183-6 Collapse of a Coral Refugium: Taphonomic Succession of Acropora cervicornis Skeletons in Coral Gardens, Belize

Session: Recent Advances and New Voices in Marine and Coastal Geoscience (Posters)

Poster Booth No.: 37

Presenting Author:

Astrid Schurr

Authors:

Schurr, Astrid¹, Baz-Aguilar, Alessandra², Lujan, Daymon³, Rose, Emmie⁴, Wirth, Karl R.⁵, Falls, Emily⁶, Greer, Lisa⁷

(1) Washington and Lee University, Lexington, VA, USA, (2) Washington and Lee University, Lexington, Virginia, USA, (3) Washington and Lee University, Lexington, Virginia, USA, (4) Washington and Lee University, Lexington, Virginia, USA, (5) Macalester College, St. Paul, MN, USA, (6) Washington and Lee University, Lexington, VA, USA, (7) Washington and Lee University, Lexington, VA, USA,

Abstract:

Coral Gardens, Belize, a shallow patch reef environment, was identified as a refugium for the threatened coral species Acropora cervicornis in 2023. Five permanent transects were established at Coral Gardens to track the percentage of live A. cervicornis annually from 2012 to 2025. At Transect 5 (T5), coral growth was particularly exceptional, with live A. cervicornis cover reaching nearly 60% in 2012 and remaining relatively high at over 35% in June 2023, despite widespread regional declines. This persistence was abruptly interrupted when a marine heatwave in late 2023 caused complete mortality of all A. cervicornis at Coral Gardens. This study investigates post-mortem skeletal degradation and colonization of A. cervicornis over an 18-month period. A total of 107 skeletal samples were collected: 17 in December 2023, 34 in June 2024, 29 in December 2024, and 27 in June 2025. Samples were visually assessed for corallite preservation, erosion, and colonization, with representative samples selected to illustrate variation at each point in time. Skeletal microstructure and internal bioerosion were analyzed using scanning electron microscopy (SEM) paired with energy-dispersive X-ray spectroscopy (EDS). Following mortality, the coral substrate was rapidly overgrown by opportunistic taxa, including macroalgae (primarily Dictyota spp.), an unidentified orange encruster, sponges, foraminifera, and other endolithic and epilithic organisms. Over the study period, skeletal surfaces exhibited increasing degradation, marked by intensified colonization and loss of corallite structure. SEM/EDS analyses revealed the presence of micro- and macroborers, with features interpreted as clionid excavation scars, various sponge spicules, polychaete tubes, and endolithic algae. The rapid degradation of A. cervicornis' skeletal framework highlights the vulnerability of reef structures as coral mortality accelerates and ecosystems undergo phase shifts. Understanding post-mortality dynamics is essential for predicting habitat loss, assessing reef resilience, and anticipating impacts on shoreline protection. The temporal resolution of this study also provides valuable context for interpreting fossil coral records and reconstructing past reef responses to climate and environmental stressors.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7322

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.