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Ecology Lecture 4: Life in Water and the Hydrologic Cycle - Prof. Brent Blair, Study notes of Ecology and Environment

An overview of the ecology (biol 250) lecture 4, focusing on life in water and the hydrologic cycle. Topics include climate, solar radiation, air circulation, the hydrologic cycle, the ocean's depths, temperature, and physical conditions. Discussions on oceanic provinces, pelagic zones, benthic zones, oceanic circulation, and shallow marine waters are also included.

Typology: Study notes

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Uploaded on 08/16/2009

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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
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Today’s Outline

Ecology (BIOL 250)

Lecture 4: Life in Water

Climate - Overview Solar radiation Air circulation 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

Ocean - Physical Conditions Water Movements

Oceans are never still.

Wind-driven surface currents across open ocean create gyres that move right in the Northern Hemisphere and left in the Southern Hemisphere. Deepwater currents cause upwelling. Oceanic Circulation Ocean Oxygen Changes Shallow Marine Waters  Reef Categories  Fringing reefs: Hug shore of continents.  Barrier reefs: Stands between open sea and lagoon.  Coral atolls: Coral inlets built up from submerged ocean island.  Kelp Beds  Structure similar to terrestrial forests.  Canopy at water’s surface. Shallow Marine Waters  Reefs and kelp beds both grow in surface waters with sufficient light for photosynthesis.  Both limited by temperature.  Currents deliver oxygen and nutrients, and remove waste products.  Biological productivity may depend on flushing action.  Reefs and kelp beds among most productive and diverse ecosystems.  Coral reefs appear to be in decline around the world!  WHY?  Coral reef decline in Florida  (1) Diversion of water causing an increase in salinity  (2) water quality decline due to fertilizer, pesticide, and herbicide runoff.  (3) increasing water temperature due to global warming.  (4) perhaps some combination of factors or other unknown issue. Shallow Marine Waters