Contents

Preface to the Second Edition xiii

1 An introduction to fluvial ecosystems 1

Fluvial Ecosystem Diversity 1

The fluvial hierarchy 2

Longitudinal patterns 5

The stream and its valley 5

The Fluvial Ecosystem 6

Energy sources 6

Food webs and biological communities 7

The river ecosystem 8

The Status of Rivers Today 9

2 Streamflow 13

The Water Cycle 14

Global water cycle 16

Water balance of a catchment 16

Surface versus groundwater pathways 18

Streamflow 19

The hydrograph 21

Flow Variation 22

The likelihood of extreme events 23

Effect of land use on streamflow 24

The flow regime 25

Environmental flows 30

Summary 31

3 Fluvial geomorphology 33

The Drainage Network 34

The Stream Channel 35

Hydraulic geometry 36

Sinuosity 38

Pool-riffle features 39

The floodplain 41

Sediments and their Transport 41

Bed material 41

Bank and bed erosion 43

Sediment load 44

Factors influencing sediment concentrations and loads 46

Fluvial Processes along the River Continuum 49

Fluvial processes and channel morphologies 50

Channel dynamics over long timeframes 53

Channel classifications and their uses 53

Riverine landscape diversity 55

Summary 55

4 Streamwater chemistry 57

Dissolved Gases 57

Major Dissolved Constituents of River Water 59

Variability in ionic concentrations 62

The dissolved load 64

Chemical classification of river water 65

The Bicarbonate Buffer System 65

Influence of Chemical Factors on the Biota 68

Variation in ionic concentration 68

Salinization 69

Effects of acidity on stream ecosystems 70

Summary 74

5 The abiotic environment 75

The Flow Environment 76

Channel and near-bed flow environments 79

Hydraulic variables 79

Quantification of flow conditions 81

Influence of flow on the biota 82

Substrate 88

Inorganic substrates 89

Organic substrates 90

The influence of substrate on stream assemblages 92

Temperature 94

Influence of thermal regime on the biota 98

Summary 102

6 Primary producers 105

Benthic Algae 105

Benthic algal distribution and abundance 107

Light 109

Nutrients 112

Current 115

Substrate 120

Temperature 120

Grazers 120

Temporal and spatial variation in benthic algae 121

Primary production by benthic algae 122

Fate of benthic primary production 124

Macrophytes 125

Limiting factors for macrophytes 126

Macrophyte production and its fate 128

Phytoplankton 129

Limiting factors for phytoplankton 130

Primary production by river phytoplankton 132

Summary 133

7 Detrital energy sources 135

The Decomposition of Coarse Particulate Organic Matter 135

Stages in the breakdown and decay of CPOM 139

The influence of detritivores on litter decomposition 144

Other CPOM 146

Fine Particulate Organic Matter 147

FPOM originating from leaf decomposition 148

Other sources of FPOM 149

Dissolved Organic Matter 150

Uptake of DOC 152

Biofilms 154

Bacterioplankton 158

Summary 160

8 Trophic relationships 163

Microbial Food Webs 164

Invertebrate Feeding Roles 167

Consumers of CPOM 168

Consumers of FPOM 173

Herbivory 177

Predaceous invertebrates 180

Vertebrates in Lotic Food Webs 183

Fishes 184

Other vertebrates 188

Secondary Production 190

Summary 195

9 Species interactions 197

Herbivory 197

Grazer responses to food supply 197

Grazer effects on periphyton 199

Structural responses 200

Functional responses 202

Disturbance and herbivory 203

Top-down and bottom-up effects on periphyton 204

Predation 205

The predator-prey interaction 206

Vertebrate predators 206

Invertebrate predators 207

Prey defenses 209

Effects of predation on prey populations 210

Nonconsumptive effects of predation 211

Experimental scale 213

Trophic cascades 214

Competition 217

Resource partitioning 217

Algae 217

Invertebrates 218

Fishes 219

Experimental studies of competition 222

Summary 225

10 Lotic communities 229

Regional Patterns in Species Diversity 230

Species-area relationships 230

Latitudinal gradients 231

History 231

Local Diversity 233

Community Structure 238

Consistency in assemblage composition 239

The habitat template and species traits 240

Disturbance 242

Species-level effects of disturbance 244

System-wide effects 245

Food Webs 246

Resource subsidies 249

Landscape position 250

Community Composition and Ecosystem Function 251

Summary 253

11 Nutrient dynamics 255

Sources and Cycling of Nitrogen and Phosphorus 256

Nitrogen sources and quantities 257

Nitrogen cycling 259

Phosphorus sources and quantities 261

Phosphorus cycling 264

Transport and Spiraling 265

Physical transport 265

Nutrient spiraling 267

Methodological issues 268

Factors Influencing Nutrient Dynamics 269

Abiotic controls of nutrient dynamics 269

Hydrologic processes 270

Biotic controls of nutrient cycling 272

Assimilatory uptake 273

Dissimilatory transformations 275

Role of consumers 277

Nutrient Budgets 279

Nitrogen 280

Phosphorus 283

Summary 284

12 Stream ecosystem metabolism 287

Autochthonous Production 289

Algae 289

Macrophytes 290

Allochthonous Inputs 291

Coarse particulate organic matter 291

Fine particulate organic matter 292

Dissolved organic matter 294

Processes 297

Benthic respiration 297

Coarse particulate organic matter dynamics 298

Fine particulate organic matter dynamics 299

Benthic organic matter retention 300

Dissolved organic matter dynamics 302

Stream Ecosystem Metabolism 303

Organic matter budgets 303

The P/R ratio 308

Stream ecosystem efficiency 313

The fate of organic matter 314

Summary 315

13 Human impacts 317

Freshwater Biodiversity 318

Species imperilment 319

Imperilment of major groups 320

Threats to Rivers 321

Habitat alteration 321

Altered hydrology 323

Channelization 327

Land use 330

Nonindigenous species 333

Causes of species invasions 333

Invasion success 334

Impacts of invasive species 337

Pollution 339

Point source contaminants 339

Runoff from the land 339

Atmospheric deposition 341

Overexploitation 342

Climate change 345

River Management 347

Bioassessment 348

Restoration and recovery of lotic ecosystems 350

Protected areas 354

Summary 356

14 The foundations of stream ecology 359

The Spatial Framework 360 Community Assembly is Determined by the Species Pool,

Habitat Sorting, and Species Interactions 362

Streams are Transporting Systems 364 Primary Production and Allochthonous Detritus are Basal Resources in Lotic Ecosystems 366

Rivers are the Product of their Landscapes 369

References 373

Subject Index 429

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