Vertical zonation of ocean –
Different zones moving from the surface of the water to the ocean floor (along the water column)
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Based on benthic environment
- Intertidal zone – Includes areas that are exposed to tides
- Littoral zone – Extends from the high tide line down to about 200m at the edge of the continental shelf. Often the shallowest part of the littoral zone is sub-divided on the degree of exposure by tides – A supralittoral zone is an environment moistened by sea spray only. The portion of the littoral zone between the high tide line and 60 m is often distinguished as the eulittoral zone. It receives enough sunlight to support active coral reef building and algal growth. The remaining depth below is called sublittoral zone.
- Deep sea:
- Archibenthic zone – Extends from the edge of the continental shelf down to about 1000m. It includes the edge of the continental margin and upper part of the continental slope. The water in this benthic zone is lightless, cold and usually oxygen-deficient. In many parts of the ocean, the oxygen minimum intersects the bottom of the seafloor across this depth zone.
- Bathys benthic zone – Extends from 1000-4000m depth and includes most of the continental slope. The water here is lightless and cold. There is low biological productivity. Submarine canyons and currents cut across this region. The top of most of the mid-ocean ridges fall within this depth-range. This part of the ocean is bathed in water with greater oxygen content than the overlying areas.
- Abyssobenthic zone – Extends from 4000-6000m depth and includes the deep ocean floor, seamounts, abyssal hills and flanks of the mid-ocean ridges. There is little material input from land into this environment. It is a cold and dark zone.
- Hadobenthic zone – Includes the unusually deep parts of the seafloor found in trenches. Little is known about the characteristics of this zone. This zone is also cold and dark.
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Based on depth
- Epipelagic zone – Extends from the shoreline down to 200m. Productivity is quite high in the presence of nutrients due to availability of sunlight. Water is warm.
- Mesopelagic zone – Extends from 200-1000m. Little light is available. Water temperature is cold and oxygen poor.
- Bathypelagic zone – Extends from 1000-4000m. There is no light excluding that from bioluminescent creatures and occasional lava flows. Biological productivity is low and water is cold.
- Abyssopelagic zone – Extends from 4000-6000m depth. No light available and cold water.
- Hadopelagic zone – Extends from 6000, to the deepest depths in the ocean. No light available and cold water. This area is covered with deep, narrow trenches.
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Based on the shape of the ocean floor
- Continental shelf – It is the shallow platform extending from the shore line down to about 200 m depth. The continental shelf is the submerged edge of the continent. The lower edge of this shelf is called continental break.
- Continental slope – Marks the end of underlying oceanic crust. The continental slope is the steep are between the continental shelf and rise. Deep submarine canyons carry terrestrial materials across the continental shelf and slope into the deep sea.
- Continental rise – It is the area sloping gently seaward beyond the continental slope.
- Abyssal plain – It is the deep area of the sea floor beyond the continental rise.
- Deep sea trench – The trenches are narrow and abnormally deep parts of the ocean floor marking zones of subduction. The deepest point of the ocean is the Mariana Trench.
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Based on light availability
- Euphotic zone – In this zone there is enough sunlight penetration for photosynthesis to take place. Thickness of this zone depends on the turbidity of the water column. It can extend down to 200m in clear water areas.
- Disphotic zone – There is light penetration but not enough for photosynthesis.
- Aphotic zone – No sunlight penetration
http://earthguide.ucsd.edu/earthguide/diagrams/vertical/verticalzonation.html