Peculiar polycyclic aromatic hydrocarbons accumulation patterns in a non-zooxanthellate scleractinian coral

Assessing the sources and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) in corals is critical, as they threaten coral ecosystem resilience in addition to other anthropogenic pressures. We determined acenaphthene, fluorene, fluoranthene, and pyrene concentration in the skeleton and soft tissue of 7 adult and 29 old specimens of the non-zooxanthellate coral Leptopsammia pruvoti from the Mediterranean Sea. Leptopsammia pruvoti accumulated 2-72 times higher PAH concentrations than the previously investigated zooxanthellate Balanophyllia europaea living at the same site at shallower depth, likely in relation to the different trophic strategy. Low molecular weight PAHs were preferentially accumulated compared to high molecular weight PAHs. Detected PAHs were mainly petrogenic, consistently with local pollution sources. Populations of L. pruvoti immobilized PAHs in the skeleton 3-4 orders of magnitude more efficiently than B. europaea. This highlights the need to investigate other non-zooxanthellate species, which represent the majority of Mediterranean scleractinians, but are widely overlooked with respect to the few zooxanthellate species.