protected] * Correspondence: [email protected] Received: 7 January 2018; Accepted: 12 March 2018; Published: 19 March 2018 Abstract: The world’s oceans are a major sink for atmospheric carbon dioxide (CO2). The biological carbon pump plays a vital role in the net transfer of CO2 from the atmosphere to the oceans and then to the sediments, subsequently maintaining atmospheric CO2 at significantly lower levels than would be the case if it did not exist. The efficiency of the biological pump is a function of phytoplankton physiology and community structure, which are in turn governed by the physical and chemical conditions of the ocean. However, only a few studies have focused on the importance of phytoplankton community structure to the biological pump. Because global change is expected to influence carbon and nutrient availability, temperature and light (via stratification), an improved understanding of how phytoplankton community size structure will respond in the future is required to gain insight into the biological pump and the ability of the ocean to act as a long-term sink for atmospheric CO2. This review article aims to explore the potential impacts of predicted changes in global temperature and the carbonate system on phytoplankton cell size, species and elemental composition, so as to shed light on the ability of the biological pump to sequester carbon in the future ocean.
    [Show full text]
  • From Nano-Gels to Marine Snow: a Synthesis of Gel Formation Processes and Modeling Efforts Involved with Particle Flux in the Ocean
    gels Review From Nano-Gels to Marine Snow: A Synthesis of Gel Formation Processes and Modeling Efforts Involved with Particle Flux in the Ocean Antonietta Quigg 1,* , Peter H. Santschi 2 , Adrian Burd 3, Wei-Chun Chin 4 , Manoj Kamalanathan 1, Chen Xu 2 and Kai Ziervogel 5 1 Department of Marine Biology, Texas A&M University at Galveston, Galveston, TX 77553, USA; [email protected] 2 Department of Marine and Coastal Environmental Science, Texas A&M University at Galveston, Galveston, TX 77553, USA; [email protected] (P.H.S.); [email protected] (C.X.) 3 Department of Marine Science, University of Georgia, Athens, GA 30602, USA; [email protected] 4 Department of Bioengineering, University of California, Merced, CA 95343, USA; [email protected] 5 Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824, USA; [email protected] * Correspondence: [email protected] Abstract: Marine gels (nano-, micro-, macro-) and marine snow play important roles in regulating global and basin-scale ocean biogeochemical cycling. Exopolymeric substances (EPS) including transparent exopolymer particles (TEP) that form from nano-gel precursors are abundant materials in the ocean, accounting for an estimated 700 Gt of carbon in seawater. This supports local microbial communities that play a critical role in the cycling of carbon and other macro- and micro-elements in Citation: Quigg, A.; Santschi, P.H.; the ocean. Recent studies have furthered our understanding of the formation and properties of these Burd, A.; Chin, W.-C.; Kamalanathan, materials, but the relationship between the microbial polymers released into the ocean and marine M.; Xu, C.; Ziervogel, K.
    [Show full text]
  • B.-Gioli -Co2-Fluxes-In-Florance.Pdf
    Environmental Pollution 164 (2012) 125e131 Contents lists available at SciVerse ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol Methane and carbon dioxide fluxes and source partitioning in urban areas: The case study of Florence, Italy B. Gioli a,*, P. Toscano a, E. Lugato a, A. Matese a, F. Miglietta a,b, A. Zaldei a, F.P. Vaccari a a Institute of Biometeorology (IBIMET e CNR), Via G.Caproni 8, 50145 Firenze, Italy b FoxLab, Edmund Mach Foundation, Via E. Mach 1, San Michele all’Adige, Trento, Italy article info abstract Article history: Long-term fluxes of CO2, and combined short-term fluxes of CH4 and CO2 were measured with the eddy Received 15 September 2011 covariance technique in the city centre of Florence. CO2 long-term weekly fluxes exhibit a high Received in revised form seasonality, ranging from 39 to 172% of the mean annual value in summer and winter respectively, while 12 January 2012 CH fluxes are relevant and don’t exhibit temporal variability. Contribution of road traffic and domestic Accepted 14 January 2012 4 heating has been estimated through multi-regression models combined with inventorial traffic and CH4 consumption data, revealing that heating accounts for more than 80% of observed CO2 fluxes. Those two Keywords: components are instead responsible for only 14% of observed CH4 fluxes, while the major residual part is Eddy covariance fl Methane fluxes likely dominated by gas network leakages. CH4 uxes expressed as CO2 equivalent represent about 8% of Gas network leakages CO2 emissions, ranging from 16% in summer to 4% in winter, and cannot therefore be neglected when assessing greenhouse impact of cities.
