Lecture 10

Question 1

What is one of the greatest threats to estuaries globally?

Answer 1

Rising sea levels

Question 2

Why do greater temperatures cause sea level rise?

Answer 2

Through thermal expansion and the melting of polar glaciers

Question 3

What would happen to sea level if you fully melted the Greenland, west Antarctic ice sheets and the entirety of Antarctica?

Answer 3

• 7m sea level rise for Greenland
• 6m sea level rise for west Antarctic
• 61m sea level rise for full Antarctic

Question 4

What are the five global ocean?

Answer 4

Pacific, Atlantic, Indian, arctic

Question 5

Whist is special about the Arctic Ocean?

Answer 5

Waters are most uniform and in terms of physical features and they are highly productive

Question 6

What is the mixing regime in oceans?

Answer 6

Horizontal cane vertical currents

Question 7

How does the Coriolanus effect influence currents in oceans?

Answer 7

The horizontal currents form via the Coriolanus effect.
In the norther hemisphere currents move clockwise
In the Southern Hemisphere currents move anti clockwise

Question 8

Which current rotates around 5e South Pole? Give details of it

Answer 8

The Antarctic circumpolar current . Rotates at a rate of 0.4-0.5 m/s

Question 9

Which causes upwelling ,divergence or convergence?

Answer 9

Divergent

Question 10

In which global region does lots of upwelling occur?

Answer 10

At the equator, diverging currents cause lots of mixing. This essentially disturbs the deep water, causing upwelling

Question 11

In which regions is food web productivity high in the global oceans? Why?

Answer 11

Regions of upwelling, as the high influx of nutrients supports many algae (primary producers) and a stable food web
At continental shelves, as the shallow depth of the oceans means that mixing is more likely to occur

Question 12

Why does all the oceans deep water originate at polar regions?

Answer 12

Salt dissolves out of melting ice, increasing the salt content of oceans. This then causes the water to be highly saline, and dense.
This and the coldness of the poles causes it to sink, forming deep water that slowly disperse at depth to the other oceans (in a slow process)

Question 13

Where does all the worlds deep water come from?

Answer 13

Polar regions

Question 14

What is the stratified status of all oceans?

Answer 14

They are meromictic (permanently stratified)

Question 15

What are the depths for the temperature division in the ocean?

Answer 15

Warm surface layer: 400m
Gradual decrease: 400-1800 m
Constant cold: >1800m

Question 16

What is the salinity at the sea base?

Answer 16

35 practical salinity units

Question 17

Why is salinity greater in hotter areas?

Answer 17

The higher temperatures cause increased evaporation, and increased concentration of saline ions

Question 18

What are the psi values for tropical and arctic waters?

Answer 18

Surface tropical: 35psu

Arctic Ocean: 29psu

Question 19

Subtropical waters have greater a greater psu value than arctic waters, why don’t they sink?

Answer 19

Unequal distribution iPod incoming solar radiation makes these waters warmer, and more buoyant

Question 20

Why does oxygen solubility increase in cold waters?

Answer 20

The h2o molecules have less kinetic energy, and the forces holding oxygen in water molecules are less likely to break

Question 21

Which had more oxygen, top or bottom oceans?

Answer 21

Bottom layer, due it’s cooler temperatures allowing it to hold more oxygen

Question 22

Why do oceans have a clearer light climate than rivers?

Answer 22

The bulk of oceans (as coastlines are just a small part) have no catchments so there’s no influx of unwanted humid material. There is also little sediment in surface waters, as the ocean depth is so deep

Question 23

What is the average section depth in oceans?

Answer 23

300 m

Question 24

Which light wavelengths penetrate the deep ocean and which are absorbed by surface layers?

Answer 24

Blue light (short wavelength)penetrates deep layers, red light is absorbed at the surface

Question 25

What are the two uses of blue light in oceans?

Answer 25

Photosynthesis and bioluminescence

Question 26

Which algae produce white light when disturbed? What’s produced when undistrubed?

Answer 26

Dinoflagellates. Blue light

Question 27

What is the trophic status of all oceans?why?

Answer 27

Oligotrophic as no nutrient inflow from catchments

Question 28

What are the limiting nutrients in oceans?

Answer 28

Iron and nitrogen

Question 29

What are the four main ocean depths? In order from surface to bottom

Answer 29

Epipelagic
Mesopelagic
Bathypelagic
Abyssopelagic

Question 30

In which ocean zone is phytoplankton based?

Answer 30

The epipelagic

Question 31

Which are the main algae in oceans? Hint:frustruals

Answer 31

Diatoms, requiring silica for frustruals

Cocoliphophores

Question 32

Which of the two dominant species blooms closer to land? Why?

Answer 32

Cocoliphophores, as they require higher levels of nutrients than diatoms

Question 33

What is the general distribution of algae in oceans?

Answer 33

Random, with hotspots and coastlines containing higher primary production as more nutrients are preset (eg from a river catchment). The rest of oceans are fairly nutrient poor, so contain lesser algae biomass

Question 34

What is the difference between the freshwater and ocean microbial loop?

Answer 34

The only difference is the lesser variety of algae than freshwater, and the fact that all the nutrients within the loops and in house

Question 35

Where do bacteria in the microbial loop get carbon?

Answer 35

As there’s no river catchments, they rely solely on algae for carbon

Question 36

What is the metazooplanton distribution in oceans?

Answer 36

Copepods dominate with very few cladocerans or Rotifers. There is no seasonal variability like in the peg model

Question 37

What is a holoplankton?

Answer 37

Plankton that spend their entire life in the water column. Eg . Krill

Question 38

What is meroplankton?

Answer 38

Meroplsnkton are organisms that are planktonic in their larvae stage and benthic when they become adult invertebrates