Date: Fri, 13 Nov 1998 10:30:13 -0600 (CST) From: "Richard B. Aronson" Subject: Re: Bleaching in Belize To: Roy Caldwell <4roy@socrates.berkeley.edu> cc: coral-list@coral.aoml.noaa.gov 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