final exam oceanography

Question 1

Describe the forces that produce tides

Answer 1

Gravitational force- of moon & sun

Inertial force- outward by rotation of earth-moon and earth-sun system

Question 2

What is a lunar day?

Answer 2

24 hours 50 min.
Moon continues its orbit around the earth in 24 hours while it takes another 50 min to catch up to the moon.

Question 3

Why is lunar day different from a solar day? How does that explain the
timing of tides?

Answer 3

lunar day is 50 minutes longer than a solar day. While solar day is only 24-hour.

lunar is longer in timing becuase the moon moves around the Earth in same direction the Earth is rotates on its axis. Making the Earth take an extra 50 minutes to catch up to the moon.

Question 4

What is the relative importance of the sun vs. the moon in generating tides?

Answer 4

Tide generating force of sun is only 46% of moons force

Question 5

What are spring tides and neap tides? When (phase of moon) and how/why do they
occur? Be able to recognize periods of spring and neap tides on monthly tidal graphs

Answer 5

spring tides- full and new moon because the solar and lunar tide-generating forces are combined to produce the largest tidal range.

neap tides- 1st and 3rd quarter moon because the solar and lunar tide-generating forces are oppose each other to produce the smallest tidal range.

Question 6

What are diurnal, semidiurnal, and mixed tidal patterns (how many high tides and low
tides per day; how do successive tides compare in terms of height)?

Answer 6

Mixed tidal- 2 high 2 low (very different in height) per day but its all over the place

Semidiurnal tidal- 2 high tides and 2 low tides (about the same height) per day but more aligned

Diurnal tidal- 1 high and one low tide per day

Question 7

What influences the number and types of tides in the actual oceans

Answer 7

The influence of the shape, size and depth of the ocean basin or coastline.

Question 8

Where in the ocean are marine autotrophs, benthic organisms and pelagic organisms
most abundant?

Answer 8

autotrophs are more in shallow coastal ocean seafloor

benthic are more in shallow coastal ocean in deeper waters

pelagic are more in water column of coastal, ocean, and lake waters.

Question 9

What are intertidal habitats? What are their characteristics and what conditions are
present?

Answer 9

Is the area exposed at low tide and underwater at high tide.
* Water availability can be an issue
* Can be a stressful place to live!
* Many adaptations
* Still very productive (light,
nutrients)

Question 10

What are subtidal habitats? What are their characteristics and what conditions are
present?

Answer 10

Is the area always covered in hallow lots of sunlight
* Water is mixed by waves tides:
abundant nutrients
* High primary production (lots of
autotrophs!), very productive
* Habitat for many benthic and
pelagic organisms, including many
juveniles

Question 11

How do abiotic factors (light, temperature, salinity, density) vary from the surface to the deep ocean?

Question 12

How do abiotic factors (temperature, salinity, density) vary from the tropics to the poles? Why?

Question 13

How do temperature and salinity affect density of seawater?

Answer 13

Cold water is denser than warm water so it tends to sink. Seawater is denser than freshwater.

Water with higher salinity is denser than water with lower salinity. As water warms it expands and becomes less dense, as water cools it contracts and becomes more dense

Question 14

What and where are the surface mixed layer, halocline, thermocline, pycnocline, and deep ocean layer?

Answer 14

• mixed water = no layers (at the top)
  • generated by wind blowing across water
  •causes mixing of water down to pycnocline
  •arranged into large gyres
• pycnocline = (below) mixed layer
  • change in density with depth
• thermocline = (layer between warmer mixed water at the surface and cooler deep water below)
  • change in temperature versus depth, usually a graph
• halocline = (originate at surface)
  • a strong halocline indicates a stratified water column and multiple water sources

-deep ocean layer = (below pycnocline layer)
• sink at high latitudes due to increasing density of surface water spread out below pycnocline

Question 15

What are the three different zones of ocean and where do they occur (max. depth)?

