This document provides an overview of coral reefs, coral animals, types of corals, and the symbiotic relationship between corals and algae. It discusses the phenomenon of coral bleaching which occurs when corals expel algae due to stressors like high water temperatures. The ecological, economic, and environmental importance of coral reefs is outlined. Methods for protecting corals from bleaching include avoiding physical contact, stopping destructive fishing practices, and establishing marine protected areas for long-term monitoring.

1. SC-249 Environmental Concepts & Issues
Taichi Kikuchi

2. Outline
1. What is Coral Reef?
2. What is Coral Animal?
3. Type of corals
4. Phylum: Cnidaria
5. The symbiotic relationship
6. What is Coral Bleaching?
7. Why do we have to care about Corals?
8. How can we protect Corals from bleaching?
9. Projects to survey and protect Corals
10. References

3. What is Coral Reef?
 “The coral reef is a unique shallow water community of
organisms living on limestone rock that was built by
some of the reef organisms (Lerman 426).”
 The main reef builders are corals and coralline algae.
 Marine organisms that secrete calcium carbonate such
as clams, snails and sponges accumulate to form reefs
after their death.
 In other words, a reef is a clump of calcareous rock
derived from diverse organisms living on the reef.

4. What is Coral Animal?
 Phylum : Cnidaria (same group as jelly fish, sea
anemone)
 Corals inhabit in shallow, clear water within tropics.
 They have symbiotic tiny algae (zooxanthellae) within
the body.
 In the daytime, they get nutrition via photosynthesis
by zooxanthellae.
 They hunt for food at night with their tentacles.
 There are 215 scleractinian (58 genera) and 7 non-
scleractinian corals in Palau (PICRC 12).

5. Type of corals
 Solitary (mushroom coral)/ colonial corals
 Stony corals: brain, staghorn, antler, lettuce, and
flower coral
→ They secrete a cup-shaped skeleton of calcium
carbonate, called corallite.
 Soft corals(octocorallia): seafans, sea pens, whip corals
→They secrete soft, flexible skeletons made of keratin.
 Abundant stony corals in Pacific reefs.
 Abundant soft corals in Caribbean reefs.

6. Phylum: Cnidaria
The classification of the major groups of coral animals

7. The symbiotic relationship
 Corals excrete their wastes to tiny algae.
 The tiny algae produce nutrition for coral polyps.

8. What is Coral Bleaching?
 Coral Bleaching = Corals which lost their symbiotic
algae appear whitish.
 Corals are compelled to expel the algae because of its
toxin when they are under stressful condition.
 Unusual high water temperature is thought as the
main cause of the mass bleaching event in 1997~98.
 Some species can survive bleaching but the aftereffect
includes slower growth, fragile body and higher risk of
disease.

9. Why do we have to care about
Corals?
 Ecological value: corals sustain rich marine biodiversity.
(ex. Shelter for some animals, food for other animals
 Economical value: tourism, fishery industry
(ex. Divers, tourists, and food supply
 Environmental value: they provide protection for us.
(ex. Breaking storm wave, tsunami, typhoon
 Coral reefs have a great importance for Palau in many
aspects.

10. How can we protect Corals from
bleaching?
 Not to touch corals physically.
 Stop destructive actions such as dynamite fishing, over
coastal development causing sedimentation.
 Have an interest on coral reef and take actions to
spread knowledge.
 Proper instruction for any people trying to play around
coral reefs.

11. Projects to survey and protect
Corals
 The Marine Protected Areas (MPAs)
= the place where people are prohibited or restricted
to enter and use resources.
 PICRC National Long-Term Coral Reef Monitoring
Program in 2001
・21 monitoring sites around the main islands
・Coral reefs are recovering for 3 years from 2001.
・It suggests that some species are more resistant to
pressure.

12. References
Marshall, P and Schuttenberg, H. A Reef Manager’s Guide to Coral
Bleaching. Townsville: Great Barrier Reef Marine Park
Authority, 2006.
Lerman, M. “Chapter 13 Coral Reefs.” Marine Biology. California:
The Benjamin/Cummings Publishing Company, Inc, 1986.
Palau International Coral Reef Center, and Japan International
Cooperation Agency. Coral Reefs of Palau. Palau: Palau
International Coral Reef Center, 2007.