[B] Coral Reefs

• True stony corals that primarily deposit calcium carbonate

  Scleractinian corals
• Coral species that produce reef

  Hermatypic
• Non-reef building coral species

  Ahermatypic
• Hermatypic corals typically harbor zooxanthellae, ahermatypic corals do not
• Smallest unit of a coral colony

  Coral polyp
• Colony Development

  Planula larva settles → Attachment to solid surface → Development to coral polyp → Secretion of calcium carbonate cup (corallite) → Asexual reproduction to produce colonies
• Label the types of coral reef:

  A) Fringing reef

  B) Barrier reef

  C) Atoll

  
• Develop along shores of tropical or subtropical islands, most directly affected by human activity

  Fringing reefs
• Similar to fringing reefs, but are separated from the landmass by lagoons or deepwater channels

  Barrier reef
• Somewhat elliptical with a centrally located lagoon

  Atolls
• Reef geomorphology

  • Vertical growth
  • Reef crest rises as sea level increases
  • Horizontal growth
  • Differential growth horizontally
  • Spur-and-groove formations
  • Diversity of habitats
• The reef crest contains the highest diversity of corals due to sunlight

  • Coral-eating fishes congregate, attracting a diversity of trophic levels
• Very steep reef front forming a vertical wall

  Drop-off
• Disperses wave energy, helps prevent damage to the reef and its inhabitants

  Spur-and-groove formations
• Highest point on the reef, part that receives full impact of wave energy

  Reef crest
• Grooves of the spur-and-groove zone that penetrate the algal ridge

  Surge channels
• Occur where wave impact is strong, consists only of coralline algae and lacking other organisms

  Algal ridge
• The reef flat of fringing reefs ends at the shoreline, descends into the lagoon in atolls and barrier reefs
• Reefs based on depth:

  • Shallow or Altiphotic
  • 0 - 35 m
  • Upper mesophotic
  • 35 - 60 m
  • Middle mesophotic
  • 60 - 90 m
  • Lower mesophotic
  • 90 - 150 m
  • Rariphotic
  • 150 - 200 m
• Shallow reefs are more diverse
• Ecological interactions:

  1. Cleaner fishes
  2. Cleaner wrasse
  3. Herbivory
  4. Feed on algae on reef substrate
  5. Parrotfish
  6. Corallivory
  7. Obligate
  8. Facultative
• The Diadema die-off due to ciliate disease led to proliferation of algae, loss of coral