Abstract:In recent years, global warming and the release of hot wastewater from nuclear power plants have caused the temperature of sea water to rise, leading to severe thermal pollution of the oceans. Marine ecosystems and the survival of marine life face huge challenges from ocean warming. Research on the thermal tolerance of marine organisms will help us to understand the heat tolerance of different marine species and determine how to control thermal discharge from nuclear power plants. This study investigated the heat tolerance of four marine species (Chaeturichthys stigmatias, Sebastes schlegeli, Oratosquilla oratoria, and Charybdis japonica) in Liaodong Bay using a dynamic temperature-rising test. The lethal temperature of 50% (LT50) was assessed at five acclimation temperatures (8.0℃, 14.0℃, 18.0℃, 24.0℃, 28.0℃) and nine temperature-rising rates (0.5, 1.0, 2.0, 3.0, 4.0, 6.0, 9.0, 12.0, 15.0℃/h) to evaluate heat tolerance. The results showed that both the acclimation temperature and temperature-rising rate significantly affected the LT50 value of the experimental animals (P<0.05). The LT50 values were significantly positively correlated with the acclimation temperature (P<0.05), while the effects of the temperature-rising rate varied with acclimation temperature in a species-dependent manner. In this study, the dynamic temperature-rising test included a higher number of acclimation temperatures and temperature-rising rates than used in previous studies, and we established the LT50 value as an important indicator for evaluating the heat tolerance of marine species. These results suggest that as an evaluated index, LT50 comprehensively reflects the heat tolerance of experimental species, which is of scientific and ecological significance and could be widely used in the assessment of heat tolerance.
