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Biogeochemistry of Marine Systems

De
384 pages
Marine systems vary in their sensitivities to perturbation. Perturbation may be insidious – such as increasing eutrophication of coastal areas – or it may be dramatic – such as a response to an oil spillage or some other accident. Climate change may occur incrementally or it may be abrupt, and ecosystem resilience is likely to be a complex function of the interactions of those assemblages or species mediating key biogeochemical processes.

Biogeochemistry of Marine Systems considers issues of marine system resilience, focusing on a range of marine systems that exemplify major global province types but are also interesting and topical in their own right, on account of their sensitivity to natural or anthropogenic change or their importance as ecological service providers. Authors concentrate on advances of the last decade.

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Contents
Preface Contributors
1
2
Mangroves of Southeast Asia M. HOLMER
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
Introduction Mangrove forest structure and function Water column biogeochemistry Organic matter sources in mangrove forests 1.4.1 Decomposition of detritus Sediment biogeochemistry 1.5.1 Total microbial activity in mangrove sediments 1.5.2 Mineralization pathways in mangrove sediments 1.5.3 Phosphorus cycling Factors influencing the biogeochemistry 1.6.1 Effect of forest type and age 1.6.2 Influence of macrofauna 1.6.3 Effect of seasonal variations on mangrove forest biogeochemistry Sediment biogeochemistry and implications for mangrove vegetation Biogeochemistry in mangroves affected by anthropogenic activities References
Coral reefs M.J. ATKINSON and J.L. FALTER
2.1 2.2 2.3
Introduction Coral reef morphology and zonation Basic biogeochemistry 2.3.1 Carbon 2.3.2 Dissolved organic matter 2.3.3 Nitrogen 2.3.4 Phosphorus
xii xv
1
1 2 3 7 9 11 12 15 23 25 25 26
28
29
31 34
40
40 41 43 43 47 48 50
vi
3
4
CONTENTS
2.3.5 Silica 2.3.6 Iodine 2.4 Interstitial geochemistry and hydrology of coral reef frameworks 2.5 Mass transferlimited biogeochemical rates 2.6 Coral growth in high nutrient water 2.7 Measurement techniques 2.8 Summary statements References
Fjords J.M. SKEI, B. MCKEE and B. SUNDBY
3.1 3.2 3.3
Introduction 3.1.1 Definition and origin of fjords 3.1.2 The public and scientific interest in fjords Sediment diagenesis in oxic fjords 3.2.1 The Saguenay Fjord 3.2.2 Sedimentation 3.2.3 Composition of the rapidly deposited layers 3.2.4 Sulfate reduction and sulfide accumulation 3.2.5 Mercury diagenesis 3.2.6 Phosphorus and arsenic geochemistry 3.2.7 Nonsteadystate diagenesis Elemental cycling in anoxic waters 3.3.1 Chemical tracers 3.3.2 Cycling of carbon and nutrients 3.3.3 Trace element and radionuclide cycling 3.3.4 Fe–S systematics 3.3.5 Sulfate reduction and methane oxidation 3.3.6 Elemental cycling in sediments underlying anoxic waters 3.3.7 Preservation of organic matter References
The Eastern Mediterranean MICHAEL D. KROM, STEVEN GROOM and TAMAR ZOHARY
4.1 4.2 4.3
Introduction History of the Mediterranean basin Basic description of the bathymetry and physical oceanography of the Eastern Mediterranean 4.3.1 Bathymetry
51 51 52 54 56 58 59 59
65
65 66 67 69 69 69 70 70 73 73 75 76 76 77 78 81 83
84 85 86
91
91 92
93 93
5
CONTENTS
