Coral Reefs Flashcards
How many types of coral are there?
800
What percentage of the worlds seas contain coral reefs?
1%
What percentage of the worlds marine species live in coral reefs?
25%
What are the conditions that coral needs to grow?
- Temperature: (18°c +) grow best when in 22°-25°
- Light: can’t grow in water deeper than 30 m
- Wave action: Where the waves break is where the coral grows the highest due to the food and oxygen are most abundant
- Salinity:high salt levels preferred
- Sediment: polyps need clean, clear, sunlight
- Sea bed: has to be a solid surface on which to grow
What are the characteristics of fringing reefs?
- low, narrow bands of coral
- grown out from the land connected to it
- shallow lagoon between land and edge of reef
- outer edges slope steeply into the sea
What are the characteristics of barrier reefs?
- similar structure to fringing reefs but are usually several km from the land
- separated from the land by wide, deep lagoons, too deep for coral to live in
- floor of lagoon usually made of old coral which indicates that used to be fringing but has grown outwards
- outer edges slope steeply down into the sea
What are the characteristics of atoll reefs?
- Narrow, circular reefs broken by channels
- surround a circular deep lagoon
Explain Darwin’s theory of coral reefs
1) barrier reef around a sinking island
2) coral grows upwards to maintain its access to light, oxygen and food while island sinks so lagoon is created
Why are coral reefs important for food?
Coral reefs can yield up to 15 tons of seafood per km2 in one year. In Asia alone 1 billion people rely on food from coral reefs
Why are coral reefs important for commercial products
Coral and shells are made into jewellery
Live coral and fish are sold to aquarium
Why are coral reefs important for tourism
Provides income for LICs
Tourism is a growing industry
Why are coral reefs important for medical products?
Organisms can produce chemicals that can cure disease including skin cancer
Why are coral reefs important for coastal protection?
- Protect the coast from storm waves
- Protection from coastal erosion, flooding and can shelter ships in ports and harbors.
How much economically do coral reefs contribute to the global economy
$100 billion
What happens if the coral is used unsustainably
Conditions become stressful for the algae and they leave the polyps, turning the coral white- bleaching
What threat does global warming have to coral?
- Increase in temperature means coral die in warmer water
- Rising sea levels mean that the coral cant keep up and drown in deep water
- More carbon dioxide in water increases the acidity of the water which makes it difficult for the polyps to build and maintain their limestone shells
What happened in 1998 which had a huge impact on the coral reefs of the world
sea temperatures were so high that 16% of the worlds coral was bleached
What threat does pollution have to coral?
- Pollutants from the land get into the sea via rivers and fertilizers encourage the growth of phytoplankton which increases the number of crown of thorn starfish
- Oil pollution from shipping especially in the Persian gulf.
- Plastic waste smothers the coral
What threat does physical damage have to coral?
- Over fishing reduces the biodiversity of the coral reefs
- walking on the coral kills them, swimmers stir up the sediment and divers break pieces off the reef- tourism
- Natural hazards: that area of the world very susceptible to to tropical storms eg. boxing day tsunami of 2004 damaged reefs in the Indian ocean
What was the state of the world population of coral in 2011?
10% of reefs had been damaged beyond repair and 75% of remaining reefs were under threat.
Give some of the solutions to saving coral reefs
- Reducing emissions of greenhouse gases to combat global warming
- Reducing local threats such as trampling, mining, over fishing, sedimentation and coral bleaching.
- designating coral reef nature reserves
- providing local people with jobs that don’t involve damaging the coral
