Heatmap for the basal level of hsps in two congeneric oyster species under ambient field conditions. Asterisks indicate significant difference between species at each habitat (Ca_QD versus Cg_QD, Ca_XM versus Cg_XM; *0.05 < p < 0.01, **p < 0.01). Ca, C. angulata; Cg, C. gigas; QD, Qingdao; XM, Xiamen. (Online version in colour.)