Coral Bleaching in the Vatu-I-Ra Seascape: How Bad Is It?

Wakaya Island impact from Cyclone Winston. Photo by Sangeeta Mangubhai ©WCS.

By Sangeeta Mangubhai

[This is the fourth in a series of blogs by WCS-Fiji Director Sangeeta Mangubhai assessing the damage to coral reefs caused by Cyclone Winston, a Category 5 storm that hit Fiji on February 20]

Before Cyclone Winston hit Fiji, we were following closely the El Niño cycle, the drought, and reports of coral bleaching from dive operators. The local newspaper, the Fiji Times, ran a number of stories about fish kills and there was a lot of speculation about whether this was caused by the elevated sea surface temperatures we were experiencing across Fiji.

Wakaya Island impact from Cyclone Winston. Photo by Sangeeta Mangubhai ©WCS.

Temperatures on inner reef flats along the Coral Coast recorded temperatures as high as 35°C. A similar story emerged from Vanuatu.

I have been spending part of each dive collecting data on the scale and intensity of bleaching across a range of habitats – including fringing patch and lagoonal reefs, channels, and bommies – using a rapid assessment technique developed by my colleagues Dr. Tim McClanahan and Dr. Emily Darling at the Wildlife Conservation Society.

Large bleached 3m diameter Porites coral. Photo by Sangeeta Mangubhai ©WCS.
Large bleached 3m diameter Porites coral. Photo by Sangeeta Mangubhai ©WCS.

Over the last four days, I have documented mild levels of bleaching, with common coral genera like Acropora, Pocillopora, Porites (massive forms), Montipora and Pavona mostly affected.

By mild, I mean that corals are either iridescent or slightly pale, rather than fully white (i.e. bleached). The tissue on these corals is still very much alive. A few very large colonies of Porites and Pavona are severely bleached in the shallow —> Read More

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