 Divisions of Marine Environment
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Benthic and Pelagic
I. Benthic- Refers to Ocean Bottom
- Divided into Littoral and Deep Ocean System
Littoral- Deals with ocean bottom close to continent or continental shelf, nutrient rich zone
(upwellings)
o Supralittoral- almost always exposed, very rugged, immersed only during periods of high
tide and storm produced waves
o Eulittoral- region that is periodically exposed @ low tide, extends to depth of 40-60 meters,
Highly varied marine life
Best studied marine biological environment, especially by divers
The width of this zone depends on tidal influence and the slope of the ocean bottom
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o Sublittoral-outer part of littoral system
Extends to depth of 200m or more
Going from Eulittoral to Sublittoral there is a decrease in plant life and an increase in animal life
Generally conforms to shape of continental shelf
Highly exploited by fisherman
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Deep Sea System – deals with the deep ocean floor
o Devoid of higher plant life (no light), (however contains bacteria living at the thermal vents)
o Oceanographic conditions generally uniform
Decreasing Temp. w/ depth
Salinity essentially constant
Pressure increase 1atm with 10m (33 ft)
Divided into
Bathyal: 200-2000m
Abyssal: 2000-6000m; most sea floor
Hadal: below 6000m; deep ocean trenches
Little known because of the sampling difficulty
o Relatively little is known about the biological environment of the deep sea
o There are many Bizarre forms
o Food is less abundant as the littoral system, b/c decomposition and disintegration.
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II. Pelagic- refers to the water
- Divided into Nearshore (neritic system and
offshore (ocean system)
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Neritic system – close to shore
o Large diversity of conditions: temp, salinity, and nutrients
o Upwelling mixes nutrients, more plankton attracts more life forms
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Oceanic System – open ocean
o Euphotic zone- with light <100 m (328 ft)
o Aphotic zone – no light > 100 m (328ft)