Lecture 7 - DA Flashcards
Name the 5 oceans.
Indian Pacific Atlantic Arctic Southern
Define bathymetry.
Topography of the sea floor.
What is the neritic zone defined by?
The edge of the continental shelf.
What is the oceanic zone?
From the edge of the continental shelf, to the abyssal zone/floor - is beyond the shelf.
What is the bathyal zone?
Zone at the very edge of the continental shelf, where it slopes down to the abyssal zone.
What is the hadal zone?
Zone beyond the abyssal zone, is deeper.
How are continents created?
Plates of earths crust.
How do the plates of earths crust move? Do they move independently?
They move independently and are driven by the movement of the magma in the mantle.
In what manner does the magma in earths mantle move?
Convective.
Where are hydrothermal vents found, and whats special about the food web in these areas?
Mid-ocean rises.
Release hot water >400*C from beneath the crust.
The dissolved minerals precipitate immediately, and release high concentrations of hydrogen sulphide.
Endemic species with unique adaptations to these vents exist here, such as chemosynthetic bacteria, who are the primary producers of these food webs.
What are 2 most abundant ions in sea water? Name 3 others.
Sodium and chlorine, but also magnesium, calcium, and potassium.
What salinity gradient exists for the ocean? Explain why it is so.
Increases going from high to low latitude. This is because evaporation is more intense at warmer climates. But there is a band low salinity at the equator. This is because there is low atmospheric pressure here, and the trade winds allow higher rainfall.
What is the buffering system of the ocean like compared to freshwater?
Is the same as in freshwater, but more effective, because there is more carbon gas in the ocean.
What is the pH stability of the ocean like compared to freshwater? What is happening to it now?
Ocean pH is more stable, but is falling due to excess carbon in the air.
Define thermocline and pycnocline.
Thermocline - region of rapid temperature change with depth - temperature gradient.
Pycnocline - region of rapid density change with depth - density gradient.
Describe the vertical structure of the water column in oceans.
Mixed surface layer, followed by the thermocline/pycnocline, then deep water.
Does inverse stratification occur in lakes? What about in oceans?
Yes in lakes, but never in oceans.
What is the salinity of oceans like with depth? Is this true of low latitude areas? Explain why.
Lower near the surface as saline water is more dense.
Low latitude areas can have higher salinity water at the surface than below it.
This is due to higher temperatures of the low latitude regions making the water less dense despite the salinity.
Define halocline.
Profile for salinity.
What effect does a high tide have on the salinity gradient at an estuary? What about low tide? What happens to organisms living here?
High tide will compress it low tide will expand it.
Some organisms deal with the change, others can only tolerate a certain range, and may move as needed.
Does a spring overturn occur in oceans as they do in temperate lakes? Explain why.
Doesnt, because seawater will not become more dense as it warms up to 4*C.
Does seawater become less dense as it cools to ice? What happens to the salt, and what effect does this have below the ice?
Doesnt become less dense, and the salt can be excluded, making the water beneath more saline and therefore more dense.
Which cardinal direction do the trade winds blow from?
From East to West.
What are equatorial currents important for?
Upwelling.
What are gyres? What are the nutrient levels like here?
Large oligotrophic systems created by circulating currents, are a low nutrient area due to poor mixing in the centre.
Which currents are the strongest, and where do they carry water to/from?
Western boundary currents, carrying tropical water to temperate latitudes.
Which currents cause coastal upwelling? How does the rotation of the earth affect this?
Eastern boundary currents cause coastal upwelling, only from the eastern side due to the coriolis effect.
The coriolis effect deflection can move water onshore or offshore. Which way does this occur in the northern/southern hemisphere?
To the left in the southern hemisphere, and right in the northern hemisphere.
