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Third Oceanography Exam


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cold water is ___ dense than warm water and ___ (sinks/rises)
more dense & sinks
saltier water is ___ dense than fresher water and ___ (sinks/rises)
more dense & sinks
light levels are highest at the ___ of the water
light levels are highest in this season
western boundary currents are ___ (shallow/deep) and ____ (slow/fast)
deep and fast
upwelling is inhibited in the centers of ____ current gyres
what causes most waves?
what group of organisms is at the bottom of the food web?
autotrophs: usually phytoplankton
what causes tides?
the gravitational attraction of the Moon & Sun
what is centripetal force?
the force required to keep identical-sized particles in identical-sized orbits as a result of the rotation of the earth-moon system around its center of mass
what is, and how long is, a lunar/tidal day?
it is the time elapsed between when the Moon is directly overhead and the next time it is directly overhead---24 hours 50 minutes
this force is the same for all particles in the earth
centripetal force
how many degrees does the Moon move during a complete rotation of the Earth?
12.2 degrees eastward
how long is a tidal month?
29.5 days (moon arounid earth)
tidal forces from the sun are ___ (less/more) powerful than tidal forces from the moon
sun = less powerful tidal forces (b/c of distance)
what are spring tides and on what 2 moon phases do they occur?
they are when the solar and the lunar bulge are in the same direction (left to right w/ solar bulge smaller) they occur during the Full Moon and the New Moon
what are neap tides and on what 2 moon phases do they occur?
they are when the lunar bulge is up and down and the solar bulge is left and right. they occur during First Quarter Moon and Third-Quarter Moon
solar eclipses occur when there is a ____ moon while lunar eclipses only occur when there is a ___ moon
solar eclipses = new moon
lunar eclipses = full moon
with ____(neap/spring) tides the tides reach their highest high and their lowest low
spring tides
for deep-water waves the ___ the wavelength the ____ the wave travels
longer wavelength = faster wave
what is a swell? under what conditions do they form?
they form when wind speeds diminish and the waves eventually move faster than the wind. when this occurs, wave steepness decreases and waves become long-crested waves called swells. they are uniform and symmetrical and carry energy efficiently over long distances.
what is a fetch?
the uninterrupted distance over which the wind blows without a change in direction
what causes a wave to break? (what conditions are necessary)
as waves come into shallow water and feel bottom, their speed and wavelength decrease while their wave height and wave steepness increase, causing the water to break
What causes tsunamis (seismic sea waves)? Does horizontal or vertical water displacement cause tsunamis?
they are generally cause by fault movement (underwater earthquakes that rupture sea floor and displaces the crust) also they can be caused by underwater avalanches or underwater volcanic eruptions

vertical displacements cause tsunamis not horizontal
how fast (roughly) do tsunamis travel? how tall are they?
well over 700 km/hr (435 mph)

0.5 meters tall (1.6 ft)
What geographic areas are subject to tsunamis
colliding tectonic plates of the Pacific Rim (fault lines, underwater volcanoes, etc.)
How do a wave's characteristics change as it enters shallow water?
wave speed decreases, decreased wavelength, wave height increases, wave steepness increases
what 3 factors control how high the highest wind waves will be?
1. wind speed
2. duration (length of time during which the wind blows in one direction)
3. fetch (distance over which the wind blows in one direction)
what is the alignment of the earth, moon and sun during spring tides? neap tides?
spring tides: M E S or E M S (straight line)

neap tides: E (moon is at 45 degree angle above or below earth) S
is the earth's tidal bulge centered on the equator?
What other 4 factors influence the tide?
1. declination of moon's orbit (18 degrees to 28 degrees in an 18.6 year cycle)
2. earth-moon distance
3. earth-sun distance
4. weather (low pressure = water rises / wind blowing towards shore = higher tides)
What are the three kinds of tides a coastal area can experience in a tidal day? what patterns do they form? what is the tidal period (time between high tides) of each?
1. Diurnal Tides: 1 high tide + 1 low tide (tidal period = 24 hours 50 minutes)

