Unit 5: Oceans

What percentage of Earth's surface do oceans cover?

About 70%.

What is the average depth of the oceans?

Approximately 2.5 miles (~14,000 feet).

What is the deepest point in the oceans?

36,200 feet

Are oceans fully explored?

No, oceans are still largely unexplored

How have humans impacted the oceans?

Significantly impacted the oceans despite their vastnes

What is salinity?

The total mass of salts relative to the mass of water in which they are dissolved

What is the main source of salts in the ocean?

From land due to chemical weathering

How do streams contribute to ocean salinity?

Carry dissolved ions from land to the ocean

What role do volcanic eruptions play in ocean salinity?

Contributes to ocean salinity

How is salinity concentrated in the ocean?

Concentrated by the evaporation of water

How do organisms affect ocean salinity?

Organisms with shells remove salts from the ocean, helping maintain stable salinity levels

What is the surface temperature near the tropics?

30°C (86°F).

What is the surface temperature in the Arctic?

4°C (39°F)

What is the temperature of 1,000 feet of tropical waters?

Warm

What is the temperature of deeper waters in the ocean?

Above freezing

How does temperature variation change with depth?

Decreases with depth as you move away from the tropics

Why are oceans layered?

Due to differences in density

What is density?

Measures the mass of a substance in a specific volume

How does temperature affect density?

Decreases density

How does salinity affect density?

Increases density

What is the depth of the Mixed Layer?

Up to 200 meters

What are the characteristics of the Mixed Layer?

Warm surface waters and lower density

What is the depth of the Transition Layer?

200 to 2,500 meters

What happens to temperature and salinity in the Transition Layer?

Temperature and salinity decline, and density increases

What are the characteristics of the Deep Ocean?

Temperature and salinity remain constant, and density is high

Where is layering most pronounced in the oceans?

In tropical waters

What are currents?

Are the directional and continuous flow of seawater.

What are upwellings?

Are flows from the deep ocean to the surface

Why are upwellings nutrient-rich?

They bring nutrients (nitrogen and phosphorus) to the surface, increasing productivity

How do upwellings affect marine life?

They grow faster in nutrient-rich waters

What is an example of an area with significant upwelling?

Peru and Chile account for about 10% of global fish capture due to upwelling zones

What are downwellings?

Are flows from the surface to the deep ocean

How do upwellings and downwellings impact ocean temperature?

They play a major role in regulating ocean temperature

What is thermohaline circulation?

It refers to global surface and deep ocean currents driven by differences in temperature and salinity

Where does the Gulf Stream originate?

Begins in the tropics and flows northward

What happens to the water and salinity as the Gulf Stream moves north?

Increases due to evaporation

What occurs near Greenland in the Gulf Stream?

The water cools and becomes denser

What happens to the denser water from the Gulf Stream?

It sinks into the deep ocean

Where does the water flow after sinking in the Gulf Stream?

It flows southward into the Southern Hemisphere

How does ocean circulation affect global climate?

Plays a significant role in regulating global climate

What can disrupt ocean circulation?

Human actions causing climate change can disrupt ocean circulation

What does thermohaline circulation do?

It moves warm water from the poles to higher latitudes

How does thermohaline circulation affect North America and Europe?

It keeps parts of North America and Europe warmer than they would be otherwise

What factors can affect ocean circulation?

Changes in salinity (salt levels) and temperature can change ocean circulation

What is happening to ocean temperatures currently?

Are rising, which may impact circulation and climate

What are El Niño and La Niña?

They are natural changes in ocean temperatures that can significantly affect global climate

How often does El Niño occur?

Occurs approximately every five years and lasts for months to years

What characterizes El Niño?

Unusually warm surface water in the equatorial Pacific

What happens to trade winds during El Niño?

Weaken or reverse, causing warm water to move to the central Pacific

What are the effects of El Niño?

Increased rainfall in the southern U.S. and California, changes weather patterns, and can lead to more moisture in the atmosphere

What characterizes La Niña?

Unusually cold surface water in the equatorial Pacific

What happens to trade winds during La Niña?

