Oceanography

I. Introduction to Oceans A. Oceanography – the study and exploration of the world’s oceans. A. Oceanography – the study and exploration of the world’s oceans. B. Formation of the ocean waters – water vapor and condensation of vapor as rain in the ocean basins B. Formation of the ocean waters – water vapor and condensation of vapor as rain in the ocean basins

II. Properties of Ocean Water A. Composition of Ocean Water 1. H 2 O is 96.5 % 1. H 2 O is 96.5 % 2. other elements is 3.5% 2. other elements is 3.5% 3. salinity – dissolved salt content of a body of water 3. salinity – dissolved salt content of a body of water B. Temperature of Ocean Water 1. as temperature increases, density decreases 1. as temperature increases, density decreases 2. surface temperature – from 2 O C (Arctic) to 28 O C (equator) 2. surface temperature – from 2 O C (Arctic) to 28 O C (equator) 3. subsurface temperature – from 1 O C to 3 O C 3. subsurface temperature – from 1 O C to 3 O C  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 D. Color – natural color is blue, but can be affected by pollutants or microscopic plants

III. Oceans – a continuous body of saltwater that covers approximately 70% of the Earth A. PACIFIC – the largest, deepest, covers 1/3 of the Earth’s surface, contains approximately ½ of the Earth’s 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

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 1. phytoplankton – plant plankton – example – diatoms 2. zooplankton – animal-like plankton example- protists, crustaceans 2. zooplankton – animal-like plankton example- protists, crustaceans B. Nekton – organisms that swim in the ocean freely. examples – larger fish, squid, sea turtles, whales 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 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 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 2. pelagic environment – ecological realm that includes the entire ocean water column

Threats to the Ocean  The oceans are huge but are becoming increasingly more polluted.  Overfishing is also destroying fish populations.

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

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 salt salinity salt

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

Estuaries

Coral Reef  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. limestone diverse warm light

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.

Coral Reefs

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

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.

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.

To understand upwelling, 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. s1904/es1904page01.cfm?chapter_no=visualization

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.

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.

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?

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

Even though upwelling areas account for only 1% of the ocean surface, they support 50% of the worlds fisheries.

Phytoplankton come in many shapes and forms. Collectively they form the base of oceanic food webs. Without upwelling many of the world’s fisheries would not thrive.

Some climatic events can reduce upwellings. El Nino ~

Along Peru’s 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.

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.El Niño

VI. Instruments of Investigation A. SCUBA – Self-Contained Underwater Breathing Apparatus. Tanks of compressed air strapped on a diver’s back and connected by hoses to a mouthpiece for breathing B. SONAR – Sound Navigation And Radar. Methods of mapping the ocean floor by transmission and reflection of sound waves

Instruments of Investigation (cont.) C. Geostationary operational Environmental Satellites (GOES) orbit the Earth at 22,000 miles. They are highly advanced observation platforms supplying detailed imagery of the Earth’s oceans D. Underwater Laboratories – The Aquarius Underwater Laboratory is the only undersea laboratory dedicated to marine science operating in the world. Aquarius provides life support systems that allow scientists to live and work underwater, in reasonably comfortable living quarters, with sophisticated research capabilities

Instruments of Investigation (cont.) E. Deep ocean submersibles – Over the last few decades, engineers have developed technologies capable of meeting the many challenges that the deep sea imposes upon explorers.

VIII. Waves and Wave Action A. Causes – wind and earthquakes B. Characteristics of Waves 1. crest – highest point of a wave 1. crest – highest point of a wave 2. trough – lowest point of a wave 2. trough – lowest point of a wave 3. wavelength – distance between 2 adjacent wave crests or wave troughs 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 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 5. wave period – time between the passage of two wave crests(or troughs) at a fixed point

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

10. swells – formation of long-wavelength surface waves, more stable then normal wind waves, travel long distance, 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 12. shallow water waves – waves that reach water shallower than ½ their wave height

C. Tsunami – a great sea wave caused especially by undersea movement or volcanic eruption D. storm surge – an offshore rise of water associated with a low pressure weather system D. storm surge – an offshore rise of water associated with a low pressure weather system caused by high winds pushing on the oceans surface E. undertow - Strong undercurrent flowing in a different direction from the surface current. F. longshore current – an ocean current running parrallel to the shore

IX. Tides - define A.Tidal range – the vertical difference between the high tide and the succeeding low tide 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 2. low tides – occur twice a day, when the two areas of the earth are not experiencing high tide B. Spring Tide – The exceptionally high and low tide that occur at the time of the new moon or the full moon when the sun, moon, and earth are approximately aligned C. Neap Tide - During the moon's quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide GOOGLE Moon Tides

X. Currents and Climates A. Surface currents – Horizontal movement of seawater in the ocean 1. are driven by winds and can affect movement to a depth of several hundred meters 1. are driven by winds and can affect movement to a depth of several hundred meters 2. either cool or warm the air above it influencing the climate of the land near the coast (example – Gulf Stream) 2. either cool or warm the air above it influencing the climate of the land near the coast (example – Gulf Stream) B. Ocean Currents 1. Deep Currents 2. Upwellings

At the shoreline  Water becomes shallow, wave height increases because wave length decreases  Waves become steeper, then collapse (breakers)

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

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

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

Headlands may be eroded back leaving a remnant (stack)

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

Coastal deposition  Result of longshore drift and a lot of sediment  = produces extensions of deposit from the shoreline

 May grow across a bay (baymouth bar)  May link an island to the main land (tombolo) spit = curved extension

Types of Coastline Submergence and emergence changes coastlines Pocket beaches

Emergent coast  Uplifted land surface  Coastal landforms are found above present sea level a wave-cut platform when elevated - uplifted marine terrace

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