Ecotoxicology of mercury concentrations in arctic lamprey (Lethenteron camtschaticum).

Arctic lamprey (Lethenteron camtschaticum) is an important dietary resource for rural and indigenous communities in parts of Alaska, with some commercial use. As with many fish species harvested for human consumption, there are concerns regarding mercury concentrations ([Hg]) in Arctic lamprey that may impact human health. To date, information regarding the life cycle and diet of Arctic lamprey is scarce, with no published studies examining [Hg] in Arctic lamprey tissues. Our goals were to investigate the feeding ecology of Arctic lamprey from the Bering Sea, determine how diet and potential dietary shifts might influence [Hg] in muscle, and determine if current [Hg] may pose a human health risk. The mean total [Hg] in Arctic lamprey muscle (n = 98) was 19 ng/g wet-weight. Log transformed total [Hg] were not associated with any measured biological variables including length, mass, δ13C values, or δ15N values. A stable isotope mixing model estimated that capelin (Mallotus villosus) accounted for 40.0 ± 4.0% of the Arctic lamprey diet, while Pacific sand lance (Ammodytes hexapterus) and Pacific herring (Clupea pallasii) accounted for 37.8 ± 3.1% and 22.2 ± 3.5% respectively. Finally, diet percentage compositions shifted based on size class (i.e., medium versus large). These results indicated that feeding location, bioaccumulation, and biomagnification are not important drivers of [Hg] in Arctic lamprey and current [Hg] do not pose a human health risk. Taken together, this research further expands our knowledge of Arctic lamprey trophic ecology in the eastern Bering Sea.

Ecological drivers of mercury concentrations in fish species in subsistence harvests from Kotzebue Sound, Alaska.

The State of Alaska assesses human exposure to mercury (Hg) via fish consumption producing consumption guidelines for fish tailored for children and women of childbearing age. Under these guidelines, unrestricted consumption is suggested for many fish species, while limited consumption is recommended for others. Subsequent questions have arisen regarding ecological drivers influencing [Hg] in fishes consumed by Alaskans. This community-assisted public health study evaluates [Hg] in fishes from Kotzebue Sound to examine factors that may drive observed [Hg]. We examined eight species of subsistence harvested fish (least cisco, chum salmon, Pacific herring, humpback whitefish, sheefish, starry flounder, Pacific tomcod, and fourhorn sculpin) from Kotzebue Sound. We report total Hg concentrations ([THg]) and monomethyl Hg+ concentrations ([MeHg+]) in the context of various factors (such as species, fork length, carbon and nitrogen stable isotope (δ15N or δ13C)) values that may influence [Hg] and [MeHg+]. Across all 297 fish, [THg] ranged from 3.4 - 235.2 ng/g ww. [THg] was positively correlated with fork length in six of eight fish species, as well as with trophic level (indicated by δ15N values) in five species. [MeHg+] was positively correlated with fork length in four species, and with δ15N values over all specimens examined, and specifically for three individual species. In six of the seven species analyzed, %MeHg was >80% of [THg]. This value decreased with fork length in three species, with no relationship for δ15N values in any species. Among top ranked models based on Akaike Information Criterion correction (AICc), fork length was more frequently included as an explanatory factor for [Hg] than δ15N or δ13C values. The food web magnification factor for [THg] was 11.3, and 12.6 for [MeHg+]. Biomagnification is likely driving [THg] and [MeHg+] over the entire food web, while within species, bioaccumulation is likely a stronger driver of [THg] and [MeHg+] than feeding ecology or trophic position. The [THg] for all species fell within the established unrestricted consumption guideline of 200 ng/g weight wet as established by the State of Alaska's fish consumption guidelines for Hg.