Journal Article

Biomonitoring selenium, mercury, and selenium:mercury molar ratios in selected species in Northeastern US estuaries: risk to biota and humans

Burger, Joanna, Gochfeld, Michael

2021

Overview

The mutual mitigation of selenium and mercury toxicity is particularly interesting, especially for humans. Mercury is widely recognized as a pantoxic element; all forms are toxic to all organisms. Less well known is that selenium in excess is toxic as well. The high affinity between these elements influences their bioavailability and toxicity. In this paper, we use selected species from Barnegat and Delaware Bays in New Jersey to examine variations in levels of selenium and mercury, and selenium:mercury molar ratios between and within species. We report on species ranging from horseshoe crab eggs ( Limulus polyphemus ), a keystone species of the food chain, to several fish species, to fish-eating birds. Sampling began in the 1970s for some species and in the 1990s for others. We found no clear time trends in mercury levels in horseshoe crab eggs, but selenium levels declined at first, then remained steady after the mid1990s. Concentrations of mercury and selenium in blood of migrant shorebirds directly reflected levels in horseshoe crab eggs (their food at stopover). Levels of mercury in eggs of common terns ( Sterna hirundo ) varied over time, and may have declined slightly since the mid2000s; selenium levels also varied temporally, and declined somewhat. There were variations in mercury and selenium levels in commercial, recreational, and subsistence fish as a function of species, season, and size (a surrogate for age). Selenium:mercury molar ratios also varied as a function of species, year, season, and size in fish. While mercury levels increased with size within individual fish species, selenium levels remained the same or declined. Thus selenium:mercury molar ratios declined with size in fish, reducing the potential of selenium to ameliorate mercury toxicity in consumers. Mercury levels in fish examined were higher in early summer and late fall, and lower in the summer, while selenium stayed relatively similar; thus selenium:mercury molar ratios were lower in early summer and late fall than in midsummer. We discuss the importance of temporal trends in biomonitoring projects, variations in levels of mercury, selenium, and the molar ratios as a function of several variables, and the influence of these on risks to predators and humans eating the fish, and the eggs of gulls, terns. Our data suggests that variability limits the utility of the selenium:mercury molar ratio for fish consumption advisories and for risk management.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Animals / Aquatic birds / Aquatic Pollution / Atmospheric Protection/Air Quality Control/Air Pollution / autumn / Bioaccumulation / Bioavailability / Biological Monitoring / Biomonitoring / Biota / blood / Crustaceans / Delaware / Earth and Environmental Science / Eating / Ecotoxicology / Eggs / Environment / Environmental Chemistry / Environmental Health / Environmental Monitoring / Environmental science / Estuaries / Fish / fish consumption / Fishes / food chain / Food chains / Health and Well Being: A Global pollution Problem / Humans / Impacts in Environmental Trends / Keystone species / Limulus polyphemus / Mathematical analysis / Mercury / Mercury (metal) / Mercury - analysis / New Jersey / Predators / Ratios / risk / Risk management / Selenium / Selenium - analysis / species / Sterna hirundo / Summer / Toxicity / Trends / Variation / Waste Water Technology / Water Management / Water Pollutants, Chemical - analysis / Water Pollution Control