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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