Investigating metabolomic alterations in caged Sinanodonta woodiana exposed to stream pollution

Agricultural runoff containing pesticides, herbicides, fertilizers, and other chemicals is a significant source of stream pollution, affecting water quality, aquatic organism health, and public safety. This study evaluated the metabolomic responses of the freshwater mussel Sinanodonta woodiana when exposed to pollution in the Winongo stream, Special Region of Yogyakarta, Indonesia. To simulate varying pollution conditions, mussels were transplanted to three stations along the stream for 28 days, representing lightly (S1), moderately (S3), and heavily polluted (S2) environments. The investigation focused on metabolomic responses, antioxidant enzyme activities (superoxide dismutase [SOD] and catalase [CAT]), and metallothionein (MT) concentrations in the gills of S. woodiana. Targeted metabolomic analysis successfully identified 15 amino acids, with principal component analysis (PCA) explaining 74.1 % of the total variance on day 3 and 65.2 % after 28 days. These findings highlight significant metabolic alterations related to pollution exposure. The trends observed in MT concentration and the activities of SOD and CAT reflect an adaptive response to pollution. MT levels increased significantly, peaking around day 14, especially at the most polluted station (S2), which indicates enhanced detoxification activity. After day 14, the decline in MT levels may suggest either environmental acclimatization or a reduction in pollutant levels. Similarly, SOD and CAT activities peaked around day 14 in response to oxidative stress induced by reactive oxygen species (ROS). Subsequently, they fluctuated, tending to decrease the intensity of pollution. Overall, the study demonstrates that pollution in the Winongo stream induces various toxicological effects on S. woodiana, providing valuable insights into the biological impacts of environmental contamination on freshwater organisms.