1. Threats to Coral Reefs
Natural and Human

2. Where Can You Find Coral Reefs?
 Coral is found all over
the world:
 Tropical
 Temperate
 Polar Coral reefs around the world
 Only tropical corals
build reefs

3. Coral reefs around the world

4. REEFS WORLDWIDE ARE
THREATENED
• 11% of reefs have been lost
• 16% of reefs severely damaged
• ~60% of studied reefs threatened by
human activities
• No pristine reefs left

5. Threats to coral and
coral reefs:
• 1) Natural
• 2) Anthropogenic
–of human origin

6. Natural disturbances that affect corals
and coral reefs?
• Hurricanes
• Tsunamis
• Volcanoes
• Earthquakes
• Predators & competitors
• Bleaching
• Pathogens

7. Hurricanes
• Physical damage
• Smothering
• Freshwater poisoning
• Destruction of other ecosystems upon
which coral reefs depend

8. Tsunamis
• Physical damage
• Erosion
• Possible disruption of
reproduction and recruitment

9. Volcanoes
• Depends upon
where volcano
occurs
• Heat
• Smothering and
sedimentation

10. Earthquakes
• Little direct impact
• Indirect impacts
-triggers tsunamis
-coastal landslides

11. Predators
• crown of thorns
starfish
• snails
• parrotfish
• butterflyfish

12. Crown of Thorns Starfish

13. Coral-eating Snails

14. Competitors
• algae

15. • Loss of zooxanthellae
• causes
– higher than usual
ocean temperature
– sharp changes in
salinity
– heavy UV light
exposure

17. Pathogens
• Diseases on the rise
– new pathogens (8+)
– land pathogens
(Aspergillus)
– occurring at all
depths
– More susceptible
when stressed

18. Threats from Nature
• Unusually strong waves such as those
from a hurricane
• Water temperature changes
• Dramatic changes in saltiness of water
• Predators, such as snails and crown of
thorns starfish
• Overgrowth of algae

19. Threats to coral and
coral reefs:
• 1) Natural
• 2) Anthropogenic
–of human origin

20. Anthropogenic threats
to coral reefs:
• Overfishing
• Development
• Mining and dredging
• Recreation

21. Overfishing
• Ecological imbalance

22. Overfishing
• Ecological imbalance

23. Overfishing
• Destructive fishing practices

24. Development
• Sediment smothering
• Freshwater input
• Pollutants & nutrients
(sewage, pesticides, fertilizer, heavy
metals, pathogens)

25. Development

26. Development

27. Pollution

28. Power Plants

29. Mining for construction
materials and dredging
• Destruction of reef structure
• Stirs up sediment

30. Recreation
Anchors, boats, flippers, hands, feet
•Kill animal tissue
•Skeleton breakage

31. Threats from Humans
• Pollution
– Sediments block light from zooxanthellae
– Chemicals either poison corals or allow too
much algae to grow
• Power plants
– Filter water and kill fish and plankton
– Releasing hot water kills organisms

32. More Threats from Humans
• Deforestation
– Causes erosion which clouds the water
– Burning of trees could be a factor in climate
change
• Destructive fishing
– Blasting with dynamite
– Cyanide poison
– Boats running aground, anchors
– Overfishing

33. Synergistic effects
• interaction of natural changes &
human activity
• multiple insults

34. Global climate change
• Reduced reef building
• Increase in frequency and intensity
of hurricanes
• Increases in bleaching
• Increased in disease

36. A New Home
• Corals now have a
choice of where to
live
• Corals are very
sensitive and are
rapidly dying
• People are trying
to help by creating
artificial reefs

37. Arguments for Artificial Reefs
• It can help build
or rebuild a reef
• It will increase
fish populations
by making new
habitats

38. Arguments Against Artificial Reefs
• Moveable
• Chemical leaking and
leaching into the ocean
• It does not increase fish
populations but rather
moves them to one
location away from their
natural habitat which
makes them easier to catch

39. The Great Barrier Reef

40. Tubbataha Reef

41. It’s up to Us to Save Coral Reefs
Be Responsible.