Environmental factors controlling community structure, morphology and linear extension of Mid-Holocene reef corals from Cañada Honda, Southwestern Dominican Republic

Abstract

The Cañada Honda (CH) fossil coral reef, located in SW Dominican Republic, provides a unique opportunity to examine reef accretion in a high-sedimentation environment between 9.0-5.0 ky ago. Annual linear extension of fossil corals was determined for comparison with data from modern coral reefs. The reef is characterized by the high abundance of sediment-tolerant coral species, their tendency to form almost monospecific stands and grow as domes-cones with ragged margins. Also, colonies of Montastraea faveolata commonly contain bands of sediment incorporated within their skeletons. Calibrated radiocarbon ages of fossil corals range from 9,256±137 to 6,737±94.5 BP. Correlation with Holocene sea-level curves indicate that most corals on CH developed at depths greater than 15m. Growth rates varied from 0.09-0.44 cm/yr and suggest reduced light penetration caused by coral growth at such depths. Reef sediment is characterized by more than 85% carbonate material. A significant portion of the carbonate is allochthonous and was derived from nearby Neogene limestones. The reef was able to survive under these conditions because of the high carbonate content of incoming terrigenous sediment and that storms probably occurred sporadically providing intervening low sedimentation periods during which reef corals could respond and grow back, “keeping-up” with sedimentation.