Spatiotemporal trends in polychlorinated biphenyl concentrations in seafood based on long-term monitoring and remediation in New Bedford Harbor, Massachusetts

Electrical manufacturing near New Bedford Harbor (NBH), MA in the mid-1900s led to severe polychlorinated biphenyl (PCB) contamination, which resulted in the harbor’s designation as a Superfund Site. Restrictions on the harvest of seafood from NBH have been in effect since 1979. Efforts to reduce the overall mass of PCBs in NBH by dredging PCB-contaminated sediments have been ongoing since the late 1980s. One goal of dredging is to reduce PCB concentrations in NBH seafood, monitored annually by Massachusetts Department of Environmental Protection (DEP) and Massachusetts Division of Marine Fisheries (MDMF). We used PCB concentrations in quahogs (2003-2016) and scup (2003-2014) to evaluate PCB distribution across seafood management areas and over time. Seafood PCB concentrations were used to evaluate improvements in environmental quality by examining total PCBs and patterns of PCB congeners within homolog groups, and by assessing human cancer risk from seafood consumption in the past (1980) and present (2012-2016). PCB concentrations in quahogs generally declined with increased time and distance from the PCB source, as does the cancer risk associated with their consumption. PCB concentrations in scup follow similar spatial patterns but show high annual variability. We conclude that quahogs are a reliable proxy for in-situ conditions, environmental quality, and human health risk.

Evolutionary Toxicogenomics of the Striped Killifish (Fundulus majalis) in the New Bedford Harbor (Massachusetts, USA)

In this paper, we used a Genotyping-by-Sequencing (GBS) approach to find and genotype more than 4000 genome-wide SNPs (Single Nucleotide Polymorphisms) from striped killifish exposed to a variety of polychlorinated biphenyls (PCBs) and other aromatic pollutants in New Bedford Harbor (NBH, Massachusetts, USA). The aims of this study were to identify the genetic consequences of exposure to aquatic pollutants and detect genes that may be under selection. Low genetic diversity (HE and π) was found in the site exposed to the highest pollution level, but the pattern of genetic diversity did not match the pollution levels. Extensive connectivity was detected among sampling sites, which suggests that balanced gene flow may explain the lack of genetic variation in response to pollution levels. Tests for selection identified 539 candidate outliers, but many of the candidate outliers were not shared among tests. Differences among test results likely reflect different test assumptions and the complex pollutant mixture. Potentially, selectively important loci are associated with 151 SNPs, and enrichment analysis suggests a likely involvement of these genes with pollutants that occur in NBH. This result suggests that selective processes at genes targeted by pollutants may be occurring, even at a small geographical scale, and may allow the local striped killifish to resist the high pollution levels.