Our OCEANs

Salinity

• Salinity is the amount of salt dissolved in the water.• Salts in the ocean come from minerals that have

washed off of rocks as rivers make their way to the ocean.

• The salinity of the ocean varies from place to place (depending on how much freshwater is being added by heavy rains or rivers) but on average it is around 3.5%.

Temperature• The temperature of ocean water varies depending

on how much sun the water receives.• Water at the poles is MUCH cooler (and therefore

DENSER) than water near the equator due to the tilt of the Earth’s axis.

• The sun’s rays travel slower and they bend (scatter) in water. At a certain depth (1,000 meters or 3,280 feet) sunlight can penetrate no further and the water becomes extremely cold

(0 °C/32 °F to 6 °C/43 °F)

Dissolved Gases• Carbon dioxide is about 60 times as plentiful in

the oceans as in the air. • Oxygen is scarcer in seawater than in air.• Just as in freshwater, the amount of oxygen in

seawater is affected by the water temperature; cooler water has more dissolved oxygen than warm water.

• Gas exchange between plants and animals occurs in the ocean just as it does on land.

PressurePressure is the amount of force applied over an area.

Volume & pressure are indirectly related V PTemperature & pressure are directly related T PTemperature & volumeare directly related T P

• Water is quite heavy (about 8 lbs per gallon) so it can apply a great deal of force.

• The deeper you go into the water the higher the pressure.

• Since humans are full of dissolved gases that can come out of solution (and migrate to any part of the body), they can only safely descend to ~ 40 meters/120 ft.

Water Pressure

Currents

Currents are large streams of water within the ocean that provide the following things for living organisms:

• Food• Transportation• Suitable climates

Surface Currents• Surface currents are

driven by the wind.• They are curved around

due to the placement of the continents and spinning of Earth on its axis (this is known as the Coriolis Effect).

• Surface currents carry warm water from the equator to the poles.

Deep Currents•Deep currents are caused by differences in the density of ocean water.

• The density of water depends on its temperature & salinity.

• As ice forms near the poles, the salinity of the water increases from the salt left behind during freezing. As its temperature decreases and its salinity increases, the water becomes denser and sinks.

• Deep currents carry cool water from the poles to the equator.

The Great Ocean Conveyor BeltThe Earth’s climate exists as it does due to a continuous flow of ocean water in what is known as the great ocean conveyor belt.

Upwelling• At the shoreline, as winds blow away the warm

surface water, cold water rises to replace it. • Upwelling brings up tiny ocean organisms, minerals,

and other nutrients from the deeper layers of the water therefore zones of upwelling are usually home to huge schools of fish.

Ocean Pollution• At least 85 percent of ocean pollution,

including pollutants such as oil, toxic wastes, and medical wastes, comes from activities on land, near the coasts.

• Sensitive coastal ecosystems, such as coral reefs, are the most effected by pollution.

Oil Spills• Each year, about 37 million gallons of oil from

tanker accidents are spilled into the ocean.• Such oil spills have dramatic effects, but they are

responsible for only about 5 percent of oil pollution in the oceans. Most of the oil that pollutes the oceans comes from cities and towns.

• Limiting these nonpoint-sources of pollution would go a long way toward keeping the oceans clean.

Cases of Oil Spill in History

• In 1989, the Exxon Valdez oil tanker went off course, hit rocks, and released large amounts of oil into Alaska’s Prince William Sound.

• This accident cost some US$2.1 billion to clean up.

Photo of tanker oil spill in Prince William Sound, Alaska.

Photo of oil on the beach.

Cases of Oil Spill in History

In 2002, the oil tanker Prestige sank off the coast of Spain and over two years leaked twice as much oil as the Exxon Valdez.

Cleaning up the Oil

Spill!

