Survival and Developmental Responses of Acartia hudsonica Nauplii to Polystyrene Microplastics and Thermal Variation

Microplastics (MPs) are ubiquitous marine pollutants whose ecological impacts can be modulated by temperature. Temperature regulates copepod physiological responses in marine environments. Copepods can show stress responses at deviations from the optimal temperature range, particularly during early life stages. Naupliar stages are more sensitive to environmental stressors. This developmental stage can present population-level vulnerability. This study aimed to investigate the effects of MPs, temperature, and their interaction on the survival and development of Acartia hudsonica nauplii. This study investigated survival and development under nine experimental conditions via combining three MP concentrations (0, 100, and 10,000 μg/L) with three temperatures (15, 20, and 25 °C). The survival rate differed significantly among temperature treatments. The differences between MP exposure treatments were significant in terms of survival rate only at 15 °C. Stage-specific and cumulative developmental times were shortest at 20 °C. The final naupliar stage (NVI) attainment rate was significantly affected by both temperature and MP concentration. These results indicate that temperature is the dominant stressor for the naupliar stages of A. hudsonica. The effect of MPs was modulated by temperature, as the effect decreased under high-temperature conditions. Therefore, the ecological effects of MPs should be evaluated in terms of considering their interactions with temperature in aquatic environments.