What is Coral Bleaching?


As the oceans warm, some fish species are migrating away from equatorial waters towards cooler areas closer to the poles.

The optimum temperature range for coral is between 18 and 29 degrees Celsius. Corals can withstand short periods of warmer or cooler water. Corals in some areas have been shown to be much more tolerant of fluctuations in temperature and studies suggest this may be a source of hope for the future of coral reefs.

Higher temperatures are also leading to an increase in large-scale, prolonged, coral bleaching events. Coral bleaching is one of the most visual indicators of thermal stress due to climate change.


Corals exist in a symbiotic relationship with microscopic algae called zooxanthellae that live in the corals’ tissues and, through a process of photosynthesis, produce vital food for the coral polyps[/icon_timeline_item][icon_timeline_item]

When water temperatures are consistently too warm, the corals and zooxanthellae become stressed. The zooxanthellae will leave their coral hosts. The coral loses its colour, turning white. This will normally happen over a period of 4–6 weeks[/icon_timeline_item][icon_timeline_item]If water temperatures do not drop, the coral will starve and die. The remaining skeleton will be colonised by algae, making it impossible for the coral to recover[/icon_timeline_item][/icon_timeline]

For the rest of this article (Asian Geographic No.134 Issue 1 /2019 ) and other stories, check out our past issues here or download a digital copy here

The 25th anniversary of the largest and longest running dive show, Asia Dive Expo (ADEX) is set to occur on the 11-14th April 2019. Centred on the theme – Plastic free Future, ADEX is more than just a dive show with its commitment to the environment. Among an exciting lineup of programs, attendees can look forward to a Future Forward Series of Panel Discussion on the Single-Use Plastic Conundrum in Asia, on 13th April.

So join us at the event, get inspired and for all you know, you might just liberate the inner diver in you! More details of the event here


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