DETERMINING STORM EVENTS THROUGH MICROFAUNA-DISTRIBUTION ANALYSIS: A SEDIMENTOLOGIC STUDY OF PONDS ON SAN SALVADOR, BAHAMAS

The Bahamian island of San Salvador is frequented by strong storms and hurricanes that influence deposition in coastal hypersaline ponds across the island. Cores were studied from ponds along the island’s eastern and southern shores as part of an ongoing investigation into effects of shoreline orientation and topography, coastal vegetation, and nearshore morphology on storm-sedimentation patterns. Storm deposits in these coastal ponds, traditionally recognized as sediment layers containing high sand percentages, were evaluated for their foraminiferal content to evaluate the potential of these microscopic organisms as additional storm indicators in the sediment record of San Salvador.

Microscopic analysis of interpreted storm-sediment facies revealed mature and juvenile species of benthic foraminifera, which mainly inhabit reef environments around Florida and the Bahamas: Archais angulatus, Peneroplis bradyi, Laevipeneroplis proteus, and Homotrema rubrum. Their occurrence in these particular sediments suggests that these ocean-dwelling foraminifera were deposited by storm-surge and beach over-wash events, making them a suitable proxy for investigating down-core trends in storm activity in addition to grain size, which is shown to not always demark storm layers clearly from background sedimentation.

Future analysis of microfauna should play an integral part in resolving San Salvador’s historic storm record. A current investigation is underway to evaluate site-specific differences in storm deposition as a function of the aforementioned geographic variables and how these might also influence types and abundances of foraminifera.