OceansCharacteristics
FeaturesLife Forms
The World’s Oceans
■ 70% of the Earth’s surface is covered by water.
■ The oceans contain 97% of the earth’s water.
■ All the oceans and seas are actually one continuous body of water.
■ Oceanographers are scientists who study the ocean and its processes.
Why is it important?• Oceans affect all
living things—even those far from the shore.
• Oceans provide a place for many organisms to live.
The Ocean
• Ocean water covers most of Earth.
– 97% or 97.5%of water on Earth is sea/salt water.
– All sections of the ocean are connected.
Oceans■ The oceans are the Atlantic,
Pacific, Indian, Arctic and Southern.
■ The Pacific Ocean is the largest ocean.
■ The area and volume of the Pacific Ocean are greater than the Atlantic and Indian combined.
Seas■ A sea is one of the largest bodies of saltwater, less than an ocean, found on the earth’s surface.
■ The Mediterranean, Arctic and Black Sea are really part of the Atlantic Ocean.
Properties of Ocean Water■ Ocean water is a mixture of
gases and solids dissolved in pure water.
■ Oceanographers believe oceans contain all the natural elements on Earth.
■ 85 of 90 have been found in the ocean.
Major Elements in the Ocean■ Ocean water is 96.5% pure water.
■ Chlorine (1.9) and sodium (1.1) make up the next largest concentration of elements.
■ Sodium chloride (NaCl) is table salt.
Salinity■ Salinity describes the amount of
dissolved salt in the ocean.■ Salinity is expressed in parts per
thousand or million
Salinity
The Dead Sea
Dissolved Gases in Ocean Water
■ The most abundant gases in ocean water are carbon dioxide, oxygen and nitrogen.
■ The amounts of these elements vary with depth. They are more abundant at the ocean’s surface where sunlight causes more plant life.
Temperature of Ocean Water■ Warm water holds less dissolved
gases than cold water.■ When ocean water is cold, like in
polar regions, it sinks and carries oxygen rich water to the ocean depths.
■ As a result, fish and other animals can live in deep parts of the ocean.
The Ocean has 3 main Temperature/Density layers
The upper (warm) and deep (cold) layers have the same temperature throughout.Between is the THERMOCLINE, which is is the transition layer between warmer mixed water at the ocean's surface and cooler deep water below. In the THERMOCLINE, the temperature decreases rapidly from the mixed layer temperature to the much colder deep water temperature.
Waves
• A wave in water is a rhythmic movement that carries energy through the water.
• Waves are caused by high winds blowing on top of the water.
Tides• Throughout a day, the water level at
the ocean’s edge changes. This rise and fall in sea level is called a TIDE.
• Tides are created by the gravitational attraction of Earth and the Moon and of Earth and the Sun.
• Most coastal locations have two high tides and two low tides a day. These highs and lows typically aren't equal.
Tides• Tides are
created by the gravitational attraction of Earth and the Moon and of Earth and the Sun.
∗ An Ocean Current is a mass of moving water in the
ocean
∗ Surface Currents originate from strong winds
blowing over the ocean that are set in motion by
uneven heating of Earth’s surface; cover large area.
∗ The upper 400 meters of the ocean
∗ Northern Hemisphere – Clockwise
∗ Southern Hemisphere – Counter Clockwise
∗ Ex. Gulf Stream
Ocean Currents
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Explain the movement of surface current using this diagramBecause the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. This is called the Coriolis effect
∗ Northern Hemisphere –
Clockwise
∗ Southern Hemisphere –
Counter Clockwise
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∗ Dense ocean water is by the poles, because it is
cold.
∗ The cold water travels along the ocean floor
Deep Currents
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Ocean Temperature decreases from the surface to the
bottom
Ocean Density increases from the surface to the
bottom
Ocean salinity increases from the surface to the
bottom
Ocean pressure increases from the surface to the
bottom
Ocean Water
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Dive down into the ocean even a few feet, though, and a noticeable change occurs. You can feel an increase of pressure on your eardrums. This is due to an increase in hydrostatic pressure, the force per unit area exerted by a liquid on an object.
The deeper you go under the sea, the greater the pressure of the water pushing down on you. For every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi.
