Oceanography Final
Earthquakes occur:
all types of plate boundaries
During photosynthesis, water is:
an electron donor
Which group acquires carbon from inorganic sources
autotrophs
Sessile organisms in the rocky intertidal zone must be able to:
avoid dessication and predation
The Coriolis force causes currents to turn:
b and d
Zooxanthellae are single-celled, dinoflagellate algae that have a symbiotic relationship with:
corals
For measurements of primary productivity, the dark bottle is used to:
correct for respiration
The hydrogen and oxygen atoms within water molecules are held together by:
covalent bonds
In the ocean, nitrogen fixation is done mainly by:
cyanobacteria
Which form of navigation is associated with the least error (which would you use if you wanted to get from Norfolk to Bermuda in one piece)?
Satellite navigation
What is not true about sea level rise?
Sea level has been constant for much of Earth's history
Fully developed seas refer to:
Seas where the maximum wave size possible has been achieved given a wind of specific strength, duration, and fetch
The conversion of CO2 to biomass is considered part of which part of the Earth's carbon cycle?
Short term (days to years)
Other than the hydrogen and oxygen in the water molecules themselves, what are the two most abundant ions in seawater
Sodium (Na+) and chloride (Cl-)
Due to geostrophic circulation:
The pycnocline is depressed in the central part of the gyre
Wave diffraction is caused by:
The propagation of waves around obstacles
The Principle of Constant Proportions states that:
The ratio of major salts in seawater from different places in the ocean is constant
The dynamic theory of tides incorporates
The shape of the ocean basins
Wave refraction is caused by
The slowing and bending of waves as they move into shallow water
Primary production in the ocean is comparable to that on land
True
Individual waves in a wave train travel at a speed equal to:
Twice that of the wave train
Semidiurnal tides consist of:
Two high tides and two low tides of equal amplitude each day
During an El Nino year, which would you expect to happen:
Warmer than normal water along the coast of South America
The speed of a shallow water wave can best be estimated by knowing the:
Water depth
Why doesn't flow around a gyre spiral toward the center due to Coriolis forcing?
Water moves down the pressure gradient from the hill of water in the central gyre
In an Ekman spiral:
Water moves with decreasing speed with increasing depth from the surface
The speed of a deep water wave can best be estimated by knowing the
Wave length
Waves can be initiated as a result of tropical storms. During fictional Hurricane Ingrid, waves of different wavelengths were generated and reached the Virginia Beach. Which is true about the first waves to reach the beach?
Waves with the longest wavelengths reached shore first ahead of the storm
What was the idea of continental drift first based on?
Wegner's observations of the fit of the continents and fossil evidence
Warm water tends to "pile up" on which side of ocean gyres:
West
The winds at the latitude of Norfolk, Virginia due to general atmospheric circulation are:
Westerlies
Which current would you expect to move fastest:
Western boundary current
Where is the earth's meteorological equator?
Where ever there is thermal equilibrium between hemispheres
The immediate source of energy driving ocean surface currents is
Wind
If I want to predict what time a tsunami originating in Alaska were going to hit Hawaii, the most useful information for me would be
a bathymetric chart
Thermocline
a layer in a large body of water, such as a lake, that sharply separates regions differing in temperature, so that the temperature gradient across the layer is abrupt.
Pycnocline
a layer of water in which there is a rapid change of density with depth
The saturation state Ω quantifies whether:
a mineral dissolves or precipitates
What is the order of light regimes in the ocean with increasing depth (surface, intermediate, deep water):
euphotic, disphotic, aphotic
An organism that can adapt to a wide range of temperatures is said to be:
eurytherma
Under El Nino conditions, water off the west coast of South America
gets warmer and upwelling is shut down
The wavelengths of light that penetrate deepest into the ocean are
green and blue
Net primary production is _________ minus ___________
gross production, respiration
The most abundant dissolved gas in seawater is
nitrogen
How is primary production different in a pelagic community versus a hydrothermal vent community?
