Floodplain methylmercury biomagnification factor higher than that of the contiguous river (South River, Virginia USA)

Inter‐ and Intraspecific Variation in Mercury Bioaccumulation by Snakes Inhabiting a Contaminated River Floodplain

“…Although aquatic species also had higher δ 15 N values, this difference was likely attributable to differences in baseline δ 15 N values between terrestrial and aquatic habitats (e.g., δ 15 N values of primary producers). Newman et al reported that δ 15 N values of aquatic periphyton and terrestrial producers at the South River differed by approximately 8 ‰, which corresponds well with the difference we observed (∼8 ‰) between aquatic and terrestrial snakes. Thus, after correcting for differences in baseline δ 15 N values, trophic levels of terrestrial and aquatic snakes were similar (Fig.…”

“…The results of the present study also indicate that body size and diet are key factors influencing Hg accumulation in snakes, but that sex differences are not significant after accounting for body size. Finally, by examining multiple snake species with different habitat and feeding ecologies at a single site, we show that aquatic snakes are exposed to the highest levels of Hg bioaccumulation, presumably as a result of feeding on aquatic prey, which tend to have higher Hg concentrations than terrestrial prey at the South River [31]. Our results provide information critical for understanding which snake species, guilds, or demographic groups may be at highest risk of Hg exposure at the South River or other aquatic sites contaminated with Hg.…”

“…4A). In conjunction with a positive correlation between d 15 N and THg values, these data suggest that, as a watersnake grows, it is exposed to increasing levels of Hg bioaccumulation through consumption of larger and/or higher trophic-level prey, such as centrarchid fish or catfish, which can have elevated Hg concentrations compared with smaller species, such as minnows [30,31,[40][41][42]. Although the present study was not designed to comprehensively evaluate diet, our anecdotal observations support this conclusion.…”

“…Within the aquatic species, trophic position appears to be a strong driver of Hg bioaccumulation. The slightly higher THg concentrations and d 15 N values of watersnakes, relative to queen snakes, reflected the relative isotopic and Hg composition of their primary prey, fish and crayfish, respectively [18,31]. Within the more terrestrial species, however, garter snakes had substantially higher mean THg concentrations (1.28 mg/kg) than rat snakes (0.26 mg/kg; Fig.…”

Effect of laying sequence on egg mercury in captive zebra finches: An interpretation considering individual variation

“…Marine birds and some waterfowl, as top predators with direct exposure to aquatic mercury sources, are commonly used to evaluate mercury bioavailability [4][5][6][7][8]. Recent studies have also found evidence of high methylmercury bioaccumulation in a terrestrial food web adjacent to a contaminated river [9,10]. Consequently, more attention is now being paid to terrestrial ecosystems.…”