ABSTRACT

Global climate change has led to more frequent extreme temperature (extreme heat and cold) events, posing aserious threat to coral reef ecosystems. Higher latitudes are considered potential refuges for reef-building corals,but their response to extreme temperature stress in these regions remain unclear. This study, indoor simulatedstress experiments ranging on Porites lutea fromWeizhouIsland in the northern part of the South China Sea,simulating suitable (26℃) to extreme high (34℃) and extreme low (12℃) temperatures. Physiological,biochemical, and transcriptional responses, wereanalysed. Results showed P.lutea’stentacles contracted, andsymbiotic relationships broke down at both high and low temperatures; leading to oxidative stress, and a higherrisk of disease. The coral host’s response to temperature stress was positively regulated, mainly throughapoptosis and metabolic inhibition pathways, whereasSymbiodiniaceaeC15 showed no significant response toeither high- or low-temperature stress. The coral host played a dominant role in theholobiont’sstress response,using similar mechanisms for both high- and low-temperatures with some differences in the details. This studyenhances understanding the temperature response mechanisms of the dominant coral species, P. lutea in therelatively high-latitude regions of theSouth China Sea.