Oceanography

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Oceanography
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I. Introduction to Oceans

• A. Oceanography the study and exploration of
  the worlds oceans.
• B. Formation of the ocean waters water vapor
  and condensation of vapor as rain in the ocean
  basins

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II. Properties of Ocean Water

• A. Composition of Ocean Water
• 1. H2O is 96.5
• 2. other elements is 3.5
• 3. salinity dissolved salt content of a
  body of water
• B. Temperature of Ocean Water
• 1. as temperature increases, density
  decreases
• 2. surface temperature from 2OC (Arctic) to
  28OC (equator)
• 3. subsurface temperature from 1OC to 3OC
• 4. thermocline zone where there is a sharp
  difference in temperature between surface and
  deeper water.
• C. Pressure pressure increases as the ocean
  depths increases
• D. Color natural color is blue, but can be
  affected by pollutants or microscopic plants

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III. Oceans a continuous body of saltwater that
covers approximately 70 of the Earth

• A. PACIFIC the largest, deepest, covers 1/3 of
  the Earths surface, contains approximately ½ of
  the Earths water.
• B. ATLANTIC second largest, contains
  Mediterranean, Caribbean and North Seas,
  shallower than Pacific and Indian
• C. INDIAN - deeper than the Atlantic, shallower
  than the Pacific
• D. ARCTIC surrounds the geographic North Pole

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IV. Life in the Ocean

• A. Plankton drifting organisms in aquatic
  environments (marine and freshwater). The base of
  the food web in these environments
• 1. phytoplankton plant plankton example
  diatoms
• 2. zooplankton animal-like plankton
  example- protists, crustaceans
• B. Nekton organisms that swim in the ocean
  freely.
• examples larger fish, squid, sea turtles,
  whales
• C. Benthos community of organisms that live on,
  in, or near the ocean floor
• examples crabs, coral, starfish, clams,
  sea anemones
• 1. benthic environment region near or at
  the bottom of a pond, lake, or ocean, including
  organisms that live there
• 2. pelagic environment ecological realm
  that includes the entire ocean water column

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Threats to the Ocean

• The oceans are huge but are becoming increasingly
  more polluted.
• Overfishing is also destroying fish populations.

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V. Marine Ecosystems

• Includes estuaries, coral reefs, oceans, and
  polar ecosystems
• Marine ecosystems contain dissolved _____.
• In oceans, lack of water is not a problem.
  Therefore, the types of organisms present are
  dependent upon __________, sunlight available,
  and ___________.

salt
temperature
nutrients
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Estuaries

• An ecosystem where _____ _____ from rivers and
  streams mixes with _____ _____ from the ocean.
• Estuaries contain plenty of light and nutrients
  which support large populations of plants and
  animals.
• Plants and animals that live in estuaries are
  able to tolerate variations in ________ because
  the _____ content of the water varies as the
  fresh and salt water mix.

fresh
water
water
salt
salinity
salt
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Threats to Estuaries

• Estuaries provide harbors, access to the ocean,
  and connections to rivers. As a result, many of
  the worlds largest cities are built on
  estuaries.
• Because of this, many estuaries have become
  polluted.

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Estuaries
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Coral Reef
limestone

• Coral reefs are __________ islands in the sea
  that are built by coral animals called polyps.
• Thousands of species of plants and animals live
  in the cracks and crevices of coral reefs, making
  coral reefs among the most ________ ecosystems on
  Earth.
• Corals can only live in _____ salt water where
  there is enough ______ for photosynthesis.
  Therefore, coral reefs are only found in shallow,
  tropical seas.

diverse
warm
light
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Threats to Coral Reefs

• If the water surrounding a reef is too hot or
  cold, or if fresh water drains into the water
  surrounding a reef, corals have trouble producing
  limestone.
• If the water is too muddy, too polluted, or too
  high in nutrients, algae that live within the
  corals will die or grow out of control and
  smother the corals.
• Oil spills, sewage, pesticide, and silt runoff
  have all been linked to coral reef destruction.

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Coral Reefs
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Polar Ecosystems

• The ice-covered polar caps can be considered
  marine ecosystems because nearly all food is
  provided by phytoplankton in the ocean.
• The ______ Pole is in the Artic Ocean and the
  ______ Pole is in Antarctica.
• ________ provides the main source of food at both
  poles.

North
South
Plankton
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Threats to Polar Ecosystems

• Oil extraction, tourism, and garbage are the
  worst threats to the polar ecosystems.
• Conservationists want these areas to become world
  wildlife refuges.