Blow stronger, pushing warm water west and causing cold water to rise off the coast of South America (upwelling)

What are the effects of La Niña?

It leads to drier conditions in the southern U.S. and California, and storms are deflected toward the Pacific Northwest, drying out the Southwest

How do El Niño and La Niña influence moisture levels?

By altering atmospheric circulation patterns, primarily by impacting jet streams and ocean’s temperature

How do these climate phenomena affect water-borne diseases?

They can affect water-borne disease outbreaks in Africa

What impact do El Niño and La Niña have on ocean productivity?

They impact ocean productivity, especially in South America due to upwelling

Do the intensity and cycles of El Niño and La Niña follow a consistent pattern?

No, the intensity of climate events varies and doesn't follow a consistent pattern

What is the range of strength for these climate events?

+3 (strong positive effect) to -3 (strong negative effect)

What does a strength of zero indicate?

It indicates an average year with no significant climatic changes

What is the intertidal zone?

The area between high and low tides

What is the coastal zone?

The area from land to the edge of the continental shelf; it has the highest biodiversity

What is the pelagic zone?

The open ocean from the surface to the bottom

What is the benthic zone?

The zone near the ocean floor

What is the abyssal zone?

The deepest, coldest parts of the ocean with hydrothermal vents

Where does fresh and saltwater mix?

In the coastal zone

Why is the coastal zone important?

It supports a diverse habitat for many species and is critical for bird population

What is an estuary?

A transition area between a river and the ocean where saltwater, freshwater, and sediments mix

What are examples of highly productive estuary environments?

Wetlands, mangroves, and coastal marshes

Where are deltas found?

At the mouths of rivers

Why are deltas highly threatened?

Due to proximity to large cities, extensive urban development, and loss of mangroves

What percentage of mangroves were destroyed from 1980 to 2010?

35%

How much wetland has New Orleans lost since the 1930s?

1,900 square miles

Where are coral reefs found?

In shallow coastal waters

What are coral reefs made of?

Living corals, coral skeletons, and calcium-rich deposits

What do coral polyps produce?

Calcium carbonate exoskeletons

What gives coral reefs their bright colors?

Algae living in the exoskeletons

How much seafloor do coral reefs cover?

About 110,000 square miles

What percentage of the world’s fish species live in coral reefs?

25%

Why are coral reefs economically valuable?

They generate around $100 billion per year, including $36 billion from tourism

What are major threats to coral reefs?

Overfishing, pollution, and climate change

How much of the world’s coral reefs have been destroyed?

About 20%, with half seriously threatened

What is coral bleaching?

When corals lose their algae, slowing growth and increasing the risk of death

What causes coral bleaching?

Harvesting, pollution, ocean acidification, and rising temperatures

What percentage of Earth's surface does the pelagic zone cover?

About 70%.

What role does the pelagic zone play in the atmosphere?

It absorbs carbon dioxide

Where do phytoplankton live, and why are they important?

They live in shallow waters and provide energy for marine organisms

What happens to decomposed phytoplankton?

They sink and become ocean sediments

What characterizes the abyssal zone?

It contains hydrothermal vents and unique organisms

How do organisms in the abyssal zone get energy?

They use sulfur compounds for energy

What is the benthic zone?

The zone near the ocean floor

What types of organisms are found in the benthic zone?

Bacteria, fungi, and invertebrates like crustaceans

What are plankton?

Tiny organisms that float with ocean currents

What are phytoplankton?

Microscopic, photosynthetic algae that are primary producers

What are zooplankton?

Tiny floating animals that eat phytoplankton or other small organisms

What is nekton?

Larger animals that actively swim, like fish, whales, and marine reptiles

What is benthos?

Organisms living on or near the ocean floor, like crabs and starfish

What some producers near hydrothermal vents uses to create energy without sunlight?

Sulfur compounds

How deep does sunlight reach in the ocean?

Up to 300 meters deep (about 200 meters on average)

What is the photic zone?

The upper layer of the ocean where light penetrates and photosynthesis occurs

What is the aphotic zone?

The dark layer below the photic zone where no light penetrates