Comparison of toxic effects of phenanthrene and perfluorooctane sulfonate on Chinese tongue sole Cynoglossus semilaevis larva in a muti-biomarker approach.

Phenanthrene (Phe) and perfluorooctane sulfonate (PFOS) are among the most frequently detected contaminants in the coastal environment of China. However, comparative studies on the toxic effects of these two chemicals in fish are limited. This study examined biomarker responses in Chinese tongue sole (Cynoglossus semilaevis) larvae exposed to sublethal Phe/PFOS (10 and 100 μg/L) for 7 days. The results showed that both Phe and PFOS significantly altered antioxidant indexes, such as activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and the detoxification metabolic parameters including glutathione S-transferase (GST) and glutathione (GSH). Both Phe and PFOS affected the activity of acetylcholinesterase (AchE) and the expression of androgen receptor gene (AR), and estrogen receptor genes (ERα and ERβ). PFOS significantly upregulated AR expression, with levels reaching 2.4-fold that of the control group, whereas AR gene expression was significantly suppressed under Phe exposure. Both PFOS and Phe upregulated the expression of ERα and ERβ genes. The ERα gene expression was 9.17-fold higher in the 100 μg/L PFOS group and 1.88-fold higher in the 100 μg/L Phe group compared to the control. The integrated biomarker response (IBRv2) index revealed that high concentration of PFOS was more toxic than Phe at the initial stage of exposure. Principal component analysis (PCA) further confirmed the distinct separation between the control and high concentration treatment groups, highlighting the immunotoxic and reproductive toxic effects of Phe and PFOS. These findings underscore the importance of monitoring and regulating the environmental presence of these pollutants to protect aquatic life.