2017 Assessment of Legacy Organic Contaminants, Trace Metals, and Contaminants of Emerging Concern in the Gulf of Mexico

In 1986, the National Mussel Watch Program (MWP) was designed by the National Oceanic and Atmospheric Administration (NOAA) to monitor the Nation's coastal waters for chemical contaminants and biological indicators of water quality. The MWP is based on the periodic collection and analysis of bivalves (oysters and mussels) and sediment from a network of monitoring sites located throughout the Nation's coastal zones. Currently, five regions (Northeast, Southeast, Gulf of Mexico, West Coast, and Great Lakes) are sampled on a five-year rotation, with one region being sampled each year. In 2017, 60 historic MWP sites were surveyed in the Gulf of Mexico region across five states (Texas, Louisiana, Mississippi, Alabama, and Florida) in the northern Gulf of Mexico on the US coast. Out of those 60 sites, Crassostrea virginica were able to be collected and analyzed for a suite of chemical contaminants at 44 sites, with the remaining sites lacking sufficient populations despite being sampled historically. The chemical contaminants routinely monitored by the MWP include legacy contaminants (e.g., chlordanes, PAHs, PCBs, DDTs), trace metals (e.g., mercury, nickel, cadmium, lead, zinc, silver), and contaminants of emerging concern (e.g., alkylphenols, flame retardants, currently used pesticides, pharmaceuticals, PFAS). Results of these analyses are explored in a series of technical reports published by NOAA, National Center for Coastal and Ocean Science (NCCOS), Stressors and Detection Impacts (SDI) Division, and are summarized within these documents. These results include identification and discussion of the general presence and distribution of contaminants in bivalve tissues collected from the 44 sites collected in 2017 as well as data previously collected by the MWP to provide historical context. In general, the 2017 Gulf of Mexico survey results indicated the persistence of some groups of legacy contaminants in this region, the relatively low frequency of detection of contaminants of emerging concern compared to other regions of the country, and the local influences on metals and their overall gulf-wide trends. As a national program, the authors do not attempt to offer many direct explanations for the local trends and variations in the data, instead leaving that analysis to the managers and stakeholders that have a better understanding of the local dynamics and potential sources. Thus, the aim of these reports, and those published by the MWP, is to contextualize recent regional monitoring data in both time and space and to provide a perspective that may not be attainable at the local level. By doing so, we hope to support the allocation of resources and the ongoing studies and efforts necessary to manage coastal chemical contaminants nationwide. The MWP will be sampling in the Gulf of Mexico region in January of 2024 to continue the regional monitoring approach. The data collected from this future sampling effort will be combined and compared to the data analyzed within these reports that was collected in 2017. This upcoming sampling will provide a vital update to the data from the Gulf of Mexico region and will help to determine both the current presence and contamination levels of Gulf of Mexico oysters.