Dietary mercury exposure and bioaccumulation in amphibian larvae inhabiting Carolina bay wetlands

Unrine, Jason M.; Jagoe, Charles H.; Brinton, A.C.; Brant, Heather; Garvin, N.

doi:10.1016/j.envpol.2004.11.003

Cited by 23 publications

(23 citation statements)

References 12 publications

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“…Although tadpoles are omnivorous grazers, this observation is consistent with the literature that many pond-breeding larvae are excellent accumulators of trace metals because they are closely associated with the benthos [16,44]. Although many metals, including some Hg, may be bound to the gut epithelium in tadpoles [17,18], evidence suggests that Hg becomes mobilized during metamorphic climax and is retained in amphibian tissues after metamorphosis is completed [4,18]. After metamorphosis, B. americanus juveniles and adults are highly terrestrial and mobile [25].…”

Section: Amphibian Mercury Bioaccumulation and Nondestructive Indicessupporting

confidence: 88%

“…These characteristics also suggest that amphibians may have high rates of contaminant bioaccumulation compared with other animals of similar trophic positions. In addition, the complex life cycles of many amphibians potentially make them important in transferring contaminants from aquatic to terrestrial food chains [16,17], especially for Hg, because evidence suggests that most Hg accumulated by larvae is retained through metamorphosis [4,18].…”

Section: Introductionmentioning

confidence: 99%

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Mercury accumulation along a contamination gradient and nondestructive indices of bioaccumulation in amphibians

Bergeron

Bodinof

Unrine

et al. 2010

Enviro Toxic and Chemistry

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Mercury (Hg) is an important environmental contaminant due to its global distribution, tendency to bioaccumulate, and toxicity in wildlife. However, Hg has received little attention in amphibians compared to other vertebrates. Amphibians vary widely in life history strategies and feeding ecologies, which could influence Hg exposure and accumulation. To determine whether species and life stage affects Hg bioaccumulation, adults from three species (Plethodon cinereus, Eurycea bislineata, and Bufo americanus) and larvae from the latter two species were collected along a contamination gradient on the South River (VA, USA). Total Hg (THg) concentrations in the contaminated site were 3.5 to 22 times higher than in the reference site. Differences were found in THg concentrations in amphibians that were consistent with their habitat requirements and feeding preferences. In general, adults (3,453 +/- 196 ng/g, dry mass) and larvae (2,479 +/- 171 ng/g) of the most river-associated species, E. bislineata, had the highest THg concentrations, followed by B. americanus tadpoles (2,132 +/- 602 ng/g), whereas adults of the more terrestrial B. americanus (598 +/- 117 ng/g) and P. cinereus (583 +/- 178 ng/g) had the lowest concentrations. In addition, nondestructive sampling techniques were developed. For the salamander species, THg concentrations in tail tissue were strongly correlated (r>or= 0.97) with the remaining carcass. A strong positive correlation (r = 0.92) also existed between blood and whole-body THg concentrations in B. americanus. These results suggest that amphibians and their terrestrial predators may be at risk of Hg exposure in this system and that nondestructive methods may be a viable sampling alternative that reduces impacts to local populations.

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Section: Amphibian Mercury Bioaccumulation and Nondestructive Indicessupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Mercury accumulation along a contamination gradient and nondestructive indices of bioaccumulation in amphibians

Bergeron

Bodinof

Unrine

et al. 2010

Enviro Toxic and Chemistry

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“…American toad larvae collected from contaminated portions of the South River had THg tissue concentrations that averaged 2.1 mg/g (dry wt) at GS 28 to GS 32 [9]. In the present study, dietary Hg concentrations of 2.5 mg/g and 10.1 mg/g THg (dry wt) resulted in respective whole-body THg tissue concentrations that averaged 1.1 mg/g (dry wt) and 3.7 mg/g (dry wt) at GS 46, after the significant mass loss that occurs during metamorphosis [21,31,40]. In the companion study, recently metamorphosed toads that were raised individually rather than communally had whole-body THg tissue concentrations that averaged 0.8 mg/g (dry wt) and 1.7 mg/g (dry wt) for the low-Hg and high-Hg diets, respectively [11].…”

