"Coral Bleaching Event in Hawai'i"

Cindy Hunter cindyh at hawaii.edu
Fri Sep 13 23:20:36 EDT 1996

The current coral bleaching event in Hawaii is not limited to Kane'ohe 
Bay.  Corals in Kailua Bay, a shallow but more open-coast environment 
southeast of Kane'ohe Bay on Oahu, have shown exceptional bleaching 
responses over the past two weeks.  

The bleaching in Kailua Bay was first evident on Labor Day weekend--just 
after a period of very warm, nearly windless weather conditions.  
Near-shore seawater temperature in Kailua Bay on September 2nd was 31 
degrees C. Up until that time (over the past four years), we had not 
measured temperatures higher than 29.5 degrees in Kailua Bay [on 9/7/95]. 
All coral species (large massive bommies=Porites evermanni and P.  lobata;  
rice and lavendar coral=Montipora verrucosa and M. flabellata; rose and 
lace coral=Pocillopora meandrina, P. ligulata, and P. damicornis)  were 
bleached to varying extent, except the common finger coral, Porites 
compressa; bleaching in this species didn't appear for another three to 
four days.  Of note is that colonies of Montipora patula, an encrusting 
species found in the same habitat and often adjacent to bleached Montipora 
verrucosa and M. flabellata, has _not_ bleached.  

As of yesterday (September 12th), nearly every coral in Kailua Bay from 
shore to about 1.5 km out--in depths to 5 m--appeared bleached, with most 
colonies being white or very pale. In the past 10 years of our studies on 
corals in Kailua Bay, we have not seen anything close to such a bleaching 
response, both in terms of extent of pigment loss and numbers of species 

Seawater temperatures returned to normal (about 28 degrees) rapidly 
(within a week). Since we have not previously observed such an extreme 
bleaching event in Hawaii, we cannot predict how long corals will take to 
recover. Some mortality is already apparent in colonies of the most 
rapidly bleached species-- Pocillopora damicornis and P. meandrina (lace 
and rose coral).  

Cindy Hunter 
Celia Smith  
Botany Dept. 
University of Hawaii 

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