Physical Oceanography
Why is the ocean important? The ocean covers most of Earth’s surface. It is an important source of food and mineral resources. We use it for transportation and recreation. The ocean stores heat—water has high specific heat, so it takes a lot of energy to heat it up. Water holds on to this heat energy and stays warmer longer than the air. The stored heat in the ocean drives much of Earth’s weather and causes climate near the ocean to be milder than climate in the interior of continents. Ocean currents distribute energy (heat) and resources.
Major Oceans The five major oceans are : 1._______-largest, deepest, coldest, least salty. 2.__________- second largest, shallow, warm, salty. 3. _________- intermediate in depth, temperature, and salinity. The _______Ocean near the north pole, and the ____________ Ocean near the south pole contain vast expanses of sea ice. Pacific Atlantic Indian Arctic Southern
What gases are dissolved in the ocean? Ocean water has many different gases dissolved in it, mostly nitrogen, oxygen, and carbon dioxide. The movement of wind over the ocean and waves agitates (mixes up) the water at the surface, speeding up the exchange of gases between the ocean and the atmosphere (like shaking a soda bottle!). Marine (ocean) plants need carbon dioxide dissolved in the water to go through photosynthesisphotosynthesis releases oxygen into the water, which is then used by ocean organisms (like fish) to go through respiration. As atmospheric levels of gases rise, so do levels of those gases dissolved in ocean water.
Methods of Studying the Ocean The Topex/Poseidon _____________ orbits 1331 km above the Earth, gathering information about the oceans. satellite Sonar _____________ maps ocean floor topography by timing how long it takes sound waves to bounce off the ocean floor. submersibles Underwater vessels called _________________ investigate the deepest ocean trenches.
Sonar (also called echo-sounding) Sound waves travel how fast in seawater? How deep is the water if it takes ten seconds for the sound wave to go from ship to ocean floor and back to ship? 1,454 m/s 7,270 m Calculation: (10 s times 1,454 m/s divided by 2 )
submersible The picture below is of a _____________.
Salinity NaCl The amount of salt per unit water is known as salinity. The most abundant salt in seawater is ________, but there are many other salts present in the form of ions. The average salinity of seawater is _____ ppt. Therefore, for every 1,000 ml water, there are ___ grams of dissolved salts. 35 35 Near the equator salinity is __________ than average due to ___________________. lower greater precipitation lower Near the poles salinity is __________ than average due to _______________. melting sea ice higher In the Mediterranean the salinity is __________than average due to __________. evaporation
Where does the salt come from? The ocean is salty due to dissolved chemicals eroded form the earth’s crust and washed into the sea. Solid and gaseous ejections from volcanoes, suspended particles swept to the ocean from the land by onshore winds, and materials dissolved from sediments deposited on the ocean floor. Main reason – surface water washes over rock containing salts such as sodium chloride (common table salt) Also: Volcanoes
The salinity here would likely be: 35 ppt 34 ppt 36 ppt
Colorful Seawater What makes the ocean water in the picture to the left different colors? Why would a shrimp that appears bright red at the surface appear black at greater depths, and why might this be beneficial? differences in depth Longer (red) wavelengths are absorbed before reaching deep water. Shrimp can hide and not become a meal.
Label the three ocean temperature layers in the diagram below. Surface layer Thermocline Deep layer
How does wind affect the ocean? Wind causes waves: A wave is an up-and-down motion along the surface of a body of water. Moving air drags across the water’s surface and gives energy to the water, causing waves. Wind blows over the ocean, causing surface currents. carry warm water away from the equator & cold water away from the poles Earth’s rotation makes them spin in circles (clockwise in N. Hemisphere, counterclockwise in S. Hemisphere) Ocean current: mass of moving water; many currents in the ocean distribute heat and nutrients Currents move water, waves move energy.
What are deep ocean currents? Deep currents are caused by differences in density (due to temp, salinity, etc) Downwelling: water moving from the surface DOWN to the bottom carries oxygen down allows animals to live in the deep ocean Upwelling: water moving UP to the surface Occurs when warm surface water is blown offshore by wind. This allows the cold water at the bottom of the ocean to rise. carries nutrients up large numbers of animals gather in areas where upwelling occurs because of the availability of nutrients.
Upwelling Water that rises to the surface as a result of upwelling is typically colder and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Therefore, good fishing grounds typically are found where upwelling is common.
Ocean Floor Continental shelf – starts at the shore and slopes into the ocean Continental slope – where the slope starts to get deeper Abyssal plain – huge, dark flat region that encompasses most of the ocean floor / covered with mud and remains of marine life Mid-ocean ridge – underwater mountain range separated by rift valley (where new oceanic crust is made, hydrothermal vents discovered here) Ocean trench – large, V-shaped valley
Seafloor Topography C B Match the following terms to their correct letter in the diagram: E C. Island Continental shelf Continental slope Abyssal plain Seamount Continental rise Trench Guyot F B. E. D A. G F. G. A H. A D. H
Chapter Review What is the average salinity of seawater? What is the deepest area of the seafloor? What is the largest ocean? Why is the ocean “blue”? What is the force responsible for surface currents? What causes density currents? Name the ocean that borders North Carolina. 35 ppt trench Pacific shorter wavelengths not absorbed wind differences in temperature and salinity Atlantic
Ocean Feeding Relationships What is a Food Chain? A food chain is a way to describe the feeding relationships between different organisms.
What are animals that eat plants called again? Primary Consumers What is a feeding relationship? A feeding relationship describes who is eating what in a particular habitat. What are animals that eat plants called again? Primary Consumers
Carnivores, or animals that eat primary consumers, are called secondary consumers. So a food chain shows who eats what in a particular habitat. For example, a piece of willow (tree) is eaten by a moose, which is then eaten by a wolf.
The arrows between each item in the chain always point in the direction of energy flow- in other words, from the food to the feeder.
in other words, from the food to the feeder. A food web is a model that shows all the possible feeding relationships between organisms living in an ecosystem. The arrows between each item in the chain always point in the direction of energy flow- in other words, from the food to the feeder.
What is a keystone species? Keystone Species: a species that has a greater-than-expected effect on an ecosystem; if it is removed from the environment, the entire ecosystem is affected dramatically (sometimes, it completely “collapses”). Many keystone species are top predators (killer whales, starfish, wolves, bears) Example: In the food web above, killer whales are the keystone species. If they are removed from the environment, there will be too many salmon, which will provide more food for the seals and sea lions who’s population will increase, then seals and sea lions along with salmon will eat all of the herring, which will lead to too many zooplankton, which will eat all of the phytoplankton, which will lead to not enough food for the baleen whale (and less oxygen).
Classwork Create a chart or list of who eats what in the food web on the previous slide