Symbiodiniaceae Shifts Over the Last Decade on the Hottest Coral Reefs on Earth

Authors

Anna Fiesinger, University of Konstanz
Rachel Alderdice, University of Konstanz
Luigi Colin, University of Konstanz
Hannah Manns, University of Konstanz
Gabriela Perna, University of Konstanz
Kathryn H. Stankiewicz, Institute of Systems Biology
Jacob J. Valenzuela, Institute of Systems Biology
Line K. Bay, Australian Institute of Marine Science
Daniel J. Barshis, Old Dominion UniversityFollow
Nitin S. Baliga, Institute of Systems Biology
Iliana B. Baums, Helmholtz-Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB)
John A. Burt, New York University Abu Dhabi
Christian R. Voolstra, University of Konstanz

Document Type

Article

Publication Date

2025

DOI

10.1007/s00338-025-02767-x

Publication Title

Coral Reefs

Volume

44

Issue

6

Pages

2049-2064

Abstract

Corals in the Persian/Arabian Gulf (PAG) are resilient to various stressors, whose levels exceed those of coral reefs globally. These corals thereby offer insight into mechanisms underlying thermal resilience, e.g., regarding the role of endosymbiotic microalgae in the family Symbiodiniaceae. Previous studies have identified the thermotolerant species Cladocopium thermophilum as broadly associated with corals in the southern PAG. However, algal-host specificity at the within-species level and the temporal stability of these associations are not well understood. Here we sampled two dominant stony corals (Porites harrisoni, n = 119 and Platygyra daedalea, n = 79) at three sites in the southern PAG and the neighboring Gulf of Oman (GO) to explore algal symbiont assemblage and specificity, whereby a prior dataset provided the opportunity to assess symbiont community stability in P. daedalea across a decadal time frame. Using high-throughput ITS2 marker gene sequencing and the SymPortal framework, we identified distinct, largely non-overlapping ITS2 type profiles of C. thermophilum as the dominant symbiotic partners in P. harrisoni and P. daedalea in the southern PAG, highlighting high host fidelity at the subspecies level. Despite this, we observed notable changes in C. thermophilum genotype diversity and an overall decrease over the course of a decade. By comparison, algal symbiont diversity in the neighboring GO corals increased, with formerly prevalent ITS2 type profiles being replaced by novel genotypes. Decadal data on P. daedalea suggest a shift in algal symbiont assemblage signified by the decline of formerly dominant algal type profiles and the emergence of novel genotypes. It is currently unknown whether the respective coral colonies associated with novel algae or became rare or extinct themselves. Understanding long-term algal population dynamics is critical to forecast how algal lineage loss or, alternatively, an increase in algal diversity will impact coral resilience and survival.

Rights

© 2025 The Authors.

This article is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original authors and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

Data Availability

The SymPortal analysis of the dataset of P. harrisoni and P. daedalea collected in 2022 can be accessed at: https://symportal.org/data_explorer/?Study=202307_afiesinger_UAE_GS. The combined SymPortal analysis including P. daedalea from 2012 (Howells et al. 2020) and 2022 (this study) used for the decadal comparison can be accessed at https://symportal.org/data_explorer/?Study=202402_afiesinger_UAE_GS_10yearcomp. Source code for all analyses and figures is available at the following GitHub repository: https:/github.com/afiesinger/UAE_PAG_Symbiodiniaceae. Raw FASTQ sequencing files are accessible at NCBI under BioProject PRJNA1188806 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA1188806) as part of the Umbrella Project PRJNA749006 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA749006).

Original Publication Citation

Fiesinger, A., Alderdice, R., Colin, L., Manns, H., Perna, G., Stankiewicz, K. H., Valenzuela, J. J., Bay, L. K., Barshis, D. J., Baliga, N. S., Baums, I. B., Burt, J. A., & Voolstra, C. R. (2025). Symbiodiniaceae shifts over the last decade on the hottest coral reefs on Earth. Coral Reefs, 44(6), 2049-2064. https://doi.org/10.1007/s00338-025-02767-x

Repository Citation

Fiesinger, Anna; Alderdice, Rachel; Colin, Luigi; Manns, Hannah; Perna, Gabriela; Stankiewicz, Kathryn H.; Valenzuela, Jacob J.; Bay, Line K.; Barshis, Daniel J.; Baliga, Nitin S.; Baums, Iliana B.; Burt, John A.; and Voolstra, Christian R., "Symbiodiniaceae Shifts Over the Last Decade on the Hottest Coral Reefs on Earth" (2025). Biological Sciences Faculty Publications. 668.
https://digitalcommons.odu.edu/biology_fac_pubs/668

ORCID

0000-0003-1510-8375 (Barshis)