DEVELOPING A FIFTEEN HUNDRED YEAR RECORD (6,200 +/- 80 TO 4,760 +/- 90 YR B.P.) OF SEA SURFACE TEMPERATURE AND CORAL REEF DEVELOPMENT FROM A REEF EXPOSURE IN CAñADA HONDA, DOMINICAN REPUBLIC

During the past few decades, scientists have addressed dramatic changes in modern coral reef ecosystems. Coral bleaching, algal overgrowth and deceases, among others, are changing the character of modern reefs. An important way to obtain adequate information to address the nature of these changes is to study fossil records of well-preserved reefs at a fine temporal scale and compare them to modern reefs. Twenty one fossil coral skeletons (Montrastrea sp.) from Enriquillo Valley, Dominican Republic were x-rayed and their growth bands measured using the Coral X-Ray Densitometry System (Coral XDS). These corals formed in a restricted carbonate environment of high sediment influx that allowed a pristine preservation.

Significant variations were found in the centennial record of annual growth bands suggesting variations in the environmental parameters of the reef. Growth rates reported on this study range from 7.5-10.59 mm/yr and in previous work 0.90-4.44 mm/yr (Cuevas et al. 2009). Growth rates reported from modern reefs in Puerto Rico range from 6.3-9.7 mm/yr (Torres and Morelock, 2002) Growth rates reported from modern reefs in other areas (growing at normal conditions) reported up to 10.0 mm/yr (Gladfelter, et al., 1978; Hubbard and Scaturo, 1985; Goenaga, 1988; Van Veghel and Bosscher, 1995). The decadal record of annual growth bands present in most of the individual corals measured show cyclical behavior.

Sedimentation rates were also measured from the coral skeletons. They range from 9.4 mm/yr to 10.4 mm/yr. Variations in the sedimentation rates measured from three specimens are not significant and suggest constant rate of sedimentation during the centennial interval studied. Variations along the stratigraphic interval studied (1.5m) show no trends either. Previous studies of sedimentation rates on this same site reported much lower (1.7 mm/yr) sedimentation rates than the ones obtained (Cuevas et al. 2005). Average sedimentation rates reported in the literature for Holocene reefs are also lower (1 mm/yr) than the ones obtained here (Tucker and Wright, 1990).