What is a Coral Reef?
• Wave resistant coastal structures
– Constructed by organisms
• The most diverse marine communities
– The Tropical Paradox
What is Coral?
• Cnidarians
– Body plan
• Corals
– Secrete a calcite skeleton
– Hermatypic versus ahermatypic
– Zooxanthellae - mixotrophs
– mutualism
Where do Corals Live?
• Reef Corals = tropical
• What do corals need to survive?
– Shallow, warm, clear water
– turbulence
Reef Parts
• Reef Zones - growth forms
• Forereef
– Buttress
• Reef Crest and Flat
– Carbonate Factory (< 10 m)
– Build to sea level
• Backreef
– Lagoon
– Patch reefs
How old are reefs?
• Individual Reefs - 5 to 10 ky
• Coral Reefs - 170 million yrs
• Reef Environments - 3 billion yrs
• Other Reef Builders
– Cyanobacteria
– Coralline algae
– Coralline sponges
– clams
Growth & Reproduction
• 4 to 20 cm/yr
• Zooxanthellae
• Storms and disturbance
• Sexual Reproduction
– Spawning versus brooding
Reef Types
• 4 major types
• Fringing Reefs
• Barrier Reefs
• Atolls
• Patch Reefs
Other Reef Organisms
• Competition for space
• Algae
• Sponges
• Boring organisms
• Fish
Threats to Coral Reefs
• Human Activities
– Agriculture (nutrients)
– Shipping
– Fishing
• Biological
• Global Warming
– Bleaching
– Dust
• Disease