Exploring the Wonders of the Ocean: Biodiversity, Climate, and Resources

2. Oceans cover most of the Earth’s surface • The oceans influence global climate, team with biodiversity, facilitate transportation and commerce, and provide resources for us • They cover 71% of Earth’s surface and contain 97% of Earth’s surface water • Oceans influence the atmosphere, lithosphere, and biosphere

3. The oceans contain more than water • Ocean water is 96.5% water • Plus, ions of dissolved salts • Evaporation removes pure water and leaves a higher concentration of salt • Nutrients (nitrogen and phosphorus) • Dissolved gas • Oxygen is added by plants, bacteria, and atmospheric diffusion

4. Ocean water is vertically structured • Temperature declines with depth • Heavier (colder saltier) water sinks • Light (warmer and less salty) water remains near the surface • Temperatures are more stable than land temperatures • Water’s high heat capacity • It takes much more heat to warm water than air • Oceans regulate the earth’s climate • They absorb and release heat • Ocean’s surface circulation

5. The ocean has several layers • Surface zone • Warmed by sunlight and stirred by wind • Consistent water density • Pycnocline = below the surface zone • Density increases rapidly with depth • Deep Zone = below the pycnocline • Dense, sluggish water • Unaffected by winds, storms, sunlight, and temperature

6. Ocean water flows horizontally in currents • Currents = the ocean is composed of vast riverlike flows • Driven by density differences, heating and cooling, gravity, and wind • Influence global climate and El Niño and La Niña • Transport heat, nutrients, pollution, and the larvae of many marine species • Some currents such as the Gulf Stream are rapid and powerful • The warm water moderates Europe’s climate

7. The upper waters of the oceans flow in currents

8. Surface winds and heating create vertical currents • Upwelling = the vertical flow of cold, deep water towards the surface • High primary productivity and lucrative fisheries • Also occurs where strong winds blow away from, or parallel to, coastlines • Downwellings = oxygen-rich water sinks where surface currents come together

9. Seafloor topography can be rugged and complex • The seafloor consists of… • Underwater volcanoes • Steep canyons • Mountain range • The planet’s longest range is under water • Mounds of debris • Trenches • Some flat areas

10. Understanding underwater geography • Maps show… • Bathymetry = themeasurement of ocean depths • Topography = the physical geography or the shape and arrangement of landforms • Continental shelves = gently sloping areas that underlie the shallow waters bordering continents • Shelf-slope break = sudden drop off of the continental shelf • Continental slope = connects the continental shelf to the ocean floor

11. A stylized bathymetric profile of the ocean

12. Regions of ocean differ greatly • Some zones support more life than others • Photic zone = well-lighted top layer that supports high primary productivity • Pelagic = habitats and ecosystems occurring between the ocean’s surface and floor • Benthic = habitats and ecosystems occurring on the ocean floor

13. Open ocean systems vary in biodiversity • Microscopic phytoplankton constitute the base of the marine food chain in the pelagic zone • Algae, protists, and cyanobacteria • These organisms feed zooplankton • Which then feeds fish, jellyfish, whales, etc. • Predators at higher trophic levels include larger fish, sea turtles, sharks, and fish-eating birds

14. Animals of the deep ocean • Animals adapt to extreme water pressure and the absence of light • Scavenge carcasses or organic detritus • Some are predators, while others have mutualistic relationships with bacteria • Some species carry bacteria that produce light chemically by bioluminescence • Hydrothermal vents support tubeworms, shrimp, and other chemosynthetic species

15. Coral reefs consist of millions of corals • Coral reef = a mass of calcium carbonate composed of the skeletons of corals • Consists of millions of densely packed individuals • Protect shorelines by absorbing waves • Innumerable invertebrates and fish species find food and shelter in reef nooks and crannies

16. Coral reefs are in worldwide decline • Coral bleaching = occurs when zooxanthellae leave the coral • Coral lose their color and die, leaving white patches • From climate change, pollution, or unknown natural causes • Nutrient pollution causes algal growth, which covers coral • Divers damage reefs by using cyanide to capture fish • Acidification of oceans deprives corals of necessary carbonate ions for their structural parts

17. Intertidal zones undergo constant change • Intertidal (littoral) ecosystems = where the ocean meets the land • between the uppermost reach of the high tide and the lowest limit of the low tide • Tides = periodic rising and falling of the ocean’s height due to the gravitational pull of the sun and moon • Intertidal organisms spend part of their time submerged in water and part of their time exposed to sun and wind

18. A typical intertidal zone

19. Intertidal zones are a tough place to live • But they have remarkable diversity • Rocky shorelines, crevices, pools of water (tide pools) • Anemones, mussels, barnacles, urchins, sea slugs, starfish, and crabs • Temperature, salinity, and moisture change dramatically from high to low tide • Sandy intertidal zones have slightly less biodiversity