Lecture 2 Flashcards
Different ocean regions by depth
- Epipelagic: 0-200m (photic zone)
- Mesopelagic: 200-1000m
- Bathypelagic: 1000-4000m
- Hadalpelagic: below 4000m
What is the area of water above a continental shelf called?
Neritic zone
What makes ocean salinity increase?
River run-off
Volcanic activity
Rain and snow
Hydrothermal vents
Where is the highest sea surface salinity?
Mediterranean
Atlantic
What six ions make up 99% of the salts dissolved in the ocean?
Chloride Sodium Sulphate Magnesium Calcium Potassium
Why are ocean surface concentrations of salts so important?
Control primary productivity
What is an oxygen minimum zone?
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
How does pressure affect marine organisms?
They need air-filled bladders to adjust their position in the water column
How to measure light penetration in oceans
Secchi disc
Submersible ‘photocells’
Quantum metres
What is the wavelength of photosynthetically active radiation?
400-700nm
At what depth does only blue light remain?
60m
What is the correlation between the open ocean profiles of temperature and density?
They are mirror images of each other:
Temperature reduces with depth, whilst density increases
Where can seasonal thermoclines be observed?
In temperate and polar waters
How is downwelling caused by seasonal changes in ocean depth profiles? What does this cause?
In Autumn, the surface water cools, becoming denser and sinking. It displaces the deeper water which then rises, in a process called the overturn
Where is there the greatest amount of ocean circulation due to winds acting on surface water
Near South Pole
What is the Coriolis effect?
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
What causes the winds that move ocean surface water?
Rising of sun warmed air and sinking of cold air
What is an Ekman spiral?
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
What are the three major circular surface ocean currents? What are they called?
Indian, Pacific and Atlantic oceans
Called gyres
How do the oceanic gyres affect distribution of organisms
They affect the average temperature of the sea surface
Tropical organisms prefer west coasts whilst kelps occupy eastern shores
