1. Zonation in the Ocean

3. Marine Zones
Learning Objective: Understand how the ocean is divided into zones, and why those zones exist.

4. Vocabulary Marine: ocean (salt water)
Salinity: the measurement of salt content in the water
Climate: the year-to-year weather patterns
Ecosystem: A number of species living and interacting with each other as well as their environment

5. Think-Pair-Share
Is every part of the ocean the same?
Why or why not?

6. The ocean is a very big place!
Some parts of the ocean are warm, others cold.
Some parts are full of life, and in others life is scarce.
Some areas are more influenced by waves, light, salt and other nutrients than others
Scientists needed ways to divide up the ocean into areas based on these different factors

7. Zones based on Climate
The ocean, like the land, can be divided into regions based on climate (year-to-year patterns)

8. Polar Marine Ecosystems
Found at both the Arctic and Antarctic poles.
The least salty ocean, but salinity levels are consistent year-round
Temperatures are very cold year-round (the water is about 28o F)
The Arctic Ocean

9. Temperate Marine Regions
The “middle” of each hemisphere (where we live)
Water temperatures vary greatly with seasons
Salinity varies greatly with seasons

10. Tropical Marine Regions
Found only around the equator
Saltiest water
Warmest water, year-round
Very little change in temperatures

11. Annual Mean Surface Temperatures (Celcius)

12. Salinity is highly impacted by currents

13. Local Marine Regions
In a particular area, the ocean can be divided up into several different regions, based on different factors:
Light
Proximity to the shore
Proximity to the bottom
Depth/Salinity/Temperature

14. Light Photic zone = the region of the ocean that light can reach.
In the open ocean, the Photic Zone ends at about 200 m (about 650 feet)
Aphotic zone = the region of the ocean where light cannot reach, but life here relies on nutrients from above
Abyssal zone = the region at the very bottom of only some parts of the ocean which does not rely on food generated through photosynthesis.

19. Proximity to the Shore
Intertidal zone = the area of the ocean that touches the shore. This area changes with the tides.
Neritic zone = the relatively shallow area of ocean near the shore
Oceanic or Pelagic zone = the part of the ocean that never comes into contact with land.
Pelagic Bait Ball

24. Proximity to the Bottom
Benthic Zone = The area of water that is on or near the bottom
ROV on the ocean floor
Pelagic Zone = The area of water that never comes into contact with the bottom or the shore

28. Regions based on Depth, Temperature and Salinity

29. Regions based on Depth, Temperature, and Salinity
Epipelagic – The Sunlight Zone
Epi = Above
Mesopelagic – The Twilight Zone
Meso = Middle
Bathypelagic – The Midnight Zone
Bathy = Deep
Abyssopelagic – The Abyss
Abysso = Bottomless
Hadalpelagic – The Trenches
Hadal = Hell (Hades)
Baiting the Ocean Floor

31. Compare and Share
Partner A: How would life be different for an organism living in the benthic zone to an organism in the pelagic zone?
Partner B: How would life be different for an organism living in the photic zone to an organism living in the aphotic zone?

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