World’s oceans

1. World’s oceans Sources of water Water from magma that had been trapped since the formation of the Earth Water from solar system attracted by Earth’s gravity Comet and meteor bombardment 1.3 Billion cubic kilometers of Seawater!!

2. Water characteristics Salinity Definition: amount of dissolved ions present in water (usually in parts per thousand) 3.5% salinity on average (35 ppt) Seven primary ions

3. Water characteristics Salinity Salt levels fluctuate depending on regional and local conditions - Baltic sea -large amount of rivers: 2ppt - Persian gulf - high temps, few rivers: 45 ppt Trace ions (gold example)

4. Water characteristics Temperature Oceans (and lakes) stratify into 3 broad vertical layers A warm upper layer, high temperatures The thermocline– place where temperatures drop quickly Consistently cold bottom layer that usually do not mix with upper layers

6. Water characteristics Density Ocean water (“salt” water) is most dense at 1-2° C Fresh water is most dense at 4° C. Changes in temperature and density cause water movement, and currents

7. Waves, tsunamis & currents Water movement Wind: speed, length of time blown, and fetch (distance wave has moved uninteruppted by land Only the surface of the water moves with waves Tsunamis are not typical waves! Rather, they are the result of water displacement by: - elastic rebound from earthquakes - landslides

8. Water movement Tsunamis “Local” Tsunamis can also be cause by above ground landslides in mountainous areas (Alaska, Chile) call fjords These waves can be much taller, up to 1000 feet high! Lituya Bay, Alaska example (Megatsunami from BBC Nature)

9. Ocean environments Influential factors • Three factors influence where life may be found: • Depth (light penetration) • Nutrient availability • - upwellings & sandstorms • Substrate availability • Algae/phytoplankton - the base of the food pyramid – need • Sunlight • Nutrients

10. Ocean environments Upwellings Most marine life lives within 100m of the ocean surface Most nutrients exist in the benthic zones (sea floor) Upwellings allow for life to exist at the surface - Winds that run parallel to the shoreline cause this - Often times upwellings are seasonal (Why?)

11. Warm surface water blown offshore & replaced by cooler bottom water

12. Ocean environments Littoral zones Shallow seas, usually less than 100m deep (300ft) Light reaches the sea floor Rely on nutrients from either upwellings or terrestrial storms to support life

14. Ocean environments Reefs & Grass beds Proliferated by corals,(animals from phylum Cnidaria) that filter the water for organic particles Light reaches the sea floor, exist either on continental margins or atolls Atolls form on top of mid-ocean volcanoes. Volcano sinks, but coral reef building keeps living corals in the littoral zone

15. Ocean environments Atoll reefs Edge of volcano rim Lagoon

16. Ocean environments Pelagic zone Open ocean, area where light penetrates but not to the sea floor Plankton: organisms that float in pelagic waters; -include photosynthetic organisms (phytoplankton, primary and secondary consumers (zooplankton) Nekton: organisms that swim actively in open waters. - Include sharks, squid, dolphins, whales, tuna, etc.

17. Pelagic organisms Diatoms Diatoms have either silica or calcium “shells” Significant portion of phytoplankton & basis for limestone Eaten by zooplankton, krill, and larval fish

18. Krill Daphnia

19. Bait ball: method of protection for smaller nektonic fish; safety in numbers!!

20. Ocean environments Bathyal zone Deep ocean where light does not penetrate; very high pressure areas Detritus: dead and decaying organic matter - Marine snow: detritus that falls from pelagic zones; forms the basis of bathyal food webs Benthos: organisms that live in aquatic sediments (sea floor) ***Giant squid***

21. Ocean environments Bathyal zone Hydrothermal vents provide warmth and nutrients for bacteria that may begin a food pyramid - chemosynthetic bacteria

22. Bathyal zone Whale falls

23. Deep sea diving impacts

24. Climate change Oceans and climate Ocean currents involve the movement or warm and cool water Coastlines have risen and fallen many times in geologic history - tectonic events - climate change (glacial advance and retreat) Sea level at peak of last glacial period: 150 m less than today - Worldwide ice free sea level: 70 m higher than today

27. Climate change Mechanisms 2nd Law of Thermodynamics: - ocean water and air are rarely the same temp.

28. Climate change Mechanisms Positive feedback loops (↑ in x = ↑ in y OR ↓in x = ↓ in y) - population growth and # of births (viscous cycles) - Stress and lack of sleep

29. Climate change Mechanisms Negative feedback loops (↑ in x = ↓ in y OR ↓in x = ↑ in y) - body temp ↑  sweat  body temp ↓ - ↑ in supply  ↑ in price  ↓ in demand

30. Climate change Pack ice Ocean water freezes at -1.9º C (28.5° F), and forms pack ice Ice reflects heat, dark colored water absorbs heat – creates a feedback loop The reflection or absorbtion of sunlight is called the albedo

31. Climate change Albedo – warmer feedback loop Less ice, more dark colored water Melting Absorbed sunlight Lower Albedo

32. Climate change Albedo – colder feedback loop More ice, less dark colored water Freezing Reflected sunlight Higher Albedo

33. Ocean pollution CO2 Oceans contain up to 60X more CO2 than the atmosphere CO2 becomes trapped in oceans; oceans serve as a carbon sink - More CO2 is trapped than CO2 released from respiration CO2 becomes carbonic acid when dissolved, and thus increases oceanic acidity

34. Spikes from volcanic activity Troughs from oceanic carbon sequestration

35. Ocean pollution CO2 Increase acidity results from increase temperatures - Impacts on clams • Removes available calcium (CaCO3) • - CO2 binds with calcium to make chemical limestone • Calcium normally used by diatoms, coral, & crustaceans (shrimp, crabs, etc)

36. Ocean pollution Mercury Atmospheric mercury comes from industrial sources: - coal burning powerplants - trash incinerators - chlorine producing factories • Converted by microbes into methyl-mercury – very toxic to humans and other animals • Methylmercury is not easily metabolized: bioaccumulation • Alternatives to pesticides

37. Ocean pollution Eutrophication • 2008: USA uses approximately 50 million tons of fertilizer • - 82% of nitrogen applied to fields remains in the soil • Non-point source pollution: “run-off” of these materials into streams • Eutrophication: accumulation of fertilizers in waterways causes blooms of algae • - when algae die, bacteria eat them and consume all available oxygen!

40. Ocean pollution Eutrophication Dead zone in Lake Erie and Gulf of Mexico • Gulf zone varies from 1200 to 8400km² since 2000 • - indirect impacts cover 20,000km² • How can it be reduced?

42. Ocean pollution Trash Very large amounts of plastics and chemicals exist in the oceans – perhaps 3.5 million tons • Vastly underestimated by at least 2.5X, perhaps up to 27X • Great Pacific garbage patch?