Ocean Exploration

There are 3 main obstacles to ocean exploration:• Lack of LIGHT• Extreme COLD temperatures• Extreme PRESSURE

Why?If it’s so difficult, why do we even need to explore the ocean? Here are just a few important reasons:• We need to understand how to sustain fisheries

that are critical to human survival.• The ocean’s energy producers (diatoms) absorb

the majority of our CO2 and creates more than 60% of the oxygen we breathe.

• Overcoming the challenges to ocean exploration results in new technologies that can be applied to solving problems on land.

• The oceans currents are responsible for driving our climate.

Ocean Acidification

Anthropogenic CO2 is absorbed by the ocean & reacts with H2O to form carbonic acid (H2CO3) effectively stealing away the calcium carbonate (CO3) that shellfish and corals need to build their homes.

SOund Navigation And Ranging• Scientists send sound waves, or

pulses, down from a ship.• Sound waves moves through

water, bounce off ocean floor, and return to the ship.– Deeper water = longer trips– Depth calculated by

multiplying half the travel time by the speed of sound in water (1500 m/s).

SONAR

• Continental Shelf: begins at the shoreline and slopes gently down toward the open ocean.

• Continental Slope: begins at the edge of the continental shelf.

• Continental Rise: the base of the continental slope, made of large piles of sediment.

• Abyssal Plain: the broad, flat part of the deep-ocean basin.

The Ocean Floor

Marine life is classified by how it moves and where it lives:

• PlanktonFree-floating microscopic organisms drifting in the

waters of aquatic environments.Phytoplankton – plant likeZooplankton – animal like

• NektonOrganisms swimming actively in the open ocean.Ex: Whales, dolphins, sea lions, sharks, and other free-

swimming fish species.• BenthosOrganisms living on or attached to the ocean floor.Ex: Crabs, starfish, worms, coral, sponges, seaweed,

clams, oysters.

Ocean Life

The ocean floor is divided into ecological zones based on where different organisms live.

Ocean Habitats

Intertidal Zone• The intertidal zone is where the ocean meets the

shore between the low-tide and high-tide limits.• Includes: salt marsh, beach, rocky shoreline,

ESTUARIES• This area is not covered by water all the time and

strong waves can batter the creatures that live there.

Intertidal Zone

The Neritic Zone• Extends from the low-tide line out to the edge of

the continental shelf.• HUGE variety of organisms - lots of nekton• Sunlight and nutrients (from nearby land and

upwelling) enable the growth of large plantlike algae which serve as a food source and shelter for other organisms.

NEKTON

• A very special neritic zone habitat in warm, shallow water with the largest concentration of marine life mainly because of abundant sunlight.

• Millions of tiny coral animals build limestone homes/shells. When they die other new corals build on them creating the “reef.”

• Atolls are islands made of coral that have raised up above sealevel.

Coral Reefs

• Kelp are giant sheets of seaweed (sea plants). It grows in abundance in the neritic zone due to the abundant sunlight.

• Many marine organisms call kelp forests home including countless species of fish, sea otters & urchins.

Kelp Forest

The Open-Ocean Zone• Extends from the continental shelf down into the

abyssal plain (and mid-ocean trenches).• Sunlight only penetrates into the surface zone

which is where the majority of the organisms live.• Organisms that live in the deep, dark abyss subsist

mainly on what drifts down from the surface zone.

• Hydrothermal vents in the trenches create unique habitats.

• The DRIFTERS that move with the ocean current.• Phytoplankton are plant-like so they create oxygen;

they supply 60% of the oxygen we breathe.• Zooplankton are animal – like and they eat the

phytoplankton.• Plankton are the base or foundation of all marine

food webs; without them life in the ocean would not exist.

Plankton

Zooplankton(Animal-like)

Phytoplankton(plant-like)

Krill

• Bioluminescence is a chemical reaction that produces light.

• It is rare on land; seen mostly just in fireflies and mushrooms but VERY common in the ocean, especially at great depths.

• It is used for defense and attracting food, & mates.

Bioluminescence

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