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Threats to Coral Reefs

Coral reefs are ancient ecosystems, often described as rainforests of the sea even though in terms of species biodiversity they far outweigh their terrestrial counterparts. They are highly sought after resources, for fishing and recreation with over 275 million people living within 30km of a coral reef ecosystem.

Coral reefs provide so much more than aesthetic value and fisheries resources, they provide coastal protection for 150,000 km of shoreline in over 100 countries. They are the mating, feeding, and breeding grounds for open ocean species, and support the ecosystem services provided by mangroves and seagrass.

Unfortunately, today’s coral reefs face an uncertain future. 75% of all reefs are currently threatened by a combination of global and local pressures.


Rising carbon dioxide levels and other greenhouse gases have led to rising temperatures of the atmosphere and therefore in sea surface temperatures as well. This rise in temperature has two main effects on our coral reefs on top of compounding local threats.

1. Thermal stress
"Mass coral bleaching, a stress response to an increase in water temperatures, has occurred in every region and is becoming more frequent as higher temperatures are becoming more common. Extreme bleaching events kill corals outright, while less extreme events can weaken corals, affecting their reproductive potential, reducing growth and calcification, and leaving them vulnerable to disease." (Reefs at Risk Revisited, 2011)

2. Ocean acidification
"Rising levels of CO2 in the oceans are altering ocean chemistry and increasing the acidity of ocean water, reducing the saturation level of aragonite, a compound corals need to build their skeletons." (Reefs at Risk Revisited, 2011)

The most common LOCAL THREATS include:

  1. Overfishing
  2. Destructive fishing techniques (dynamite, cyanide, trawling, etc)
  3. Coastal Development, often from tourism
  4. Pollution from land run-off
          Divers damaging corals All of these impacts are increasing as our population increases, with areas of the highest population growth rates coexisting in tropical areas where coral reefs exist. Currently more than 50% of the world’s population live within 100km of the coast and by the end of the decade this is expected to increase to more than 75%. This is of serious concern, considering that currently coastal ecosystems where coral reefs are found contribute 8% of the global GDP and open oceans contributing 25%. GDP.           
As underwater observers, divers and snorkellers are at the frontline of coral reef protection. They are the eyes and ears of the reefs and are usually the first to see the effects of these threats. They have the unique opportunity to champion reef protection by raising awareness about reef conservation, minimizing impacts from diving activities, to lead by example, and minimize any additional damage, allowing coral reefs to be more resilient to the larger scale threats but also coral diseases that are more likely to infect stressed corals.      Anchor on coral