Polycyclic Aromatic Hydrocarbons (PAHs) On The Coral Reef Regions:Distribution Characteristics And Ecotoxicological Effects

Coral reefs are of extremely high ecological value in tropical and subtropical coastal zones worldwide.In last years,corals have experienced the heavy degeneration continuously.Apart from temperature and ocean acidification,marine pollution is also the important factor which affects the health of corals,resulting in coral bleaching.Here,the levels of 16 US EPA PAHs were investigated in corals,ambient seawater and sediments of Hainan Island,using Gas Chromatography-Mass Spectrometer(GC-MS).Then,A.formosa and A.nasutain were exposed to B[a]P,oxidative stress and functional gene expression levels were measured together to study and compare their different responses,providing scientific data for the ecological risk assessment and breeding of environmental tolerant corals.1.The total PAHs(?PAHs)concentrations ranged from 273.79 to 407.82 ng·L-1 in seawater.Besides,the concentrations of ?PAHs in corals(333.88 to 727.03 ng·g-1 dw)were markedly(p<0.05)higher than ambient sediments(67.29 to 196.99 ng·g-1 dw),demonstrating the bioaccumulation ability of PAHs by corals.The highest concentration of ?PAHs was detected at site S2 in Pavona decussate,which also bore the highest ?PAHs levels in both seawater and sediments2.Although LMW PAHs were predominant and accounted for 69.27%to 80.46%of the ?PAHs in corals and ambient environment,the levels of HMW PAHs in corals also demonstrated potential danger for corals and organisms around coral reefs.The massive corals are easily enriched in PAHs than branching corals,and there are obvious differences of compositional characteristics and sources of PAHs in corals.The sources of PAHs are mainly petroleum pollutant and combustion in seawater and sediments,PAHs in corals maybe bioaccumulate through pathways like absorbing from seawater,symbiosis and feeding habitats.3.The SOD activity and Hsp90 gene indicated their potential as biomarkers to monitor the health of corals.Comparing the gene expression levels of Acropora spp.,the P-gp gene are more sensitive in A.formosa whereas the Hsp70 gene was more sensitive in A.nasutain.There are different response mechanisms of Acropora spp.,A.formosa is more sensitive than A.nasutain exposure to B[a]P.