Quantitative Shotgun Proteomics Associates Molecular-Level Cadmium Toxicity Responses with Compromised Growth and Reproduction in a Marine Copepod under Multigenerational Exposure.

In this study, the copepod Tigriopus japonicus was exposed to different cadmium (Cd) treatments (0, 2.5, 5, 10, and 50 μg/L in seawater) for five generations (F0-F4), followed by a two-generation (F5-F6) recovery period in clean seawater. Six life-history traits (survival, developmental time of nauplius phase, developmental time to maturation, number of clutches, number of nauplii/clutch, and fecundity) were examined for each generation. Metal accumulation was also analyzed for generations F0-F6. Additionally, proteome profiling was performed for the control and 50 μg/L Cd-treated F4 copepods. In F0-F4 copepods, Cd accumulated in a concentration-dependent manner, prolonging the development of the nauplius phase and maturation and reducing the number of nauplii/clutch and fecundity. However, during F5-F6, Cd accumulation decreased rapidly, and significant but subtle effects on growth and reproduction were observed only for the highest metal treatment at F5. Proteomic analysis revealed that Cd treatment had several toxic effects including depressed nutrient absorption, dysfunction in cellular redox homeostasis and metabolism, and oxidative stress, resulting in growth retardation and reproduction limitation in this copepod species. Taken together, our results demonstrate the relationship between molecular toxicity responses and population-level adverse outcomes in T. japonicus under multigenerational Cd exposure.