great barrier reef

• Temporal (changes over time)~

  The reef has evolved over millennia. It has been exposed and flooded by changes in sea level associated with glacial and interglacial cycles. 

  During glacials, sea levels fell leaving the reefs as flat-topped limestone hills undergoing sub-aerial weathering. 

  During interglacials, the rise in sea level created islands and allowed phases of coral growth. Today’s reef has been growing during the past 15,000 years meaning that a unique biodiversity has developed.
• threats posed by climate change are perhaps the most serious to arise from human activities. 

  In a catastrophic nine-month heatwave in 2016, 30% of the reef’s corals died due to bleaching. The impacts of coral death have extended to other creatures as habitats and food disappear. The loss of variety in the Reef is known as ‘biotic homogenisation’, a tendency towards similarity and a lack of diversity.
• threat from human activities. Irresponsible tourists and people involved in the tourist industry, commercial fisheries, and agriculture and mining can cause physical damage, over-exploitation and accidental trapping of animals such as turtles and dugong in nets, and excess run-off of fertilisers and sediment which disturb nutrient balance and decrease water quality.
• • It is a popular tourist destination with over two million visitors each year.

  Tourism to the reef generates approximately $4 billion per year to the Australian economy and over 60,000 full-time jobs.
• physical resources

  • The Great Barrier Reef is a vast linear structure made up of coral reefs, cays, large islands and lagoons
  • Extending for 2,300 kilometres along the north eastern coastline of Australia, in the Coral Sea 
  • Marine Park designated and protected by Australia
  • World Heritage location by the United Nations Educational, Scientific and Cultural Organisation (UNESCO). 
  • World’s largest collection of coral reefs containing 400 types of coral
  • It is also home to many species, which rely on the reef as a habitat, such as the large green turtle,
• 9 month heatwave in 2016, 30% of the GBR corals bleached and died. 

  Due to interconnections within any ecosystem, impacts of coral death have extended to other creatures such as molluscs and fish, with most suffering decline in numbers as habitats and food disappear. 

  The loss in variety in the Reef is known as ‘biotic homogenisation’, a tendency towards similarity and a lack of diversity.
• human threats

  • 1987 283 oil spills
  • 2010 shipping accident caused 3km damage that could take 10-20yrs to recover
  • overfishing eventhough $1m made annually
• coral bleaching

  zooxanthellae and coral need to exist together for them to survive and for them to be healthy

  warmer temp cause zooxanthellae expell from coral cause coral to bleach

  without zooxanthellae coral only exist 4-6 weeks

  2002 60% great barrier reef affected by coral bleaching due to warmer weather causing increase in sea temp

  if no change made rising temp great barrier reef will bleach 97% each year by 2050