The more humanity acidifies and warms the world's oceans with carbon emissions, the harder we will have to work to save our coral reefs.
That's the blunt message from a major new study by an international scientific team, which finds that ocean acidification and global warming will combine with local impacts like overfishing and nutrient runoff to weaken the world's coral reefs right when they are struggling to survive.
Modelling by a team led by Dr Ken Anthony of the ARC Centre of Excellence for Coral Reef Studies and The University of Queensland's Global Change Institute has found that reefs already overfished and affected by land runoff are likely to be more vulnerable to increasing CO2 in the atmosphere caused by the burning of fossil fuels.
Their study is the first to integrate global scale processes, such as warming and acidification, with the local factors overfishing and runoff, to predict the combined impact on coral reefs.
"As CO2 levels climb to 450-500 parts per million as they are now expected to do by 2050 how well we manage local impacts on reefs like fishing and runoff will become absolutely critical as to whether they survive as coral reefs, or are overtaken by algae that compete with corals for space on reefs," Dr Anthony says.
Warmer conditions cause periodic mass coral deaths by bleaching, while acidifying sea water due to CO2 dissolving out of the atmosphere weakens the corals by interfering with their ability to form their skeletons, making them more vulnerable to impact by storms. If the corals are also affected by heavy nutrient runoff from the land which fertilizes the algae and overfishing of parrot fishes and others that keep the reefs clear of weed, then corals can struggle to re-establish after a setback, he explains. "In those situations, the reef can become completely overgrown by algae."
The team's modelling, which they say is on the con
|Contact: Ken Anthony|
ARC Centre of Excellence in Coral Reef Studies