Document Type

Abstract

Publication Date

2025

DOI

10.5343/bms.2024.0122

Publication Title

Bulletin of Marine Science

Volume

101

Issue

1

Pages

594

Conference Name

5th Asia-Pacific Coral Reef Symposium, 19-23 June 2025, Nus, Singapore

Abstract

Reef-building corals are being impacted by increasing seawater temperatures, with marine heatwaves leading to mass bleaching events and extensive mortality. However, corals can display variation in thermal tolerance, both within and among species. In this study, we sampled four coral species (Acropora hyacinthus, Montipora grisea, Pocillopora verrucosa, and Porites lobata) from two sites on Tutuila, American Samoa, with contrasting environmental regimes but similar Maximum Monthly Means (MMM). Coral fragments were subjected to short-term acute heat stress experiments using the Coral Bleaching Automated Stress System (CBASS). PAM Fluorometry was used to measure the symbiont’s effective quantum yield (Fv/Fm) following heat stress and calculate colony-level ED50s (Effective Dose temperature at which Fv/Fm declined by 50% relative to initial values), interpreted as a thermal threshold of corals. Thermal thresholds primarily varied among species, with M. grisea and P. verrucosa displaying the lowest ED50s (36.29°C and 36.47°C respectively) of the assayed corals. P. lobata from both sites had the highest ED50s (37.07°C and 36.79°C), aligning with previous findings that massive Porites spp. often display higher resilience to environmental stress relative to other species. Importantly, these ED50s are 7.5– 8.5°C above the historical MMMs for the area, which are among the highest relative ED50s measured to date across assayed Indo-Pacific sites. Overall, our approach demonstrates the value of acute thermal assays as a time- and cost-effective approach to determining coral thermal performances and identifying corals for potential use in conservation and restoration efforts.

Rights

© 2025 The Authors.

This article is Open Access under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license.

Original Publication Citation

Weeriyanun, P., Evensen, N., R., Parker, K., E. , Radice, V., Z. , & Barshis, D., J. . (2025). A multispecies, multisite assessment of coral thermal tolerances in American Samoa, using acute heat stress assays. Bulletin of Marine Science, 101(1), 594. https://doi.org/10.5343/bms.2024.0122

ORCID

0000-0003-3318-5593 (Evensen), 0000-0003-1510-8375 (Barshis)

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