LAUSR

Abstract Zhikong scallop (Chlamys farreri Jones et Preston 1904) is one of the most economically important shellfish in the aquaculture industry of China. Improving thermal tolerance of the scallop by breeding has become a critical task for the sustainable farming industry. The detection of the majority of the current indicators of the thermal tolerance of the scallop is generally short-term, low-throughput and laborious/time-consuming. In the present study, we first monitored variations in Arrhenius break temperature (ABT) with annually natural seawater temperature changes and found that ABT showed seasonal characteristics. Then, correlation analysis between ABT and survival rate in both scallop sexes was conducted, revealing that the correlation coefficient between |Δ ABT| and |Δ survival rate| of Zhikong scallops was relatively high and significant (r = 0.863, P = 0.050). Notably, a tremendous decrease in ABT and natural survival rate, and significant differences between scallop sexes were simultaneously observed in October. Further verification of reproductive cycle of Zhikong scallops with seasonal changes demonstrated that ABT could be applied for detecting seasonal and sexual differences of thermal tolerance in Zhikong scallops. Finally, correlation coefficients (r = −0.710, P = 0.001) between heart rate (HR) variations and the ultimate ABT values were further evaluated, representing the first report of the feasibility of HR at 11 °C to be an indirect indicator for thermal tolerance detection in Zhikong scallops (ABT = -0.427*HR11 °C + 33.159, R2 = 0.5028). Our results emphasize the importance of ABT in detecting seasonal and sexual differences of thermal tolerance in scallops and provide a valuable indicator detection method for developing breeding strategies for Zhikong scallops.