4.3.2 Physical circulation of the Eastern Mediterranean 4.3.2.1 Formation of LDW 4.3.2.2 Formation of LIW 4.3.3 Recent water mass changes in the Eastern Mediterranean 4.3.4 Current patterns 4.4 Nutrients and chlorophyll distribution across the Eastern Mediterranean 4.4.1 General comments 4.4.2 Seasonal distributions 4.4.2.1 Winter 4.4.2.2 Spring into summer 4.4.3 Nutrient distribution below the nutricline 4.5 Total chlorophyll distribution and characteristics 4.5.1 Light penetration 4.5.2 Species composition 4.5.2.1 The prochlorophytes 4.5.2.2 The unicellular cyanobacteria 4.5.2.3 The eukaryotes 4.5.2.4 Heterotrophic bacteria 4.6 Primary production 4.6.1 Gradient in biomass and productivity from coastal waters to the open sea 4.7 Effects of mesoscale features on nutrient and chlorophyll distribution and phytoplankton productivity 4.7.1 Biogeochemical processes in mesoscale features 4.7.1.1 Rhodes coldcore (cyclonic) eddy 4.7.1.2 Cyprus warmcore (anticyclonic) eddy 4.7.1.3 Effects of other mesoscale features 4.8 Seasonal changes in phytoplankton biomass as detected by remote sensing 4.9 Nutrient limitation in the Eastern Mediterranean 4.10 Magnitude of maninduced changes in nutrient inputs and their possible effects on the Eastern Mediterranean 4.11 Summary and conclusions Acknowledgements Glossary References
The Arctic seas MICHAEL L. CARROLL and JOLYNN CARROLL
5.1 5.2
Summary Main features
vii
93 94 95 96 97
98 98 98 98 100 100 100 102 102 102 103 104 104 105
107
108 108 108 112 113
113 116
118 120 121 122 122
127
127 128
viii
6
CONTENTS
5.2.1 Water masses 5.2.2 Continental shelves 5.2.3 Sea ice 5.3 Biogeochemical cycles and ecological processes 5.4 Environmental changes 5.4.1 Climate variability 5.4.2 Longterm climate change 5.4.3 Ozone and ultraviolet radiation 5.4.4 Contaminants 5.5 Natural resources and ecological services 5.5.1 Indigenous people 5.5.2 Nonindigenous regional populations 5.5.3 National/international/global users Acknowledgements References
The Arabian Sea S.W.A. NAQVI, HEMA NAIK and P.V. NARVEKAR
6.1 6.2 6.3 6.4
6.5
6.6
6.7
Introduction Geographical setting Climate and circulation Nutrients and primary production 6.4.1 Subsurface nutrient trap 6.4.2 Primary productivity 6.4.3 New production 6.4.4 Phytoplankton composition and size distribution 6.4.5 Chlorophyll and POC 6.4.6 Effect of changes in mixed layer depth Heterotrophic biomass and production 6.5.1 Heterotrophic bacteria 6.5.2 Nano and microheterotrophs 6.5.3 Mesozooplankton Food web structure and export of material to the deep sea 6.6.1 Phytoplankton growth and mortality 6.6.2 Particle fluxes to deep sea 6.6.3 Role of Arabian Sea as a source or sink of carbon dioxide (CO ) 2 Oxygendeficient zones 6.7.1 Denitrification 6.7.2 Intermediate nepheloid layer 6.7.3 Other redoxsensitive elements 6.7.4 Biological effects
128 131 132 133 138 138 140 143 143 144 144 145 146 147 147
157
157 157 158 163 163 164 166 167 171 172 174 174 175 177 179 179 180
185 185 186 191 192 193
7
8
6.8 Benthic processes References
CONTENTS
The northeastern Pacific abyssal plain ANGELOS K. HANNIDES and CRAIG R. SMITH
7.1 Introduction 7.2 Key habitat parameters of deep seafloor communities 7.2.1 Key habitat parameters 7.2.1.1 Substratum type 7.2.1.2 Nearbottom currents 7.2.1.3 Bottomwater oxygen 7.2.1.4 Sinking POC flux 7.2.1.5 Redox conditions 7.2.2 Variation of key habitat parameters in the northeastern Pacific abyssal plain 7.2.2.1 Sediment types 7.2.2.2 Nearbottom currents and oxygen concentrations 7.2.2.3 POC flux and redox conditions 7.3 Northeastern Pacific abyssal zones 7.3.1 The eutrophic equatorial abyss 7.3.2 The mesotrophic (subequatorial) abyss 7.3.3 The oligotrophic central gyre abyss 7.4 Sensitivity and resilience to natural and anthropogenic change 7.4.1 General thoughts 7.4.2 Potential sensitivity and resilience to specific changes 7.4.2.1 Climate variation in the equatorial and North Pacific 7.4.2.2 Global increase in atmospheric greenhouse gases and temperatures 7.4.2.3 Manganese nodule mining 7.4.2.4 Iron fertilization 7.5 Concluding remarks Acknowledgments References
