Coral Bleaching (eBook)

Madeleine J.H. van OppenAustralian Institute of Marine Science, PMB 3, Townsville MC, Queensland 4810, Australia and School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australiae-mail: madeleine.van@unimelb.edu.auJ.M. LoughAustralian Institute of Marine Science, PMB 3, Townsville MC, Queensland 4810, Australia and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811, Australiae-mail: j.lough@aims.gov.au

Acknowledgements 6
Contents 7
Chapter 1: Introduction: Coral Bleaching-Patterns, Processes, Causes and Consequences 9
References 13
Chapter 2: The Evolution of the Coral-Algal Symbiosis and Coral Bleaching in the Geologic Past 17
2.1 Introduction 17
2.2 Detecting Photosymbiosis in the Fossil Record 19
2.3 Mesozoic Reef History and Coral Evolution 20
2.4 Late Triassic Dinoflagellate Symbionts? 24
2.5 Geological Perspectives on Photosymbiosis and Coral Bleaching 27
References 29
Chapter 3: Coral Bleaching in Space and Time 35
3.1 Introduction 35
3.1.1 Early Bleaching Records (Pre-1982) 36
3.1.2 Bleaching Records from 1982 Onwards 37
3.2 Global Patterns of Coral Bleaching 40
3.2.1 Temporal Patterns 40
3.2.1.1 Location Records 40
3.2.1.2 Identification of Global Bleaching Events 41
3.2.2 Spatial Patterns in Bleaching Reports 43
3.2.3 Trends in Bleaching Severity 43
3.3 Great Barrier Reef 45
3.3.1 Time Series 45
3.3.2 Spatial Patterns 46
3.4 Relationships Between Global Bleaching and El Niño Events 48
3.5 Discussion 49
References 54
Chapter 4: Climate Variability and Change: Monitoring Data and Evidence for Increased Coral Bleaching Stress 58
4.1 Introduction 58
4.2 Data for Understanding Heat Stress and Bleaching Patterns Worldwide 60
4.2.1 Century-Length Global SST Reconstructions from Instrumental and Paleoclimatic Data 60
4.2.2 Satellite Observations of SST and Heat Stress 61
4.2.2.1 SST Anomaly 63
4.2.2.2 HotSpot 64
4.2.2.3 Degree Heating Week 64
4.2.2.4 Bleaching Alert Area 65
4.2.2.5 Reprocessed and Heritage Satellite Observations of SST 65
4.2.2.6 Bleaching Prediction Using Climate Models 66
4.2.2.7 Bleaching Weather: The Doldrums Product 67
4.2.2.8 Additional Products 67
4.3 Tropical SST Trends Since the Nineteenth Century 69
4.3.1 Tropical SST and Global Temperature Trends 69
4.3.2 Regional Trends in Heat Stress 72
4.3.3 Role of El Niño-Southern Oscillation and Other Large-Scale Patterns 76
4.4 Local Environmental Variables 81
4.5 Summary 82
References 83
Chapter 5: Detecting and Monitoring Coral Bleaching Events 92
5.1 Introduction 92
5.2 Broad-Scale Approaches 94
5.2.1 Remote Sensing of Bleaching Events 94
5.2.2 Remote Sensing of Indicators of Bleaching Likelihood 99
5.2.3 Summary of Remote-Sensing Tools 101
5.3 Field-Based Observations 102
5.3.1 Describing Bleaching 103
5.3.2 Assessing Mortality 106
5.3.3 Broader Patterns Across the Reef 107
5.3.4 Summary of In Situ Field Protocols to Document Coral Bleaching 108
5.3.5 Colony Scale and Finer 108
5.3.6 Temporal Context 111
5.4 Summary 111
References 113
Chapter 6: Bleaching Resistance and the Role of Algal Endosymbionts 118
6.1 Introduction 118
6.2 Genetic Diversity of Symbiodinium 121
6.3 Biogeographic Patterns in Symbiodinium Diversity: In Hospite and Ex Situ 124
6.4 Physiological Differences Among Genetically Distinct Symbiodinium Types 128
6.5 Shifts in Symbiont Communities as a Mechanism to Cope with Environmental Change 135
6.6 Prediction of Changes in Symbiodinium Diversity and Distribution over the Next Several Decades 139
6.7 Conclusions, Overview of Recent Progress and New Questions 141
References 142
Chapter 7: How Does the Coral Microbiome Cause, Respond to, or Modulate the Bleaching Process? 159
7.1 Introduction 159
7.2 The Coral Holobiont 160
7.3 Holobiont Response to Thermal Stress and Bleaching 162
7.3.1 Diazotrophy and the Bleaching Response 169
7.3.2 Coral Mucus and the Mucus Microbiome in Response to Bleaching 172
7.4 Microbiome-Symbiodinium Interactions 174
7.5 Coral Bleaching in Relation to Coral Disease 175