photosynthesis or photoautotrophy versus chemosythesis or chemoautotrophy
Ichthyoplankton are
planktonic forms of larval fish
In general, the amount of carbon 'fixed' in a unit volume per unit time; specifically, the number of grams of carbon bound into organic matter per cubic meter per year is known as what?
primary productivity
The microbial loop refers to what
rapid cycling of elements among a microbial food web in surface waters
The process whereby organisms liberate and utilize stored energy by degrading carbohydrates is known as:
respiration
Which sediment type is most abundant in the ocean?
terrigenous
What does not contribute to variability in the solar radiation reaching the earth?
the amount of ice on Earth
Most of the world ocean has the temperature properties of:
the deep and bottom waters
The buffer capacity of the ocean maintains
the pH
The salinity of the ocean, at the present time, seems to be:
In equilibrium, with dissolved components entering equal to dissolved components leaving
If two oceanic plates collide, what will happen?
The older one will be subducted
Which potentially transfers more heat?
Latent heat of vaporization
What is the average salinity of the ocean?
35 ppt
How old is the earth approximately?
4.57 billion years
In general, the water column is vertically stable because:
Less dense water sits on top of more dense water
The depth to which light can penetrate the ocean depends on:
All of the statements are true
What is the oxidation state of Cr in Cr2O72-?
+6
Calculate the residence time of water in the ocean if the volume of water in the oceans is 1,350 x 10e15 cubic meters. Fluxes to the ocean include groundwater and runoff (37 x 10e12 cubic meters/year) and precipitation (324 x 10e12 cubic meters/year). Fluxes out of the ocean are evaporation (361 x 10e12 cubic meters/year).
3740 years
You dissolve 1 mole of NaCl in 500 mL water. How many moles of Na+ and Cl- are in solution?
1 mole of Na+, and 1 mole of Cl-
What are the global estimates of sea level rise?
1-2 mm/yr
If one includes silicon in the conventional Redfield ratio (106:16:1), its value would be:
15
I am measuring bathymetry using echo-sounding from a ship. On average, sound travels 1,484 m/s. If I send a ping from my boat and I receive the sound back at my boat after 6 seconds, how deep is the water?
4452m
Approximately what percentage of the globe is covered with ocean?
70%
What is the average pH of today's ocean?
8
Thermohaline circulation controls the flow of about how much of the water in the ocean?
90%
The El Nino Southern Oscillation (ENSO) refers to:
A change in atmospheric pressure cells across the tropical Pacific
A biologically-influenced vertical profile of a plant nutrient in the ocean has which shape?
A curve with low concentrations at the surface and high concentrations at depth
Wave formation requires:
A disturbing force
A marine community is:
A group of populations that interact at a particular place during a specified time
A seiche is:
A standing wave
The abundance of bacteria in the ocean is approximately
About 1,000,000 cells per milliliter
I want to go to the beach on Saturday with my kids when it is low tide. Today, Tuesday, low tide was at 6 am. What time should I plan to be there on Saturday?
About 10 am
The abundance of viruses in the ocean is approximately:
About 10,000,000 viruses per milliliter
What is the role of gills on a fish?
Acquiring oxygen from water
How does the amount of ice on the Earth's surface affect Earth's heat budget? As polar ice caps melt, is this a positive or negative feedback on Earth's warming and why?
Affects the earth's albedo or reflectivity Positive feedback because earth's albedo will decrease allowing the earth to absorb more of the incoming solar radiation and heat up more
Symptoms of coastal eutrophication include
All are correct
What controls bacterial growth in the ocean
All are correct
Wave interference results in
All are true
Variations in tidal height from day to day are due to
All can influence tidal height
The hydrogen bonds of water molecules account for which of the following?
All the answers provided are relevant
What do light and sound have in common?
All the answers provided are true
What causes deviations from equilibrium gas concentrations between the ocean and atmosphere?
All the things described do
What is a mixotroph?
An organism that can obtain carbon as an autotroph and a heterotroph
What is a habitat
An organism's physical location in its community
What is a niche?
An organism's role in the community
The most dense water mass found in every ocean basin is
Antarctic Bottom Water
The largest of all ocean surface currents is the:
Antarctic Circumpolar Current
The conversion of fossil fuels to CO2 is considered part of which part of the Earth's carbon cycle?
