Short-term improvement of heat tolerance in naturally growing Acropora corals in Okinawa

PeerJ

article

Tanya Singh¹  Kazuhiko Sakai¹  Jun Ishida-Castañeda²  Akira Iguchi³ 

[1] Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus;Graduate School of Engineering and Science, University of the Ryukyus;Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology;Research Laboratory on Environmentally-Conscious Developments and Technologies [E-code], National Institute of Advanced Industrial Science and Technology

关键词: Acclimatization;    Acropora;    Coral bleaching;    Heat stress;    Heat tolerance;    Naturally growing;    Ocean warming;   

DOI  :  10.7717/peerj.14629

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Mass bleaching and subsequent mortality of reef corals by heat stress has increased globally since the late 20th century, due to global warming. Some experimental studies have reported that corals may increase heat tolerance for short periods, but only a few such studies have monitored naturally-growing colonies. Therefore, we monitored the survival, growth, and bleaching status of Acropora corals in fixed plots by distinguishing individual colonies on a heat-sensitive reef flat in Okinawa, Japan. The level of heat stress, assessed by the modified version of degree heating week duration in July and August, when the seawater temperature was the highest, was minimally but significantly higher in 2017 than in 2016; however, the same colonies exhibited less bleaching and mortality in 2017 than in 2016. Another study conducted at the same site showed that the dominant unicellular endosymbiotic algal species did not change before and after the 2016 bleaching, indicating that shifting and switching of the Symbiodiniaceae community did not contribute to improved heat tolerance. Colonies that suffered from partial mortality in 2016 were completely bleached at higher rates in 2017 than those without partial mortality in 2016. The present results suggest that either genetic or epigenetic changes in coral hosts and/or algal symbionts, or the shifting or switching of microbes other than endosymbionts, may have improved coral holobiont heat tolerance.

【 授权许可】

CC BY