Aquaculture Reports (Aug 2024)
Effects of thermal stress from nuclear power plants on the survival rate, behavioral changes, and biochemical and molecular responses of abalone
Abstract
Global warming poses a significant threat to coastal ecosystems and aquaculture. Moreover, nuclear power plants (NPPs) also release excess thermal energy into the environment, contributing to rising seawater temperatures and exacerbating this threat. However, studies on the potential negative impacts of thermal pollution on mariculture are scarce, especially in field environments. Herein, a comparative investigation of hybrid abalone (Haliotis discus hannai ♀ × Haliotis fulgens ♂) under thermal stress was performed in laboratory and field to evaluate the potential ecological risks of NPP thermal discharge. The survival rate, behavioral changes, antioxidant enzyme activity, and transcriptional profiles of antioxidant-relevant genes were determined in hybrid abalones under thermal stress. Under a natural water temperature of 29 °C, an increase of 4 °C led to the death of all abalones. In the field study, a temperature increase of 2 °C resulted in the partial death of these abalones and a decrease in their adhesion capacity, which did not occur in laboratory. In addition, thermal stress caused considerable changes in the antioxidant enzyme activity in these abalones, including superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase, and malondialdehyde content. Moreover, transcriptional levels of sod, cat, and heat shock protein 70 genes were substantially induced in laboratory and field studies. The integrated biomarker responses version 2 (IBRv2) method was used to comprehensively assess the effects of thermal discharge on the abalones. The relationship between the IBRv2 values and thermal stress is not linear. These results provide valuable information for policy makers regarding the impacts of thermal discharge on marine aquaculture and the importance of establishing aquaculture safety zones near NPPs.
