Screening‐level risk assessment of methylmercury for non‐anadromous Arctic char (Salvelinus alpinus)

Abstract

Non‐anadromous forms of Arctic char (Salvelinus alpinus), those that are restricted to lakes and rivers, typically have higher mercury (Hg) concentrations than anadromous forms, which migrate to and from the sea. Using tissue burden data from the literature and our own analyses, we performed a screening‐level risk assessment of methylmercury (MeHg) for non‐anadromous Arctic char. Our assessment included 1569 fish distributed across 83 sites. Site‐specific mean total Hg concentrations in non‐anadromous Arctic char muscle varied considerably from 0.01 to 1.13 µg/g wet weight, with 21% (17 of 83 sites) meeting or exceeding a threshold‐effect level in fish of 0.33 µg/g wet weight, and 13% (11 of 83 sites) meeting or exceeding a threshold‐effect level in fish of 0.5 µg/g wet weight. Of the sites in exceedance of the 0.33‐µg/g threshold, 7 were located in Greenland and 10 in Canada (Labrador, Nunavut, and Yukon). All but one of these sites were located in interfrost or permafrost biomes. Maximum total Hg concentrations exceeded 0.33 µg/g wet weight at 53% of sites (40 of the 75 sites with available maximum Hg values), and exceeded 0.5 µg/g wet weight at 27% (20 of 75 sites). Collectively, these results indicate that certain populations of non‐anadromous Arctic char located mainly in interfrost and permafrost regions may be at risk for MeHg toxicity. This approach provides a simple statistical assessment of MeHg risk to non‐anadromous Arctic char, and does not indicate actual effects. We highlight the need for studies that evaluate the potential toxic effects of MeHg in non‐anadromous Arctic char, as well as those that aid in the development of a MeHg toxic‐effect threshold specific to this species of fish. Environ Toxicol Chem 2019;38:489–502. © 2018 SETAC

Dried Blood Spot Sampling of Landlocked Arctic Char (Salvelinus alpinus) for Estimating Mercury Exposure and Stable Carbon Isotope Fingerprinting of Essential Amino Acids

“…Notably, THg in blood, muscle, liver, and brain of landlocked Arctic char is present almost exclusively as MeHg (Lescord et al 2015; Basu 2017), demonstrating that THg is an excellent proxy for more costly MeHg analyses. Though we sampled only 8 populations for the present study, the range in mean muscle [THg] was similar to that reported for 83 nonanadromous populations of Arctic char (Barst et al 2019). As a result, we suggest that DBS can be used to estimate [THg] in muscle, liver, and brains of Arctic char (by using the linear regression equations herein) with a high level of confidence across a wide range of [THg].…”

“…The remaining lakes (Small, Meretta, Resolute, North, Char, and Amituk) are located on Cornwallis Island, Nunavut (Figure 1). Arctic char from these lakes have been sampled as part of past contaminant monitoring efforts, and mean muscle [THg] are known to span a wide range across the populations (Barst et al 2019). We present details of sample collection sites and the numbers of landlocked Arctic char captured from each lake in Supplemental Data, Table S1.…”

“…Sampling of certain landlocked Arctic char populations for the purpose of monitoring the spatial and temporal patterns of contaminants began in the Canadian High Arctic in the early 1990s (Muir et al 2005; Hudelson et al 2019). These long‐term data sets, and others like them, indicate that mean muscle total Hg concentrations ([THg]) in resident and landlocked Arctic char vary greatly among populations (approximately 0.01–1 µg/g wet wt; Barst et al 2019). The drivers of this variation are the topic of ongoing research and may involve differences in Hg inputs, Hg methylation rates, water chemistries, and/or food‐web relationships among aquatic systems (Lescord et al 2015; Chételat et al 2015, 2017; Hudelson et al 2019).…”

“…Landlocked Arctic char ( Salvelinus alpinus ) has been identified as an ecological health bioindicator of Hg contamination for the Arctic (Evers et al 2016; Barst et al 2019). This top predator fish is an excellent sentinel for Hg contamination in the Arctic because it is often the only fish inhabiting arctic lakes, has a circumpolar distribution, is long‐lived, and is sensitive to environmental change (Power et al 2012).…”

Temporal trends, lake-to-lake variation, and climate effects on Arctic char (Salvelinus alpinus) mercury concentrations from six High Arctic lakes in Nunavut, Canada

“…Non-migratory, or landlocked Arctic char (Salvelinus alpinus) are excellent biomonitors for freshwater ecosystems in the Arctic, because they are long-lived aquatic top predators, remain in a single ecosystem, are sensitive to environmental changes, and are a minor but dependable food source for some Arctic communities (Power et al, 2012, Barst et al, 2018.…”