Biological Oceanography: An Introduction (eBook)

Carol Lalli, Timothy R. Parsons (Autoren)

eBook Download: EPUB

1997 | 2. Auflage
320 Seiten
Elsevier Science (Verlag)
978-0-08-052799-4 (ISBN)

Infos

This popular undergraduate textbook offers students a firm grounding in the fundamentals of biological oceanography. As well as a clear and accessible text, learning is enhanced with numerous illustrations including a colour section, thorough chapter summaries, and questions with answers and comments at the back of the book.

The comprehensive coverage of this book encompasses the properties of seawater which affect life in the ocean, classification of marine environments and organisms, phytoplankton and zooplankton, marine food webs, larger marine animals (marine mammals, seabirds and fish), life on the seafloor, and the way in which humans affect marine ecosystems.

The second edition has been thoroughly updated, including much data available for the first time in a book at this level. There is also a new chapter on human impacts - from harvesting vast amounts of fish, pollution, and deliberately or accidentally transferring marine organisms to new environments.

This book complements the Open University Oceanography Series, also published by Butterworth-Heinemann, and is a set text for the Open University third level course, S330.

• A leading undergraduate text
• New chapter on human impacts - a highly topical subject
• Expanded colour plate section

Inhalt

Front Cover 1
Biological Oceanography: An Introduction 4
Copyright Page 5
CONTENTS 6
ABOUT THIS VOLUME 12
CHAPTER 1. INTRODUCTION 14
1.1 SPECIAL PROPERTIES AFFECTING LIFE IN THE SEA 14
1.2 CLASSIFICATIONS OF MARINE ENVIRONMENTS AND MARINE ORGANISMS 15
1.3 BASIC ECOLOGICAL TERMS AND CONCEPTS 17
1.4 THE HISTORICAL DEVELOPMENT OF BIOLOGICAL OCEANOGRAPHY 20
1.5 SUMMARY OF CHAPTER 1 26
CHAPTER 2. THE ABIOTIC ENVIRONMENT 29
2.1 SOLAR RADIATION 29
2.2 TEMPERATURE 34
2.3 SALINITY 38
2.4 DENSITY 43
2.5 PRESSURE 46
2.6 SURFACE CURRENTS 47
2.7 SUMMARY OF CHAPTER 2 49
CHAPTER 3. PHYTOPUNKTON AND PRIMARY PRODUCTION 52
3.1 SYSTEMATIC TREATMENT 53
3.2 PHOTOSYNTHESIS AND PRIMARY PRODUCTION 59
3.3 RADIATION AND PHOTOSYNTHESIS 63
3.4 THE EFFECT OF NUTRIENTS ON GROWTH RATE 66
3.5 PHYSICAL CONTROLS OF PRIMARY PRODUCTION 71
3.6 GLOBAL PHYTOPLANKTON PRODUCTIVITY 80
3.7 SUMMARY OF CHAPTER 3 83
CHAPTER 4. ZOOPLANKTON 87
4.1 COLLECTION METHODS 87
4.2 HOLOPLANKTON: SYSTEMATICS AND BIOLOGY 89
4.3 MEROPLANKTON 99
4.4 VERTICAL DISTRIBUTION 103
4.5 DIEL VERTICAL MIGRATION 107
4.6 SEASONAL VERTICAL MIGRATIONS 111
4.7 ZOOGEOGRAPHY OF THE HOLOPLANKTON 113
4.8 LONG-TERM CHANGES IN ZOOPLANKTON COMMUNITY STRUCTURE 121
4.9 SUMMARY OF CHAPTER 4 122
CHAPTER 5. ENERGY FLOW AND MINERAL CYCLING 125
5.1 FOOD CHAINS AND ENERGY TRANSFER 125
5.2 FOOD WEBS 130
5.3 MEASURING SECONDARY PRODUCTION 136
5.4 A COMPARISON OF MARINE AND TERRESTRIAL PRODUCTION OF ORGANIC MATERIAL 147
5.5 MINERAL CYCLES 149
5.6 SUMMARY OF CHAPTER 5 156
CHAPTER 6. NEKTON AND FISHERIES OCEANOGRAPHY 160
6.1 NEKTONIC CRUSTACEA 160
6.2 NEKTONIC CEPHALOPODS 161
6.3 MARINE REPTILES 162
6.4 MARINE MAMMALS 162
6.5 SEABIRDS 166
6.6 MARINE FISH 169
6.7 FISHERIES AND FISHERIES OCEANOGRAPHY 175
6.8 MARICULTURE 185
6.9 SUMMARY OF CHAPTER 6 187
CHAPTER 7. BENTHOS 190
7.1 BENTHIC PLANTS 191
7.2 BENTHIC ANIMALS 193
7.3 DETERMINANTS OF BENTHIC COMMUNITY STRUCTURE 205
7.4 SUMMARY OF CHAPTER 7 206
CHAPTER 8. BENTHIC CORAMUNITIES 209
8.1 INTERTIDAL ENVIRONMENTS 209
8.2 ROCKY INTERTIDAL SHORES 211
8.3 KELP FORESTS 215
8.4 SAND BEACHES 218
8.5 ESTUARIES 222
8.6 CORAL REEFS 226
8.7 MANGROVE SWAMPS 235
8.8 DEEP-SEA ECOLOGY 239
8.9 HYDROTHERMAL VENTS AND COLD SEEPS 251
8.10 SUMMARY OF CHAPTER 8 256
CHAPTER. 9 HUMAN IMPACTS ON MARINE BIOTA 260
9.1 FISHERIES IMPACTS 261
9.2 MARINE POUUTANTS 264
9.3 INTRODUCTIONS AND TRANSFERS OF MARINE ORGANISMS 269
9.4 IMPACTS ON SPECIFIC MARINE ENVIRONMENTS 271
9.5 SUMMARY OF CHAPTER 9 276
APPENDIX 1: GEOLOGIC TIME SCALE 279
APPENDIX 2: CONVERSIONS 280
SUGGESTED FURTHER READING 282
ANSWERS AND COMMENTS TO QUESTIONS 283
GLOSSARY 300
ACKNOWLEDGEMENTS 317
INDEX 320

