Experimental Response Of Reef-Building Coral Symbiotic System In Weizhou Island To Abnormalous Temperature Stress

Under the background of global warming,global corals have suffered a large-scale degradation of losing symbiodinium(Coral Bleaching).The response characteristics of coral symbiosis to abnormal temperature vary with different objects,species and regions,and the mechanism is remains unclear.In this study,four scleractinian corals form Weizhou Island(Acropora cytherea?Echinophyllia aspera?Favites halicora and Pavona minuta)were subjected to acute temperature stress through laboratory simulation experiments,the changes of key symbiotic microbial communities and the analysis of differential metabolites of corals host in response to thermal stress(TS)and cold stress(CS)were investigated from three micro-aspects.80 DNA coral samples and 6 metabolic samples were obtained from temperature stress experiments,and 16S rRNA and ITS2 high-throughput sequencing techniques were used to investigate and analyze symbiotic bacteria and symbiodinium in the samples,in order to compare the diversity of coral symbiosis and its community structure at different temperatures;At the same time,the differential metabolites of host corals at different temperatures were analyzed by LC-MS technique,and the metabolic changes of coral hosts under temperature stress were explored.Results expressed:(1)Among the four corals,F.halicora was the most tolerant and A.Cytherea the worst.Analysis of the diversity of coral symbiotic bacteria showed that the higher the diversity of symbiotic bacteria in healthy corals,the better their tolerance to abnormal temperatures is.At the same time,coral tolerance is also affected by the stability of coral symbiotic bacteria community.(2)The types of symbiodinium have great influence on coral tolerance,subclade-C1 is the most dominant symbiodinium within the four coral species in Weizhou Island,but F.halicora with clade-D is more tolerant to high temperature,but short-term abnormal temperature stress has little effect on the structure of the main group of symbiodinium.(3)Coral hosts have similar stress responses to abnormal temperatures(TS and CS),secreting anti-inflammatory metabolites to repair damaged cells,but corals under TS secrete more anti-inflammatory metabolites than CS,this indicates that the stress effect under high temperature stress is stronger than that under low temperature.(4)When the coral symbiotic system is subjected to temperature stress,Symbiodinium mainly affects the tolerance of coral species to abnormal temperature stress,the symbiotic bacterial community mainly affects the tolerance of coral to two kinds of temperature stresses(TS and CS).the bacterial components,symbiodinium and coral hosts of coral symbiosis are all restoring functions while responding to stress,restoring the life activities of the coral symbiotic system together,the three components are a unified whole,mutually beneficial symbiosis and interaction.