1. The Changing Marine Environment Charting the Deep Charting the Deep Understanding of the sea requires a shift in perspective toward a “geological perspective” that allows for our five-billion-year history and vast distances greater than several thousand kilometers. Understanding of the sea requires a shift in perspective toward a “geological perspective” that allows for our five-billion-year history and vast distances greater than several thousand kilometers.

8. The Changing Marine Environment

9. Charting the Deep Charting the Deep The interrelated concepts of continental drift and plate tectonics have radically changed our view of the ocean’s structure. The interrelated concepts of continental drift and plate tectonics have radically changed our view of the ocean’s structure.

10. The Changing Marine Environment Fig. 1.5 The major plates of the earth's crusts. Fig. 1.5 The major plates of the earth's crusts.

14. The World Ocean –Earth’s oceans exist as a large inter- connected system of mixing seawater. Fig. 1.10 An equatorial view of the world ocean. Visualizing the World Ocean

15. The World Ocean Seeing in the Dark Seeing in the Dark –Water is nearly opaque to light, yet very transparent to sound.

18. The World Ocean Fig. 1.11 Some large-scale features of the North Atlantic seafloor. Fig. 1.11 Some large-scale features of the North Atlantic seafloor.

19. Properties of Seawater Pure Water Pure Water

20. Properties of Seawater Pure Water Pure Water –The unique characteristics of pure water are established by an electrical charge separation within water molecules that forms hydrogen bonds between adjacent water molecules. Fig. 1.14 Hydrogen bonding between adjacent molecules of liquid water. Blue dashed lines represent hydrogen bonds. Fig. 1.13 The arrangement of H and O atoms in a molecule of water.

21. Properties of Seawater Seawater Seawater Salt water contains a great variety of dissolved salts, gases, and other inorganic and organic substances. Salt water contains a great variety of dissolved salts, gases, and other inorganic and organic substances. These dissolved molecules and compounds affect many characteristics of seawater, including its density, osmotic properties, buffering capacity, and other biologically significant features. These dissolved molecules and compounds affect many characteristics of seawater, including its density, osmotic properties, buffering capacity, and other biologically significant features.

22. Properties of Seawater Fig. 1.20 A comparison of the osmotic conditions of a sea cucumber and a salmon in seawater and fresh water. Fig. 1.20 A comparison of the osmotic conditions of a sea cucumber and a salmon in seawater and fresh water.

23. Properties of Seawater Fig. 1.21 Fate of sunlight as it enters sea water. The violet and red ends of the visible spectrum are absorbed first. Fig. 1.21 Fate of sunlight as it enters sea water. The violet and red ends of the visible spectrum are absorbed first.

24. Properties of Seawater Fig. 1.27 Earth's sea surface temperatures obtained from two weeks of satellite infrared observations July 1984. Fig. 1.27 Earth's sea surface temperatures obtained from two weeks of satellite infrared observations July 1984.

25. Properties of Seawater Fig. 1.30 Variations in water temperature (orange curve) and salinity (blue curve) at a GEOSECS station in the western South Atlantic Ocean. Fig. 1.30 Variations in water temperature (orange curve) and salinity (blue curve) at a GEOSECS station in the western South Atlantic Ocean.

26. The Ocean in Motion The sea is constantly moving, both horizontally and vertically. Winds, waves, tides, currents, sinking water masses, and upwelling all contribute to the remarkable homogeneity of the world ocean. The sea is constantly moving, both horizontally and vertically. Winds, waves, tides, currents, sinking water masses, and upwelling all contribute to the remarkable homogeneity of the world ocean.

27. The Ocean in Motion Wind Waves Wind Waves The character of wind-driven ocean waves depends on the wind’s speed, duration, and fetch. The character of wind-driven ocean waves depends on the wind’s speed, duration, and fetch. Fig. 1.35 Wave form and pattern of water motion in a deepwater wave as it moves to the right in to shore.

28. The Ocean in Motion Surface Currents Surface Currents –Ocean surface currents are driven by stable patterns of surface winds.

29. The Ocean in Motion Fig. 1.38 The major surface currents of the world ocean. Fig. 1.38 The major surface currents of the world ocean. Adapted from Pickard and Emory, 1982. Adapted from Pickard and Emory, 1982.

30. The Ocean in Motion Ocean Tides Ocean Tides –Ocean tides are driven by the gravitational interactions of the Sun, Earth, and Earth’s moon.

31. The Ocean in Motion Fig. 1.40 A point on the earth's surface (indicated by the marker) experiences high tides when under tidal bulges and low tides when at right angles to tidal bulges. Fig. 1.40 A point on the earth's surface (indicated by the marker) experiences high tides when under tidal bulges and low tides when at right angles to tidal bulges. Fig. 1.41 Weekly tidal variations caused by changes in the relative positions of the earth, moon, and sun.

32. The Ocean in Motion Vertical Water Movements Vertical Water Movements –Vertical circulation of ocean water results from density-driven sinking processes.

33. The Ocean in Motion Fig. 1.44 The general pattern of deep-ocean circulation in the major ocean basins. Adapted from Broecker et al, 1985. Fig. 1.44 The general pattern of deep-ocean circulation in the major ocean basins. Adapted from Broecker et al, 1985.

36. Classification of the Marine Environment Energy from the sun warms the sea’s surface and creates winds that result in a two-layered world ocean, with a shallow, well-mixed, warm, sunlit layer overlaying a much deeper, cold, dark, high-pressure layer of slowly moving water below. Energy from the sun warms the sea’s surface and creates winds that result in a two-layered world ocean, with a shallow, well-mixed, warm, sunlit layer overlaying a much deeper, cold, dark, high-pressure layer of slowly moving water below.

37. Classification of the Marine Environment The three-dimensional marine environment can be separated into two broad divisions, The three-dimensional marine environment can be separated into two broad divisions, – the benthic realm of the sea floor – and the pelagic water column. These in turn may be subdivided into smaller categories based on water depth, light availability, and ambient temperature. These in turn may be subdivided into smaller categories based on water depth, light availability, and ambient temperature.

38. Classification of the Marine Environment The marine environment is a large and complex system, so we create classification systems to better understand the relationships between the physical characteristics of the ocean. The marine environment is a large and complex system, so we create classification systems to better understand the relationships between the physical characteristics of the ocean.

39. Classification of the Marine Environment Fig. 1.46 A system for classifying the marine environment. Fig. 1.46 A system for classifying the marine environment. Adapted from Hedgpeth 1957. Adapted from Hedgpeth 1957.