Textauszug

CHAPTER 1 INTRODUCTION

The oceans occupy about 71% of the Earth’s surface. The deepest parts of the seafloor are almost 11 000 m from the sea surface, and the average depth of the oceans is about 3800 m. The total volume of the marine environment (about 1370 × 106 km3) provides approximately 300 times more space for life than that provided by land and freshwater combined. The name given to our planet, ‘Earth’, is a synonym for dry land, but it is a misnomer in that it does not describe the dominant feature of the planet — which is a vast expanse of blue water.

The age of Earth is thought to be about 4600 million years. The ocean and atmosphere formed as the planet cooled, some time between 4400 and 3500 million years ago, the latter date marking the appearance of the first forms of life (see the Geologic Time Scale, Appendix 1). The earliest organisms are believed to have originated in the ancient oceans, many millions of years before any forms of life appeared on dry land. All known phyla (both extinct and extant) originated in the sea, although some later migrated into freshwater or terrestrial environments. Today there are more phyla of animals in the oceans than in freshwater or on land, but the majority of all described animal species are non-marine. The difference in the number of species is believed to be due largely to the greater variety of habitats on land.

1.1 SPECIAL PROPERTIES AFFECTING LIFE IN THE SEA

Why should life have arisen in the sea, and not on land?

Marine and terrestrial environments provide very different physical conditions for life. Seawater has a much higher density than air, and consequently there is a major difference in the way gravity affects organisms living in seawater and those living in air. Whereas terrestrial plants and animals generally require large proportions of skeletal material (e.g. tree trunks, bones) to hold themselves erect or to move against the force of gravity, marine species are buoyed up by water and do not store large amounts of energy in skeletal material. The majority of marine plants are microscopic, floating species; many marine animals are invertebrates without massive skeletons; and fish have small bones. Floating and swimming require little energy expenditure compared with walking or flying through air. Overcoming the effects of gravity has been energetically expensive for terrestrial animals, and perhaps it should not be surprising that the first forms of life and all phyla evolved where the buoyancy of the environment permitted greater energy conservation.

Two other features of the ocean are especially conducive to life. Water is a fundamental constituent of all living organisms, and it is close to being a universal solvent with the ability to dissolve more substances than any other liquid. Whereas water can be in short supply on land and thus limiting to life, this is obviously not the case in the marine environment. Secondly, the temperature of the oceans does not vary as drastically as it does in air.

On the other hand, certain properties of the sea are less favourable for life than conditions on land. Plant growth in the sea is limited by light because only about 50% of the total solar radiation actually penetrates the sea surface, and much of this disappears rapidly with depth. Marine plants can grow only within the sunlit surface region, which extends down to a few metres in turbid water or, at the most, to several hundred metres depth in clear water. The vast majority of the marine environment is in perpetual darkness, yet most animal life in the sea depends either directly or indirectly on plant production near the sea surface. Marine plant growth is also limited by the availability of essential nutrients, such as nitrates and phosphates, that are present in very small quantities in seawater compared with concentrations in soil. On land, nutrients required by plants are generated nearby from the decaying remains of earlier generations of plants. In the sea, much decaying matter sinks to depths below the surface zone of plant production, and nutrients released from this material can only be returned to the sunlit area by physical movements of water.

