014 Coral Reefs
Coral Reef Biology
Kingdom Animalia Phylum Cnideria Class Hydrozoa- hydroids Class Scyphozoa- jellies Class Cubozoa- box jellies Class Anthozoa- corals and anemones
The Cnidarian Life Cycle The Hydrozoan Life Cycle
Class Hydrozoa Hydrozoan Colony
Hydrozoan Colonies “Stinging Limu”
Fire Coral
By-the-Wind-Sailor A Floating Colony of Polyps
Man-of-War Phylum Cnidaria Coloniality Man-of-War Phylum Cnidaria
Close Up of a Portuguese Man-Of-War
Class Scyphozoa
Class Cubozoa Box Jellies & Sea Wasps
Corals: true stony corals and octocorals Class Anthozoa Sea Anemones & Corals: true stony corals and octocorals
Sea Anemones
Sea Anemone Anatomy
Hermatypic corals: possess zooxanthellae are reef builders Light: Clear water Warm temperature: 18-32oC Low nutrients Low productivity in water Ahermatypic corals: no zooxanthellae rely on tentacular feeding can live in aphotic zone
Distribution of Coral Reef Communities
Hawaiian Coral Zonation 0 m High light levels Moderate wave energy 6 m Cauliflower coral (Pocillopora meandrina) Moderate light levels Occasional storm wave energy Lobe coral (Porites lobata) 13 m Low light levels Low wave energy Finger coral (Porites compressa) 25 m Very low light, Primarily downwelling No wave energy Plate coral (Porites rus)
“True” Stony Corals
“True” Stony Corals Hermatypic- reef building, zooxanthellae Common species: Acroporidae- table Acroporidea- rice Agariciidae- flat lobe, corregated Faviidae- crust, ocellated Fungiidae- humpback, mushroom Pocilloporidae- lace, antler, cauliflower Poritidae- finger, lobe, plate
Family Pocilloporidae Lace coral, antler coral, and cauliflower coral Pocillopora damicornis antler cauliflower Pocillopora eydouxi Pocillopora meaandrina
Table coral, rice coral and spreading coral Family Acroporidae Table coral, rice coral and spreading coral rice coral Montipora patula Montipora flabellata table Acropora cytheria Montipora capitata
Family Poritidae Finger coral, lobe coral, Evermann’s coral, plate and pillar coral Porites evermanni Porites lobata Porites rus Porites compressa
flat lobe coral, corrugated coral Family Agariciidae flat lobe coral, corrugated coral corrugated Flat lobe Pavona duerdeni Pavona varians
Humpback coral, mushroom coral Family Fungiidae Humpback coral, mushroom coral mushroom Fungia scutaria
Family Faviidae crust coral, ocellated coral Leptastrea bottae Cyphastrae ocellina Leptastrea purpurea
A Solitary Coral Polyp
Colonial Coral Polyps
Zooxanthellae in Gastrodermal Cells of Corals
Zooxanthellae: Symbiodinium microadriacticum
Ahermatypic Corals Octocorals, wire corals, black corals, sea pens Both hard and soft forms exist non reef-building no photosynthesis
Ahermatypic Corals
Heterotrophic Nutrition General feeding modes: predaceous carnivores capturing live prey detritus feeding absorption of dissolved organic matter from surrounding water
Nematocyst Discharge
Autotrophic Nutrition Photosynthesis 6H2O + 6CO2 + light C6H12O6 + 6O2
Zooxanthellae in Coral Polyp
Benefits to the Algal Symbiont Zooxanthellae gets a place to live Receive chemical wastes from animal metabolism (CO2 & NH3). Surrounding animal tissues can concentration substantial amounts of ultraviolet light absorbing compounds.
Benefits to the Coral Host Higher rates of calcification (skeleton deposition). Receive DOM & O2 Removal of chemical wastes from animal metabolism (CO2 & NH3). Receive chemicals that absorb damaging ultraviolet light (Micosporine-like amino acids (MAAs)).
