What Can Measurements of Mercury Concentrations in Marine Fish Tell Us?
David Evans, NOAA/NCCOS/CCFHR - Beaufort Laboratory
22 Mar 2013
Seafood is the largest source of methylmercury exposure to much of the U. S. population. For this reason, most coastal states and some Federal agencies monitor the mercury concentrations of commercially and recreationally caught seafood In order to identify species or locales with potentially high levels. A single measurement of mercury in an individual fish can determine if that fish would contribute to an unacceptably elevated mercury exposure to a consumer. More is possible, however.
By measuring the mercury concentrations in multiple samples of different species of fish, of different sizes, from different locations, we can capture the variability in mercury concentrations and infer some of the underlying causes of higher or lower concentrations. Some of the inferences include:
What are the trophic levels, feeding habits, and life history attributes of fish with high or low mercury concentrations?
What habitats produce methylmercury from inorganic mercury that then finds its way into fish
Are there point sources or dispersed sources of mercury getting into fish?
Have mercury concentrations increased or decreased over time and what does this imply about our efforts to curb mercury pollution?
If we also measure the methylmercury concentration in the prey of fish (stomach contents), we can learn about fish bioenergetics, in particular about growth efficiency.
If we measure both methylmercury and total mercury or inorganic mercury in fish, we can infer the degree of detoxification of the former.
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