Hard-core corals living in extreme environments may be the key to the survival of our reefs, but scientists need your help!
OUR OCEANS ARE
changing at an alarming rate – alongside localised pollution, reefs worldwide are becoming warmer and more acidic – which together threaten the survival of coral reefs. 2016 has seen the world’s third mass coral bleaching event. (Not sure what “coral bleaching” is? See the box opposite.) We have all seen images and videos from around the world showing fields of white coral skeletons, where only weeks before existed colourful, healthy coral reefs.
THE WATER’S HOTTING UP
Warmer seawater is often the cause of coral bleaching; this year alone, it is estimated that over a third of Australia’s Northern Great Barrier Reef has been killed due to coral bleaching from the warmer-than-normal water associated with an El Niño event.
• Above average seawater temperature is the main culprit causing coral bleaching but it can also occur from other stressors such as disease, high light, pollution and changes in salinity.
• Corals can only recover from bleaching if “host tissue” remains intact on the bleached skeleton to reacquire zooxanthellae and rebuild energy reserves. This is only possible given enough time between repeat El Niño (or stress) events.
Corals that lose their host tissue are dead, and collapse of the reef framework follows. Corals can only repopulate impacted areas from neighbouring reefs that are unimpacted or through “reef restoration” practices.