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VI. Upwellings
Upwelling refers to deep water that is brought to
the surface. Areas of upwelling are created by
surface winds that pull water away from an area.
This deficit of water on the surface invites
water to come up from deeper regions.
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To understand upwellings, you must be familiar
with how the Coriolis Effect affects ocean
surface currents. The Coriolis Effect acts on
moving water, because it is not attached to the
rotating Earth. As water flows over the rotating
earth, it appears to deflect to the right in the
Northern Hemisphere and the left in the Southern.
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The deep water that surfaces in upwelling is
cold by looking at Sea Surface Temperature maps
we can identify cool upwelled water versus hotter
surface water.
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Upwelled water also contains nutrients (nitrate,
phosphate, silicate) and dissolved gases (oxygen
and carbon dioxide) that are not utilized at
depth because of a lack of sunlight.Now on the
surface, these nutrients and gases help to fuel
photosynthesis by small algae called
phytoplankton.
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Phytoplankton photosynthesize using specialized
color pigments called chlorophyll. Thus, Ocean
Color maps are another way to identify areas of
upwelling. Where on this ocean color map are
high phytoplankton concentrations?
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Ecological and Economic effects of upwelling

• Upwelling leads to more phytoplankton
• More phytoplankton leads to more fish
• More fish lead to commercial fishing jobs and to
  more seafood

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Even though upwelling areas account for only 1
of the ocean surface, they support 50 of the
worlds fisheries.
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Phytoplankton come in many shapes and forms.
Collectively they form the base of oceanic food
webs.
Without upwelling many of the worlds fisheries
would not thrive.
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Some climatic events can reduce upwellings.

El Nino
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Along Perus coast, an El Nino event decreases
the coastal winds. Thus the upwelling from below
is slowed.
An El Nino condition results from weakened trade
winds in the western Pacific Ocean near
Indonesia, allowing piled-up warm water to flow
toward South America.
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What is La Niña?

• La Niña is characterized by unusually cold ocean
  temperatures in the Equatorial Pacific, compared
  to El Niño, which is characterized by unusually
  warm ocean temperatures in the Equatorial Pacific.

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VII. Waves and Wave Action

• A. Causes wind and earthquakes
• B. Characteristics of Waves
• 1. crest highest point of a wave
• 2. trough lowest point of a wave
• 3. wavelength distance between 2 adjacent
  wave crests or wave troughs
• 4. wave frequency the number of waves that
  pass a point in a certain amount of time
• 5. wave period time between the passage of
  two wave crests(or troughs) at a fixed point

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• 6. wave height vertical distance between
• crest and trough of a wave
• 7. breaker high wave crest that has been
  pulled down by gravity
• 8. surf area between the breaker zone and
  the shore
• 9. white caps wave crests breaking into
  white foam

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• 10. swells formation of long wavelength
  surface waves more stable than normal wind waves
  and formed by storms
• 11. deep water waves waves that move in water
  deeper than ½ their wavelength
• 12. shallow water waves waves that reach
  water shallower than ½ their wave height

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• C. Tsunami a great sea wave caused especially
  by undersea earth movement or volcanic eruption

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• D. Storm surge an offshore rise of water often
  associated with a low pressure weather system,
  typically tropical cyclones
• E. Undertow the current beneath the surface
  that sets seaward or along the beach when waves
  are breaking on the shore
• F. Longshore current an ocean current that
  moves parallel to the shore

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VIII. Tides

• Tidal range the vertical difference between
  high and low tides
• 1. high tides occur twice a day, when the
  ocean water bulges as a result of the
  gravitational pull of the overhead moon
• 2. low tides occur twice a day, when the
  two areas of the earth are not experiencing high
  tide
• B. Spring Tide exceptionally high and low tides
  that occur at the time of the full and new
  moons, when the sun, earth, and moon are
  approximately aligned
• C. Neap Tide times when the difference between
  high and low tide are minimized. Occur during
  quarter moons

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IX. At the shoreline

• Water becomes shallow, wave height increases
  because wave length decreases
• Waves become steeper, then collapse (breakers)

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Wave refraction

• Close to coast, water gets more shallow
• Waves are slowed down
• If waves arrive at an angle, one part is slower
  than the rest
• Causes waves to bend wave refraction

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• Waves arriving at bays are slow (deposition)
• At headlands, faster (erosion)

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• A sequence of features is produced as headlands
  are degraded
• Sea cliffs
• Waves erode base -undercutting

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• Headlands may be eroded back leaving a remnant
  (stack)

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Longshore drift

• Waves arrive at a coast at an angle (swash)
• Backwash returns at 90 degrees

Sand is moved along the beach longshore drift
or longshore current
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Coastal deposition

• Result of longshore drift and a lot of sediment
• produces extensions of deposit from the
  shoreline

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spit curved extension

• May grow across a bay (baymouth bar)
• May link an island to the main land (tombolo)

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Types of Coastline
Submergence and emergence changes coastlines
Pocket beaches
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Emergent coast

• Uplifted land surface
• Coastal landforms are found above present sea
  level

a wave-cut platform when elevated - uplifted
marine terrace
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Barrier Island Coasts

• Occur on low lying coasts with gentle gradients
• BARRIER ISLANDS - low ridges of sand built by
  waves
• behind the islands are lagoons
• shallow water with tidal deposits
• TIDAL INLETS - gaps between the islands