Oceanography I. Introduction to Oceans A. Oceanography the study and exploration of the worlds 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 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 Earths surface, contains approximately 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 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 worlds 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. 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. 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. 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 worlds fisheries would not thrive. Some climatic events can reduce upwellings. El Nino ~ 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. What is La Nia? La Nia is characterized by unusually cold ocean temperatures in the Equatorial Pacific, compared to El Nio, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific.El Nio VII. 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 6. wave height vertical distance between crest and trough of a wave 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 than normal wind waves and formed by storms 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 their wavelength 11. deep water waves waves that move in water deeper than their wavelength 12. shallow water waves waves that reach water shallower than their wave height 12. shallow water waves waves that reach water shallower than their wave height C. Tsunami a great sea wave caused especially by undersea earth movement or volcanic eruption 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 VIII. Tides A. 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 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 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 IX. 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