Ye, Y.; Chen, K.; Zhou, Q.; Xiang, P.; Huo, Y., and Lin, M., 2018. Impacts of thermal discharge on phytoplankton in Daya Bay. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 135–147. Coconut Creek (Florida), ISSN 0749-0208.
A monthly survey on the species composition of phytoplankton was conducted at 14 stations in Yaling Bay, Dapeng Bay and the mouth of Daya Bay in 2016, and 4 stations were selected as main sections to analyze the effects of thermal discharge on the phytoplankton community structure. In this study, the 12 months in 2016 were divided into the high temperature period and the low temperature period with 25°C as the boundary. The results suggested that the response of phytoplankton to elevated water temperature was significantly different during different periods: during the high temperature period, algae proliferated, among which diatom was the dominant species; during the low temperature period, diatom was still the dominant species, but its abundance fell significantly. During the low temperature period, however, Phaeocystis globosa and Akashiwo sanguinea were dominant species, dinoflagellate was not the dominant species, but its abundance rose. During the high temperature period, the proportion of Chaetoceros spp. rose to above 60%. Mechanical loading, high temperature, high pressure and residual chlorine from the nuclear power plant might damage or kill some phytoplankton cells, so in the drainage outlet area, the abundance of phytoplankton was lower than that in other stations and the diversity index of phytoplankton species was low. Thermal discharge increased zooplankton biomass during the low temperature period, and the top-down effect led to a high mortality rate of edible phytoplankton, while non-edible phytoplankton became the dominant species in the community. Compared with historical surveys, from the trial operation of the Daya Bay Nuclear Power Plant to 2016, the water temperature difference between the core sea areas directly affected by thermal discharge and the rest of the areas became large first and then small, and the data showed that too high water temperature may reduce phytoplankton abundance and species diversity, while appropriately high water temperature may increase them.