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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?
Humans have 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?
Most salts come from land due to chemical weathering
How do streams contribute to ocean salinity?
Streams carry dissolved ions from land to the ocean
What role do volcanic eruptions play in ocean salinity?
Volcanic activity contributes to ocean salinity
How is salinity concentrated in the ocean?
Salinity is 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)
How warm is the top 1,000 feet of tropical waters?
he top 1,000 feet are warm
What is the temperature of deeper waters in the ocean?
Deeper waters are just above freezing
How does temperature variation change with depth?
Temperature variation decreases with depth as you move away from the tropics
Why are oceans layered?
Oceans are layered due to differences in density
What is density?
Density measures the mass of a substance in a specific volume
How does temperature affect density?
Increasing temperature decreases density
How does salinity affect density?
Increasing salinity 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?
Layering is most pronounced in tropical waters
What are currents?
Currents are the directional and continuous flow of seawater.
What are upwellings?
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?
Marine organisms 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?
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?
The Gulf Stream begins in the tropics and flows northward
What happens to the water as the Gulf Stream moves north?
The water warms, and salinity 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?
Ocean circulation 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?
Ocean temperatures 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?
El Niño occurs approximately every five years and lasts for months to years
What characterizes El Niño?
It is characterized by unusually warm surface water in the equatorial Pacific
What happens to trade winds during El Niño?
Trade winds weaken or reverse, causing warm water to move to the central Pacific
What are the effects of El Niño?
It causes 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?
La Niña involves unusually cold surface water in the equatorial Pacific
What happens to trade winds during La Niña?
Trade winds 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?
They can influence moisture levels in the atmosphere and how it flows across continents
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?
Strength can range from +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
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