43 Sedimentary Geology (Posters)

Tuesday, 24 March 2026
8:00 AM - 12:00 PM
CCC, Ballroom C

Benthic foraminiferal record of Holocene reef development on the inner shelf of the Great Barrier Reef, Australia

Paper number: 43-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Understanding coral reef development over millennial timescales reveals how reefs respond to environmental change, interact with their physical setting, and recover from disturbance. Low Isles Reef in the northern Great Barrier Reef is among the world’s longest-studied reefs, with nearly a century of observations documenting shifts in geomorphology and benthic communities driven by storms, infilling, and other disturbances. However, its longer-term development remains poorly constrained, motivating this study to reconstruct the reef’s late Holocene history and provide context for interpreting recent change and predicting future reef resilience. This work documented changes in lithology, grain size, and skeletal composition through four vibrocores acquired from the Low Isles reef flat. In addition, the Foraminifera in Reef Assessment and Monitoring Index (FI), which compares abundances of benthic foraminifera in three functional groups, was applied to assess water quality and suitability for coral growth through time. Results are considered in the context of data from the modern reef flat, and age is constrained by radiocarbon dating. Results indicate that Low Isles was most productive 3,000-2,000 y BP. Skeletal component data indicate that around this time, coral abundance hit a peak before declining upward, consistent with decreasing accommodation space. The decrease in coral abundance is matched by an increase in Halimeda and foraminifera, consistent with an expanded reef flat and shallowing of the lagoon. Despite variations in carbonate lithofacies, FI values suggest that reef conditions remained generally suitable for coral growth, with some evidence for transient stressful conditions from which the reef recovered. Together, these results place recent change at Low Isles within a millennial-scale framework, highlighting long-term reef resilience despite shifts in sedimentary and ecological conditions.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411162

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