Temperature and salinity are two of the most potent abiotic factors infl uencing marine mollusks.In this study,we investigated the individual and combined ef fects of temperature and salinity on the survival and growth of juvenile Pacifi c abalone,Haliotis discus hannai Ino,and also examined the DNA methylation alteration that may underpin the phenotypic variation of abalone exposed to dif ferent rearing conditions.The single-factor data showed that the suitable ranges of temperature and salinity were 16–28°C at a constant salinity of 32,and 24–40 at a constant temperature of 20°C,respectively.The two-factor data indicated that both survival and growth were signifi cantly af fected by temperature,salinity and their interaction.The optimal temperature-salinity combination for juveniles was 23–25°C and 30–36.To explore environment-induced DNA methylation alteration,the methylation-sensitive amplifi ed polymorphism(MSAP)technique was used to analyze the genomic methylation profi les of abalone reared in optimal and adverse conditions.Neither temperature nor salinity induced evident changes in the global methylation level,but 67 and 63 dif ferentially methylated loci were identifi ed in temperature and salinity treatments,respectively.The between-group eigen analysis also showed that both temperature and salinity could induce epigenetic dif ferentiation in H.discus hannai Ino.The results of our study provide optimal rearing conditions for juvenile H.discus hannai Ino,and represent the fi rst step toward revealing the epigenetic regulatory mechanism of abalone in response to thermal and salt stresses. Temperature and salinity are two of the most potent abiotic factors infl uencing marine mollusks. In this study, we investigated the individual and combined ef fects of temperature and salinity on the survival and growth of juvenile Pacifi c abalone, Haliotis discus hannai Ino, and also examined the DNA methylation alteration that may underpin the phenotypic variation of abalone exposed to dif ferent rearing conditions. The single-factor data showed that the suitable ranges of temperature and salinity were 16-28 ° C at a constant salinity of 32, and 24- 40 at a constant temperature of 20 ° C, respectively. Both two-factor data indicated that both survival and growth were signifi cantly af fected by temperature, salinity and their interaction. The optimal temperature-salinity combination for juveniles was 23-25 ​​° C and 30-36. To explore environment-induced DNA methylation alteration, the methylation-sensitive amplifi ed polymorphism (MSAP) technique was used to analyze the genomic methylation prof i les of abalone reared in optimal and adverse conditions. Neither temperature nor salinity induced evident changes in the global methylation level, but 67 and 63 dif ferentially methylated loci were identifi ed in temperature and salinity treatments, respectively. between the between-group eigen analysis also showed that both temperature and salinity could induce epigenetic dif ferentiation in H.discus hannai Ino.The results of our study provide optimal rearing conditions for juvenile H.discus hannai Ino, and represent the fi rst step toward revealing the epigenetic regulatory mechanism of abalone in response to thermal and salt stresses.