Tropical coral reefs

• What phylum do tropical coral reefs belong to 


  Cnidaria , same as jellyfish
• where does coral nutrition come from

  cilia, finger like projections on polyp tentacles that trap planktonic items floating past the polyp which are passed down to the stomach where they are digested
• what are nematocysts


  stinging cells that harpoon planktonic organisms floating past the polyp
• what are zooxanthelia?


  photosynthetic algae that live inside coral polyp cells. absorb sunlight and provide energy for themselves and the coral.
• how do polyps and algae recycle nutrients and have a symbiotic relationship 


  c02 and excretory waste are absorbed directly by algae for photosynthesis. algae produce glucose and oxygen for polyps. coral gain 95% of food energy via this symbiotic relationship, algae have a protected habitat and supply of nutrients.
• what forms coral

  surplus carbon dioxide produced by respiration of the polyps is incorporated into calcium carbonate
• what are reef building corals


  corals that secrete limestone base which builds up the reef to provide habitats and food sources
• abiotic conditions of coral reefs


  bright sunlight in shallow water for at least 12 hours a day, constant temp range between 25 and 29 degrees, immersion in water where there is a small tidal range, low turbidity and stable salinity inside range of tolerance
• importance of tropical reefs to fisheries 


  support species exploited for food including lobsters
• importance of tropical reefs for medicinal discoveries

  toxic chemicals used for protection may be useful as medicines in controlled amounts, for example bone grafts
• importance of tropical reefs for climate control


  coral skeleton made of carbonate absorbes carbon dioxide acting as a carbon sink
• importance of coral reefs for erosion protection


  coral reefs absorb wave energy that would have eroded low lying land, irregular shapes dissipate the energy of the waves and fragments build up shores
• importance of coral reefs for tourism


  reefs are a popular tourist destination for ecotourism activities such as scuba diving and snorkling
• physical damage threats to coral reefs


  hard objects kill polyps, litter,lost fishing gear and careless divers damage reefs. as well as extraction of coral for construction
• collection of ornaments/souvenirs damage


  e.g. sea fans and coral. trade restricted 2000 species of coral by CITES appendix II
• sedimetation threats on coral reefs


  turbid water carried by rivers or sediments can kill corals
• pollution damage to coral reefs


  Oil spills, phosphates from agricultural runoff and sewage stimulate growth of algae, shading reduces growth of symbiotic alga. Ocean acidification makes ocean more acidic making it more difficult for polyps to produce a skeleton
• coral bleaching threats on reefs


  Raised light levels , increased water temp, low oxygen levels, and pollution expell symbiotic algae
• coral bleaching threats on reefs


  Raised light levels , increased water temp, low oxygen levels, and pollution expell symbiotic algae Raised light levels , increased water temp, low oxygen levels, and pollution expell symbiotic algae
• introduced species threat on coral reefs


  non indigenous species introduced by escaped fish from farms, water discharge from ships and accidental release from aquaria. e.g. red lion fish introduced to Caribbean in 1990 and spread rapidly
• fishing threat on coral reefs


  over-fishing reduce fish populations
• costal development threats on coral reefs


  expansion of towns, tourist resorts and ports destroy marine reefs and increase turbidity
• loss of associated habitat threats on reefs


  mangroves and Seagrass trap suspended sediments and reduce turbidity as well as providing nursery grounds for fish
• managment practiced used to protect coral reefs

  mooring buoys installed so boats do not need to use anchors , divers taught not to touch coral, fishing controlled, sustainable development of ecotourism and environmental protection
• control of fishing methods to protect coral reefs


  Length o fishing season restricted, imposing maximum catching size to protect older individuals that may produce young, restrictions on damaging fishing methods/trawling and no take zones
• what are no take zones


  allows larger populations of breeding adults to develop, surplus young will spread out and colonise areas where fishing is permitted. e,g, great barrier reef
• control of tourism to protect coral reefs


  spear fishing banned,collection of souvenirs banned, turtle nesting beached protected
• reef creation to protect coral reefs


  artificial reefs created from concrete structures such as ‘reef balls’ or by sinking structures like old ships. in Gulf of Mexico 400 oil rigs and several old war ships have been used to create artificial reefs
• sustainable exploitation to protect coral reefs


  removal of soft coral sea fans regulated by CITES appendix 2