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Oceanography Final: Prelim 1+2 Answers

Terms in this set (98)

How do stars form?
Stars form when cold hydrogen and helium (and sometimes other heavy elements) condense under gravity to form very large masses that generate great internal pressure and temperatures ignite thermonuclear fusion to produce, among other things, visible light and heat energy.
Where did all the carbon atoms that make up your own body today initially come from?
The carbon atoms in your body formed inside of a boiling hot star.
How did the moon form?
A Mars-sized object struck the earth and ejected a large mass of material from the earth that cooled and entered earth's orbit.
How much more time do the sun and earth have left to live?
The sun will burn for 4 billion more years and then, before dying, its outer layer will expand beyond the orbit of the earth and completely incinerate the earth back to dust. In other words, the full history of earth from its creation is currently at the halfway point of its life and then it will definitely be gone.
If you were on a boat at 10N and 30W which ocean would you be in?
Atlantic
What is the nature of the earliest known fossil?
A Chemical fossil
When did life on earth transition from being just simple
prokaryotic organisms floating around in the ocean to more complex eukaryotic organisms?
About 2 billion years ago
When did the Cambrian Explosion Occur?
About 550 million years ago
When did mammals begin to rise to greater prominence and become the dominant large animals on earth?
65 million years ago
Which of the following is true about mass extinction events?
All of the above:

a. Mass extinctions typically clear niche space and allow previously minor groups of organisms to fill the space and become prominent components of the global biota.

b. There have been 5 mass extinction events in the geologic past.

c. Humanity is now powerful enough to cause a mass extinction event.
Does the thin outer crust of the earth actually float on top of and interior mantle layer?
Yes
The symmetric banding of magnetic anomalies as you move away from a mid-ocean ridge axis is really a proxy for...
A symmetrical increase in the age of ocean crust as you move away from the ridge axis.
Have the continents come to their final resting position or will they keep moving and eventually collide back together to form a new super continent similar to Pangaea's formation 225 million years ago?
Continents will continue to move and will eventually all collide again to form a new super continent.
An example of a divergent tectonic plate boundary is:
Both a and b:

a. Mid-Atlantic Ridge

b. Red Sea
When ocean crust collides with continental crust, which one slides down underneath?
Ocean Crust
Which of the following locations is an example of ocean crust colliding with ocean crust?
Japanese Islands
Why did India not slip back down into the Mantle when it collided with Eurasia?
Continental Crust of the Indian Continent is too buoyant to sink into the mantle.
What type of earth process is recorded over millions of years in ocean sediment cores?
All of the above:

a. Ocean Temperature

b. Ocean Productivity

c. Large Volcanic Events

d. Ice Ages and Iceberg Formation
Siliceous and Calcareous Oozes are typically found in:
Biologically productive open-ocean regions
How can scientists obtain information about past ocean temperatures from sediment cores?
Chemical isotope ratios (e.g., 16O:18O) of the fossil shells
A wave crest moving across the ocean surface is an important mechanism by which mass is propagated across large ocean distances. True or False?
False
A bunch of waves with a 25-meter wavelength and a bunch of waves with a 1-meter wavelength propagate southward out from under a big storm system in the Gulf of Alaska. Which type of wave will reach Hawaii first?
25 meter waves
What happens to wave energy as it approaches a coastline?
Wave energy gets focused on the headland and spreads out in an embayment.
Why would there likely be strong laws and regulations against building rock walls/jetties that extend outward from a beach and into the ocean on someone's private property?
Because it could block longshore transport of sand and shrink an adjacent property owner's beach.
What should you do if you are caught in a rip current?
First, swim parallel to the beach for 10 or 20 meters and then swim back to shore - and call Bruce.
Which aspect of wind forcing sets the maximum upper limit on ocean wave height?
Wind Speed
What is the definition of wind fetch?
The unobstructed distance over which the wind blows
How do oceanographers decide that a tsunami has been generated?
By the detection of a passing tsunamis wave using moored buoys that are fitted with bottom pressure sensors and can detect small change in sea surface height as the tsunami wave passes overhead.
Which of the following would best describe your actions if you were to ignore a tsunami warning and instead head down to the beach to watch the awesome big waves come in?
You would be a sad, stupid-ass, pathetic idiot.
What force besides gravity is involved with the creation of the two tidal bulges that make up the tides?
Centrifugal force
If you went down to the beach on Saturday at 5:00am to dig clams at low tide, what time would you need to go down to the beach on Sunday to catch the same low tide to dig more clams?
5:50am
What is needed to get all three daily tidal patterns (i.e., diurnal, semi-diurnal and mixed semi-diurnal) on earth?
Two tidal bulges and a lunar orbit at 28 degrees from the equator
If you are on the beach and the moon is full, would you expect the tide range to be exceptionally large or relatively small?
Large
Why do we get rotary tides?
Both A and B

a. Continents block the propagation of the tidal wave.