Answer 15

Euphotic zone- In sea level area where sunlight is rarely shown deeper than this zone

dysphotic zone- In 200 meters where sunlight decreases quickly deeper in the depth. photosynthesis is not possible here.

aphotic zone- In 1,000 meters where sunlight isn’t shown at all this zone is in complete darkness.

Question 16

What the difference between autotrophs and heterotroph?

Answer 16

Autotrophs are producers who prepare their own food.

While Heterotrophs are consumers who depend on other sources for their food they get food by eating autotrophs or other heterotrophs.

Question 17

How does density affect the ability of water to mix? Or to form layers (stratification)?

Answer 17

Layers are based on water density: denser water remains below less dense water in stable stratification in the absence of forced mixing

Question 18

The three different groups of marine autotrophs where they live and why, which contribute more and which contribute less to the food web.

Answer 18

marine autotrophs- seed-bearing plants (true plants), macroalgae (seaweeds) live in benthic because its limited to shallow water near the coast.

Phytoplankton- microalgae & cyanobacteria live in pelagic because it can grow anywhere in
euphotic zone, not limited to coasts.

Phytoplankton contributes more as it is responsible for 95% of marine primary production!

Question 19

At which latitudes is the water column the most stratified? Why? At which latitudes is it most mixed? Why?

Answer 19

(Most stratified) 30 N, 0, 30 S =surface and deep ocean layers are separated by pycnocline, do not mix (lower latitudes)

(Most mixed) 60 N, 60 S= surface and deep ocean layers mix (high latitudes)

Question 20

What are some examples of variables that are affected by density stratification?

Answer 20

Nutrients , CO2, pH, oxygen, pycnocline: 1000 m

Question 21

What happens during photosynthesis? What is required for photosynthesis, and what is
produced?

Answer 21

process uses sunlight, water, and carbon dioxide to create oxygen and energy to sugar.

sunlight, carbon dioxide, and water are the necessary for photosynthesis

what produced is sugar

Question 22

What are the inorganic nutrients? Where are nutrients more abundant: in surface waters or deeper down? Why?

Answer 22

They are nitrogen and phosphorus.

They are abundant in deeper waters because dead organisms sink and the decomposition releases nutrients

Question 23

In which layers of the ocean (surface mixed layer, pycnocline, deep ocean) do surface currents and deep currents occur?

Answer 23

• surface mixed layer = top layer
• pycnocline = below surface mixed layer
• deep ocean = below pycnocline

Question 24

What causes surface currents? What is a gyre?

Answer 24

(in surface mixed layer)
• generated by wind blowing across water
• causes mixing of water down to pycnocline
• arranged into large gyres (=large rotating water current)

Question 25

What causes the deep ocean currents? Where do they come from: where do they go?

Answer 25

(Thermohaline circulation)
• originate at surface
• sink at high latitudes due to increasing density of surface water
• spread out below pycnocline

Question 26

What problem do marine autotrophs face in the ocean in obtaining sunlight and nutrients?

Answer 26

They face low in surface water and high in/below pycnocline.

Question 27

how do water column stratification and ocean mixing affect nutrient availability at the
ocean surface? And how is autotroph abundance (and primary production) affected?

Answer 27

stratification water column the nutrients stay in
deep water while ocean mixing nutrients can be mixed into surface waters.

Autotrophs at the top have nutrients and sunlight.

Question 28

Compare high (polar) latitudes to low (tropical) latitudes in terms of autotroph abundance/productivity. Explain why one latitude is sometimes productive and the other
one is not. What limits primary production in each?

Answer 28

High latitudes is temperate and near polar. It has high chlorophyll. It has abundance autotroph, high productivity in spring/summer while low productivity in fall/winter. Nothing limits the production of spring/summer while light limits fall/winter.

Low latitudes is tropics and subtropics. It has Low chlorophyll. Its abundance in autotroph is low, low productivity. Nutrients limits the production of tropics.

