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Mele Coral Biology
- 1. Coral Biology & Ecology
- 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
- 8. Coral Family Tree Phylum Cnidaria Defining characteristic: cnidae (nematocyst) Polyp and Medusa stages Polyp only Scyphozoa Anthozoa Hydrozoa true jellies Hard, soft, and precious corals, sea fans, hydroids, medusae zooanthids, anemones, sea pens Cubozoa box jellies
- 9. Polyp Cross Section • Upright hollow cylinders of tissue - Tentacles - Mouth - Stomach - Mesenterial filaments • 2 tissue layers - Epidermis - Gastrodermis - Mesogloea (matrix between layers • Hard corals: - Calcium carbonate skeleton
- 10. Coral Tissue • 2 tissue layers Epidermis Gastrodermis Nematocyst Mucous Cells Zooxanthellae
- 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
- 14. Hard or Stony Corals
- 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)
- 17. Sexual Reproduction Settlement Planulae Primary Polyp Zygote Budding & Fission (cloning) Planulae released Mature Colony Synchronous release Eggs Sperm Sperm Broadcasters Brooders External fertilization Internal fertilization
- 18. Asexual Reproduction Attachment Attachment Budding & Fission (cloning) Mature Colony Polyp Bail-out Fragmentation
- 19. Coral Reefs of the World
- 20. Why are corals only in the tropics?
- 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
- 23. What eats coral?
- 26. What are coral disease and bleaching?
- 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
- 28. Coral Disease • Montipora tissue loss • Porites Trematodiasis • Band Disease • Tumors: Hyperplasia
- 29. Hawaiian Corals
- 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.)