In the deepest ocean, the pressure is equivalent to the weight of an elephant balanced on a postage stamp, or the equivalent of one person trying to support 50 jumbo jets!
How does pressure change with ocean depth?
Movement of Water■ Upwelling is the upward movement of cold water from the ocean depths.
Coastal UpwellingUpwelling brings up nutrients, tiny ocean organisms, minerals, and other nutrients from the deeper cold, densed layers of the water; without upwelling the surface of the ocean would be nutrient deficient.
Coastal DownwellingCoastal downwelling, the surface layer of warm, nutrient-deficient water thickens as water sinks. Downwelling reduces biological productivity and transports heat, dissolved materials, and surface waters rich in dissolved oxygen to greater depths.
El Nino
■ El Nino is an abnormal climate event that occurs every 2-7 years in the Pacific Ocean, causing changes in the winds, currents, and weather patterns.
Ocean Zones
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∗ The intertidal zone, sometimes referred to as the
“seashore”, is the area that is above water at low tide and
under water at high tide.
∗ This area can include many different types of habitats,
with many types of animals, such as crabs, starfish, sea
urchins, and numerous species of coral. ∗ Organisms living in the intertidal zone have adapted to an
environment of harsh extremes
∗ the temperature range can be anything from very hot
with full sun to near freezing in colder climates.
Intertidal Zone
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∗ Low Tide – The intertidal zone becomes dry
from low water levels.
∗ High Tide – The intertidal zone becomes
submerged with water.
Intertidal Zone
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∗ The neritic zone is the relatively shallow part of the
ocean between the low tide mark and the continental
shelf.
∗ The neritic zone receives plenty of sunlight with a
relatively stable temperature, making it suitable for
aquatic plant life.
∗ The consistent temperatures and low pressure allow
for marine life as small as plankton all the way to
large fish, to thrive.
Neritic Zone
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Oceanic Zone∗ It is the region OPEN SEA beyond the edge of the continental
shelf where the water measures 200 meters deep, or deeper.
∗ The oceanic zone has a wide array of undersea terrain,
including crevices that are often deeper than Mount Everest is
tall, as well as deep-sea volcanoes and ocean basins.
∗ While it is often difficult for life to sustain itself in this type of
environment, some species do thrive in the oceanic zone.
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Oceanic Zone∗ Oceanographers divide the oceanic zone into zones
according to how far down sunlight penetrates.
∗ Photic Zone: 0-200m
∗ Epipelagic (Sunlight)
∗ Aphotic Zone: 200-4,000m
∗ Mesopelagic (Twilight) & Bathypelagic (Midnight)
∗ Abyssal Zone: ≥ 4,000m
∗ Abyssopelagic (The Abyss) & Hadalpelagic (The
Trenches)38
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The Ocean Floor■ The ocean floor has higher
mountains, deeper canyons, and larger flatter plains.
■ Earthquakes occur more often.■ The rocks are very different.■ The crust is thinner.
The Ocean Floor
Continental Shelf■ The continental shelf is the
gradually sloping end of a continent that extends under the ocean.
■ The ocean covering the continental shelf can be as deep as 350 m.
■ Large mineral, oil and natural gas deposits are found here.
Continental Slope■ At the edge of the continental
shelf, the ocean floor plunges steeply 4 to 5 kilometers.
■ The continental slope extends from the outer edge of the continental shelf down to the ocean floor.
Abyssal Plains■ Large, flat areas on the ocean
floor are called abyssal plains.■ The abyssal plains are larger in
the Atlantic and Indian than in the Pacific due to the deposition of sediments by large rivers.
■ The Pacific Ocean has large cracks that trap sediments and result in smaller abyssal plains.
Abyssal Plains■ Abyssal plains are close to the
continent and are made of mud, sand and silt.
■ Farther out on the abyssal plains, some of them contain the remains of tiny organisms that form ooze.
■ Where ocean life is not abundant, the floor of the ocean is covered with red clay.
Seamounts and Guyots■ Seamounts are underwater volcanic
mountains that rise more than 100 meters above the ocean floor. Most have been found in the Pacific Ocean.
■ Some seamounts reach above the surface of the water to form islands, like the Azores in the Atlantic and the Hawaiian islands in the Pacific.
■ Guyots are flat-topped seamounts.
