Biogeography & Geomorphology Flashcards

Flashcards about Biogeography & Geomorphology

Coral Reef Distribution

Mainly occur between 30 degrees N & S of the equator, covering about 280,000km2 (<1% of ocean’s surface).

Temperature Range for Coral Reefs

18-34°C; cold temperatures inhibit calcification.

Aragonite Saturation (Ωa)

Coral reefs typically form in regions where Ωa > 3.3.

Ocean Currents and Coral Reefs

Limit the dispersal of planula larvae away from regions of great abundance, such as the coral triangle.

Bathymetry Influence

The Eastern Pacific lacks shallow areas needed for coral reef habitat.

Impact of Freshwater & Sediments

Freshwater and sediments from rivers like the Amazon can negatively affect coral reefs.

Upwelling Effect on Coral Reefs

Coral reefs are absent in areas of upwelling.

Light Requirements for Coral Reefs

Shallow coral reefs form where average daily irradiance > 250 µmol/m/s (roughly equal to 10% of surface irradiance).

Coral Triangle Biodiversity

Greatest diversity of coral species globally.

Habitat Heterogeneity in Indonesia

Indonesia's archipelago provides diverse habitats for coral reefs.

Types of Coral Reefs

Coastal fringing reef, Island fringing reef, Atoll, Barrier reef.

Coastal Fringing Reefs

May experience large amounts of sediment and freshwater runoff.

Barrier Reef Formation

Formed by subsidence of coastlines.

Sea Level Changes and Reefs

Reefs in the GBR have shifted seaward (as sea levels fell) and landward (as sea levels rose).

Cay Formation

Form when suspended sediments are transported to a depositional zone on the reef and accumulate.

Shingle Cays

Form on the windward side of reefs.

Sand Cays

Form on the leeward side of reefs.

Great Barrier Reef (GBR)

Extends ~2300 km from north to south, the world's largest coral reef ecosystem with >2900 individual reefs.

Inner-Shelf Reefs

Fringing reefs attached to mainland or continental islands.

Mid-Shelf Reefs

Crescentic reefs with extensive reef flats.

Outer-Shelf Reefs

Variable, divided into distinct geographic and geomorphic groups.

Northern Deltaic Reefs

Occur along the margin of a very steep continental shelf and have delta-like lobes on the inner side of each passage.

Ribbon Reefs

Extend from 11-17°S along edge of continental shelf, lacking delta-like lobes.

Pompey Complex

Largest reefs in the GBR with intricate lagoons and sinkholes.

Swain Reefs

Numerous small planar and lagoonal reefs.

Capricorn Bunker

Set well back from the edge of the continental shelf with mainly planar and lagoonal reefs.

Latitudinal Patterns of Coral Species Richness

General latitudinal decrease in species richness, with anomalous decline in Cooktown-Townsville region attributed to rainfall and cyclones.

Cross-Shelf Species Richness

General increase in species richness from inshore to offshore.

Reef Zonation

Includes Fore reef/slope, Crest, Flat, Back reef, Lagoon, and Cay.

Fore Reef/Slope

Dominated by massive coral forms.

Spur and Groove Morphology

Common on fore reefs with moderate wave energy, acting as natural barriers.

Reef Crest

High wave energy, dominated by heavy branching and digitate corals.

Reef Flat

Often exposed at low tide, common for microatolls.

Back Reef

Permanently submerged, low wave energy, with patch reefs.

Lagoon

Unvegetated sand, seagrass meadows, and Halimeda beds.