Pollution status and trophic transfer of polycyclic aromatic hydrocarbons in coral reef ecosystems of the South China Sea

Coral reef ecosystems are important fishing grounds in tropical and subtropical areas and have been widely contaminated by chemicals. However, the current understanding of the pollution status and trophic transfer of exogenous chemicals in coral reef ecosystems is still limited. This study aims to characterize the occurrence of 16 priority polycyclic aromatic hydrocarbons (PAHs) in sediments, corals, and other biotas in the trophic-complex coral reef ecosystems in the Xisha and Nansha Islands of the South China Sea. PAH transfer characteristics in the highly diverse coral reef food webs were analyzed through stable isotope ratios and trophic magnification factors (TMFs). PAHs were observed in sediment and biota samples of both Xisha and Nansha coral reef ecosystems. The TMFs ranging from 0.46 to 2.18 for the Xisha food web indicate limited trophic transfer of PAHs, while those ranging from 1.07 to 5.25 for the Nansha food web indicate trophic magnification of PAHs. The octanol-water partition coefficient (Kow) of PAHs may positively influence the PAH biomagnification via accumulation along the trophic levels. This study provides new insights into PAH contamination patterns and their trophodynamic behaviour in highly diverse coral reef ecosystems, which can serve as a scientific basis for ecological risk assessment, biodiversity conservation, and coastal function management in global coral reef systems.