Recent status of total mercury and methyl mercury in the coastal waters of the northern Gulf of Mexico using oysters and sediments from NOAA's mussel watch program.

The current status of mercury concentrations in the Gulf of Mexico (GOM) were assessed using the Mussel Watch Program (MWP) contaminant monitoring data, which is based on the analysis of oyster tissue and sediment samples. In both matrices, tHg and MeHg concentrations varied broadly. Significant concentration differences (p<0.05) between the sub-regions of the eastern, central and western Gulf were observed with maximum concentrations (hotspots) found at specific sites all across the Gulf. Compared to the Food and Drug Administration's action level in seafood, maximum mercury values were low. Based on the long-term MWP data, tHg in tissues show fairly static temporal trends along the central and western Gulf coast, while strong decreasing trends were observed in the eastern Gulf. However, the presence of mercury hotspots indicates that mercury is still a concern in the GOM. The results complement existing information to further the understanding of mercury distributions in the GOM. Published by Elsevier Ltd.