PARTIAL WHITENING IN PORITES PORITES (CNIDARIA, SCLERACTINIA) AT THE ISLA VERDE REEF, VERACRUZ, MEXICO

Samples of Porites porites with bleached tip branches were collected in the flat of Isla Verde Reef, Veracruz, Mexico. For each colony the density of zooxanthellae was higher in the areas with normal appearance, while the ratios chlorophyll a/zooxanthellae were higher in the bleached areas. The chlorophyll a concentrations per square centimeter did not differ significantly between the two areas. The bleaching on the tip branches of P. porites migth be caused by environmental factors, and it does not appear to affect the photosyntethic area.