Using Epibiont Successional Patterns to Determine the Mode of Accumulation of Late Pleistocene Fossil Reefs

April 11th, 2011

Coral colony orientation data obtained from Late Pleistocene reef coral assemblages preserved on Curaçao, Netherlands Antilles, Great Inagua and San Salvador Islands, Bahamas, indicates that the same gradient in hurricane frequency observed today also was present during Late Pleistocene time. We conduct an independent test of this hypothesis by examining the successional patterns exhibited by epibionts that grew on coral colonies during a distinct reef-building event that is spectacularly preserved in the upper Hato Unit of the Lower Terrace Limestone, exposed on Curaçao, Netherlands Antilles.

Corals were removed along vertical transects constructed on replicate leeward and windward fossil reef exposures (total of four sites) on Curaçao. Coral colony samples were taken approximately every 20-40 cm over an average of 5 meters of transect per site. A total of 51 coral samples were obtained for analysis. Thin sections were used to identify epibiont species preserved in and on corals, quantify their degree of coverage, and elucidate successional patterns preserved on individual corals.

Windward exposures exhibit sequences of robust Acropora palmata colonies with thick epibiont coverage, while leeward exposures exhibit colonies retaining thinner encrusting layers with more sediment fill around coral colonies. We interpret this difference to be the result of contrasting wind and wave energy regimes.  Ongoing analyses of epibiont successions within each site will allow for a discrimination of high versus low disturbance frequencies during accumulation of the fossil reefs.

Elizabeth Erickson, ’11
Colby, KS
Majors: Geology, Environmental Studies

Sponsor: Benjamin Greenstein

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