Tropical Coral Reefs

Question 1

Why are coral reefs important?

Answer 1

• Supports marine life -> coral builds limestone bases, habitat for others
• Fishery -> Reefs support many fish exploited for food
• Medicinal discoveries -> species uses toxins that may be useful medicines
• Climate control -> growing coral = carbon sinks
• Erosion protection -> Reef absorb wave energy, coral fragments form sand on beaches
• Tourism -> high economic value, creates job opportunities

Question 2

Threats to coral reefs

Answer 2

• Climate change
• Physical damage
• Collection for decor/souvenirs
• Sedimentation
• Pollution
• Fishing
• Introduced species
• Costal development
• Loss of associated habitat

Question 3

How can climate change affect coral reefs?

Answer 3

• Increased temp = coral bleaching
• Rising sea levels = less photosynthesis
• Ocean acidification = less coral growth
• More storms = more damage and turbidity
• Change in current = change in nutrients and temp

Question 4

What can cause physical damage to coral reefs?

Answer 4

• Trampled by tourists
• Damaged by litter

Question 5

Collection of ornaments and souvenirs

Answer 5

• Many species collected to be sold as ornaments
• Trading of approx 2000 species of coral banned by CITES

Question 6

How can sedimentation affect coral reef?

Answer 6

• Turbid water carried by river or disturbed sediment by costal development
• Can cover or kill
• Blocks cillia & mouth -> prevents feeding
• Blocks light for photosynthesis

Question 7

What kind of pollution can affect coral reefs?

Answer 7

• Large oil spills
• Agricultural runoff-> eutrophication
• Ocean acidification

Question 8

How can fishing damage coral reefs?

Answer 8

• Impact from boats, anchors and fishing gear
• Overfishing = decreased fish pop -> affects interdependent species

Question 9

What is an example of the effects of overfishing?

Answer 9

Crown of thorns starfish is a predator of coral
Overfishing of their predators, giant triton mollusc or titan triggerfish = increased starfish population = more coral eaten

Question 10

How can introduced species be introduced and affect coral reefs?

Answer 10

• Introduced by ballast water, fish farms, aquariums
• Can predate upon or outcompete native species

Question 11

How can costal development affect reefs?

Answer 11

• Destroy reefs directly
• Increase turbidity

Question 12

What is an example of an associated habit to the coral reefs?

Answer 12

• Mangrove forests and grass beds
• Trap sediment and lower water turbidity
• Provides nursery grounds for many reef living species

Question 13

What is coral bleaching?

Answer 13

• Water temp increases
• Zooanthellae in polyps start producing an irritant to the coral
• Get ejected
• Coral can’t produce enough energy to sustain itself long term
• If they regain zooanthellae, coral can survive

Question 14

What is zooanthellae?

Answer 14

Symbiotic algae inside the polyps of coral that produce sugars via photosynthesis

Question 15

How can we conserve coral reefs?

Answer 15

• Designating MPA’s/national parks
• Regulating fishing
• Reef creation

Question 16

How can designating MPA’s/ national parks help reefs?

Answer 16

• Establish no-take zones -> nothing taken from the reef
• Sustainable development of ecotourism
• Installing fixed mooring buoys to decrease use of anchors

Question 17

How can the regulation of fishing help reefs?

Answer 17

• Restricting length of fishing season to avoid breeding or hatching times
• Imposing a min and max catchable size
• Banning destructive fishing methods eg: dynamite fishing, trawling

Question 18

What is reef creation?

Answer 18

• Building artificial reefs from concrete or old ships etc
• Over 400 oil rigs were used to create them in Gulf of Mexico