b. The Coriolis force acts on the tidal wave.
Why is there almost zero tidal range in Hawaii?
Because Hawaii is near an Amphodromic point.
What phenomenon is responsible for the exceptionally large tidal range in the Bay of Fundy?
The tidal forcing is at the resonant frequency for the bay's length.
The Westerlies are a global surface wind pattern that is contained within which latitude band?
30°-60° Latitude
What is required to explain the three main wind bands on earth?
The pattern of atmospheric pressure at sea level (sea level pressure) that alternates with latitude between low and high levels and the Coriolis force.
Why is the ocean's mixing depth shallower in the summer?
Warm surface waters in summer are very buoyant and buoyant surface waters cannot be mixed downward very easily by the wind.
What is Ekman Transport?
It is the movement of a relatively thin slab of ocean surface water (about 50 to 100 meters deep) in response to wind forcing. This slab moves exactly to the right or left of the direction of the wind in the northern or southern hemisphere, respectively.
Which is true about fully-developed Geostrophic Currents
The current moves along lines of constant pressure
How is the mound of surface water in the middle of the subtropical gyre formed?
Trade Winds and the Westerly winds drive the Ekman Layer toward the center of the subtropical gyre
When the surface waters mound up in the center of the subtropical gyre in the northern hemisphere it creates a center of high pressure under the mounded water. The response of the water below the mound is to:
Move out away from high pressure at first, but then to turn until it moves along lines of constant pressure in a CLOCKWISE direction around the center of high pressure.
What causes vertical up-welling of deep water along the equator?
Divergence of the Ekman Layer that is driven by the trade winds.
If the wind is blowing from the south along the west coast of the United States (Washington, Oregon and California Coasts), would the Ekman Layer move onshore or offshore?
Onshore
How are the main water masses in the ocean interior identified?
Based on temperature and salinity signatures.
How are the speeds of deep currents determined?
Measuring the rate of decrease in the abundance of 14C (a radioactive form of carbon) in deep-ocean seawater.
How long does it take for deep ocean water that sinks in the north Atlantic to make its way down around the Southern ocean and up into the deep North Pacific?
About 2000 years
The reason oceanographers care so much about the conveyor belt circulation is because:
It moves a lot of heat away from the equator to higher latitudes to moderate temperatures at both low and high latitudes.
Which of the following statements best defines Net Primary Production?
The difference between CO2 gained through photosynthesis and CO2 lost through respiration
The compensation light level refers to the light level where
Photosynthesis and respiration are equal
Why are nitrogen, phosphorous, silica and iron the principle nutrients studied by oceanographers?
They are the elements that, from time to time, can be in short supply and limit the growth of phytoplankton
Subtropical Gyres have low levels of primary production per square meter because
There is a persistent lens of warm low-nutrient surface water that depresses the thermocline and associated nutricline
What causes primary production along the equator to be high in the eastern equatorial Pacific and low in the western equatorial Pacific?
Trade winds that force an Ekman layer divergence in combination with a relatively SHALLOWER thermocline in the eastern equatorial Pacific (off Peru).
What accounts for year-round high levels of primary production in coastal regions?
Enhanced tidal mixing over shallow continental shelf regions
Which is true about the Critical Depth?
It is the depth to which phytoplankton can mix whereby the time they spend below the compensation depth losing carbon just balances the time they spend above the compensation depth gaining carbon and resulting in net primary production over the course of the day being zero.
What percentage of the oxygen you breathe each day should you give a big thank you to the ocean? In other words, what percent of global primary production takes place in the ocean?
50%
In order to make sense out of the confusing mix of all the organisms that make up pelagic communities, oceanographers classify organisms into broad groups based on which criteria?
All of the above:

Autotrophic
Heterotrophic
Body Size
The Exploitation Efficiency of the copepod community that has just come out of winter diapaus (hibernation) at the start of the North Atlantic spring phytoplankton bloom is expected to be:
LOW
The main reason that coastal upwelling regions have much higher amounts of harvestable fish production each year is because:
None of the above

They are close to fishing port cities and are therefore efficiently harvested by coastal fishing fleets

They have the largest number of trophic steps between primary production and harvestable fish

