Cold tolerance of subtropical Porites lutea from the northernSouth China Sea

• Published in: 海洋学报：英文版 Vol. 35; no. 12; pp. 58 - 64
• Main Author: CHEN Tianran LI Shu SHI Qi CHEN Tegu
• Format: Journal Article
• Language: English
• Published: 2016
• Subjects: China; cold; coral; low-temperature; lutea; northern; Porites; Sea; South; stress; subtropical; tolerance
• ISSN: 0253-505X; 1869-1099

Marginal scleractinian corals growing at their latitudinal limits should be quite sensitive to variations in wintersea surface temperatures （SSTs）. An extreme cold event occurring in early 2008 offered a unique opportunityto examine the effect of cold-water anomalies on Porites lutea corals and their physiological tolerance andacclimation in the subtropical northern South China Sea （NSCS）. Besides in-situ observation, a subsequentaquarium-based experiment was designed for reproducing the chilling process and a 50-year-long Sr/Ca ratioprofile from two P. lutea skeletal slabs was analyzed for reconstructed the historical annual minimum SSTswhich ceased Porites calcification. The 2008 low-temperature anomaly caused the minimum daily mean SSTsdropped below 13℃ in the Daya Bay. The stress symptoms displayed by local P. lutea colonies included polypretraction, reduced coloration and pale, but none showed tissue sloughing. The ability of P. lutea to surviveimplied its tolerance of extreme low temperatures. Here we suggest a model on the tolerance of high-latitudePorites under low-temperature stresses, which is when SSTs drop below 18℃, Porites corals contract theirtentacles （losing heterotrophic capability）, then cease calcification （reducing energy consumption）, andmeanwhile maintain relatively high levels of zooxanthellae density （sustaining host＇s life via photosyntheticcapacity of symbiotic zooxanthellae）. This study revealed remarkable acclimatization of P. lutea corals to lowtemperature extremes. This acclimatization is beneficial for Porites corals in the NSCS to expand their livingranges towards the higher-latitude areas and have the potential to be the incipient reef former.