Lecture 2

Question 1

Different ocean regions by depth

Answer 1

• Epipelagic: 0-200m (photic zone)
• Mesopelagic: 200-1000m
• Bathypelagic: 1000-4000m
• Hadalpelagic: below 4000m

Question 2

What is the area of water above a continental shelf called?

Answer 2

Neritic zone

Question 3

What makes ocean salinity increase?

Answer 3

River run-off
Volcanic activity
Rain and snow
Hydrothermal vents

Question 4

Where is the highest sea surface salinity?

Answer 4

Mediterranean

Atlantic

Question 5

What six ions make up 99% of the salts dissolved in the ocean?

Answer 5

Chloride
Sodium
Sulphate
Magnesium
Calcium
Potassium

Question 6

Why are ocean surface concentrations of salts so important?

Answer 6

Control primary productivity

Question 7

What is an oxygen minimum zone?

Answer 7

A zone in which oxygen saturation in seawater is at its lowest due to physical and biological processes losing the oxygen concentration and restricting the water from mixing with surrounding waters

Question 8

How does pressure affect marine organisms?

Answer 8

They need air-filled bladders to adjust their position in the water column

Question 9

How to measure light penetration in oceans

Answer 9

Secchi disc
Submersible ‘photocells’
Quantum metres

Question 10

What is the wavelength of photosynthetically active radiation?

Answer 10

400-700nm

Question 11

At what depth does only blue light remain?

Answer 11

60m

Question 12

What is the correlation between the open ocean profiles of temperature and density?

Answer 12

They are mirror images of each other:

Temperature reduces with depth, whilst density increases

Question 13

Where can seasonal thermoclines be observed?

Answer 13

In temperate and polar waters

Question 14

How is downwelling caused by seasonal changes in ocean depth profiles? What does this cause?

Answer 14

In Autumn, the surface water cools, becoming denser and sinking. It displaces the deeper water which then rises, in a process called the overturn

Question 15

Where is there the greatest amount of ocean circulation due to winds acting on surface water

Answer 15

Near South Pole

Question 16

What is the Coriolis effect?

Answer 16

Due to the rotation of the Earth, currents and winds are:
1. Deflected to the right in the Northern hemisphere
2. Deflected to the left in the Southern hemisphere
Larger gyres (circular systems) created

Question 17

What causes the winds that move ocean surface water?

Answer 17

Rising of sun warmed air and sinking of cold air

Question 18

What is an Ekman spiral?

Answer 18

When wind blows over water causing the current to move in a certain direction, each layer of water moves farther to the right as you head down the water column with the net effect of water moving at right angles to the wind direction overall

Question 19

What are the three major circular surface ocean currents? What are they called?

Answer 19

Indian, Pacific and Atlantic oceans

Called gyres

Question 20

How do the oceanic gyres affect distribution of organisms

Answer 20

They affect the average temperature of the sea surface

Tropical organisms prefer west coasts whilst kelps occupy eastern shores