Trenches■ Trenches are the
deepest parts of the ocean found along the edge of the ocean floor.
■ The Mariana Trench in the Pacific Ocean contains the deepest spot (1100 meters) on Earth known as Challenger Deep.
Mid-ocean Ridges• A mid-ocean ridge is the area in an ocean
basin where new ocean floor is formed.■ The mid-ocean ridges form an almost
continuous mountain belt that extends from the Arctic Ocean down through the middle of the Atlantic Ocean around Africa into the Indian Ocean and across the Pacific Ocean.
■ In the Atlantic it is called the mid-Atlantic Ridge and in the Pacific, the Pacific-Antarctica Ridge.
∗ The Mariana Trench or
Marianas Trench is the
deepest part of the world's
oceans. It is located in the
western Pacific Ocean, to the
east of the Mariana Islands
∗ http://www.youtube.com/wat
ch?v=Y2tm40uMhDI
∗ http://www.virginoceanic.com
/
Mariana Trench
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∗ Areas of the sea floor, where hot water, heated by
magma, rushes out
Hydrothermal Vent
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The process by which certain microbes create energy by mediating chemical reactions. So the animals that live around hydrothermal vents make their living from the chemicals coming out of the seafloor in the vent fluids!
Because they are a local food source, hydrothermal vents typically have high biomass, in stark contrast to the very sparse distribution of animals outside of vent areas where animals are dependent on food dropping down from above.
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Chemosynthesis
Ocean Life Zones■ The plant and animal life in the
ocean is affected by several factors.
■ One factor is the amount of sunlight that penetrates the ocean.
■ Another factor is the temperature of the ocean water.
■ Water pressure is also a factor.
Major Groups of Ocean Life■ Plants and animals in the
ocean are classified into three major groups based on their habits and the depth of the water in which they live.
■ The three major groups are plankton, nekton and benthos.
Plankton■ Plankton float at or near the surface
where sunlight can penetrate.■ Phytoplankton and Zooplankton■ Most of the plankton are very small,
such as algae.■ These organisms drift with the
currents or tides.■ Plankton are the main food for many
larger organisms. They account for most of the organisms in the ocean.
Plankton■ Jellyfish, which float on the ocean surface, is one example of plankton.
Nekton■ Whales, seals, dolphins, squid
octopuses, barracuda and other fish are all nekton.
■ Nekton are free-swimming organisms that feed on other nekton as well as on plankton.
■ Many have adaptations enabling them to function at depths that have great pressure and no light using Bioluminescence
Nekton■ This beautifully colored fish is
classified as nekton.
Benthos
■ Organisms that live on the ocean floor are benthos.
■ Crabs, and lobster are just a few examples of benthos.
■ The deep bottom environments are sparsely populated with benthos.
■ Some benthos are plants that live on the ocean floor in shallow waters where sun can penetrate.
Benthos■ A starfish is an example of benthos.
Ocean Exploration
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If we’ve never really explored the
deepest parts of the ocean, how do we
know what the seafloor looks like?
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Divers
∗ Deep sea divers were the very first methods of exploring the ocean.
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∗ Sonar = SOund Navigation And Ranging
∗ A system that sends sound pings to measure the
distance between objects in water
Sonar
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∗ Satellites, sonar, and divers only scratch the surface
of the oceans. Submersibles alone enable us to
explore the abyssal depths.
∗ Submersible are capable of meeting the many
challenges that the deep sea imposes upon
explorers.
∗ Main types of submersibles:
∗ Submarines
∗ ROV (remotely operated vehicle)
∗ Underwater Habitat
Submersibles
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Remotely Operated Vehicle ROV
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Underwater Habitat
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Humans & Our Oceans
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Overfishing ∗ When people catch
fish at a faster rate
than they reproduce
http://www.youtube.com/watch?v=cbN161yBBGA
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By-Catch
∗ Are the fish
that are caught
by a net, but
are thrown
back to sea,
30% of fish go
back to sea,
dead or alive
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Ocean Pollution ∗ 44% of Ocean pollution comes from
runoff
∗ 33% is from air pollution
∗ 12% is from shipping and oil spills
∗ 10% is from ocean dumping
∗ 1% is from offshore drilling
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Ocean Pollution
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