Asexual Reproduction budding and fission accidental fragmentation nonaccidental fragmentation partial colony mortality polyp bail-out
Budding Polyp within calyx
Fission Polyp within calyx
Accidental Fragmentation Wave Damage
Nonaccidental Fragmentation Radial Division in Cycloseris fragilis
Nonaccidental Fragmentation Transverse Division in Fungia scutaria anthocyathus anthocaulus
Nonaccidental Fragmentation Transverse Division in Fungia scutaria stalk regenerates new disk
Partial Colony Mortality The Phoenix Effect in Porites compressa Cut surface of a broken finger showing living tissue beneath the surface of the skeleton P. Jokiel Normal colony next to a colony exposed to freshwater
Polyp Bail-Out D. Gulko
zygote planula larvae egg sperm Sexual Reproduction
Planula Larvae
Sexual Reproduction Hermaphroditic vs gonochoric Broadcast spawning vs brooding
Sexuality Hermaphroditism: sexes in same individual Gonochoric: separate sexes Acropora sp., a hermaphoditic coral Fungia scutaria, a gonochoric coral eggs egg cloud sperm packet
Brooding Versus Broadcast Spawning eggs develop to planula stage in gastrovascular cavity of parent polyp Broadcast Spawning eggs and sperm are shed into the water column where fertilization and development occurs D. Gulko released gametes planula in polyp Pocillopora damicornis, a brooder broadcast spawner
Environmental Factors Affecting Corals Water Motion Depth: photic vs aphotic zone & water motion Sedimentation Salinity: 32-35o/oo Temperature: 18-32 oC Tidal fluctuations Nutrients: Eutrophic vs oligotrophic
Hanauma Bay Mamala Bay Kaneohe Sunset Beach
Coral reefs presently exist on every island and shallow bank in the Hawaiian chain Fringing Reef- 100-1000 years to form youngest is on west coast of Hawaii Barrier Reef- 2.5 ma to form Kaneohe & Moanalu Bay Atoll- 10 ma to form first atoll French Frigate Shoals, dated 11.7 mya
Hawaiian Island Chain Coral reef growth limited by: wave exposure sea level Sheltered sites: Hanauma Bay and Kaneohe Bay Reef accretion ~ 2mm/yr Wave exposed sites: Mamala Bay and Sunset Beach Reef accretion ~ 0 mm/yr shallow (1m) and deep (12m)
Environmental Factors Affecting Corals Water Motion Depth: photic vs aphotic zone & water motion Sedimentation Salinity: 32-35o/oo Temperature: 18-32 oC Tidal fluctuations Nutrients: Eutrophic vs oligotrophic
Oligotrophic vs Eutrophic
Reef Critters coralivore
Coral Reefs: Threats Starfish: “crown of thorns” (why?) Coral is a source of building materials Pollution: particles in the water
Aquarium/Souvenir Trade Overfishing Pollution Dredging Human impacts on coral includes: Aquarium/Souvenir Trade Overfishing Pollution Dredging Coastal Development Tourism Global Climate Change Ozone Depletion
Coral Reefs: Human Impact Worldwide disappearance Fishing with explosives Waste oil dumping Sediments Philippines: 75% of the reefs damaged
Dynamiting Reef
Destructive Resource Extraction Practices
Toxic Chemical Spills
Sediment Plume Entering the Ocean
Corals Smothered in Sediment
Dredging
Coastal Development
Anchor Damage
Diver Damage
Ecotourism Pennekamp Reef, Key Largo, FL
Net Damage
Net Entanglement
Overfishing and Bycatch
Ornamental Trade: Fan worm Threadfin Butterfly fish
Introduced Species Acanthophora, Eucheuma, & Gracillaria
Feeding Fish
Hanauma Bay
Kaneohe Bay and Bubble algae
Nutrients and Algae Growth Dictyosphaeria cavernosa
Bleaching
Global Bleaching (2002) none low moderate severe severity unknown
Acid Rain in Marine Environment reduces ability of marine organisms to utilize calcium carbonate Coral calcification rate reduced 15-20% Skeletal density decreased, branches thinner
Sea Level Rise