coral reefs

• what are coral reefs?

  • structures that live at, or slightly below sea level, on the seabed
  • an ecosystem that consists of living things like plants, fish and other creatures
  • coral reefs consists colonies that contain of millions of coral animals known as polyps
• relationship between coral reefs and algae

  • symbiotic relationship
  • coral reefs provide algae with carbon dioxide and nutrients
  • algae provides coral reefs with oxygen and sugars
• distribution of coral reefs

  • between the tropics of cancer in the northern hemisphere and the tropics of capricorn in the southern hemisphere
• environmental conditions affecting growth of coral reefs

  • warm waters ranging from 23°C-25°C
  • clear water → water with high turbidity restricts light penetration
  • low sedimentation → waters with lots of sediments may suffocate corals
  • average seawater salinity
  • no deeper than 50 meters → sunlight cannot penetrate through waters that are too deep
  • plenty of sunlight to aid photosynthesis
  • cannot grow in freshwater
• economic values

  • serve as tourist attractions : eco-tourism
  • provides jobs for locals, GBR provides 69,000 jobs for locals with 64,000 being full time jobs
  • helps contribute to products sold in the tourism industry → Jewellery and ornaments made from corals are often favoured as souvenirs by tourists visiting coral reefs
  • helps generate revenue for the tourism industry - GBR contributes 6 billion dollars to the tourism industry each year
• environmental value & supporting habitats

  • coral reefs support natural ecosystems, providing marine species with suitable habitats to breed and grow
  • coral reefs are home to 25 percent of the earth’s marine fish species
• protecting shorelines and reducing coastal erosion

  • serve as natural barriers due to their ability to cause waves to break offshore, reducing the energy impacting coastlines
  • GBR can reduce up to 97 percent of wave energy, protecting adjacent shorelines and developments from coastal erosion in coastal areas
• pressures on coral reefs : overcollection

  • Overfishing in reefs and surrounding waters.
  • Depletion of fish disrupts the delicate balance of the ecosystem’s food chain
• pressures on coral reefs : fishing methods

  • Dynamite blasting and use of cyanide to stun fish
  • Coral reef habitat destroyed
• pressures on coral reefs : recreational use of coastal areas

  • Tourism activities in coastal areas.
  • Waste may be discharged into water and stress corals; boat anchors may damage corals
• pressures on coral reefs : pollution

  • Excess fertilizers and pesticides washed from agricultural: landwaste from industrial areas; sewage from urban areas.
• pressures on coral reefs : pollution effect

  • Water can become turbid or murky, preventing sunlight from reaching the corals hence preventing photosynthesis.
  • Toxic untreated sewage waste can kill coral reefs.
  • Fertilizers and excess nutrients from sewage can lead to algae bloom that can take over the reefs.
• pressures on corals : siltation

  • Sediments from coastal areas being cleared of forests are washed into waters
  • Water can become turbid or murky, preventing sunlight from reaching the corals hence preventing photosynthesis.
  • Corals suffocated by excess sediments.
• pressures on coral reefs : coastal development

  • the clearing of vegetation, development of urban structures like housing, piers, etc and the increase in human activities like fishing, tourism, etc
• pressures on corals : climate change

  • rapid increase in sea temperatures and levels may be faster than the corals ability to adapt to the changes
  • coral bleaching occurs when corals are stressed and expel algae, becoming white/bleached.
  • more prone to diseases, stunts growth, affects reproduction
  • severe bleaching can kill corals