Antioxidative responses in the skin mucus of Periophthalmodon schlosseri as biomarkers for the assessment of heavy metal pollution in the coastal wetlands of Kuala Lupak estuary of the Barito River

Abstract

Abstract. One of the main factors that concern the well-being of estuarine water ecosystems is heavy metal pollution by anthropogenic activities. Heavy metals can cause oxidative stress in fish by increasing the formation of reactive oxygen species (ROS) and, thus, directly disrupt the antioxidant defense system. This article aimed to determine the responses of antioxidant enzymes in the skin mucus of Periophthalmodon schlosseri as a biomarker of oxidative stress. P. schlosseri or the giant mudskipper is a typical fauna of the contaminated Barito River estuary. The study showed that the activity of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) was higher in the skin mucus of the mudskipper from estuary waters compared to that from coastal waters, while the level of H2O2 was lower. According to in silico studies, heavy metals can act as activators for binding Nrf2-KEAP1, causing antioxidant expression to be disrupted. The activity of antioxidant enzymes such as SOD, CAT, and GSH-Px in P. schlosseri skin mucus has the potential to be used as an oxidative stress biomarker in non-invasive biomonitoring assessment of heavy metal pollution in estuaries. The giant mudskipper has the potential to be a sentinel species and a sensitive bioindicator in monitoring/assessing heavy metal pollution in estuaries for ecotoxicological studies in polluted water bodies.