The Eastern Mediterranean Sea scleractinian Oculina patagonica, demonstrates high resilience to repeated seasonal bleaching events, a trait potentially allowing the species to survive through a radically changing climate. However, the physiological and morphological contributors that make this plasticity of O. patagonica possible are poorly understood. Here we use a long-term in vitro induced bleaching experiment where colonies were reared in a dark environment to examine how O. patagonica colonies can survive without endosymbionts. We assessed the physiological, morphological and genetic adaptations that accompany our controlled bleaching. Measurements reveal changes to respiration and calcification rates both at 3 and 12 months following the initiation of the darkness experiment, coupled with corresponding macromorphology traits. Upon placing in the dark environment, O. patagonica begins the bleaching process while demonstrating acclimation in which the coral appears to divert its energy to survival resulting in the expulsion of the Symbiodiniaceae population. In addition, the coenosarc exhibits degradation where the coral transforms from a colonial living to a solitary one. Once bleached, we observe adaptation by the solitary polyps characterized by a lower respiration rate yet, regaining their calcification activity and are continuing gametogenesis. However, under bleaching conditions, the newly formed skeletons differ substantially from non-bleached colonies, clearly suggesting an environmental influence on the skeleton morphology. Overall, our study reveals that O. patagonica shows phenotypic plasticity allowing the species to withstand losing their beneficial endosymbionts so as to prosper as a solitary coral. The mechanisms used by this highly resilient coral may provide clues to what corals may require to be able to adapt to life without photosynthetic symbionts.
Bibliographical noteFunding Information:
We thank Dr. E. Shemesh, Dr. R. Almuly, H. Nativ, and the technical staff of the Moris Kahn Marine Research Station for their invaluable help. We also thank The Mantoux Bioinformatics Institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science. This study was performed in accordance with regulations and guidelines set by the Israel Nature and Parks Authority. Funding. This research was supported by the United States–Israel Binational Science Foundation Grant BSF-2016321.
This research was supported by the United States–Israel Binational Science Foundation Grant BSF-2016321.
© Copyright © 2019 Zaquin, Zaslansky, Pinkas and Mass.
- coral bleaching
- phenotypic plasticity
- stress response genes
ASJC Scopus subject areas
- Global and Planetary Change
- Aquatic Science
- Water Science and Technology
- Environmental Science (miscellaneous)
- Ocean Engineering