Anthropogenic
Geostrophic currents:
Are a balance between the pressure gradient and the Coriolis force
Eastern boundary currents
Are slow, shallow, and have poorly defined boundaries
Which of the following statements about pH is not true?
As a whole, the pH of the ocean is mildly acidic
What is the name of the partially molten upper mantle?
Asthenosphere
In nature, the net motion of wind-driven surface water flows is actually about
At 20o to 40o to the right of the wind in the Northern Hemisphere
Tsunami represent a major hazard in the Pacific Ocean because:
At its margins there are subduction zones that result in a large number of earthquakes
Internal waves form
At the boundary between water layers of different density
Where is the true edge of a continent?
At the shelf break
Which basin is opening?
Atlantic ocean
Why is the ocean good at taking up CO2? (2 points) What maintains the influx of CO2 from the atmosphere to the oceans? (2 points)
Because of carbonate equilibrium reactions. Keeps CO2 concentrations in the water lower than that in the air creating a diffusive flux into the ocean
Why do clay particles sink more slowly than sand?
Because they have smaller diameter
At the current pH of the ocean, most of the inorganic carbon in seawater is present in the ocean as:
Bicarbonate (HCO3-) ions
Which sediment type covers the greatest area of ocean floor?
Biogenous
How is it that the ocean accounts for about half of global primary productivity but less than 1% of total global plant biomass? (2 points)
Biomass is turned over rapidly. High rates of primary production
Depth profiles of CO2 show that:
CO2 is enriched in deep waters
Why is photosynthesis a redox reaction? Explain. (2 points)
CO2 is reduced to organic matter and water is oxidized to molecular O2
What is the carbonate pump and how does it work? (2 points)
Calcifying organisms make carbonate that can then sink (through biological pump) and dissolve in deep water below the CCD. Carbonate rocks can also dissolve
The first waves to form when wind blows are:
Capillary waves
Which is the best example of a non-conservative constituent in seawater:
Carbon dioxide (CO2)
The Redfield ratio (106:16:1) gives the molar ratio of which elements?
Carbon:Nitrogen:Phosphorus
Which is not a major component of the Milankovich cycles?
Changes in tidal forces over the year
The oceans are said to be in chemical equilibrium because
Chemically, what comes in is about equal to what goes out
Which one of the following is a process that creates carbohydrates from carbon dioxide using energy held in chemical bonds?
Chemosynthesis
Which form of water is most dense?
Liquid salt water
San Francisco's famous cold, foggy summers are caused at least in part by:
Coastal upwelling
Which one the following are single-celled autotrophs having a calcium carbonate shell or test?
Coccolithophores
An element that is always present in seawater in constant proportion and reacts very slowly in the ocean is:
Conservative
Which of the following ocean basin features is steepest?
Continental slope
Which are the most abundant zooplankton in the ocean
Copepods
Why is the pH of the deep ocean lower than that in surface waters? (2 points) How can the pH of the surface ocean (or shallow ocean) change dramatically on short time scales? (2 points)
Deep water - Lower because of high CO2 concentrations Surface waters - pH can increase due to drawdown of CO2 by plants there.
Which of the following has the lowest average sediment thickness?
Deep-ocean floor
What is not a characteristic of passive continental margins?
Deep-sea trenches
What is the process by which nitrate is converted the N2 gas
Denitrification
Thermohaline circulation is driven primarily by:
Density differences in water masses
What are pycnoclines, haloclines, and thermoclines? (3 points) Describe how the thermoclines look in tropical, temperate, and polar oceans (3 points). Would you expect the water column to be more stable in polar, tropical or temperate oceans? (1 point) Why?
Depth horizon where density, salinity, and temperature, respectively, change most rapidly with depth. tropical - strong with very warm surface waters and cold deep water polar - weak with cold surface and deep water (least stable because small density differences) temperate - intermediate and seasonal changes in surface water temps but still cold deep water
Which of the following form siliceous oozes?
