Chronic LDPE microplastic ingestion: oxidative stress and mutagenicity in reef fish Stegastes fuscus

Plastic waste is a global concern, with annual plastic production expected to surpass 600 megatons by 2030 if current trends persist. Despite being produced on land, most plastic and microplastics (MP) debris ultimately accumulates in aquatic environments, where reef ecosystems are particularly vulnerable. Here, we investigated the consequences of chronic Low-Density Polyethylene (LDPE) MPs ingestion by the damselfish Stegastes fuscus, a key reef species that shapes habitat structure and community dynamics. Fish were fed a diet containing 1 % (w/w) spherical LDPE-MPs (4-6 μm) (n = 12) or plain food (control, n = 12) for 4 months. Behavioural endpoints (locomotion and aggressiveness) were) unaffected by LPDE-MPs. However, MP ingestion increased the frequency of nuclear abnormalities in erythrocytes, and elevated reactive oxygen species (ROS) levels as well as superoxide dismutase (SOD) and catalase (CAT) activity in brain. Our results indicated that chronic ingestion of LDPE-MPs induces genotoxicity and oxidative stress in S. fuscus. These findings underscore that chronic LDPE-MP ingestion directly threatens the survival and welfare of reef fish, with potential cascading effects on reef ecosystem stability. In nature, MPs can adsorb additional contaminants, further amplifying the toxic effects, disrupting reef fish population and ecosystem balance. Thus, urgent strategies to reduce marine plastic pollution are critical to safeguarding coral reef ecosystems.