Potential impact of rising seawater temperature on copepods due to coastal power plants in subtropical areas

The major objective of this study is to understand the upper thermal limits and potential impact of temperature elevation on copepods caused by coastal power plants. Laboratory experiments were designed to evaluate the upper incipient lethal temperature (UILT) and critical thermal maximum (CTMax) of eight coastal copepod species collected from a subtropical bay in spring and summer. The 48h-UILT of copepods acclimatized at 16.0, 20.0, 28.0 °C were 26.4-29.1, 27.3-30.1, 32.9-36.9 °C, respectively. And the CTMax of copepods acclimatized at 28.0 °C was 35.80-41.03 °C. The UILT of copepods increased significantly with rising acclimatization temperatures, but the difference values between UILT and acclimatization temperatures decreased, which indicated that the seawater temperature elevation induced the growing mortalities of copepods with increasing natural seawater temperatures from the thermal addition of power plants. The results also showed that estuarine copepods had more tolerances to the thermal stress than those from other more stable marine environments. As to the calanoid copepod species, there was a significant negative correlation between the CTMax and body length (p < 0.01). So it seemed that the copepod species with large body size were more sensitive to the thermal addition than the smaller ones. Thus, owing to the temperature increase, the copepod species diversity might reduce and the composition of copepod communities might tend to be small-sized in natural sea areas close to the coastal power plants.