Diatoms
Red tides are generally blooms of what type of organism:
Dinoflagellates
Equatorial upwelling in the Pacific is a consequence of
Divergence
Where water masses converge, you would expect
Downwelling
Based on general geostrophic flow, on which side of ocean basins would you expect to find upwelling:
East
East-West surface currents of ocean gyres are driven by:
Easterly and westerly winds
Because of their large size, marine mammals make up the bulk of the living biomass in the sea
False
More heat is transferred from the equator to the poles in the ocean than by the atmosphere.
False
The uninterrupted distance over which the wind blows without significant change in direction is called:
Fetch
Surface ocean gyres
Flow around the periphery of ocean basins
In 1912 Alfred Wegner proposed a theory that is now called plate tectonics. What are two pieces of evidence he proposed in 1912 to support his theory? (2 points) Using modern technology, what is the single best proof of plate tectonics today? (2 points) Please explain this proof - how does it show plate tectonics? (2 points)
Fossils and fit of the continents. Magnetic stripes Parallel to spreading centers on each side
How do we know the earth is layered?
From evidence on how seismic waves through the earth
What information does the ratio of oxygen isotopes preserved in calcareous sediments hold?
Global ocean temperatures in the past
The equilibrium theory of tides deals primarily with:
Gravitational and inertial forces and planetary motion
For all but capillary waves, the restoring force of wind waves is:
Gravity
Milankovitch cycles
Help explain the changes in the earth's temperature over glacial and interglacial time periods
Which one the following must consume food from other organisms because they are unable to synthesize their own carbohydrates?
Heterotrophs
Imagine you are sitting on the Beach somewhere in Virginia Beach. Strong and steady winds are coming from the northeast and have been for 3 days. What would you expect?
Higher than normal tides
What does the term Isostacy describe?
How the lithospheric plates "float" on/in the asthenosphere
Hydrothermal vent deposits are what?
Hydrogenous
The amount of gas that seawater can hold in solution (or the gas solubility) is greater:
In colder water
With respect to controlling atmospheric carbon dioxide, the "solubility pump" is most important:
In polar waters
Shallow water waves occur:
In water of any depth
Wave interference refers to
Interactions between waves and wave trains of different sizes
What is the name for the marine habitat found between the highest high tide and lowest low tide
Intertidal zone
In the high-nutrient low-chlorophyll waters in the North Pacific, what is thought to limit phytoplankton production?
Iron
The core of Earth is composed primarily of what?
Iron and nickel
How does global circulation of sea water in the oceans affect sea level?
It can cause feedback effects that change rates of freezing or thawing of ice in polar waters
What is true about the solubility of the calcium carbonate in the ocean?
It increases with depth
The transmission of sound by water can best be described by which of the following statements:
It is faster than transmission by air
What is true about present day sea level rise?
It is higher than during the last glacial maximum
Why does water react with ions?
It is polar
Once an element or dissolved substance reaches the ocean
It may stay or be removed depending on the fluxes affecting the residence time of that particular element
The property of water that accounts for the ability of liquid water to absorb heat and change only very little in temperature is called
Latent heat
We are interviewing potential faculty members for the College of Business. One job candidate is currently at an institution located in Chili that was recently devastated by an earthquake. She is concerned about earthquake preparedness at ODU. What would you tell her? How would you rank the likelihood of earthquakes in Norfolk versus in Chili? Why? (2 points). This same candidate is worried about where to buy a house in Norfolk. What is a major oceanographic hazard in Norfolk and how would this temper your recommendation of where to buy a house? (2 points).
Low earthquake potential. Passive margin away from plate boundaries. Look at flooding from high tides and storms.
What is the mechanism for sea floor spreading that heralded the advent of full-blown plate tectonic theory?
Mantle convection cells
One cubic meter of which is the most dense?
Mantle rock
How is density described?
Mass per unit volume
What contributes the least to relative sea level rise?
