1. Epipelagic Zone

3. Major Ocean Currents
What drive the currents?

4. Surface Winds

5. Currents The surface currents are caused by the winds
Only a small amount of energy is transferred (2%), so even fast, hard winds don’t get the currents moving too fast.
But things don’t necessarily move in the way you would expect…

7. Ekman Spiral Just like wind, water is deflected by the Coriolis effect
As energy goes down, water is bent towards the right (in N. Hemisphere)

8. Upwelling
Coastal-
Equatorial

10. Deep Ocean Currents

11. Figure 15.02
PELAGIC ANIMALS

13. The Microbial Web

14. Primary Productivity 6CO2 + 6H2O = C6H12O6 + 6O2
With rare (relatively) exceptions, all energy comes into the system via this pathway.
Gross PP – respiration =
Net Production
Many different measurement techniques for PP

15. Phytoplankton Production
What determines the productivity of an area? Two things…

16. Light in the ocean “White” light is made of all the colors

17. Physical- Light Variation in wavelengths through water
Compensation Depth ≈ 1% surface intensity
PAR- Photosynthetically Available Radiation
Count available photons, not just all wavelengths

18. This scattering and absorption impact the colors differently
Where does the light go?
Light is Scattered by:
Suspended particles (Sediment “soil”, plankton, etc.)
Dissolved material
Light is Absorbed by:
Phytoplankton: used in photosynthesis, converted to chemical energy
Water molecules: converted to heat
In the ocean
scattered=reflected
Diagram!!!
As we know, light is different colors, and the colors are handled at different rates
, so the color spectrum shifts towards the blue.
This scattering and absorption
impact the colors differently

19. Measuring Water Clarity
Secchi Disk
Other more complicated methods

20. So…Why is the ocean blue?
The rates of scattering and absorption are LOWEST for blue, so blue light makes it down to greater depths and is more available for reflecting back to the surface.

21. Importance of light in the sea
Sunlight absorbed by the water is converted to heat.
This heat warms the upper portions of the water.
It also provides the energy for evaporation and the winds.
Photosynthesizing organisms (“plants”) are the main source of the food in the ocean!
The depth at which light penetrates the ocean controls the depth to which these organisms can occur.
This zone is called the Photic Zone.
Photosyn organisms= plants etc.

22. Other biological impacts of light
Light influenced movement
Daily Vertical Migration
Many different groups of animals migrate up and down in the water with the changing light intensity.
They typically come up to the surface to feed at night, then swim back down at dawn to escape their predators.
Many swim 100s of meters a night.
Coloration of animals
In the open ocean there is no where to hide!
Many animals have evolved interesting ways to deal with this issue using color.

23. Intensity changes With time of day With other biomass With turbidity
With season

24. Seasonal Cycles in Primary Productivity
Winter Spring Summer Fall

25. Seasonal Cycles in Primary Productivity
Winter Spring Summer Fall

26. Seasonal Cycles in Primary Productivity

27. Primary production- biomass

28. What is the midwater? All pelagic or open water environments
Land
Ocean
surface
Epipelagic
200 m
Continental shelf
Mesopelagic
1000 m
Continental slope and rise
Bathypelagic
4000 m
All pelagic or open water environments
Largest and least known habitat on earth!
Abyssopelagic
Abyssal plain
6000 m
Hadal-
pelagic
Trench
10,000 m

30. Oxygen Minimum Zone

31. Deepsea Fish

33. Feeding

34. Avoiding Predation There is nowhere to hide!
Be big/mean or small/hidden
Transparency
Bioluminescence
Mucus
Counter-shading
Low Carbon value

35. Big and/or Mean...

36. …or Small...

37. …or Hidden!

38. Counter Shading

39. Counter shading

40. Bioluminescence ? ? ?

42. ?

43. Bioluminescence Coelenterazine General reaction Communication
Protection
Hiding
Hunting
Dinoflagellate
Photoproteins- modify/control the reaction
Firefly

44. “Milky Seas” 4 x 10e22 bacteria, or 40 billion trillion
they are about the same as the total number of bacteria estimated to occupy the upper 200 m of the ENTIRE open ocean, and 100 times more than the estimates for ALL bacteria in waters overlying the continental shelf
number of grains of sand it would take to cover the entire earth with a layer 10 cm thick

45. Dark Guts to Hide Luminescent Prey
“Burglar Alarm” Hypothesis