Thermal Tolerance of Crassostrea (Magallana) ariakensis to Nuclear Plant Warm Water Discharges.

Abstract

Nuclear power plants utilize great quantities of seawater to cool down, resulting in substantial warm water discharges that may affect nearby fisheries and marine ecosystems. This study focused on Crassostrea (Magallana) ariakensis, a commercially farmed oyster species along the southern coast of China. To evaluate the thermal impacts of warm water discharges from nuclear power plants, indoor simulations replicated seasonal water temperature conditions near coastal facilities (26 °C in spring and autumn, 16 °C in winter, and 30 °C in summer). We conducted thermal tolerance static and dynamic experiments, along with a 51-day long-term experiment on suitable growth under different acclimation temperatures. The thermal effects of warm water discharges on C. ariakensis were systematically assessed through survival, growth, digestibility, and nutritional quality. The results showed that the discomfort temperature range of C. ariakensis was (48.6 ± 1.2)~(58.9 ± 3.0) °C, the critical thermal maxima (CTM) value range of C. ariakensis was (51.6 ± 1.4)~(61.2 ± 2.2) °C, and the incipient lethal temperature (ILT₅₀) of C. ariakensis was 45.61 °C, 53.71 °C, and 55.90 °C, respectively; all these values increased gradually with the rise of acclimation temperature. After the 51-day long-term experiment on suitable growth, the temperature increase of 1 °C, 2 °C and 4 °C did not affect the soft tissue wet weight, condition index, moisture content, and fat content of C. ariakensis, but the amylase activity in digestive gland tissue decreased in different temperature experimental groups. The experimental results show that the influence of temperature rise on the growth and physiological metabolism of C. ariakensis is limited. However, based on the normal habitat temperature in summer, the long-term effects of temperature rise caused by warm water discharges need to be paid attention to.