Oceanographic Processes
What is upwelling and why is it important?
Upwelling is the movement of cold, nutrient-rich water from the deep ocean to the surface; it supports high productivity and marine food webs.
What is the thermocline?
A layer in the ocean where temperature decreases rapidly with depth.
Which two celestial bodies primarily cause tides?
The Moon and the Sun.
What is eutrophication?
Excess nutrients (often from runoff) entering water, causing algal blooms and oxygen depletion.
What is the Exclusive Economic Zone (EEZ)?
An area of ocean up to 200 nautical miles from a country’s coast where that nation controls resources.
Which two factors drive thermohaline circulation?
Temperature and salinity.
Define halocline, pycnocline, and thermocline.
Halocline: rapid change in salinity with depth; Pycnocline: rapid change in density with depth; Thermocline: rapid change in temperature with depth.
What is accretion?
The process of coastal sediment returning to the visible portion of a beach.
What is the difference between point-source and non-point source pollution?
Point-source comes from a single, identifiable source (e.g., sewage pipe); non-point comes from diffuse sources (e.g., farm runoff).
How does the East Australian Current (EAC) support marine life?
It transports warm, nutrient-rich waters southward, supporting fisheries and biodiversity.
How does air pressure affect wind speed?
As air pressure decreases, wind speed increases.
How does the carbon cycle interact with the marine environment?
The ocean absorbs CO₂, storing it in phytoplankton, sediments, and through shell-building organisms, helping regulate climate.
How does wave refraction shape coastlines?
Waves bend around headlands, focusing energy and causing erosion, while bays receive less energy and accumulate sediment.
How does turbidity affect estuaries?
Physically, it reduces light penetration; biologically, it decreases photosynthesis and smothers organisms.
What is the relationship between depth and salinity in estuaries?
Generally, salinity increases with depth.
How does El Niño affect ocean currents and Australia?
It weakens the trade winds and currents, reducing upwelling; this causes warmer waters, droughts in eastern Australia, and floods in South America.
What is the relationship between atmospheric CO₂ and ocean pH?
As atmospheric CO₂ increases, ocean pH decreases (ocean acidification).
How do groynes affect longshore drift?
They trap sand on the updrift side, interrupting the natural movement of sediment along the beach.
How do flood plumes affect the Great Barrier Reef?
They reduce water quality, increase turbidity, and stress coral and seagrass communities.
How do increasing CO₂ levels affect sea temperature and cyclones?
They increase sea surface temperatures and contribute to more intense cyclones.
How could climate change affect the East Australian Current (EAC)?
Climate change may strengthen and extend the EAC further south, bringing warmer waters and shifting species distributions.
What is one long-term impact of sea-level rise, higher sea surface temperatures, and stronger cyclones on coral reefs?
Reef degradation through bleaching, loss of habitat, and decreased biodiversity.
What is one implication of sand transport for coastal management?
Coastal developments must plan for erosion or sediment build-up to avoid property damage and habitat loss.
What are two planning actions to address sea-level rise?
Building seawalls/groynes and implementing managed retreat or zoning restrictions.
How do interacting processes shape coasts? (e.g., longshore drift + tides)
They move sediment in different directions, reshaping beaches and estuaries; interaction can cause erosion in one area and deposition in another.