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Today’s Outline
Ecology (BIOL 250)
Lecture 4: Life in Water
Climate - Overv iew
Solar radiation
Air circulati on
Life in Water
Hydraulic Cycle
Oceans
Lakes
Rivers
Over 71% of the earth’s surface is covered
by water:
Oceans contain 97%.
Polar ice caps and glaciers contain 2%.
Freshwater in lakes, streams, and ground water
make up less than 1%.
The Hydrologic Cycle
The Hydrologic Cycle
Distribution of water is not static:
Heat
Evaporation
Clouds
Precipitation
Turnover time is the time required for the
entire volume of a reservoir to be renewed .
Atmosphere 9 days
Rivers 12-20 days
Oceans 3,100 years
Deep Blue Sea - The Ocean
Average Depth
Pacific - 4,000 m
Atlantic - 3,900 m
Indian - 3,900 m
Undersea Trenches
Marianas - 10,000 m deep
Would engulf Mt. Everest with 2 km to spare.
Neritic province:
Coast to margin of continental shelf.
Oceanic province:
Everything else.
Pelagic Zone
Epipelagic 0 - 200 m
Mesopelagic 200 - 1,000 m
Bathypelagic 1,000 - 4,000 m
Abyssal 4,000 - 6,000 m
Hadal 6,000 + m
Benthic zone
Habitat on bottom of ocean.
The Oceans
Temperature
Sunlight increases velocity of water.
Rapid motion decreases density, thus warm water
floats on top of cooler water.
Thermocline: Layer of water through which
temperature changes rapidly with depth.
Creates thermal stratification.
Light
Approximately 80% of solar energy striking the
ocean is absorbed in first 10 m.
Very little, if any penetrates past 600 m.
•Leaves approximately 3,400 m of deep black water with
only light produced by bioluminescence.
The Oceans
