Effects of metabolic overload and detoxification paralysis mechanisms of PAHs on the physiological immunity of large yellow croaker

With the continuous development of China's shipbuilding and maritime industries, increasing amounts of volatile polycyclic aromatic hydrocarbons (PAHs) are being released into marine ecosystems, posing serious ecological and health risks to marine organisms. As one of the most important mariculture species in China, the large yellow croaker is highly vulnerable to PAHs exposure, with aquaculture production reaching 280,997 tons in 2024. Studies have shown significant bioaccumulation of PAHs in nearshore-farmed large yellow croaker, with concentrations in both ambient water and muscle tissue approximately 3.6 times higher than those in far sea (FS) environments. Multi-omics analyses revealed that PAHs exposure suppressed the PPAR signaling pathway in the liver, disrupting lipid metabolism regulation. However, the upregulation of fatty acid β-oxidation represents a compensatory dysregulation process, leading to adverse effects such as excessive generation of reactive oxygen species (ROS), lipid peroxidation, and inflammatory responses. Concurrently, intestinal metabolomics identified depletion of glutathione, resulting in a several-fold increase in CYP450-mediated toxic intermediates. These metabolites further induced gut microbiota dysbiosis, characterized by reduced abundance of beneficial bacterial phyla. Collectively, these effects contribute to systemic oxidative stress, manifested as decreased antioxidant enzyme activities and elevated levels of ROS and malondialdehyde (MDA). These findings elucidate a "metabolic disorder-detoxification paralysis" cascade, whereby PAHs disrupt redox homeostasis via interactions along the hepatointestinal axis. This study provides critical insights into species-specific responses to environmental pollutants and strongly recommends that coastal cities implement zoning regulations to separate aquaculture areas from port zones, thereby mitigating the devastating impact of PAHs and similar pollutants on the aquaculture industry.