Melting of arctic ice
Thermohaline circulation is also referred to as
Meridional Overturning Circulation
Because of the increase in atmospheric CO2, the ocean is becoming
More Acidic
If our planet were without its ocean, but otherwise the same as it is today, would surface temperatures be more extreme than they are now (that is, higher high temperatures in summer, and lower low temperatures in winter), less extreme, about the same or what. Why do you think that? (2 points)
More extreme. High heat capacity of water
A satellite fell to earth recently but didn't cause any loss of life. Oh no, another satellite just went out of commission and is hurtling to earth, what is the likelihood of it resulting in loss of human life and why?
Most of the globe is water so it is most likely to land in the ocean. Of land, population density is unequal and large expanses are unpopulated further decreasing likelihood of loss of life
Where are the youngest seafloor rocks found?
Nearest the mid-ocean ridges
What is a rift zone or a rift valley synonymous with?
Newly Forming divergent boundary
What is the largest reservoir of "fixed" nitrogen in the ocean
Nitrate
Tides at amphidromic points are characterized by
No tidal change in sea level
Vertical nutrient distributions in the ocean can best be described as having
Non-conservative distributions
Warm water transported by the Gulf Stream moderates the winter climate of:
Northern Europe
Deep water waves are:
Not affected by bottom friction
If N2 gas is so abundant in the Earth's atmosphere and in the oceans, how could nitrogen ever limit productivity in the ocean? (2 points
Not many nitrogen fixing organisms.
Zonation in rocky intertidal communities is determined by:
Salinity, temperature, and exposure tolerances and biotic interactions
Which gases in water are most influenced by biology? (2 points) What biological processes influence their distribution? (2 points) Describe their concentrations and the processes that control their concentrations in surface (upper 100m) (2 points), subsurface (~200-1000m) (2 points) and deep water (>2000m) (2 points)?
O2 and CO2. Photosynthesis and respiration Surface - CO2 drawn down and O2 produced due to PS Mid-depth - O2 consumed and CO2 produced at mid-depths from respiration Deep - both increase due to high pressure and cold temperature
Nonconservative constituents of seawater are:
Often tied to biological cycles or are chemically reactive
About how long does it take for surface water that sinks in the North Atlantic to resurface in the North Pacific
On the order of 1,000's of years
Diurnal tides consist of:
One high tide and one low tide each day
The trophic transfer efficiency in marine food webs is about 10%. What do I mean by this?
Only 10% of what is eaten is converted into biomass at the next trophic level
Where did the water that fills the oceans most likely come from?
Outgassing from the early earth
What causes the magnetic "striping" of the seafloor?
Periodic reversals in the polarity of the earth's magnetic field
What are sediments comprised of particles that are a mixture of sizes known as?
Poorly sorted
What is the heat of the inner earth from?
Radioactive decay
What is relative sea level rise and how to relative rates of sea level rise in Hampton Roads compare to rates globally?
Relative sea level rise is local sea level changes due to movements of land and changes in the volume and density of water. Hampton Roads has a high rate of relative sea level rise compared to other places on the globe. eustatic sea level rise (ice melting and thermal expansion) subsidence due to isostatic adjustments Subsidence due to groundwater extraction
What does the ring of fire refer to?
Ring of seismic activity around the Pacific marking the convergent plate boundaries
What is the largest reservoir of carbon on the planet?
Rocks
Describe the ocean's solubility pump and the ocean's biological pump using the pools of carbon we discussed (DIC, PIC, POC, DOC) and the processes we talked about (10 points). How are the two linked? (2 points) Where does the ocean "take up" C and where is it released from the ocean? (2 points)
Solubility pump - equilibrium reactions make CO2 more soluble in water than in air, keep water undersaturated; gas solubility enhanced in cold polar waters is transported to the deep ocean by deep water formation and is then reintroduced to the atmosphere where there is upwelling because of lower pressure and higher water temperatures at the surface Biological pump - phytoplankton take up DIC, convert it to POC (and calcifiers also make PIC) and release some as DOC. this is eaten (and repackaged by grazers to facilitate sinking, or dies and sinks and is remineralized to DIC in deep waters. DOC can also floc and form gels and sink as well. In the surface ocean solubility reactions keep DIC coming into the ocean for photosynthesis and in the deep ocean respiration contributes DIC to the deep ocean DIC pool that can be kept in solution under deep water conditions (cold and high pressure) and then contributes to CO2 emissions from upwelled deep water. solubility pump - Taken up where deep water is formed and released at sites of upwelling biological pump - taken up in surface waters and respired in deeper water
The minimum velocity layer for sound is important because
Sound is trapped in this layer so can be transmitted very efficiently for long distances there
Western intensification results in
Strong surface currents at the western sides of ocean basins
What is the reason for the islands of Japan?
