| The Holocene Canada Honda (CH) fossil reef, located in southwestern Dominican Republic, provides a unique opportunity to examine a well-preserved fossil coral reef that thrived in a high-sedimentation environment between 9,000 to 5,000 years ago. Assessments of coral species abundance, morphology, age, and distribution, as well as characterization of reef sediment, were made to determine the paleoenvironment of reef accretion. Also, measurements of coral growth rates from the corals Montastraea faveolata and Siderastrea siderea were conducted and comparisons made with growth rate data of these same species from modern coral reefs throughout the Caribbean. Evidence for high sedimentation comes from the relatively high abundance of sedimenttolerant coral species, the tendency of these to form almost monospecific stands, and the propensity of individual colonies to grow as encrusting, dome-shaped, platy-like forms resulting in the development of ragged-margins or the so-called "stack of pancakes" morphology. Sediment incorporated into coral skeletons supports the idea of siltation stress during the accretion of the reef. Calibrated radiocarbon ages of fossil corals range from 9,256+/-137 to 6,737+/-94.5 BP. Correlation of radiocarbon ages with well-established Holocene sea-level curves indicates that most corals on this reef developed at depths between 10m to 12m. Measured growth rates in Siderastrea siderea (0.2--0.4 cm/yr) and Montastraea faveolata (0.09--0.44 cm/yr) are relatively low compared with growth rates from modern reef sites, indicating reduced light intensity caused by turbidity and coral growth at depths near 12 m. Reef sediment is characterized by more than 85% carbonate material. A significant portion of the carbonate is allochtonous and was derived from nearby Neogene limestones. The reef was able to survive under high-sedimentation conditions because the high carbonate content of incoming terrigenous sediment would have allowed better light penetration and probable sporadic storms that would have provided intervening low-sedimentation periods during which reef corals could respond and grow back, keeping-up with sedimentation. This study illustrates, once again, the presence of highly resilient coral communities under multiples conditions of natural disturbance. |
