69 Joint SGD-SEPM-IAS Focus on the Sedimentary Record of Climate Change (Posters)

Explore how sedimentary records reveal Earth's climatic history and processes driving environmental change. This session highlights proxies, stratigraphy, and emerging technologies, advancing understanding of past climates and informing predictions of future climate dynamics through interdisciplinary collaboration.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Comparing Ostracode and Mollusk Community Response to Climate and Environmental Changes in Two Bahamian Inland Blue Holes

Paper number: 69-0
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Bahamas is highly susceptible to climatic changes due to the influences of the Intertropical Convergent Zone (ITCZ) and the El Niño-Southern Oscillation (ENSO). This study focuses on identifying climatic shifts within sediment records from two inland blue holes: Blue Hole Five (BH5) from San Salvador Island and Duck Pond Blue Hole (DPBH) from Eleuthera, using multi-proxy records. Sediment core transects were taken via a square-rod piston coring system in both blue holes, capturing a ~6,000-year record in each. Initial proxy data includes loss on ignition (LOI), XRF, grain size, mollusk, and ostracode counts. Bayesian age models were constructed for each blue hole using radiocarbon dates on charcoal and terrestrial vegetation. Grain size and LOI were highly variable from 6000-3600 YBP in Blue Hole Five, and 4100 YBP in Duck Pond Blue Hole. In both blue holes, XRF counts for Br and Ca positively co-varied, but Br and Sr negatively co-varied. In Blue Hole Five, there is a general increase in Br between 5150-2300 YBP, followed by a general decrease until 250 YBP. This contrasts with Sr, which shows an overall decrease throughout the core record. In Duck Pond Blue Hole, there is a significant increase in Br at 2300 YBP that corresponds with a significant decrease in Sr. These shifts correspond with the LOI data. Ostracode abundances varied from 6000-4100 YBP, with limited mollusk presence in DPBH, but not in BH5, where there was low variability in ostracode and mollusk abundances from approximately 6000-4100 YBP. Marked changes in the abundances of mollusks and ostracodes were observed in both blue holes at 2300, 1200, and 250 YBP, similar to the Br, Sr, and LOI records. These multi-proxy records indicate that both blue holes recorded similar events in the past 6000 years, and both demonstrate that the mollusks and ostracodes were responding to changes in the blue holes due to climatically driven events. By understanding how organisms respond to environmental change, we can better understand how they might respond to future climate states.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412937

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