2. Semidiurnal Tides: 2 equal high tides + 2 equal low tides (tidal period = 12 hours 25 minutes)

3. Mixed Tides: 1 high high tide + 1ow high tide OR 1 low low tide, one high low tide (tidal period = 12 hrs 25 minutes OR 24 hrs 50 minutes)
What are 3 common phytoplanktons (in order of abundance)?
1. diatoms (silica shells)
2. dinoflagellates (cellulose shells-use flagellae to propel themselves)
3. coccolithophores (calcareous shells-more spherical-use flagellae)
what are the three main divisions of marine life and what categorizes them?
1. Plankton: floaters and weak swimmers/all domains
2. Nekton: strong swimmers/only animals
3. Benthos: bottom swellers (infauna & epifauna)
what is the difference between infauna benthic creatures and epifauna benthic creatures?
infauna = live buried in mud
epifauna = at the seafloor surface
What 2 types of aurotrophic organisms are possible?
photosynthetic and chemosynthetic autotrophs
what is phytoplankton vs. zooplankton?
phytoplankton = plant plankton that uses photosynthesis (upper part of water collumn)

zooplankton = animal plankton, eat smaller plankton, don't use photosynthesis
what is meroplankton vs. holoplankton?
holoplankton = spend entire life as plankton

meroplankton = spend only part of life cycle as plankton (most fish, usually juvenile stage)
what is nannoplankton, microplankton, and netplankton
nannoplankton = bacteria plankton/viruses (b/c of small size and hard to classify)

microplankton = large plankton

netplankton = bigger than nannoplankton
what are some examples of zooplankton?
fish egg/larva, radiolaria (siliceous), copepods (really important), foraminifera, siphonophore (jelly), jelly fish, doliolum, arrow worms
Which zooplankton are between plankton and nekton?
copepods, krill
what are some examples of infauna? epifauna?
infauna = clams, snails, worms, amphipods

epifauna = corals, oysters, mussels, sea anemones, starfish, some fishes, lobsters, urchins
marine species represent ____ percent of the total number of known species on earth
within the _______ known marine species the benthic environment is home to ___ percent of the species and the pelagic environment is home to ____ percent of the species
250,000 marine species
benthic = 98%
pelagic = 2%
what is a heterotroph and an autotroph?
heterotrophs are consumers and depend on the organic compounds produced by the autotrophs for their food supply

autotrophs are producers and are able to nourish themselves through photosynthesis or chemosynthesis
why are there less species in the oceans than on land?
marine conditions are fairly constant, especially laterally in the oceans (vertical changes are much more rapid - light level, nutrients, temp, predators, pressure, seasonality), thus there is less pressure on a species to diversify or adapt.

also, there are few barries to migration/colonization
in cold water you need _____ (more/less) appendages to maintain depth and position in the water column
less ornate appendages in cold water (it is more viscous than warm water)
why does the small size of phytoplankton help them maintain their position in the upper water collumn?
they float
what 3 things do fishes do to help them maintain their position in the water column?
1. they can make fats
2. they have a swim bladder (that they can fill with gas, some through their blood, others gulp)
3. they can gulp in air at surface
how does living in warm water influence organisms?
faster biochemical reactions, faster growth, faster maturation, shorter life expectancy
what is the difference between eurythermal organisms and stenothermal organisms? what are most fishes?
eurythermal = tolerates a wide range of temps

stenothermal = tolerates a narrow range of temps
where in the ocean do you typically find euryhaline organisms? are fishes typically euryhaline?
near the coast (they can tolerate the changes in salinity)

no, most fishes are stenohaline
a marine fish is ______ (hypotonic/hypertonic). what about a freshwater fish?
marine fish = hypotonic (low salinity)
freshwater fish = hypertonic (high salinity)
how do marine fish maintain low salinity?
1. drink lots of water
2. secrete salt through special cells
3. small volume of highly concentrated urine
how do freshwater fish maintain a higher salinity?
1. do not drink
2. cells absorb salt
3. large volume of dilute urine
what are two things that kill fish w/ oxygen depletion?
1. factories take in cold water and expel warm water (w/ less oxygen)

