Global & Australian Distribution
These tropical ecosystems ring much of the equator and occur on Australia’s NE coast.
Coral reefs; Great Barrier Reef.
Name one type of reef structure along a continental margin.
Name one type of reef structure along a continental margin.
Corals first appear in the geological record over this many million years ago.
More than 250 million years ago.
The living unit of a coral colony.
Coral polyp.
One asexual and one sexual stage in a hard coral’s life cycle.
Fragmentation; gametes/planulae.
Name two regions outside Australia where coral reefs are common.
Indo-Pacific; Caribbean.
This highest-energy zone sits where waves break on the reef.
Reef crest (rim)
Approximate arrival of corals in Australian waters.
About 500,000 years ago.
Stinging cells used in feeding and defence.
Nematocysts.
Definition of larval settlement.
Planulae attach to suitable substrate and metamorphose into polyps.
Reefs thin out with this latitudinal trend due to cooler waters.
Increasing latitude (poleward).
In cross-section, name two zones landward of the crest.
Lagoon; back reef.
Post-glacial sea level began rising around this time BP.
~20,000 years before present.
Internal cavity where digestion occurs.
Coelenteron (gastrovascular cavity).
Two factors affecting larval dispersal or recruitment.
Currents; substrate. (Also: bathymetry, sediment, predation, competition.)
List two abiotic factors that limit coral distribution at a global scale.
Temperature; light availability. (Also acceptable: salinity, aragonite saturation, dissolved oxygen, low nutrients.)
Contrast inshore vs outer-shelf reefs in one sentence.
Inshore—more turbid/nutrient-influenced; outer-shelf—clearer, more oceanic.
Modern GBR configuration stabilised about this time BP.
~6,500 years BP.
Photosynthetic symbionts powering most reef corals.
Zooxanthellae (family Symbiodiniaceae).
Condition required for reefs to grow over time.
Accretion exceeds destructive processes.
Explain why aragonite saturation state matters for reef distribution.
Controls carbonate ion availability for aragonite CaCO₃ skeleton formation.
One ecological consequence of zonation for coral morphology.
Wave-exposed crests favor robust/encrusting forms; protected lagoons favor branching/plates.
How Holocene sea-level rise shaped today’s GBR distribution
Flooded shelf created new hard substrates and depth/light conditions for reef initiation and growth.
Brief chemical description of skeleton formation.
Ca²⁺ combines with CO₃²⁻ to precipitate aragonite (CaCO₃); influenced by temperature, light, pH, ion concentrations.
Two abiotic variables that shift species distributions across a reefscape and the mechanism.
Dissolved oxygen and salinity (or temperature/substrate); they alter stress tolerance and settlement success, filtering which corals recruit and survive.