Deepsea hydrothermal vents and cold seeps RICHARD J. LÉVEILLÉ and S. KIM JUNIPER
8.1
Introduction 8.1.1 Deepsea hydrothermal vents and cold seeps 8.1.2 Life at hydrothermal vents and cold seeps 8.1.3 Scope of this chapter
ix
195 198
208
208 208 209 209 210 211 211 211
212 212 212 213 213 214 217 218 220 220 221
221
223 226 229 230 231 231
238
238 238 238 240
x
8.2
8.3
8.4
CONTENTS
Deepsea hydrothermal vents 8.2.1 Distribution and general characteristics 8.2.1.1 Geochemical fluxes of gases and elements from hydrothermal vents 8.2.1.2 Offaxis diffuse flow versus axial venting 8.2.2 Subsurface biosphere at midocean ridges 8.2.2.1 Evidence for a subsurface biosphere at deepsea hydrothermal vents 8.2.2.2 Biogeochemical interactions in subsurface environments 8.2.3 Seafloor microbemineral interactions at hydrothermal vents 8.2.3.1 Microbial distribution and activity at vents 8.2.3.2 Biomineralisation at vents 8.2.3.3 Fossilisation of microbes at vents 8.2.3.4 Bacterial weathering of sulphides 8.2.4 Biogeochemical interactions in hydrothermal plumes 8.2.4.1 General features of hydrothermal plumes 8.2.4.2 Microbial ecology of hydrothermal plumes 8.2.4.3 Microbial productivity and organic carbon in plumes 8.2.4.4 Biogeochemical interactions in plumes 8.2.5 Biogeochemistry of offaxis vents and seafloor basalt 8.2.5.1 Offaxis vents 8.2.5.2 Seafloor basalts Deepsea cold seeps 8.3.1 Distribution, occurrences and general characteristics 8.3.1.1 Gas hydrates 8.3.1.2 Geochemical fluxes 8.3.2 Biogeochemistry of seep sediment pore fluids 8.3.2.1 Methanogenesis 8.3.2.2 Anaerobic sulphate reduction 8.3.2.3 Aerobic microbial oxidation of sulphide and methane 8.3.2.4 Anaerobic oxidation of methane 8.3.3 Microbial carbonates Stability and perturbations of seafloor hydrothermal vent and cold seep systems 8.4.1 Geological stability of vents and seeps 8.4.2 Future perturbations related to resource extraction 8.4.2.1 Hydrothermal sulphides 8.4.2.2 Cold seeps 8.4.3 Response of cold seeps and gas hydrates to global warming
241 241
243 245 246
246
251
252 252 256 260 260 261 261 262
263 264
265 265 266 267 267 268 269 270 271 271
272 273 274
276 276 277 277 278
278
9
8.5 Future work 8.6 Conclusion References
CONTENTS
Influence of nutrient biogeochemistry on the ecology of northwest European shelf seas PAUL TETT, DAVID HYDES and RICHARD SANDERS
9.1 Introduction 9.2 Nutrient cycles 9.2.1 Macronutrient element availability 9.2.2 Sources of macronutrients 9.2.3 Sinks of macronutrients 9.2.4 Observed distributions of macronutrient concentrations and ratios 9.2.5 Iron 9.3 Plankton biogeochemistry 9.3.1 Taxonomy and life forms in the plankton 9.3.2 Theories of floristic composition 9.3.2.1 Lightnutrientmixing explanations 9.3.2.2 Biogeochemical controls 9.3.2.3 Ecological controls 9.3.3 Variation in nutrient element ratios and its explanation in terms of plankton biochemistry 9.3.4 Quantitative theory for nutrient element ratios 9.3.5 Differences in abilities to assimilate different nutrients 9.3.6 Theoretical conclusions 9.4 Effects of ambient nutrient ratios on plankton 9.4.1 Introduction 9.4.2 Time series: Helgoland and the German Bight 9.4.3 Mesocosm and other competition experiments 9.4.4 Observations at sea 9.5 Discussion and conclusions 9.5.1 Introduction 9.5.2 Do high ambient N:Si ratios favour flagellates? 9.5.3 Do nonRedfield ambient N:P ratios perturb pelagic ecosystems? 9.5.4 The possibility of iron limitation in shelf seas 9.5.5 Trophic consequences of ratio changes – a Panglossian conclusion? 9.5.6 A flexible Redfield ratio? Dedication References
Index
xi
279 282 282
293
293 294 294 296 298
300 301 303 303 308 309 310 312
315 320 325 327 327 327 329 332 337 341 341 342
344 345
345 347 350 351
364