Coasts KQ2 (Corals) Flashcards
What are coral reef ecosystems?
- Structures that develop slightly below sea level on the seabed
- Formed by colonies of billions of polyps
- Polyps secrete calcium carbonate deposits to protect soft bodies
- Accumulate overtime to form reef structures (Mostly limestone)
Distribution: Tropics of cancer in NH and Tropics of Capricorn in SH
- Most abundant in SEA region (7 Hectares)
Environmental conditions for coral growth
1) Salinity
- Low salinity levels inhibit growth
2) Oxygen content
- Oxygen needed for algae photosynthesis
2) Turbidity + Sunlight
- Allows sunlight to penetrate for algae to photosynthesise
3) Temperature
- 17-25*
4) Water depth and light
- Clear, saline water between 10-60m deep
5) Wave action
- Increases chance of food and oxygen provided
- Prevents corals from choking on sediments
Value of corals
1) Crucial role in supporting natural ecosystem
2) Provide food for larger creatures
3) Absorb wave energy, protects coasts from erosion
How are corals crucial in supporting natural ecosystems?
- Support >25% of earths marine fish species
- Habitat for plants and animals to thrive, breed and grow
How do corals provide food for larger creatures?
- Small fish feed on living coral polyps
- Big fish feed on small fish
- Big fish provide food for local communities
How do corals protect coasts?
- Absorb wave energy as waves pass above them
- Become severely damaged during storms
- Slow recovery leaves coasts vulnerable
Pressures on corals
> Natural pressures
1) Climate change
> Human pressures
1) Overcollection
2) Fishing methods
3) Recreational use of coasts
4) Coastal developments
Natural pressure: Climate change
- Rapid increase in sea temp = coral bleaching
- Rapid increase in sea levels = corals cannot adjust, suffocate
- Increase occurrence of floods = more sediment washed into sea, suffocating corals
e.g. El nino, 2014, Great barrier reef
Human pressures: Overcollection
- For personal/commercial use
- Weakens coral ecosystem, making them more vulnerable
e.g. Philipines
Human pressures: Fishing methods
- Dynamite blasting and cyanide fishing etc
- Destroy and kills coral reef ecosystem
e.g. Philipines
Human pressure: Recreational use of coast
- Tourist activities and resorts pollute ocean, poisoning and choking corals
- Anchoring of boats on reefs destroy corals
- Unplanned developements of coastal resorts damage corals
e.g. Sri Lanka
Human Pressures: Coastal Development
- Land reclamation and extension of land
- Rock and sand dumped onto reefs suffocate and destroy reef
e.g. Japan
