A stark reminder of the effects of a warming ocean

By Jon Slayer

Over the last few years while attending various research expeditions to Chagos I have had the privilege of returning to several beautiful coral reef sites. 

I visited the archipelago at the beginning of 2016 and departed shortly before a period of extended calm, hot weather that resulted in a major bleaching event over April and May. Similar impacts were noticed around the globe as these extreme conditions of water temperature and strong sunlight were present across the Indo-Pacific. 

There were scientists in the British Indian Ocean Territory who visited the islands shortly after I left who recorded the coral bleaching under way but since then there has been little record of the aftermath. 

On my most recent trip in December 2016 I managed to visit an Acropora garden that always sticks in my head as one of the most vibrant reef communities in the area. On this occasion, six months after the bleaching event, the devastation was comprehensive. Where previously it was difficult to see the reef because the colourful fish were so plentiful and distracting, now there were comparatively few swimming overhead making the dead corals all the more noticeable. 

Almost 100% mortality. 

A solitary Goniopora colony was the only survivor in the transect that I swam. Everywhere else brown, algae covered skeletons stretching to the limit of vision. I managed to visit several other sites during our three week trip and the situation was similarly dire wherever I looked. 

The before and after videos that I took are stark reminders of the impacts mankind are having on reefs worldwide.