2.1.4 - coral reefs

What conditions are needed for Coral Reefs to form?

•Temperature

•Light

•Clear water

Where are warm reefs found?

They grow in warm, shallow, clear seas​

How do coral reefs grow?

• A polyp reproduces by dividing its own body to form two polyps, or by producing sperm and eggs.

• Each polyp builds a case of limestone around itself, using calcium from the water.

• This remains after it has died and forms a foundation for another polyp to build a flat on, putting a floor on the roof of the old one. When these limestone formations increase, they are called a coral reefs.​

• Think of each coral polyp as being a flat within an apartment block! ​

What are the threats to coral reefs?

• Overfishing, ​

• Climate change due to global warming=warmer water and more storms​

• Marine ( sea) pollution eg oil​

• Pollution form the land ( mainly sewage and farm runoff)​

• Damage from unskilled divers

Management strategies on Andros reef

• National parks​

• Marine park with conservation areas​

• Crab replenishment reserve​

• Coral nursery at the Sea Park​

• Banning dynamite fishing​

• Developing ecotourism and diver etiquette

what are Polyps

• Polyp are tiny carnivorous (meat eating) animals

What is a coral reef

• A coral reef is a line of coral polyp found in warm shallow seas.

Describe Polyps

• Polyps live in groups called colonies. A polyp has a mouth at one end. The mouth is surrounded by a number of tentacles. Polyps cannot move from their limestone homes. ​

How do coral reefs have colour

• zooxanthellae contain pigment which allows polyps to photosynthesise. Algae photosynthesise and produce food whilst enjoying a secure home, their waste is absorbed by the coral who get exclusive access to this nutritious waste!

Why do coral reefs need temperature to grow

they only live in seawater that has an average temperature of 18’C and over. The ideal temperature is between 23’C and 25’C. This explains why coral reefs are found in the Tropics where it is hot all year round.​

Why do coral reefs need light to grow

coral reefs feed on tiny algae and the algae need light for photosynthesis to grow. If there is not enough light, there will be no algae and if there is no algae there will be no coral. This explains why coral reefs are found in relatively shallow water where there is maximum light available.​

Why do coral reefs need clear water to grow

corals survive best in clear unpolluted water. Sediment in the water affects the coral’s ability to feed as well as reducing the amount of light. This explains the lack of extensive reefs close to river mouths.