Response of corals under contrast thermal regimes to different climate change scenarios

• Main Authors: Ting-Ru Chen, 陳亭儒
• Other Authors: Chaolun Allen Chen
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/h6sk7z

碩士 === 國立臺灣大學 === 海洋研究所 === 107 === It is known that corals are at substantial risk due to rising ocean temperatures associated with climate change. However, the threshold temperature inducing coral bleaching varies among different coral species, due to their partnership with specific symbionts, and exposure to different temperature regimes based on location. In this study, I aim to investigate how the above factors and their interaction influence coral’s reponse to future temperature scenarios. I used corals with different life-history strategies: Acropora nana (competitive) and Porites lutea (stress tolerant) from two different thermal environments in the Kenting National Park. One is the outlet of the 3rd NPP (larger temperature fluctuations) and the other is Wanlitong (relatively stable thermal environment compared to the 3rd NPP). Experiment to simulate three different thermal stress conditions; past (temperature of 1998 mass coral bleaching event, 29 ºC), present (current bleaching temperature, 31 ºC) and the future (IPCC predictions for 2050, 33 ºC), was carried out by exposing coral nubbins to different temperature stress for one week in 600L tanks with continuous seawater flow system. Results from PAM measurements showed that no significant stress response was found in 31 and 29 ºC treatment for both coral species. However, at 33 ºC treatment, nubbins of A. nana experienced high mortality with bleaching occurring sooner in coral nubbins from Wanlitong compared to those from the Outlet, which associated with more heat tolerant Symbiodiniaceae genus. Whereas, nubbins of P. lutea from both locations showed sign of bleaching without any mortality. Results of this study give insights on the species specific acclimatization and/or adaptation potential play an important role in response to the climate change induced seawater anomalies in the future, and some coral species might not survive in the future seawater anomalies even associated with heat tolerant Symbiodiniaceae genus.