A Mechanistic Approach to Plankton Ecology

About this book

The three main missions of any organism - growing, reproducing, and surviving - depend on encounters with food and mates, and on avoiding encounters with predators. Through natural selection, the behavior and ecology of plankton organisms have evolved to optimize these tasks. This book offers a mechanistic approach to the study of ocean ecology by exploring biological interactions in plankton at the individual level. The book focuses on encounter mechanisms, since the pace of life in the ocean intimately relates to the rate at which encounters happen.

Thomas Kiorboe examines the life and interactions of plankton organisms with the larger aim of understanding marine pelagic food webs. He looks at plankton ecology and behavior in the context of the organisms' immediate physical and chemical habitats. He shows that the nutrient uptake, feeding rates, motility patterns, signal transmissions, and perception of plankton are all constrained by nonintuitive interactions between organism biology and small-scale physical and chemical characteristics of the three-dimensional fluid environment.

Most of the book's chapters consist of a theoretical introduction followed by examples of how the theory might be applied to real-world problems. In the final chapters, mechanistic insights of individual-level processes help to describe broader population dynamics and pelagic food web structure and function.

Contents

List of Illustrations ix List of Tables xiii Preface xv CHAPTER ONE: Introduction 1 1.1 Biological Oceanography--Marine Biology--Ocean Ecology 1 1.2 The Encounter Problem 4 1.3 This Book 8 CHAPTER TWO: Random Walk and Diffusion 10 2.1 Random Walk and Diffusion 10 2.2 Example: Bacterial Motility 14 2.3 Fick's First Law 17 2.4 Diffusion to or from a Sphere 18 2.5 Feeding on Solutes 20 2.6 Maximum and Optimum Cell Size 22 2.7 Diatoms: Large yet Small 24 2.8 Diffusion Feeding 26 2.9 Non- Steady- State Diffusion: Feeding in Nauplii 28 2.10 Bacteria Colonizing a Sphere 30 2.11 Effect of Shape 31 2.12 Flux from a Sphere (or a Point Source): Chemical Signals 32 CHAPTER THREE: Diffusion and Advection 35 3.1 Moving Fluids 35 3.2 Viscosity, Diffusivity, Re, and Pe 35 3.3 Flow around a Sinking Sphere 37 3.4 Mass Transport to a Sinking Sphere 39 3.5 Example: Oxygen Distribution around a Sinking Sphere 40 3.6 Examples: Osmotrophs, Diffusion Feeders, and Bacterial Colonization of Sinking Particles 43 3.7 Eff ect of Turbulence on Mass Transport: Re, Pe, and Sh for Turbulence 45 3.8 Marine Snow Solute Plumes: Small- Scale Heterogeneity 49 3.9 The Chemical Trail: Mate Finding in Copepods 50 CHAPTER FOUR: Particle Encounter by Advection 57 4.1 Direct Interception versus Remote Detection 57 4.2 Particle Encounter by Direct Interception: Flagellate Feeding 58 4.3 Bacteria Colonizing Particles Revisited: Comparison of Encounter Mechanisms 60 4.4 Direct Interception: Coagulation and Marine Snow Formation 60 4.5 Remote Prey Detection: Encountering Prey in Calm Water 67 4.6 Turbulence and Predator- Prey Encounter Rates 69 4.7 Example: Feeding of the Copepod Acartia tonsa in Turbulence 72 4.8 When Is Turbulence Important for Enhancing Predator-Prey Contact Rates? 74 4.9 On the Downhill Side: Negative Eff ects of Turbulence on Predator-Prey Interactions 75 4.10 Encounter Rates and Motility Patterns: Ballistic versus Diffusive Motility 77 CHAPTER FIVE: Hydromechanical Signals in the Plankton 83 5.1 Copepod Sensory Biology 83 5.2 Decomposition of a Fluid Signal: Deformation and Vorticity 85 5.3 Signal Strength: Prey Perceiving Predator 87 5.4 Signal Strength: Predator Perceiving Prey 88 5.5 To What Flow Components Does a Copepod Respond? 89 5.6 Sensitivity to Hydrodynamic Signals 91 5.7 Predator and Prey Reaction Distances: Generation of a Hydrodynamic Signal 91 5.8 Attack or Flee--the Dilemma of a Parasitic Copepod 95 5.9 Maximal Signals, Optimal Sensitivity, and the Role of Turbulence 96 5.10 The Evolutionary Arms Race 98 CHAPTER SIX: Zooplankton Feeding Rates and Bioenergetics 101 6.1 Functional Response in Ingestion Rate to Prey Concentration 101 6.2 Example: The Functional Response in Oithona davisae 104 6.3 Other Functional Responses 105 6.4 The Components of Predation: Prey Selection 107 6.5 Prey Switching 113 6.6 Bioenergetics: Conversion of Food to Growth and Reproduction 113 6.7 Specific Dynamic Action: Egg Production Effi ciency in a Copepod 115 6.8 Scaling of Feeding and Growth Rates 117 6.9 Feast and Famine in the Plankton 118 CHAPTER SEVEN: Population Dynamics and Interactions 122 7.1 From Individual to Population 122 7.2 The Dynamics of a Single Population: Phytoplankton Blooms 123 7.3 Phytoplankton Population Dynamics and Aggregate Formation 125 7.4 Phytoplankton Growth and Light Limitation 127 7.5 Scaling of Growth and Mortality Rates 128 7.6 Populations with Age Structure: Life Tables 130 7.7 Behavior and Population Dynamics: Critical Population Size and Allee Eff ects 133 7.8 Life- History Strategies 135 7.9 Interacting Populations 140 7.10 From Individual to Population 149 CHAPTER EIGHT: Structure and Function of Pelagic Food Webs 151 8.1 Two Pathways in Pelagic Food Webs 152 8.2 Light and Vertical Mixing: Conditions for Phytoplankton Development 154 8.3 Bud getary Constraints: Nutrient Input and Sinking Flux 155 8.4 Cell Size, Water-Column Structure, and Nutrient Availability: Empirical Evidence 158 8.5 Cell Size and Nutrient Uptake 161 8.6 Cell Size, Turbulence, and Sinking 162 8.7 Cell Size, Turbulence, and Light 164 8.8 Why Are Not All Phytoplankters Small? The Signifi cance of Predation 165 8.9 Hydrodynamic Control of Pelagic Food- Web Structure: Examples 166 8.10 Species Diversity: The Paradox of the Plankton 170 8.11 Fisheries and Trophic Effi ciency 173 8.12 Fertilizing the Ocean--Increasing the Fishery and Preventing Global Warming? 177 References 183 Index 205

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Biography

Thomas Kiorboe is professor of ocean ecology at the National Institute of Aquatic Resources, Technical University of Denmark.