7.5.1 Bleaching-Induced Disease 176
7.6 Bacteria-Induced Bleaching 177
7.7 Virus-Induced Bleaching 178
7.8 Conclusions and Future Directions 179
References 181
Chapter 8: Cell Biology of Coral Bleaching 195
8.1 Introduction 195
8.2 Thermal Response of the Algal Symbiont 196
8.2.1 Thermal Effects on Symbiodinium Photosynthesis 196
8.2.2 Thermal Effects on the Calvin-Benson Cycle 200
8.2.3 Nutrient Availability and Susceptibility to Bleaching 201
8.3 Thermal Response of the Coral Host 202
8.4 Mechanisms of Symbiont Loss 206
8.5 Future Directions 208
References 209
Chapter 9: Bleaching and Mortality Thresholds: How Much Is Too Much? 218
9.1 Introduction 218
9.2 Methods 220
9.2.1 Statistical Modelling 220
9.2.2 Bleaching Thresholds 221
9.2.3 Mortality Thresholds 222
9.3 Results 224
9.3.1 Is Temperature Appropriate for Modelling Bleaching Thresholds? 224
9.3.2 Bleaching Thresholds 224
9.3.3 Mortality Thresholds 228
9.4 Discussion 230
References 233
Chapter 10: Consequences of Coral Bleaching for Sessile Reef Organisms 236
10.1 Introduction 236
10.2 Taxa Affected by Bleaching 237
10.3 Spatial and Temporal Variation in Bleaching and Mortality 244
10.4 Patterns of Susceptibility to Bleaching Among Taxa 245
10.5 Effect of Bleaching on Individuals 246
10.5.1 Effect of Bleaching on Reproduction 246
10.5.2 Effect of Bleaching on Growth 249
10.5.3 Size-Specific Mortality Following Bleaching in Corals 249
10.5.4 Effect of Bleaching on Coral Settlement, Recruitment, and Recovery 250
10.5.5 Diseases 250
10.6 Population and Community Structure 252
10.7 Changes Over Time 254
10.8 Changes in Ecological Processes 254
10.9 Interactions with Fisheries Management 255
10.10 Conclusions 258
References 259
Chapter 11: Effects of Coral Bleaching and Coral Loss on the Structure and Function of Reef Fish Assemblages 269
11.1 Introduction 269
11.2 Coral Bleaching and Changes in the Structure of Reef Habitats 272
11.2.1 Bleaching Selectivity and Changes in Coral Composition 272
11.2.2 Coral Loss and Increasing Predominance of Alternative Habitat-Forming Taxa 274
11.2.3 Coral Loss Versus Declines in Topographic Complexity 275
11.3 Declines in Abundance of Reef Fishes and Loss of Biodiversity and Function 276
11.3.1 Interspecific Variation in Vulnerability to Coral Bleaching and Depletion 277
11.3.2 Loss of Biodiversity and Function 280
11.3.3 Effects of Coral Reef Degradation on Tropical Fisheries Production 282
11.4 Changes in the Behaviour and Fitness of Reef Fishes 284
11.4.1 Behavioural Changes 286
11.4.2 Effects of Coral Bleaching Versus Coral Loss on Individual Fitness of Fishes 288
11.5 Conclusions 289
References 290
Chapter 12: Ocean Acidification and Coral Bleaching 298
12.1 Introduction 298
12.1.1 Ocean Acidification 298
12.1.2 Variability in Seawater Carbonate Chemistry of Coral Reefs 299
12.1.3 Impacts of Ocean Acidification on Coral Reefs 300
12.2 Ocean Acidification and Coral Bleaching 302
12.2.1 Bleaching Mechanisms and Dissolved Inorganic Carbon 302
12.2.2 Evidence of Ocean Acidification-Induced Bleaching 309
12.2.3 Photoacclimation and Photoprotection 310
12.2.4 Phylotype-Specific Responses and Symbiont Shuffling 312
12.2.5 Photosynthesis-Respiration 312
12.3 Ocean Acidification and Coral Reef Resilience 313
12.3.1 Reproduction and Recruitment 313
12.3.2 Growth and Calcification 314
12.4 Other Environmental Factors (Nutrients) 315
12.5 Conclusions 316
References 317
Chapter 13: Future Scenarios: A Review of Modelling Efforts to Predict the Future of Coral Reefs in an Era of Climate Change 327
13.1 Introduction 327
13.2 Modelling Future Climates 328
13.3 Predicting Coral Bleaching from Climate Models 330
13.4 The Great Barrier Reef: A Case Study 335
13.5 Future Improvements in Physical Modelling 338
13.6 Conclusions 339
References 340
Chapter 14: Synthesis: Coral Bleaching: Patterns, Processes, Causes and Consequences 344
14.1 Climate Change Refuges and Assisted Evolution 345
14.2 Conclusion 347
References 347
Index 350