Subducting ocean plates under another ocean plate
The ultimate source of energy responsible for deep ocean circulation comes from
Sunlight and differential heating and cooling at the earth's surface
As waves progress away from the source of the disturbance that initiated them, the residual undulating ocean surface is called
Swell
Why were WWI and WII important to oceanography?
Technological advances made during wartime were applied to science
Typically, the highest sustained ocean waves occur in:
The Southern Ocean due to westwind drift
Residence time is
The average length of time an element spends in the ocean
We can determine salinity if we know:
The chlorinity of a water sample
Which of the following directly contributes to the oxygen minimum layer
The decomposition of organic matter
The carbonate compensation depth is:
The depth below which carbonate minerals (calcium carbonate and carbonate skeletons/shells) dissolve
Increases in acidity in the ocean can result in
The dissolution of carbonate minerals or carbonate skeletons/shells of organisms
Why are relative sea levels falling in some regions around the word?
The lithosphere is rising due to isostatic rebound or tectonic processes
The carrying capacity of a population defines:
The maximum number of individuals that can be permanently supported in an environment
Caballing refers to:
The mixing of two water masses of the same density but different temperature and salinities
Spring tides occur when:
The moon, sun, and earth are in line
Biodiversity describes:
The variety of organisms or species present in a community
When the height of a wave exceeds 1/7 of its length
The wave begins to break
Ekman transport:
Theoretically moves surface water about 90o to the wind direction (but in reality much less)
What is true about Seismic P waves?
They are compressional
What is true about the earth's layer?
They are density stratified
What is true about Seismic secondary (S) waves?
They do not pass through liquids
At depths below the carbonate compensation depth, what is true of calcareous oozes?
They fail to accumulate due to increased solubility of calcium carbonate and decreased temperature
What is true about hydrogen bonds
They occur between hydrogen and oxygen atoms of neighboring water molecules
What does not contribute tor relative rates of sea level rise?
Tides
Which of the following is NOT true about tidal waves
Tides cause fast currents
How can fertilizer runoff harm Chesapeake Bay? (2 points)
Too much N can "fertilize" algae causing eutrophication
Western boundary currents:
Transport warm water toward the poles
Conservative constituents of seawater generally have long residence times.
True
Roughly how fast do most lithospheric plates move?
about 3 cm per year
In addition to forming harmful algal blooms, some dinoflagellates can also:
all are correct
The two marine prokaryotic domains are:
bacteria and archaea
Why doesn't the meteorological equator fall exactly on the geographical equator?
because of the location of earth's land masses
The pH of the ocean is buffered primarily by what acid-base pair?
bicarbonate-carbonate
Of the four types of ocean sediments, biogenous and terrigenous make up 99% of materials on the ocean bottom. What are the sources of these sediment types? Surprisingly, sediments in many of the deep abyssal plains are also terrigenous; what is the primary delivery "route" for these sediments? Why are there few calcareous oozes on deep abyssal plains? Silicious oozes are found on the deep ocean floor and their distribution is also non-random. How would you explain the distributions of these sediments? Although rare, cosmogenic sediments are found in every ocean basin at all depths. Why is this?
biogenous - organisms, mainly microbes Terrigenous - land transported there mainly by dust CCD - calcareous oozes dissolve at depth Silicious oozes are generally below high productivity waters where diatoms are abundant Cosmogenic sediments arrive randomly with meteors
How do we date the earth and rocks?
