[Coral-List] More on Western Pacific coral bleaching

[Emily Howells]

For those interested, this follows on from the previous reports of coral bleaching at Ishigaki Island in the Western Pacific. 

I visited a few of the reefs around Ishigaki at the end of last week and have taken a number of photos of the bleaching impact on the wide range of hard and soft coral genera which have been affected. I am happy to pass these on to anyone working in the region or anyone else interested.

While I did not conduct any formal surveys, my observations estimate that 90-95% of the coral colonies at in the lagoon and crest at Yonehara are bleached and most are completely white. There has been high mortality of Acropora and Montipora spp, and some recent partial mortality on large Porites colonies. On the reef slope, bleaching is less severe, but ~80% of corals down to ~5m are pale or white, and quite a number of colonies are also affected at greater depth, but with minimal morality at this stage.

At a couple of more turbid reefs on the south-west and east of Ishigaki, bleaching was less severe than at Yonehara. 60-80% of colonies were bleached on the reef flat and 40-50% on bommies in slightly deeper water (3-5m). Only a small amount of bleaching related mortality was observed at these sites. 

In addition, low levels of bleaching have also been observed around Sesoko Island in the north-west of Okinawa since early-mid July. Following a couple of weeks of hot calm days following a typhoon, some Montipora digitata and small Acropora colonies on the reef flat at Sesoko Island have completely bleached. At a nearby soft coral dominated reef (which has also been experiencing runoff following heavy rain) the majority of colonies on the reef flat, which are mostly Lobophytum, have also bleached.

Regards, 

Emily Howells

School of Marine and Tropical Biology
James Cook University
Townsville QLD 4811
Australia

emily.howells at jcu.edu.au