An assessment of temporal trends in mercury concentrations in fish

• Published in: Ecotoxicology (London) 2020-12, Vol.29 (10), p.1739-1749
• Main Authors: Grieb, Thomas M., Fisher, Nicholas S., Karimi, Roxanne, Levin, Leonard
• Format: Article
• Language: English
• Subjects: Analysis; Animal tissues; Anthropogenic factors; Aquatic resources; Atmospheric pollution deposition; Bioaccumulation; Climate change; Commercial fishing; Contaminants; Data collection; Deposition; Dimethylmercury; Earth and Environmental Science; Ecology; Ecotoxicology; Emissions; Emissions (Pollution); Emissions control; Environment; Environmental Management; Environmental monitoring; Environmental protection; Fish; Fish consumption; Fisheries; Fishery data; Food chains; Food contamination; Food webs; Fresh water; Freshwater; Freshwater fish; Freshwater fishes; Geographical distribution; Global temperature changes; Human influences; Hydrology; Identification; Indigenous species; Inland water environment; Introduced species; Lakes; Marine fish; Marine fisheries; Marine fishes; Mercury; Mercury (metal); Mercury atmosphere; Methylation; Methylmercury; Native organisms; Organic matter; Pollution monitoring; Rain; Rainfall; Rainfall intensity; Runoff; Seafood; Seafoods; Sediments; Sediments (Geology); Size distribution; Surface water; Tissue; Trends; Water level fluctuations; Water levels; Watersheds; Wet deposition
• ISSN: 0963-9292; 1573-3017
• DOI: 10.1007/s10646-019-02112-3

The importance of fish consumption as the primary pathway of human exposure to mercury and the establishment of fish consumption advisories to protect human health have led to large fish tissue monitoring programs worldwide. Data on fish tissue mercury concentrations collected by state, tribal, and provincial governments via contaminant monitoring programs have been compiled into large data bases by the U.S. Environmental Protection Agency’s Great Lakes National Monitoring Program Office (GLNPO), the Ontario Ministry of the Environment’s Fish Contaminants Monitoring and Surveillance Program (FMSP), and many others. These data have been used by a wide range of governmental and academic investigators worldwide to examine long-term and recent trends in fish tissue mercury concentrations. The largest component of the trend literature is for North American freshwater species important in recreational fisheries. This review of temporal trends in fish tissue mercury concentrations focused on published results from freshwater fisheries of North America as well as marine fisheries worldwide. Trends in fish tissue mercury concentrations in North American lakes with marked overall decreases were reported over the period 1972–2016. These trends are consistent with reported mercury emission declines as well as trends in wet deposition across the U.S. and Canada. More recently, a leveling-off in the rate of decreases or increases in fish tissue mercury concentrations has been reported. Increased emissions of mercury from global sources beginning between 1990 and 1995, despite a decrease in North American emissions, have been advanced as an explanation for the observed changes in fish tissue trends. In addition to increased atmospheric deposition, the other factors identified to explain the observed mercury increases in the affected fish species include a systematic shift in the food-web structure with the introduction of non-native species, creating a new or expanding role for sediments as a net source for mercury. The influences of climate change have also been identified as contributing factors, including considerations such as increases in temperature (resulting in metabolic changes and higher uptake rates of methylmercury), increased rainfall intensity and runoff (hydrologic export of organic matter carrying Hg II from watersheds to surface water), and water level fluctuations that alter either the methylation of mercury or the mobilization of monomethylmercury. The