by measuring the decay of radioisotopes
With increasing ocean acidification in a future ocean, coccolithophores will have increased difficulties in:
calcifying
In deep sea communities of the aphotic zone, primary production is accomplished by
chemosynthesis
Because of upwelling, the surface waters along the equatorial Pacific are generally:
cold and nutrient rich
Zooplankton that are detritivores feed primarily on:
dead organic matter
Light intensity does what with depth
decreases exponentially
Describe the depth profiles for the concentrations of the dissolved nutrients nitrate and silicate in the open ocean (shapes and concentrations). Why are they shaped the way they are in surface water (upper 100 to 200m), at mid-depths (~200-1000m), and in deep waters (> ~1000m)? Would you expect the profile of dissolved phosphate to look like that of silicate or nitrate, and why? Why are the concentrations of all nutrients in deep waters of the Pacific Ocean higher than those in the deep Atlantic? (10 points)
depleted in surface by phytoplankton, increase rapidly with depth at base of euphotic zone due to remineralization, replete in deep waters because little uptake. Silicate only if there are diatoms. Phosphate would look like nitrate because it is a plant nutrient. Deep water concentrations greater in the Pacific because the water is older
The most abundant form of nitrogen in the ocean is:
dissolved N2
Herbivorous zooplankton obtain most of their energy from
eating phytoplankton
Explain what we mean by gross productivity, net productivity, the compensation depth and the critical depth? Why does the depth of the mixed layer affect primary productivity? (10 points - 2 points for each definition and 2 points for the final question)
gross productivity = primary productivity before respiratory losses net productivity = gross productivity - respiration compensation depth = depth where ps = resp rate (no net productivity) critical depth = depth where depth integrated productivity = depth integrated resp (no productivity) affects whether there can be net productivity - cells need to be in the light; mixed layer deeper than critical depth means no productivity
The ocean is slow to heat and slow to cool. This is related to a property of water known as:
high heat capacity
Most of the carbon on Earth is stored in the:
in marine sediments and sedimentary rocks
In the ocean, concentrations of plant nutrients typically:
increase below the photic zone
Gas transfer velocity (K in cm/hr) increases with:
increasing wind speed
In polar waters, what is thought to limit primary production?
light
Polar primary production has one maximum per year that is controlled by
light intensity
Because of the tilting of Earth's axis relative to the position of the moon, the tides along the west coast of the United States are classified as
mixed tides
Ocean floor farther away from a spreading center is
older
Deep sea terrigenous sediments are primarily clays because
only small particles can be transported far enough to reach the deep ocean basins
Meroplankton are:
organisms that spend part of their life cycle in the plankton
The hydrogen atoms in a water molecule tend to bond to:
oxygen atoms of another water molecule
Maximum respiration rates generally occur at the depth of the
oxygen minimum
The pH is defined as:
pH = - log [H+]
A ________ organism lives in the water column, whereas a ________ organism lives on the ocean bottom.
pelagic, benthic
Unlike other groups of phytoplankton, diatoms uniquely require what element
silicon
The ocean's deep sound channel (SOFAR layer) is characterized as a zone in which:
sound is trapped in a horizontal band at the velocity minimum layer
Explain why Chesapeake Bay experiences seasonal hypoxia and anoxia (dead zones) in its water column. Make sure you discuss the role of primary production and what limits it, respiration, and vertical mixing in the entire water column. b) Why is hypoxia a problem in the summer, but not during the winter? c) What human activities are affecting hypoxia (making it better or worse) in the Bay? (6 extra credit points)
spring bloom (=high primary production in spring), uses N and P to depletion, sinks and creates oxygen demand, respiration consumes oxygen. Problem in summer because deep waters in Ches Bay become stratified and vertical mixing is required to reoxygenate the water. Not a problem in winter because ample mixing and lower productivity. Humans adding nutrients promoting excess algal growth
An organism that has a narrow tolerance for changes in salinity is said to be
stenohaline
The most pronounced thermoclines occur in:
the tropics
Clay particles require more shear stress to suspend them than sand particles because
they are cohesive
The ocean's biological pump does what?
transports carbon from the surface ocean to the deep ocean
The density of a parcel of seawater will increase:
when the salinity increases