Coral Reefs Flashcards
What are corals
Tiny marine animals called polyps that form reefs when millions live together in colonies
Coral skeletons are cups of what
Calcium carbonate
Which direction does coral reefs grow
Upwards and outwards above the dead coral
What relationship does coral polyps and zooxanthellae have
Symbiotic
What is a symbolic relationship
When two organisms are dependent on each other
Coral reefs cover what % of the ocean
1%
What percentage of marine animals live in coral reefs
25%
What is the structure of coral
Tentacles Soft tissue polyp Mouth Basal plate Rock like skeleton
Where are coral reefs found
Found within 30 degrees of the equator in shallow waters up to 10m best for growth
What three conditions need to be precise for corals to grow
Temperature
Light
Wave action
What does the water temperature need to be like for coral reefs
Above 18 degrees
Best growth happens between 22 - 25 degrees
Corals are unable to grow in cold sea temps
What does the light need to be like for corals to grow
Corals feed on plankton which needs light for photosynthesis meaning that light needs to be able to reach the plankton
What water is best for coral growth
Shallow agitated water
What does the wave action need to be like for corals to grow
Outer edge of reef grows highest and waves need to now break it down
What does the salinity of the water need to be like for corals to grow
Salt levels are high
Between 32 - 42 psi
What are the three types of coral reefs
Fringing reef
Barrier reef
Atoll
What are the key characteristics of a fringing reef
Coral platform, grow out from the land
Lagoon fills area between island and reef
Lagoon less than 500m wide
Breaking waves oxygenate water for the polyps to survive
Edges of the reef slope down steeply to the sea below
What are the key characteristics of a barrier reef
Always over 0.5km from the shore
Deep lagoons are often to big for polyps to live
Seaward edge of the reef is the highest part and then steeply slope down into sea
What are the key characteristics of a atoll reef
Narrow, circular reefs broken by channels
Surrounding a deep circular lagoon
Very common in South Pacific Ocean
Who develop the subsidence theory
Darwin
What is Darwin’s subsidence theory
That all the three types of reef are linked
They start as fringing, develop into barriers and then turn into atolls over time
How does a fringing reef form
Grows around newly formed island subside or sea level rises to relative to land
How to fringing reefs turn into barrier reefs
Following a rise in sea level of drop in the level of land, a barrier reef is formed
How does a atoll reef for,
When island suspects above the sea the atoll reef forms by the coral growing upwards and outwards covering the hard rock island