Upwelled waters are colder so fish mature more slowly and can thus grow larger before reaching adulthood.
What happens to the Walker Circulation Cell in the transition from normal to El Nino conditions?
The Walker Circulation Cell slows down or reverses
What happens to The Cold Tong (cold sea surface temperature along the equator) in the eastern Pacific during El Nino conditions relative to normal condition?
The Cold Tong becomes less cold and shrinks back toward the Peru coast
What happens to the global average temperature during an El Nino year?
Rises pretty dramatically
How can the effects of El Nino conditions in the Pacific be transmitted to the far reaches of the globe?
Variation in the position of the Jet Stream in the atmosphere
A pelagic environment that has naturally very low plant nutrient is called
Oligotrophic; vast subtropical gyres
What are the growth requirements for heterotrophic bacteria?
They need dissolved organic matter
Prochlorococcus is
The main contributor to primary production in open-ocean oligotrophic environments.
The Biological Carbon Pump is at its most efficient in:
Eutrophic conditions
As a general rule, whenever carbon is found to be efficiently recycled in a given pelagic ecosystem, nitrogen is also efficiently recycled. True or False?
True
What typically sets the lower limit in the vertical elevation of a given species living in the rocky intertidal?
Competition with other species or predation by other species
What prevents a single rocky intertidal species from eventually out-competing all other species and becoming the only species in the rocky intertidal?
Some sort of intermediate physical disturbance such as a drift log smashing on the rocks, or big storm waves crashing on the rocks, wipes the rock clean and restarts the whole process of competition among all species.
What underling environmental factor is thought to be causing the massive starfish die-off observed from Alaska to Baja California?
Exceptionally warm coastal waters.
What happens to the abundance of kelp forests when sea otters are removed?
Kelp forest declines
What percent of the coral's overall nutrition comes from their Zooxanthellae symbionts?
60-90%
What is coral bleaching?
This occurs as a result of the breakdown in the symbiotic relationship between the coral and its Zooxanthellae
Coral bleaching, and the subsequent coral death, begins when normal ocean temperatures are:
Increased by about 1 oC for a few weeks
Which of the following comes closest to representing the earliest form of whale (Pakicetus)?
Wolf
Whale vocalizations can be used for
All of the above

Prey detection
Communication
Sexual selection
Navigation
What is a reasonable analogy for a Spectrogram that is used by whale researchers to visualize the pattern of whale vocalization?
A bar of written music
Which source of underwater sound does Professor Christopher Clark think may be the greatest threat to whale population survival?
Ambient noise from commercial ship traffic
Which of the following nations are currently hunting whales in large numbers?
Norway, Iceland and Japan
Do viruses impart any benefit to pelagic communities or would it be better for the ocean if viruses were absent or at very low levels?
Viruses can often play a positive role in pelagic ecosystems
How does the virus abundance vary with depth?
Viruses vary as a FIXED PROPORTION of the abundance of bacteria so they are high near the ocean surface and low at great depth.
What must occur in order for viral infection to propagate?
Both a and b

A.The host must be highly abundant (e.g., during a large phytoplankton bloom)

B.Viruses must be in high abundance in order to overcome the high probability of viral decay due to destructive enzymes in seawater.
What recent discovery did Professor Hewson make that has gained him a lot of professional prestige?
He recently discovered the type of virus that is causing the die-off of starfish along the west coast of the United States.
The two opposing forces and/or energies that determine the three phases of water (solid, liquid and gas) are:
H-bonds and Thermal-Kinetic energy
If you added an equal amount of heat energy to the ocean, atmosphere and land, which one would experience the smallest temperature change?
The Ocean
How much of the excess heat that has accumulated in the earth system as a result of human-caused greenhouse gas emissions has been taken up by the ocean?
93%
When winds blow over the surface ocean to cause evaporative cooling, what happens to the heat that leaves the ocean surface?
It is transferred from the ocean to the atmosphere as latent heat in the form of atmospheric water vapor
If you have a 1000-gram sample of seawater that has a salinity of 34‰ and you boiled away all of the water, how much salt would remain?
34 grams
Where is surface ocean salinity typically highest?
Subtropical Gyres
The conveyor belt circulation explains, in part, why nitrate and phosphate concentrations in the deep ocean (e.g., bottoms waters at 4000 meters depth) are
Low in the deep North Atlantic and high in the deep North Pacific
Oxygen concentration reaches a minimum level just below the sunlit layer (euphotic zone) of the ocean because:
Microbial respiration fueled by dead organic material raining down from above consumes oxygen down to low levels
What is expected to happen to the oxygen minimum zone in response to global warming?
The concentration of oxygen will decline
Carbon dioxide is high in the deep ocean because
Microbial consumption of organic matter and associated respiration produces carbon dioxide.
In which direction would carbon dioxide diffuse across the air-sea interface if deep water were brought up to the surface and into contact with the atmosphere?
CO2 would diffuse out of the ocean
How much of the total CO2 emitted by fossil carbon emissions since the start of the industrial era has the ocean taken up?
30%
At the current rate of CO2 emissions, how soon will tropical coral reef growth begin to decline or stop and polar seas begin to be corrosive to calcium carbonate shells of marine plankton as a result of ocean acidification?
Within a matter of decades
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