Currents & Circulation
What two factors influence ocean surface currents?
Wind and the Coriolis effect.
What is longshore drift?
The movement of sand along a beach by waves approaching at an angle.
What sea surface temperature is needed for cyclone formation?
Above 26.5°C.
What is eutrophication?
Excess nutrients causing algal blooms and oxygen depletion.
What does the Exclusive Economic Zone (EEZ) allow Australia to control?
Use of marine resources up to 200 nautical miles offshore.
What is downwelling?
The sinking of surface water, carrying oxygen to deeper layers.
What coastal process removes sand from the beach?
Erosion.
Which direction do cyclones rotate in the Southern Hemisphere?
Clockwise.
Give one example of a point-source pollutant.
Sewage pipe discharge.
How does the East Australian Current (EAC) affect fisheries?
It brings warm, nutrient-rich waters that support high productivity.
Why is the thermohaline circulation sometimes called the “global conveyor belt”?
It connects oceans worldwide, transporting heat, nutrients, and gases.
How does wave refraction affect headlands and bays?
Energy is concentrated on headlands (erosion) and dispersed in bays (deposition).
What is the relationship between air pressure and wind speed in a cyclone?
As pressure decreases, wind speed increases.
Why does turbidity reduce coral health?
It blocks sunlight, reducing photosynthesis in symbiotic algae.
Why does sea level rise when global temperatures increase?
Thermal expansion of seawater and melting of ice sheets/glaciers.
Explain how salinity affects water density.
Higher salinity increases density, causing water to sink.
What effect do groynes have on sand movement?
They trap sand on one side but starve the down-drift side of sediment.
How does El Niño affect rainfall in eastern Australia?
It usually causes drier conditions and drought.
How does the Great Pacific Garbage Patch form?
Ocean gyres and Ekman transport trap floating plastic debris.
How can sea-level rise affect coastal cities like Brisbane?
Increases flooding, erosion, and infrastructure damage.
Evaluate how changes in polar ice melt could disrupt thermohaline circulation.
Increased freshwater lowers salinity, reduces density, and weakens or shuts down circulation, affecting climate and ecosystems.
Suggest one negative ecological impact of artificial coastal engineering.
It can disrupt natural sediment transport, harming habitats like dunes or mangroves.
Evaluate how climate change may affect cyclone intensity.
Warmer oceans provide more energy, leading to stronger, more destructive cyclones.
Evaluate how flood plumes threaten reef ecosystems.
They bring sediments, nutrients, and pollutants, reducing water quality and stressing corals.
Evaluate two actions coastal planners could take to respond to sea-level rise projections
Build protective structures (e.g., seawalls) and plan managed retreat or stricter coastal zoning.