Coastal Environments

• coral reefs


  tiny marine animals called polyps that from reefs
• atoll type of coral reef

  narrow and circular reefs broken up by channels surrounded by deep circular lagoon

  
• fringing type of coral reef

  low and narrow next to the coasts with platform connected to land

  normally concave filled shallow lagoon in space between land edge

  
• barrier type of coral reefs

  similar to fringing

  km away from land separated by wide deep lagoons

  made by old coral

  
• Example of atoll reef

  bikini atoll
• Example of a fringing reef

  Tahiti
• Example of barrier reef

  Great Barrier Reef, Australia
• Four threats to coral reefs

  - sewage pollution

  - physical damage

  - sediment

  - enhanced global warming
• How is sewage pollution a threat to coral reefs?


  From hotels and agriculture removing 02 from water effecting conditions for the reefs
• How is physical damage affecting coral reefs?

  From divers, actors and contsruction work, kills them
• How does sediment affect coral reefs?

  Washes into sea from coastal construction this reduces sunlight which needs to reach coral reefs to survive
• How does enhanced global warming affect coral reefs?

  Sea temperatures increase by 1 or 2 degrees can cause coral bleaching

  Temporary effects cause permanent damage

  Sea levels rising down the coral

  Acidity levels increasing means more CO2
• Uses of coral reefs?

  - sea food

  - jewellery

  - tourism

  - medicine

  - protect coastline
• Four ways to manage coral reefs

  - reduce local threats

  - help LICs introduce new laws

  - designated nature reserves

  - combat global warming
• What temperature is need for coral reefs to survive?

  18+

  22-25 surface
• How deep should coral reefs be?

  No deeper than 30cm as algae need sunlight
• What should the sea and sea bed be like for coral reefs to survive?


  clean, clear, unlit and solid
• Tombolo


  ridge linking island with mainland
• How does a tombolo form?

  sediment is deposited between island and beach due to it being sheltered
• Example of a tombolo


  Chesil beach, Dorset 28km long
• Bars


  ridge of material connected to two mainland above sea level
• How can a bar be formed?


  Spit carried on by longshore drift or offshore bar pushed by waves
• Offshore bar formation


  Submerged under water formed by sand washed offshore and onshore where they meet and accumulate
• Barrier island


  An offshore bar above sea level
• Spits


  stretch of sand out to sea from mainland
• Spits causation?


  sudden change in coastline eg headland where longshore drift carries on and deposition occurs (repeated)

  also can occur occur across a bay inlet or estruary
• Two types of spits?

  simple and compound
• Simple spit description?


  curved ends due to waves from other directions
• Compound spit description?


  narrow base widens to broad curve and has ridges
• Drift-aligned coasts


  Wave crests break at an angle to the coast, so there is consistent longshore drift
• Swash aligned coasts?

  Wave crests approach parallel to the coast, so there is limited longshore movement of sediment
• Where do beaches from?


  form in inter - tidal zone
• What are tides?


  rising and falling large bodies of water create by earth and moon, moon only attracts water
• What tides occur each day?


  2 high and 2 Low
• Spring tide?


  When the tidal range is greatest. (full moon and new moon)
• Neap tide?


  When the tidal range is smallest (7 days after spring tide)
• Contructive wave?


  build and steep
• Destructive wave?


  remove and gentle
• Angle of approach of wave determined by what?


  Wind
• When do sand dunes form?


  When prevailing wind blows sediment to back of beach