The reason why one can be productive while the other not is water column stratification

Question 29

For temperate latitudes, how is primary production affected by season?

Answer 29

Productivity is limited in the summer months because of nutrients limitation and availability of light.

Question 30

be able to figure out what might be limiting/controlling primary production at a certain location

Answer 30

the availability of light, nutrient or nothing

Temperature of water is important because it shows if the nutrients or light is available in stratification or not

Question 31

Oceans are more productive near major rivers, along the coast, in upwelling areas (know
where these are and what happens there), and at higher latitudes. For each, explain why
this is the case.

Answer 31

In Freshwater runoff. The freshwater runoff discharges nutrient-rich water. Autotrophs are abundant near land and river mouths, Enhanced productivity.

In Coastal Upwelling. The surface water moves off-shore due to winds. Brings cold, deep, nutrient-rich water to the surface. Autotrophs are abundant, productivity is high.

Question 32

What is a trophic level? What is the trophic transfer efficiency? How much energy is generally transferred from one trophic level to the next?

Answer 32

trophic level: a feeding level in a food web
Trophic transfer efficiency: •Energy transferred from one trophic level to next
•Not very efficient
•Only 10% is transferred
• 90% is lost

Question 33

What is the difference between a food chain and a food web? Which one is usually a more accurate depiction of the feeding relationships between organisms? Which one is more resilient to changes in one of its components?

Answer 33

Food chain: • linear energy flow
• single pathway connecting producer to several levels of consumers

Food web: •multiple interactions
• made up of many intertwined food chains
• predators have multiple prey
• prey have multiple predators
•usually more realistic

Question 34

Why are organisms at higher trophic levels less abundant than those at lower trophic levels? What is the biomass pyramid?

Answer 34

1) • smaller, more abundant organisms
• the higher the trophic level the lower the biomass of that level

2) the total mass of all organisms in a given area or volume of water

Question 35

Be able to construct a simple food web when given different organisms, in the right direction, indicate how much energy is available at each trophic level

Answer 35

look up a image

Question 36

The ocean is a 3-dimensional environment how does that affect the food web sinking, organic matter, decomposition, and recycling of nutrients back to the surface

Answer 36

• Decomposition, recycling of nutrients
• detritus continues to sink
• nutrients return to surface (physical mixing upwelling)

Question 37

Why is marine life much more abundant in the surface waters than in the deep ocean

Answer 37

(Euphoric zone) most food in the deep ocean (aphotic zone) originates at surface only ~1% of food/energy makes it down to deep sea floor

Question 38

What are the sources of food for organisms living in the deep ocean? What does does this food come from?

Answer 38

Rain of dead organisms, large food fall
Comes from ocean surface

Question 39

Why do many animals of the deep ocean migrate towards the surface during the night and back down again at dawn

Answer 39

(predators can’t see them)

Question 40

What is marine snow?

Answer 40

Decaying plankton, chitinous molts, fecal pellets, ect, sinking down from the euphoric zone

Question 41

What are hydrothermal vents and cold seeps? Where are they found? How do hydrothermal vent and cold seep communities survive without sunlight?

Answer 41

• Deep sea ecosystems that don’t rely on euphoric zone productivity

• chemosynthetic archae produce sugars using chemical energy source (hydrogen sulfide, methane, etc.)

• they live in other organisms (hosts)

Question 42

What are some of adaptations that organisms living in the deep ocean have evolved to survive in such an environment?

Answer 42

• small size due to lack of food
• low metabolic rate to conserve energy
• dark or red color
• large eyes or (small eyes but rely on other senses)
• good sensory devices (antennae, lateral lines, smell chemical signals)
• large teeth, mouths, and expandable stomachs and bodies
• bioluminescence (attract prey, territory, communicate, seek mate, escape from predators)

Question 43

What is bioluminescence? What is it used for?

Answer 43

Angler fish (attract prey, mates)