COMPARISON OF FOSSIL AND MODERN BENTHIC FORAMINIFERAL ASSEMBLAGES TO ASSESS RECENT ENVIRONMENTAL CHANGES IN COASTAL BOCAS DEL TORO, PANAMA

The last few decades have witnessed the decline of coral reefs, and although human-induced disturbance is a current factor, reefs have naturally thrived and declined over geologic time. A comparison of fossil and modern records of environmental indicators can suggest causes for both natural and human-influenced changes. Benthic foraminifera are useful for paleoenvironmental reconstructions because they are sensitive environmental indicators, and the modern ecology of many species found as fossils is known. The purpose of this study examines communities of benthic foraminifera from coral reef and other marine environments in Bocas del Toro, Panama in their “pristine” pre-human condition and modern condition.

In this pilot study, the relative abundance of benthic foraminifera in nine sediment samples from a dredged transect spanning a coastal mangrove to fossil reef U-Th dated to ~5.7-7.2kya along the southwest coast of Isla Colon, Bocas del Toro, Panama were combined with data from 21 samples of modern foraminiferal assemblages from coastlines of Bocas del Toro. Each foraminiferal assemblage included >400 specimens. Preliminary results from cluster analysis show few similarities between the modern and fossil samples with the exception of one fossil sample which shows greater similarities with three modern lagoon samples. These results suggest that the fossil samples are more similar to each other than they are to the modern samples. Two hypotheses for these results are: 1) the coastal ecosystem has changed, which is reflected by the lack of clustering between the fossil and modern assemblages, and 2) the modern and fossil samples are generally so different because the modern samples did not effectively sample the same type of environment. Future fieldwork to include sampling of modern sediments near the fossil sample site and additional coastal locations in Bocas del Toro will be completed to eliminate the second hypothesis as a possibility. By comparing the sediments from 6,000-year-old reefs to additional modern reef sediments, we will determine how tropical coastal environments have changed and responded to human-induced disturbance, which has implications for preservation and future restoration of coral reefs along tropical coastlines.