Effects of the nutritional quality of food on the reproduction of copepods in the vicinity of Daya Bay nuclear power plant.

Abstract

This study investigated the regulatory mechanisms of polyunsaturated fatty acids (PUFAs) and environmental factors on copepods reproductive success in thermally influenced waters of Daya Bay through seasonal in-situ experiments (2022-2023). Generalized additive models revealed that fatty acid composition was the strongest predictor of reproductive variability, explaining 75.7-91.7% of variance in weight-specific egg production, in-situ egg production (IEP), and egg hatching rate (EHR). Temperature (18.15-29.63 °C) was positively correlated with IEP but exhibited a unimodal relationship with EHR, peaking at 24 °C. Salinity (31.33-33.72) suppressed IEP linearly, while particulate organic nitrogen (3.67-57.03 μg L-1) enhanced both IEP and EHR; Chlorophyll a showed no significant effect. Among PUFAs, eicosapentaenoic acid (EPA) was strongly positively correlated with all reproductive metrics, whereas docosahexaenoic acid (DHA) showed consistent negative correlations, likely due to competitive prey interactions or dinoflagellate toxin exposure. The ω-6 PUFA Linoleic acid (LA) displayed metabolic antagonism with ω-3 PUFAs, showing a unimodal relationship with IEP and negative correlation with EHR. Stations proximal to the power plant exhibited elevated summer temperatures but reduced fatty acid concentrations, highlighting that PUFAs-driven food quality, rather than phytoplankton biomass, critically governs copepods population dynamics in anthropogenically pressured ecosystems.