Subject: Bleached BELIZEAN REEFS
From: Tom Bright <[email-masked]>
Date: Wed, 16 Sep 1998 14:22:06 -0600

Memorandum To: Mr. James Azueta, Coordinator of Marine Protected Areas,
Belize Dept. of Fisheries.
From: Dr. Thomas J. Bright, Station Manager, Glover's Reef Marine Research
Station, Wildlife Conservation Society.
Subject: Wide scale Bleaching on all of Belize's Coral Reefs.
Date: Sept. 15, 1998

The entire Belizean coral reef ecosystem has experienced a massive and 
pervasive event of coral bleaching. I have personally observed serious 
bleaching down to a depth of at least 8 meters on the fore reef, top reef 
and back reef of the main barrier reef at Ranguana Pass, the patch reefs 
at Crawl Caye, Laughing Bird Caye, Scipio Caye, Bird Caye, pinnacle 
reefs between Ranguana Pass and Lighthouse Caye off Placencia, and 
the shallow water off Rum Point. Danny Wesby reports massive 
bleaching on the fore reef, top reef, back reef and patch reefs at Glover's 
Reef Atoll down to at least 7 meters depth. Chris Berlin reports serious 
bleaching off Ambergris Caye. Fishermen have told me of bleaching on 
the main Barrier Reef from Buttonwood Caye to Ranguana Pass. Divers 
observed bleaching at South Water Caye and Cocoplum Caye. All of the 
observers indicate that, although they have seen bleaching in past years 
at this time, none have ever seen it so widespread and so extensive as this 
year's event. They said that this is the warmest they remember the water 
temperature ever being. All indicate that they began noticing the bleaching 
during the last week or so.

>From this information I conclude that there has been a massive and 
heretofore unprecedented (in the memory of those Belizean fishermen, 
watermen and divers contacted) degree of zooxanthellae expulsion 
(bleaching) in the reef coral populations of the entire Belizean Reef 
ecosystem from the mainland beach out to the Atolls and including the 
main Belize Barrier Reef down to at least 8 meters depth, and probably 
deeper. Further, it appears that the bleaching is correlated in time with a 
period of exceptionally high regional sea water temperature, and calm 
weather (there has been very little wind during the last month). 

Bleaching at Crawl Caye on Sept. 2 was reported by me to Dylan 
Gomez and the National Coral Reef Monitoring Group. Bleaching was 
noted on Sept. 7 at Glover's Reef by the Wildlife Conservation Society 
staff. Since then the bleaching has intensified and spread. Thus I 
conclude that the presumed cause of the bleaching (high sea water 
temperature) manifested itself around the first of September and has not 
yet abated. Further, I feel that the bleaching started around the first of 
September, has progressed since then, has not yet run it's course, and 
could get worse than it is now.

I observed water temperature, on my fish finder, at one meter depth, 
during a sail from Belize City to Ranguana Pass and across the Gulf of 
Honduras to Punta Sal, Honduras during the time in question. It was 
consistently between 30 C and 32 C and most of the time it was 31 C. 
Danny Wesby measured the Glover's Reef Temperatures on Sept. 15. 
The surface temp. was 32 C and the temperature at 2 meters was 30 C. 
The surface waters (upper 1/3 Meter or so) on shoals and near cayes is 
warmer, often 36 to 38 C.

Some qualitative conclusions based on my personal observations are as 
follows: Almost all Milleporan and Scleractinian corals and the Zooanthid 
Palythoa exhibited some degree of bleaching. Total to high bleaching 
was prevalent in Millepora, Agaricia, Porites porites and Palythoa. High 
to moderate bleaching was prevalent in Montastrea, Siderastrea, and 
Diploria. Moderate to low bleaching occurred in Dendrogyra and 
Acropora (although A. palmata appeared only moderately bleached on the 
main Barrier Reef, totally bleached colonies were observed in places on 
the lagoonal patch reefs). Most Millepora, Porites porites, Agaricia and 
Palythoa were pure white . Many Montastrea "annularis" (all three growth 
forms) were pure white over the major part of their coralla, many were tan, 
all were affected. Other species unnamed above were also affected. Black 
band disease was observed on M. "annularis", Diploria and Gorgonia but 
not in any greater frequency than usual.

This is the most extensive case of bleaching that I have ever observed. I 
hope that subsequent mortality is minimal. A monitoring effort should be 
undertaken to assess the ultimate impact of this massive bleaching event 
on the reef coral populations of Belize.