    [Show full text]
  • Paleoceanographical Proxies Based on Deep-Sea Benthic Foraminiferal Assemblage Characteristics
    CHAPTER SEVEN Paleoceanographical Proxies Based on Deep-Sea Benthic Foraminiferal Assemblage Characteristics Frans J. JorissenÃ, Christophe Fontanier and Ellen Thomas Contents 1. Introduction 263 1.1. General introduction 263 1.2. Historical overview of the use of benthic foraminiferal assemblages 266 1.3. Recent advances in benthic foraminiferal ecology 267 2. Benthic Foraminiferal Proxies: A State of the Art 271 2.1. Overview of proxy methods based on benthic foraminiferal assemblage data 271 2.2. Proxies of bottom water oxygenation 273 2.3. Paleoproductivity proxies 285 2.4. The water mass concept 301 2.5. Benthic foraminiferal faunas as indicators of current velocity 304 3. Conclusions 306 Acknowledgements 308 4. Appendix 1 308 References 313 1. Introduction 1.1. General Introduction The most popular proxies based on microfossil assemblage data produce a quanti- tative estimate of a physico-chemical target parameter, usually by applying a transfer function, calibrated on the basis of a large dataset of recent or core-top samples. Examples are planktonic foraminiferal estimates of sea surface temperature (Imbrie & Kipp, 1971) and reconstructions of sea ice coverage based on radiolarian (Lozano & Hays, 1976) or diatom assemblages (Crosta, Pichon, & Burckle, 1998). These à Corresponding author. Developments in Marine Geology, Volume 1 r 2007 Elsevier B.V. ISSN 1572-5480, DOI 10.1016/S1572-5480(07)01012-3 All rights reserved. 263 264 Frans J. Jorissen et al. methods are easy to use, apply empirical relationships that do not require a precise knowledge of the ecology of the organisms, and produce quantitative estimates that can be directly applied to reconstruct paleo-environments, and to test and tune global climate models.
    [Show full text]
  • Soares, R. Et Al
    Original Article DOI: 10.7860/JCDR/2017/23594.9758 Assessment of Enamel Remineralisation After Treatment with Four Different Dentistry Section Remineralising Agents: A Scanning Electron Microscopy (SEM) Study RENITA SOARES1, IDA DE NORONHA DE ATAIDE2, MARINA FERNANDES3, RAJAN LAMBOR4 ABSTRACT these groups were remineralised using the four remineralising Introduction: Decades of research has helped to increase our agents. The treated groups were subjected to pH cycling over a knowledge of dental caries and reduce its prevalence. However, period of 30 days. This was followed by assessment of surface according to World Oral Health report, dental caries still remains microhardness and SEM for qualitative evaluation of surface a major dental disease. Fluoride therapy has been utilised in changes. The results were analysed by One-Way Analysis Of a big way to halt caries progression, but has been met with Variance (ANOVA). Multiple comparisons between groups were limitations. This has paved the way for the development of performed by paired t-test and post-hoc Tukey test. newer preventive agents that can function as an adjunct to Results: The results of the study revealed that remineralisation of fluoride or independent of it. enamel was the highest in samples of Group E (Self assembling Aim: The purpose of the present study was to evaluate the ability peptide P11-4) followed by Group B (CPP-ACPF), Group C (BAG) of Casein Phosphopeptide-Amorphous Calcium Phosphate and Group D (fluoride enhanced HA gel). There was a significant Fluoride (CPP ACPF), Bioactive Glass (BAG), fluoride enhanced difference (p<0.05) in the remineralising ability between the self assembling peptide P -4 group and BAG and fluoride Hydroxyapatite (HA) gel and self-assembling peptide P11-4 to 11 remineralise artificial carious lesions in enamel in vitro using enhanced HA gel group.
    [Show full text]
  • Biomineralization and Global Biogeochemical Cycles Philippe Van Cappellen Faculty of Geosciences, Utrecht University P.O
    1122 Biomineralization and Global Biogeochemical Cycles Philippe Van Cappellen Faculty of Geosciences, Utrecht University P.O. Box 80021 3508 TA Utrecht, The Netherlands INTRODUCTION Biological activity is a dominant force shaping the chemical structure and evolution of the earth surface environment. The presence of an oxygenated atmosphere- hydrosphere surrounding an otherwise highly reducing solid earth is the most striking consequence of the rise of life on earth. Biological evolution and the functioning of ecosystems, in turn, are to a large degree conditioned by geophysical and geological processes. Understanding the interactions between organisms and their abiotic environment, and the resulting coupled evolution of the biosphere and geosphere is a central theme of research in biogeology. Biogeochemists contribute to this understanding by studying the transformations and transport of chemical substrates and products of biological activity in the environment. Biogeochemical cycles provide a general framework in which geochemists organize their knowledge and interpret their data. The cycle of a given element or substance maps out the rates of transformation in, and transport fluxes between, adjoining environmental reservoirs. The temporal and spatial scales of interest dictate the selection of reservoirs and processes included in the cycle. Typically, the need for a detailed representation of biological process rates and ecosystem structure decreases as the spatial and temporal time scales considered increase. Much progress has been made in the development of global-scale models of biogeochemical cycles. Although these models are based on fairly simple representations of the biosphere and hydrosphere, they account for the large-scale changes in the composition, redox state and biological productivity of the earth surface environment that have occurred over geological time.
    [Show full text]