The greatest environmental fluctuations occur at or near the sea surface, where interactions with the atmosphere result in an exchange of gases, produce variations in temperature and salinity, and create water turbulence from winds. Deeper in the water column, conditions become more constant. Vertical gradients in environmental parameters are predominant features of the oceans, and these establish depth zones with different types of living conditions. Not only does light diminish with depth, but temperature decreases to a constant value of 2–4°C, and food becomes increasingly scarce. On the other hand, hydrostatic pressure increases with depth, and nutrients become more concentrated. Because of the depth-related changes in environmental conditions, many marine animals tend to be restricted to distinctive vertical zones. On a horizontal scale, geographic barriers within the water column are set by physical and chemical differences in seawater.

Much of this text deals with descriptions of marine communities and the interactions between physical, chemical and biological properties that determine the nature of these associations. Some attention is also given to the exploitation of marine biological resources. Despite the fact that the oceans occupy almost three-quarters of the Earth’s surface, only 2% of the present total human food consumption comes from marine species. However, this is an important nutritional source because it represents about 20% of the high-quality animal protein consumed in the human diet. Although a greater total amount of organic matter is produced annually in the ocean than on land, the economic utilization of the marine production is much less effective. One branch of biological oceanography, fisheries oceanography, is a rapidly developing field that addresses the issue of fish production in the sea.

1.2 CLASSIFICATIONS OF MARINE ENVIRONMENTS AND MARINE ORGANISMS

The world’s oceans can be subdivided into a number of marine environments (Figure 1.1). The most basic division separates the pelagic and benthic realms. The pelagic environment (pelagic meaning ‘open sea’) is that of the water column, from the surface to the greatest depths. The benthic environment (benthic meaning ‘bottom’) encompasses the seafloor and includes such areas as shores, littoral or intertidal areas, coral reefs, and the deep seabed.

Figure 1.1 The basic ecological divisions of the ocean. The neritic (or inshore) pelagic zone is separated from the oceanic (or offshore) pelagic zone by the edge of the continental shelf, which is generally at about 200 m depth. Benthic habitats are in bold type; pelagic divisions are in blue. (Not to scale.)

Another basic division separates the vast open ocean, the oceanic environment, from the inshore neritic zone. This division is based on depth and distance from land, and the separation is conventionally made at the 200 m depth limit which generally marks the edge of the continental shelf (Figure 1.1). In some areas like the west coast of South America where the shelf is very narrow, the neritic zone will extend only a very slight distance from shore. In other areas (e.g. off the north-east coast of the United States), the neritic zone may extend several hundred kilometres from land. Overall, continental shelves underlie about 8% of the total ocean, an area equal to about that of Europe and South America combined.

Further divisions of the pelagic and benthic environments can be made which divide them into distinctive ecological zones based on depth and/or bottom topography. These will be considered in later chapters.

Marine organisms can be classified according to which of the marine environments they inhabit. Thus there are oceanic species and neritic species depending upon whether the organisms are found in offshore or coastal waters, respectively. Similarly, plants or animals that live in association with the seafloor are collectively called benthos. The benthos includes attached seaweeds, sessile animals like sponges and barnacles, and those animals that crawl on or burrow into the substrate. Additional subdivisions of the benthos are given in Chapter 7.

The pelagic environment supports two basic types of marine organisms. One type comprises the plankton, or those organisms whose powers of locomotion are such that they are incapable of making their way against a current and thus are passively transported by currents in the sea. The word plankton comes from the Greek planktos, meaning that which is passively drifting or wandering. Depending upon whether a planktonic organism is a plant or animal, a distinction is made between phytoplankton and zooplankton. Although many planktonic species are of microscopic dimensions, the term is not synonymous with small size as some of the zooplankton include jellyfish of several metres in diameter. Nor are all plankton completely passive; most, including many of the phytoplankton, are capable of swimming. The remaining inhabitants of the pelagic environment form the nekton. These are free-swimming animals that, in contrast to...

Produkt-Details

• Erscheint lt. Verlag: 10.4.1997
• Sprache: englisch
• Themenwelt: Geisteswissenschaften ► Psychologie
• Themenwelt: Naturwissenschaften ► Biologie ► Limnologie / Meeresbiologie
• Themenwelt: Naturwissenschaften ► Biologie ► Ökologie / Naturschutz
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Geophysik
• Themenwelt: Naturwissenschaften ► Geowissenschaften ► Hydrologie / Ozeanografie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie
• Themenwelt: Technik
• ISBN-10: 0-08-052799-X / 008052799X
• ISBN-13: 978-0-08-052799-4 / 9780080527994