Unique quantitative Symbiodiniaceae signature of coral colonies revealed through spatio-temporal survey in Moorea

Héloïse Rouzé,Gergely Torda,Véronique Berteaux-Lecellier,Gaël Lecellier,Xavier Pochon

doi:10.1038/s41598-019-44017-5

Abstract

One of the mechanisms of rapid adaptation or acclimatization to environmental changes in corals is through the dynamics of the composition of their associated endosymbiotic Symbiodiniaceae community. The various species of these dinoflagellates are characterized by different biological properties, some of which can confer stress tolerance to the coral host. Compelling evidence indicates that the corals’ Symbiodiniaceae community can change via shuffling and/or switching but the ecological relevance and the governance of these processes remain elusive. Using a qPCR approach to follow the dynamics of Symbiodiniaceae genera in tagged colonies of three coral species over a 10–18 month period, we detected putative genus-level switching of algal symbionts, with coral species-specific rates of occurrence. However, the dynamics of the corals’ Symbiodiniaceae community composition was not driven by environmental parameters. On the contrary, putative shuffling event were observed in two coral species during anomalous seawater temperatures and nutrient concentrations. Most notably, our results reveal that a suit of permanent Symbiodiniaceae genera is maintained in each colony in a specific range of quantities, giving a unique ‘Symbiodiniaceae signature’ to the host. This individual signature, together with sporadic symbiont switching may account for the intra-specific differences in resistance and resilience observed during environmental anomalies.

Highlights

Dinoflagellate algae from the family Symbiodiniaceae are one of the keystone taxa for coral reef ecosystems
The choice of the quantitative Polymerase Chain Reaction (qPCR) assay employed in the present study was based on its ability to detect Symbiodiniaceae genera in hospite at the level of ≤200 28S copies, which approximates the number of 28S copies in a single algal cell[50]
The detection of de novo Symbiodiniaceae genera in all three coral species suggests that symbiont switching may be a common natural phenomenon in healthy adult scleractinians

Summary

Introduction

Dinoflagellate algae from the family Symbiodiniaceae are one of the keystone taxa for coral reef ecosystems. The coral holobiont’s resilience to environmental stressors is in large part based on various genotypes and biological traits[19] This includes the complex interaction and differential physiological responses of symbiotic Symbiodiniaceae populations that may be composed of one single genus or multiple genera and species[20,21] and the host[22,23,24,25]. Shifts that occur over the coral’s ontogeny have been related to physiological states (e.g. diseased vs healthy, temperature resilience)[34,35,36,37] These ecological observations support the idea that flexibility in the coral-Symbiodiniaceae partnership enables the coral holobiont to adapt rapidly to environmental stressors[38], a paradigm that is encapsulated in the Adaptive Bleaching Hypothesis[39]. We study the composition of Symbiodiniaceae communities and their quantitative regulation in tagged colonies of three coral species over a period of 10–18 months, among environmentally contrasting locations of Moorea (French Polynesia)

Methods

Results

Conclusion