Bleaching in Belize

[Richard B. Aronson]

Bleaching in Belize

To answer Roy Caldwell's question about bleaching in Belize, Tom Bright, 
James Azueta, Greg Smith, Melanie McField, Tony Rath, and several others 
reported massive bleaching in Belize, and some of this information was 
broadcast over the coral list.

Bill Precht and I dove in the central lagoon (Channel Cay and the other 
rhomboid shoals) in Belize in late October, just a couple of days before 
Hurricane Mitch.  At that time virtually every living colony from 1-21 m 
depth was bleached completely white.  Species bleached included Acropora 
cervicornis, Agaricia tenuifolia (the dominant coral), Agaricia lamarcki, 
Colpophyllia natans, Manicina areolata, Montastraea franski (only 
partially bleached at some sites), Mussa angulosa, various Mycetophyllia 
species, Millepora alcicornis, Porites divaricata, Siderastrea siderea 
and Stephanocoenia intersepta (small-polyped form).  Porites astreoides 
and P. colonensis were pale yellow.  In some areas, many of the A. 
tenuifolia colonies appeared to be recently dead; they were still 
standing in place but overgrown by a fine algal turf.  Several species of 
gorgoinans, including Erythropodium and a Eunicea, were bleached white as 
well.  The corallimorph Ricordea florida was pale yellow to white.

On the fore reef at Curlew Bank, just south of Carrie Bow Cay, A. 
tenuifolia is the dominant coral on spurs in 3-6 m depth. The margins of 
the blades of A. tenuifolia colonies were bleached, but the central 
portions, which are less exposed to light, retained most of their normal 
brown color.  Larger Siderastrea siderea colonies were bleached to a blue 
color on their tops, but retained some brown color on their sides.  
Smaller S. siderea colonies appeared less affected.  The three species of 
the Montastraea annularis complex showed bleaching patterns typical of other 
bleaching events, with some regions of colonies white and other areas 
appearing normal. Colpophyllia natans and Diploria labrynthiformis showed
extensive bleaching, but D. strigosa and D. clivosa did not, nor did 
Isophyllia sinuosa or Isophyllastrea rigida.  Most surprising was that A. 
cervicornis and A. palmata were not at all bleached on the fore reef, 
considering what we saw in the lagoon.

Other species that were bleached on the fore reef: Agaricia agaricites, 
Porites porites, Mycetophyllia ferox, Siderastrea radians, Millepora 
alcicornis, Millepora complanata, and the zoanthid Palythoa caribbea.

Other species that were not bleached on the fore reef: Stephanocoenia 
intersepta (large-polyped form), Dendrogyra cylindrus, Dichocoenia 
stokesi, Monstastraea cavernosa (1 colony was partially bleached), and 
Porites astreoides.

Surface water temperatures were 28.5-29.8 C in the lagoon and 29.6 on the 
fore reef.  At 9 m depth the lagoon was 28.5-29.1 and the fore reef was 29.3.

I would appreciate other reports of bleaching in Belize, especially from 
anyone who has been in the southern lagoon recently.

Regards,

Rich Aronson

______________________________________________________________________________
Richard B. Aronson
Senior Marine Scientist
Dauphin Island Sea Lab
101 Bienville Boulevard
Dauphin Island, AL 36528

Voice: (334) 861-7567
Fax: (334) 861-7540
email: raronson at jaguar1.usouthal.edu