Polycyclic aromatic hydrocarbons (PAHs) in corals of the South China Sea: Occurrence, distribution, bioaccumulation, and considerable role of coral mucus.

Coral reefs have suffered degradation from climate change and water quality deterioration. Studies have shown that PAHs are present widely in some coastal seawater and coral tissues. However, no studies have focused on the PAHs in coastal coral mucus and offshore coral tissues. Targeting the South China Sea, this study for the first time investigated the occurrence, tissue-mucus partitioning, and bioaccumulation of PAHs in coastal and offshore corals. The tissue and mucus of the corals were processed separately. The results indicated that the total concentration of 15 of the 16 PAHs that are prioritized by U.S. EPA (excluding naphthalene) (∑PAHs) was significantly higher in the coastal tissues (173 ± 314 ng g dw) than in the offshore tissues (71 ± 109 ng g dw), as well as in coastal seawater (196 ± 96 ng L) than in the offshore water (54 ± 9 ng L). ∑PAHs is two orders of magnitude higher in the mucus (3200 ± 6470 ng g dw) than in the tissues (128 ± 43 ng g dw). By average, 29% of ∑PAHs were accumulated in the mucus. The results suggest that mucus plays an important role in the bioaccumulation of PAHs by corals from ambient seawater.