Stable Isotope Ecology

Abstract

About this textbook Stable isotopes are frequently used as tracers in biological systems, and their ability to track changes and processes over time has made them increasingly important to ecological research. For ecologists, stable isotopes provide a natural way to directly trace details of element cycling in the environment.Stable Isotope Ecology provides a solid introduction to this advanced subject, and can also be used as an instructive review for more experienced researchers and professionals. The book approaches the use of isotopes from the perspective of ecological and biological research, but its concepts can be applied within other disciplines as well. In order to enable scientists to establish source-sink connections in ecological settings, Stable Isotope Ecology begins by reviewing fundamental topics of tracer fractionation and mixing. Several mini-reviews profile problems and successes encountered with isotope tracing in particular focus areas, while emphasizing the role that humans increasingly play in changing our planetary ecosphere. A novel, step-by-step spreadsheet modeling approach is also presented for circulating tracers in any ecological system, including any favorite system an ecologist might dream up while sitting at a computer. Just type in values and watch the isotope action unfold in the dynamic models.Fry's humorous and lighthearted style painlessly imparts the principles of isotope ecology, using a unique, hands-on approach to engage students. The mechanics of fractionation and mixing are laid out in simple steps, with numerous examples and accessible mathematics (algebra only). The book encourages students to begin their own pilot project with stable isotopes.The attached CD-ROM contains color illustrations, spreadsheet models, technical appendices, and problems and answers. The CD materials are accessible for novices and experts alike, and enhance the learning experience, adding electronic dynamics to the printed book. About the Author: Dr. Brian Fry is a Professor in the Coastal Ecology Institute and the Department of Oceanography and Coastal Studies at Louisiana State University in Baton Rouge, Louisiana. His mother and father both used isotopes in their research careers, so he is a second generation isotope scientist.Written for: Environmental scientists, graduate students, upper-level undergraduates, researchers, practicing ecologistsKeywords: Fryaquatic ecologybiogeochemistryfractionationgeologyisotopemixingstable isotopetracersContentsAcknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viiChapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 General Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3 Just for Fun---An Isotope Biography of Mr. Polychaete . . . . . . 16Chapter 2. Isotope Notation and Measurement . . . . . . . . . . . . . . . 21Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.1 The Necessary Minimum for Ecologists . . . . . . . . . . . . . . . . . . 222.2 Why Use the δ Notation? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312.3 Why Is δ a Good Substitute for % Heavy Isotope? . . . . . . . . . 342.4 δ and the Ratio-of-Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352.5 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Chapter 3. Using Stable Isotope Tracers . . . . . . . . . . . . . . . . . . . . . 40Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.1 Isotope Circulation in the Biosphere . . . . . . . . . . . . . . . . . . . . . 413.2 Landscape Ecology and Isotope Maps . . . . . . . . . . . . . . . . . . . 503.3 Community Ecology and Invasive Species in Food Webs . . . . . 543.4 Life History Ecology and Animal Migrations . . . . . . . . . . . . . . 593.5 Plants, Microbes, and Scaling Up . . . . . . . . . . . . . . . . . . . . . . . . 623.6 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Chapter 4. Isotope Chi (``I Chi'') . . . . . . . . . . . . . . . . . . . . . . . . . . 76Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 764.1 Chocolate Isotopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 774.2 Oxygen in the Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814.3 Equations for Isotope Chi (``I Chi'') . . . . . . . . . . . . . . . . . . . . . 87ixx Contents4.4 Building an I Chi Gain--Loss Model, Step by Step . . . . . . . . . . 914.5 Errors in I Chi Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 984.6 Exact Equations for I Chi Models . . . . . . . . . . . . . . . . . . . . . . . 1014.7 Cows in a Pasture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1064.8 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Chapter 5. Mixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1195.1 Isotope Mixing in Food Webs . . . . . . . . . . . . . . . . . . . . . . . . . 1205.2 Isotope Sourcery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1345.3 Mixing Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1395.4 Advanced Mixing Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . 1425.5 Mixing Assumptions and Errors or the Art and Wisdom ofUsing Isotope Mixing Models . . . . . . . . . . . . . . . . . . . . . . . . . 1495.6 River Sulfate and Mass-Weighted Mixing . . . . . . . . . . . . . . . . 1595.7 A Special Muddy Case and Mixing Through Time . . . . . . . . . 1645.8 The Qualquan Chronicles and Mixing AcrossLandscapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1675.9 Dietary Mixing, Turnover, and a Stable Isotope Clock . . . . . . 1735.10 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176Chapter 6. Isotope Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1836.1 Addition Addiction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1846.2 The Golden Spike Award for Isotopes . . . . . . . . . . . . . . . . . . . 1876.3 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190Chapter 7. Fractionation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1947.1 Fractionation Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 1967.2 Isotopium and Fractionation in Closed Systems . . . . . . . . . . . 2147.3 A Strange and Routine Case . . . . . . . . . . . . . . . . . . . . . . . . . . 2227.4 A Genuine Puzzle---Fractionation or Mixing? . . . . . . . . . . . . 2267.5 Cracking the Closed Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 2297.6 Equilibrium Fractionation, Subtle Drama in the Cold . . . . . . . 2337.7 A Supply/Demand Model for Open SystemFractionation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2427.8 Open System Fractionation and Evolution of theEarth's Sulfur Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2547.9 Open System Legacies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2647.10 Conducting Fractionation Experiments . . . . . . . . . . . . . . . . . . 2677.11 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270Chapter 8. Scanning the Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2778.1 The Isotope Scanner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2778.2 Mangrove Maude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2788.3 The Beginner's Advantage---Imagine! . . . . . . . . . . . . . . . . . . . . 2828.4 Chapter Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Appendix. Important Isotope Equations and UsefulConversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297Supplemental Electronic Materials on the Accompanying CDA. Chapter 1Color Figures and CartoonProblemsB. Chapter 2Color Figures and CartoonProblemsTechnical Supplement 2A: Measuring Spiked SamplesTechnical Supplement 2B: Ion CorrectionsTechnical Supplement 2C: The Ratio Notation and The Power of 1C. Chapter 3Color Figures and CartoonsProblemsD. Chapter 4Color Figures and CartoonsProblemsI Chi SpreadsheetsE. Chapters 5Color Figures and CartoonsProblemsI Chi SpreadsheetsF. Chapter 6Color Figure and CartoonProblemsI Chi SpreadsheetTechnical Supplement 6A: How Much Isotope Should I Add?Technical Supplement 6B: Noisy Data and Data Analysis withEnriched SamplesContents xiG. Chapter 7Color Figures and CartoonsProblemsI Chi SpreadsheetsTechnical Supplement 7A: A Chemist's View of Isotope EffectsTechnical Supplement 7B: Derivations of Closed System IsotopeEquationsH. Chapter 8Color Figures and CartoonsProblemsI. All Problems for Chapters 1--8J. All Answers to Problems for Chapters 1--8K. All Figures and CartoonsL. All I Chi SpreadsheetsM. A Reading List