Coral Reefs

Question 1

How do corals first form? Including the two types

Answer 1

1) Begin as polyps (small, soft animals).
2) Polyps attach themselves to a hard surface in shallow sea areas with sufficient light.
3) As they grow, many exude CALCIUM CARBONATE, forming stony corals.
4) These exoskeletons join together to form coral reefs.
5) Soft corals can survive without zooxanthellae.

Question 2

Give a statistic about the biodiversity of coral reefs

Answer 2

Coral reefs are home to 25% of all marine species, but occupy less than 1% of oceans and seas.

Question 3

What is the relationship between polyps and zooxanthellae?

Answer 3

Zooxanthellae are small algae growing inside the polyps, and the interdependence of them is crucial for survival of the coral.

Algae receive shelter and CO2 from the polyp.

The polyp receives O2 and sugar from the algae.

Question 4

How many species of coral are there?

What rate do they roughly grow at?

Answer 4

6,000

2.5-60cm a year

Question 5

What is the largest coral reef? How long is it and where is it?

Answer 5

The Great Barrier Reef, 1,250 miles long, NE coast of Queensland.

Question 6

Why are coral reefs important?

Answer 6

• Calcium carbonate skeletons are a store of carbon
• High biodiversity
• Natural barrier against storm surges, tsunami waves etc
• Algae and sponges have valuable medicinal qualities
• Food and income for people who live near

Question 7

1) How many people live near coral reefs?

Answer 7

1) Over 240 million within 60km of coral reefs.

Question 8

What conditions do coral reefs need to grow?

Answer 8

• TEMPERATURE between about 22-25c, over 18c at least.
• Relatively high ALKALINITY, about 8.2 at Great Barrier Reef.
• High SALINITY, 32-34 psu, rivers cause gaps in reefs.
• No AIR, exposure kills corals.
• CLEAR, UNPOLLUTED water.
• Sufficient LIGHT for algae to grow and photosynthesis.
• SHALLOW water, 10m is best, not below 25-30m.
• SOLID BASE

Question 9

What are the three types of coral reefs, describe them.

Answer 9

Fringing - Most common. Grow near coastlines, most common, separated from shore by narrow, shallow lagoon. eg Ningaloo, Aus.

Barrier - Previous fringing reef, separated by wider, deeper lagoons, extensive linear reefs parallel to the shore. eg Great Barrier Reef.

Atoll - Rings of coral, usually formed when islands surrounded by fringing reefs sink/sea levels rise, creates a protected lagoon in ring, commonly found in the Maldives.

Question 10

What are the threats to coral reefs?

Answer 10

1) Climate change:
ACIDIFICATION more co2 in water, coral bleaching (where environment too stressful, algae leaves polyps)
RISING SEA LEVELS, too deep water
TROPICAL STORMS stronger
TEMP
2) Pollution:
Both agricultural and sewage discharge, algal blooms, smother coral and block sunlight.
Marine pollution, ie oil, blocks light.
4) Physical Damage:
associated with fishing and tourism (anchors, propellors, people stepping), divers touching, coral mining for limestone.
5) Overfishing:
disturbs food web, also blast mining physical damage.
6) Coral diseases, more than 29 diseases, can threaten biodiversity and decrease coral population.

Question 11

How many coral reefs have died since 1970?

Answer 11

30%

Question 12

What are some general ways to protect reefs?

Answer 12

1) Combat global warming
2) Reduce local threats ie tourism, overfishing etc
3) Designate coral reefs as protected areas
4) Assist LICs w/ money so they can afford to restrict reefs
5) Scientific research for diseases

Question 13

What are some specific examples around the world protecting reefs?

Answer 13

• Singapore - lego for vertical farming, taking broken coral from sea.
• Indonesia - using frames to restore reefs, so far restored about 40,000sq m
• The Earthshot Prize - gives £1 mill prize to 5 different categories a year, 2021 winner was the Coral Vita Project in the Bahamas. Use land based farms, coral grows up to 50x faster.

Question 14

CORAL REEFS CASE STUDY:
* What and where?
* General facts
* Value
* Threats
* Management

Answer 14

ANDROS BARRIER REEF, Bahamas
* 200km long, 3rd largest by area.

• Fish breeding eg snapper and conch. Coastal protection, ie against Hurricane Sandy 2012. Tourism, fishing, sports fishing, cruising, snorkelling, brings in over $150 mills a year. Great location for scientific research due to it’s biodiversity and health.
• General ones. Algal blooms in Florida and Caribbean. Cruises = pollution. Bahamas lots of tropical storms, upwelling of cold water and damage.
• National parks and reserves established. Quality of reef frequently assessed. Crab Replenishment Reserve. Coral nurseries eg in Sea Park. Plans to establish new National Park at Joulter Cays. 20% protected by July 2021.