2. bacteria use oxygen to consume dead algae, and they can become too numerous
What are four defenses marine organisms use, and some examples of them?
1. Difficult to See
-schooling confusion
-disruptive coloration
-live in the dark
-small size

2. Cohabitating w/ a dangerous organism
-clown fish & sea anemone
-remara & shark

3. Poisons & venoms

4. Spines
-pufferfish (looks larger and is harder to eat)
what is the difference between littoral and neritic environments?
littoral = shoreline seabottom
neritic = near-shore pelagic environment
what is primary production?
how much carbon is fixed into organic matter by solar energy (per year basis) - mostly photosynthesis and in areas of upwelling
what is net primary production?
the amount of organic material left after photosynthesizers take care of respiration and cellular maintenance
what is the compensation depth?
it is the depth at which net photosynthesis becomes zero (up to 100m deep) it's deeper in the summer
what are the euphotic and aphotic zones and where are they located?
euphotic zone = zone that extends from surface to a depth where enough light still exists to support photosynthesis

aphotic zone = zone that has no light, way below compensation depth
what are some microorganisms that use photosynthesis?

what are some macro photosynthesizers?
micro = diatoms, coccolithophores, dinoflagellates

macro = brown algae, green algae, red algae (low light)
why do dinoflagellates cause some problems for humans?
they produce neurotoxins which cause PSP (paralytic shellfish poisoning) and Pfisteria Piscicida
what is it called when dinoflagellates "bloom"?
a red tide
what is often a limiting nutrient and why? what is another?
iron - it doesn't stay in solution so it is limited.

nitrogen is also sometimes lacking because it is not in the right form (nitrate) and it takes a while for bacteria to get nitrate trapped in an organism's amino acids back to nitrate
where are nutrients recycled? why?
the euphotic zone - it is where photosynthesis can take place
in polar regions biomass is _____ and there is a ____ number of species
large, seasonal biomass & few species
in temperate regions biomass is _____ and there is a ____ number of species
moderate biomass, moderate # of species
in the tropical/subtropical regions biomass is ____ and there is a ____ number of species
low biomass, high number of species
what is biomass?
the amount of organic carbon (i.e. plant and animal material) in an ecosystem
nutrients are limited in which ocean climate/zone? which part of the ocean?
the tropical zone/the open ocean
which ocean region has later, intense blooms?
the polar regions
coastal waters are limited by ____
limited by light (murky)
in benthic zones, organisms are limited by _____
space limits organisms on the seafloor
each step in the food web is ____ deficient
10% (so the shorter the food web, the more efficient the energy conservation)
most animals in the deep oceans are ___vores
omnivores (such limited nutrients)
what is a trophic level?
each feeding stage in the food web
which can hold more gas---cold water or warm water?
cold water
what is "standing stock"?
the mass of fish present in a fishery at a given time
what is the "Maximum Sustainable Yield"? it is variable?
it is the max fishery biomass that can be removed yearly & still be sustained by the fishery ecosystem

yes it is variable
what percentage of fisheries are overfished? at MSY limit?
what is recruitment?
how immature individuals become reproductive
what is anadromous and catadromous reproduction? give an example of each
Anadromous reproduction = spawn in freshwater streams and rivers and migrate to sea to mature (SALMON)

Catadromous reproduction = spawn in ocean/sea saltwater and mature in freshwater (EELS)
What happens to the Peruvian fishery when an el Nino hits? and why?
El Nino prevented upwelling causing a shortage of nutrients, and because of overfishing also depleting the nutrients fish excrement contains, the fishery was strongly overdepleted

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