Effects of water accommodated fractions (WAFs) of crude oil in two congeneric copepods Tigriopus sp.

Oil pollution has deleterious effects on marine ecosystems. However, the toxicity of crude oil towards Antarctic marine organisms has not been well studied. We compared the deleterious effects of water accommodated fractions (WAFs) of crude oil on reproduction, intracellular reactive oxygen species (ROS) levels, and antioxidant enzymatic activity in Antarctic (Tigriopus kingsejongensis) and temperate (Tigriopus japonicus) copepods. Reproductive rates of T. kingsejongensis and T. japonicus were significantly reduced (P < 0.05) in response to WAFs. Furthermore, T. kingsejongensis showed elevated levels of ROS and higher antioxidant enzyme (glutathione peroxidase [GPx]) activity than T. japonicus in response to WAFs. CYP genes from congeneric copepods were identified and annotated to better understand molecular detoxification mechanisms. We observed significant up-regulation (P < 0.05) of Tk-CYP3024A3 and Tj-CYP3024A2 in response to WAFs, suggesting that CYP genes may contribute to the detoxification mechanism in response to WAF exposure. These finding also suggest that WAFs may induce oxidative stress, leading to reproductive impairment in copepods. Furthermore, Tk-CYP3024A3 and Tj-CYP3024A2 genes can be considered as potential biomarkers of WAF toxicity in the congeneric copepods T. kingsejongensis and T. japonicus. This study will be helpful for enhancing our knowledge on the harmful effects of WAFs in Antarctic and temperate copepods and provides insight into the underlying molecular mechanisms.