Exposure to Oil-Associated Metals, As Documented in Otoliths, May be Detrimental to the Health of Gulf of Mexico Fishes

The incidence of external lesions on Gulf of Mexico (GoM) fishes increased just after the Deepwater Horizon (DWH) oil disaster and then declined, yet a lack of baseline data makes it difficult to definitively link cause and effect. Our objectives were to: (1) determine if fish were exposed to metals associated with the DWH oil during the time period of the oil spill, and (2) examine patterns of oil-associated metal exposure. Otoliths record both fish age and microchemistry, enabling us to describe the lifetime chemical histories of fish.  We analyzed otoliths from six offshore fish species collected from 2011 to 2013 in the GoM. Otoliths were analyzed for a suite of metals associated with DWH crude oil.  We found that the concentrations of oil-associated metals did not significantly change before, during, or after the DWH oil spill; however, metal exposure varied according to species-specific life history patterns.  Additionally, lesioned fish had elevated otolith ⁶⁰Ni and ⁶⁴Zn before and after the DWH oil disaster.  These findings suggest that lesioned individuals were exposed to a persistent source of metals in the GoM prior to the oil spill.