1. Coral bleaching
Muhammad Hafiz bin Zulkifili
UK 25364

2. What is coral bleaching?
• Loss of important cell (zooxanthellae ) inside
the coral.
• Zooxanthellae contribute coloration for coral.
• Factors that cause this cell to loss caused the
coral’s color to become white. (bleached)

4. Zooxanthellea
• Lives in the coral, as the coral act as its shield
or protective home.
• It helps to provide nutrients and oxygen
during photosynthesis.
• Provide 90% of energy to the coral to grow.

5. What are the factors?
1. Increase/decrease of water temperature.
2. Change in water chemistry.
3. Bacteria infection.
4. Increase in sea level.
5. Herbicides.
6. Cyanide fishing.
7. Low tide
8. Shipping accidents.

6. Increase of water temperature.
(global warming)
• Extreme hot sea water disrupt the nature of coral.
• Coral cannot adapt the fast changing climate
temperature.
• Sudden change of temperature caused the expulsion of
zooxanthellea
• Temperature increases of only 1.5 –2°C lasting for six to
eight weeks are enough to trigger bleaching.
Microdocs project. (2012). Coral Bleaching. Retrieved from
http://www.stanford.edu/group/microdocs/coralbleaching.html

7. Increase in sea level.
(global warming)
• Sea level increases due to melting of ice caps
as resulted from greenhouse effect, coral will
be deeper thus prevent coral to get enough
sunlight.
The Coral Reef Alliance. (2005). CORAL REEFS & GLOBAL CLIMATE CHANGE: Rising tides, temperatures
and costs to reef communities. Retrieved from http://www.icran.org/pdf/ClimateChangeIssueBriefs.pdf

8. Change in water chemistry.
• Related to the acidity of sea water.
• CO2 increases, sea water acidity increases.
• Coral act as a shield for zooxanthellae. High
water acidity disturb the formation of coral.
New England Aquarium. (2012). Climate change and the oceans. Retrieved from
http://www.neaq.org/conservation_and_research/climate_change/climate_change_and_the_oc
eans.php

9. Low tide and exposure
• Cause coral at shallow region to be exposed to
excessive ultraviolet sunlight that may dried
up the coral and trigger stress to cause the
expulsion of zooxanthellea.
National Oceanic and Atmospheric Administration. (2012). Hazards to Coral Reefs. Retrieved from
http://coris.noaa.gov/about/hazards/

10. Bacteria infection.
• Vibrio shiloi is a type of bacterium that being
released by fireworms (Hermodice
carunculata).
• V.shiloi becomes more effective as a bleaching
agent when the temperature of sea water
rises.
Lynn Dicks. (2003). Coral bleaching caused by "malaria of the oceans“. Retrieved from
http://www.newscientist.com/article/dn3606-coral-bleaching-caused-by-malaria-of-the-oceans.html

11. Herbicides
• Mass usage of herbicides on plant by farmers
being absorbed by the soil.
• Rain will wash away the chemical in the soil to
the sea.
• Hazardous chemicals cause the coral to
bleach.
Dr Heok Hee Ng. (2009). Herbicide threat to coral reefs. Retrieved from
http://www.practicalfishkeeping.co.uk/content.php?sid=2075

12. Cyanide fishing.
• Cyanide is poisonous to coral.
• Fishers use cyanide to stun the fish and make
it easy to catch alive. (fresh)

13. Shipping accidents
• groundings, vessels sinking, illegal and
accidental oil and diesel spills, and litter
overboard can pollute coral reefs.