2. Coral Questions
• What is a coral?
• What do they eat?
• How do they spread or reproduce?
• How do they get their color?
• How old are they?
• What kinds of coral do we have on the Big Island?
• What eats coral?
• What is coral disease and bleaching?
3. Coral Reefs Worldwide
• 284,300 square kilometers (110,000 square miles )
• 0.7% of the ocean floor, support over 25% of all known marine species
4. Coral Reef Facts
• Corals are over 500 million years old
• Cover over 600,000 sq kilometers of earth‟s surface Estimated 88% of
coral reefs are in Southeast Asia
• Since 1975, over 90% of live coral cover lost in Florida Keys
• Colonies may be 1,000 years old and attain a height of 25ft
• Atolls and barrier reefs can consist of coral limestone deposits up to
5,000 ft thick
5. Biogeography: Larval Dispersal
Number of species highest in “Cradle of Diversity”, with speciation
declining with distance.
- Viable larvae in plankton,
- Rafting
6. Endemism
• Endemic: unique to a defined place or region and not naturally found
anywhere else.
• Hawai„i has some of the highest endemism: overall 30% of shallow
water species are endemic
11. Stinging Cells: Cnidocytes and Nematocysts
• Cnidocytes: stinging cells on tentacles
• Nematocysts: Thread with venomous barb
12. The Coral/Algal Symbiosis
• Highly efficient nutrient cycling
- Coral fertilizes the zooxanthellae
- zooxanthellae “feeds” the coral
• Evolved to thrive in nutrient poor
waters
• Very little “outside” energy needed
13. Symbiosis: Who benefits?
• Coral benefits:
- Removes coral waste products
- Provides nutrients from photosynthesis
(up to 95% of photosynthesis product)
- Enhances coral‟s rate of calcification
• Zooxanthellae benefits:
- Gains nutrients from coral waste
- Protected in tissues
- Harmful UV light filtered by coral tissue
• Mutualistic symbiosis: both benefit
15. Coral Colony: the Wall of Mouths
Polyp
Calyx
Coensarc
Skeleton
Septa
16. Coral Diet
• Zooxanthellae provide as much as 98% of colony’s nutrients
• Carnivorous Animals
- Zooplankton
- Tentacles and nematocysts catch prey
• Mucus Membranes
- Trap organisms, cilia pass along to mouth
- Transfer nutrients between polyps
• Absorption through cell walls
- DOM (dissolved organic matter)
21. Coral Limiting Factors
Limiting factor: controls a process, such as an organism‟s growth,
a species population size, or distribution.
• Light Intensity
• Depth 0 – 150m
• Hard Substrate
• Low Nutrients
• Salinity: 32-35 ppt
• Sediments
22. Darwin‟s Point
• Point where subsistence and erosion is greater than coral growth
29o N
27. Coral Bleaching
• Coral Bleaching
• Response to stress
- Temperature
- UV
- Oxygen
- Darkness
- Sedimentation
• Who initiates bleaching?
• Can corals recover?
• Where do zooxanthellae go?
• “Free” zooxanthellae are rarely found in plankton samples
- May become benthic, sessile
- May go into dormant stage
30. Hawaiian Coral Facts
• In Hawai„i: approximately 150 species
- Approximately 45 species are reef building
- Others includes
- Octocorals and soft corals
- zooanthids
- black and wire coral
- Hawaiian names: „āko„ako„a, ko„a, puna kea
• The Hawaiian Islands have 410,000 acres of living reef in the main
islands alone, more than the landmass of O„ahu
32. Coral Zonation
Zonation driven by physical parameters:
• Encrusting
- Very high wave energy or very low light
intensity
• Branching Corals:
- Low wave energy
- High light intensity
- Exception: Cauliflower coral
• Massive:
- Moderate wave energy
- Moderate light intensity
• Columnar:
- Low wave energy
- Low light intensity
• Plate:
- No wave energy
- Very low light levels
33. The fight for space
• Nematocysts/Tentacles
• Mesenterial filaments
• Overgrowing
• Shading
34. Branching Corals
• Provides protection for small organisms
• Reproduction: Separate sexes, broadcast spawning April–May at full moon
• Predators: Acanthaster planci, butterflyfish
Antler Coral (Pocillopora eydouxi)
Cauliflower Coral (Pocillopora
Largest branching coral
meandrina)
Predators: Blue-eye damselfish and
Most common in shallow, high energy
butterflyfish
Spawning April – May at full moon
35. Rice Corals
• Reproduction: Hermaphroditic, broadcast spawning April-May, full moon
• Predators: Acanthaster planci and butterflyfish
Blue Rice Coral
Rice Coral (Montipora flabellata)
(Montipora capitata) - Endemic
- encrusting, branching and - Fluorescent pigments
plate forms
36. Acropora sp.
• Most common pacific coral, over 350 species
• In Hawai„i, only 5 species in Northwest Hawaiian Islands
• Why?
37. Lobe Coral pōhaku puna
• Massive forms, major reef builders 10 – 50 ft depth
• Colonies up to 10ft high, growth 1cm/yr
• Up to 400 years old
Green Lobe Coral (Porites lobata) Brown Lobe Coral (Porites lutea)
Endemic Polyps not fully retracted – “fuzzy
Massive and encrusting growth forms looking”
Major reef builder Reproduction: August – September
Reproduction: July – August
Predators: butterflyfish
Predators: Shortbodied blenny,
butterflyfish
38. Finger Coral
Porites compressa
• Endemic
• Most common species in wave-
protected areas
• Complex growth form provides
protection to many organisms
• Reproduction:
- Separate sexes
- Syncronized broadcast spawning,
June – August full moon
• Predators: Nudibranchs and
butterflyfish
39. Plate and Pillar Coral
• Porites rus
• Common on Kona coast
• Thick columns in shallow
water and stacked plates
deeper down
• Fragile plates
• Reproduction:
- Broadcast spawning –
Unknown
• Predators: Butterflyfish
40. Mushroom Coral
Fungia scutaria
• Free living polyp
• Prefer calm or deep areas
• Reproduction:
- Separate sexes
- Broadcast spawning
- Summer, full moon
- Juveniles grow on stalk
attached to parent
• Predators: Nudibranchs
and butterflyfish
41. Other Encrusting Corals
• Corrugated Coral (Pavona varians)
- Meandering ridges and valleys
- Often overgrows bases of Finger coral
- Separate sexes
• Crust Coral (Leptastrea purpurea)
- Large calyces
- Widely dispersed: High energy to deep reef
- Hermaphroditic
42. Non-Reef Building Corals
Black coral (antipathes sp.) Snowflake Coral
(Carijoa riisei)
Wire Coral
(cirrhipathes sp.)
Soft corals (Sinularia sp.)
Orange Cup Coral
(Tubastraea coccinea)
Zoanthid (Zoanthus sp.)