Section: Effects Of Maternal and Dietary Mercury In Amphibiansmentioning

confidence: 87%

“…The target total Hg (THg) concentration for the low-Hg treatment was 2.5 mg/g, dry weight (2.75% MeHg). This concentration corresponds to approximately twice the highest measured THg concentrations in the guts of larval southern leopard frogs (Rana sphenocephala) from ephemeral wetlands in the southeastern United States receiving Hg solely from atmospheric deposition [21]. The target THg concentration for the high-Hg treatment was 10 mg/g dry weight (1.05% MeHg (20 g) and gelatin (14 g) while stirring and heating the solution to approximately 708C on a hotplate.…”

Section: Experimental Dietmentioning

confidence: 98%

Aquatic and terrestrial stressors in amphibians: A test of the double jeopardy hypothesis based on maternally and trophically derived contaminants

Todd

Bergeron

Hepner

et al. 2011

Enviro Toxic and Chemistry

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Amphibians with biphasic life histories occupy aquatic and terrestrial habitats at different times in their lives, leading to a double jeopardy of contaminant risk in both habitats. The present study examines individual and interactive effects of mercury exposure to terrestrial adults and aquatic larvae on fitness-related traits of American toads, Bufo americanus. Eggs from reference mothers or contaminated mothers were allowed to hatch and larvae were fed diets of either no added Hg or 2.5 or 10 µg/g total Hg (dry wt). Both dietary and maternal Hg had adverse effects on developing larvae, but there was no interaction between these factors. Dietary Hg had a marginal effect of decreased survival with increasing Hg in the diet. Animals from Hg-exposed mothers weighed 14% less than those from reference mothers, and size at metamorphosis was directly correlated with hopping performance. Animals from Hg-exposed mothers also took longer to complete metamorphosis and had 2.5 times the prevalence of spinal malformations compared with those from reference mothers. Results of the present study demonstrate that amphibians do indeed face a double jeopardy of contaminant exposure stemming from terrestrial and aquatic environments, because both exposure pathways adversely affected developing offspring. The present study also demonstrates that all possible routes of exposure over an organism's life history must be examined to provide a comprehensive picture of the ecological consequences of habitat contamination.

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“…Southern leopard frog (Rana sphenocephala) tadpoles captured in wetlands near the Savannah River in South Carolina all had THg concentrations below the 0.2 ng/g (ww) detection limit (Burger and Snodgrass 2001). Unrine et al (2005) collected leopard frog tadpoles from different wetlands in the same general area as Burger and Snodgrass (2001), and reported that tadpole (minus gut content) THg concentrations ranged from 99 to 308 ng/g (dw). Bank et al (2007) reported THg concentrations (wet weight) of 19.1 ng/g for bullfrog (Lithobates catesbeiana) and 25.1 ng/g for green frog (Lithobates clamitans) tadpoles collected in Acadia National Park, Maine.…”

Section: Introductionmentioning

confidence: 98%

Mercury concentrations in wetlands associated with coal-fired power plants

2009

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There have been contradictory reports of the relative proportion of mercury from coal-fired power plants that deposits locally. Our objective was to determine any local effect of coal-fired power plants on total mercury concentrations in wetland sediment and tadpole samples. Four power plants and 45 wetlands were selected for study. Total mercury concentrations were determined in 75 sediment samples (range: 8-82 ng/g dry weight) and 100 bullfrog (Lithobates catesbeiana) and green frog (Lithobates clamitans) tadpoles (range: 5-318 ng/g wet weight). Tadpole and sediment total mercury did not significantly vary by power plant or distance from the plant. Only one power plant had a significantly greater concentration of total mercury in sediment downwind compared to upwind wetlands. A similar (but non-significant) trend was found for tadpole total mercury surrounding the same plant. Tadpole total mercury was negatively correlated with both tadpole weight and total length. Tadpole and sediment total mercury concentrations were not significantly correlated with one another. The results of the current study suggest that coal-fired power plants are not significantly affecting mercury concentrations in surrounding wetlands.

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Dietary mercury exposure and bioaccumulation in amphibian larvae inhabiting Carolina bay wetlands

Cited by 23 publications

References 12 publications

Mercury accumulation along a contamination gradient and nondestructive indices of bioaccumulation in amphibians

Mercury accumulation along a contamination gradient and nondestructive indices of bioaccumulation in amphibians

Aquatic and terrestrial stressors in amphibians: A test of the double jeopardy hypothesis based on maternally and trophically derived contaminants

Mercury concentrations in wetlands associated with coal-fired power plants

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