Intergeneric Differences in Trophic Status of Scleractinian Corals From Weizhou Island, Northern South China Sea: Implication for Their Different Environmental Stress Tolerance

Abstract

AbstractThe knowledges of trophic status (i.e., autotrophy/heterotrophy) of corals are helpful for understanding the mechanisms driving their environmental stress tolerance and bleaching resilience. We conducted this study to elucidate the differences in trophic status among corals of different genera and then explore the implication of trophic status for their different environmental stress tolerance. In this study, 117 coral samples including five genera (i.e., relatively stress‐tolerant massive genera Porites, Favites, and Favia and relatively vulnerable plating genus Pavona and branching genus Acropora) were collected from Weizhou Island, northern South China Sea. The symbiotic zooxanthellae density, δ13C of host tissues (δ13Ch), and symbiotic zooxanthellae (δ13Cz) were measured. Besides, the difference in values between δ13Ch and δ13Cz (i.e., △h‐z 13C) was analyzed. Our results indicated that both zooxanthellae density and δ13Cz values of Porites, Favites, and Favia are higher than that of Pavona and Acropora and indicate that autotrophic photosynthesis intensity of symbiotic zooxanthellae of Porites, Favites, and Favia is higher than that of Pavona and Acropora. Besides, both δ13Ch and △h‐z 13C of Porites, Favites, and Favia are lower than that of Pavona and Acropora and indicate a higher contribution of heterotrophic predation to the coral host of Porites, Favites, and Favia. These comparisons suggest that trophic status of relatively stress‐tolerant Porites, Favites, and Favia is more plasticity than vulnerable Pavona and Acropora, which is conducive to maintain a positive energy budget. This is one of important factors leading to different environmental stress tolerance and bleaching resilience among corals of different genera.