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

Todd, Brian D.; Bergeron, Christine M.; Hepner, Mark J.; Hopkins, William A.

doi:10.1002/etc.617

Cited by 31 publications

(31 citation statements)

References 40 publications

(72 reference statements)

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“…Reference and contaminated mothers had total Hg (THg) concentrations of 159.5 ± 18.6 (mean ± SE hereafter) and 2,250 ± 489.8 ng/g ww in their blood, respectively (Todd et al 2011b). Reference and contaminated eggs had THg concentrations of 20.6 ± 1.3 and 149.1 ± 17.9 ng/g dw, respectively (Todd et al 2011b). Soon after hatching, larvae were allotted to dietary treatments and fed either control diet (0.01 ± 0.001 lg/g dw THg) or a diet spiked with environmentally relevant concentrations and proportions of inorganic and methyl-Hg (10.1 ± 2.3 lg/g THg dw, 1.05% monomethyl-Hg), creating four experimental crosses: (1) reference mothercontrol larval diet, (2) reference mother-Hg larval diet, (3) Hg mother-control larval diet, (4) Hg mother-Hg larval diet.…”

Section: Experimental Designmentioning

confidence: 96%

“…Detailed methods and results of the earlier study on larvae are reported in Todd et al (2011b). Briefly, we acquired larvae from clutches of eggs from toads collected in either contaminated or uncontaminated portions of the South River floodplain near Waynesboro, VA, USA (Todd et al 2011b). Reference and contaminated mothers had total Hg (THg) concentrations of 159.5 ± 18.6 (mean ± SE hereafter) and 2,250 ± 489.8 ng/g ww in their blood, respectively (Todd et al 2011b).…”

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

“…Soon after hatching, larvae were allotted to dietary treatments and fed either control diet (0.01 ± 0.001 lg/g dw THg) or a diet spiked with environmentally relevant concentrations and proportions of inorganic and methyl-Hg (10.1 ± 2.3 lg/g THg dw, 1.05% monomethyl-Hg), creating four experimental crosses: (1) reference mothercontrol larval diet, (2) reference mother-Hg larval diet, (3) Hg mother-control larval diet, (4) Hg mother-Hg larval diet. For more information on larval diet, see Bergeron et al (2011) or Todd et al (2011b. We drew animals haphazardly during the peak of metamorphosis for placement into terrestrial enclosures (''pens'').…”

Section: Experimental Designmentioning

confidence: 99%

“…Briefly, we acquired larvae from clutches of eggs from toads collected in either contaminated or uncontaminated portions of the South River floodplain near Waynesboro, VA, USA (Todd et al 2011b). Reference and contaminated mothers had total Hg (THg) concentrations of 159.5 ± 18.6 (mean ± SE hereafter) and 2,250 ± 489.8 ng/g ww in their blood, respectively (Todd et al 2011b). Reference and contaminated eggs had THg concentrations of 20.6 ± 1.3 and 149.1 ± 17.9 ng/g dw, respectively (Todd et al 2011b).…”

Section: Experimental Designmentioning

confidence: 99%

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Do effects of mercury in larval amphibians persist after metamorphosis?

et al. 2011

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Despite widespread concern about the role of environmental contaminants in global amphibian declines, and evidence that post-metamorphic life stages contribute disproportionately to amphibian population dynamics, most studies in amphibian ecotoxicology focus on larval life stages. Studies that focus solely on early life stages may miss important effects of contaminant exposure, such as latent effects that manifest some time after previous exposure. Moreover, it is often assumed that effects observed in amphibian larvae will persist to affect survival or reproduction later in life. We used terrestrial enclosures to determine whether exposure to mercury (Hg) through maternal transfer and/or larval diet had any adverse effects in post-metamorphic American toads (Bufo americanus). We found a 5% difference in size at metamorphosis that was attributed to maternal Hg exposure persisted for 1 year in the terrestrial environment, resulting in a 7% difference at the conclusion of the study. Although patterns of survival differed among treatments through time, we found no overall difference in survival after 1 year. We also found no evidence of emergent latent effects in the terrestrial toads that could be attributed to earlier exposure. Our results indicate that adverse effects of maternal Hg exposure that were observed in larval amphibians may persist to affect later terrestrial life stages but that no novel adverse effects developed when animals were raised in a semi-natural environment. Moreover, we found no evidence of persistent effects of dietary Hg exposure in larvae, highlighting a need for greater focus on maternal effects in amphibian ecotoxicology. Finally, we suggest an increase in the use of longitudinal studies to better understand contaminant impacts to amphibian populations via effects in both aquatic and terrestrial life stages.

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Section: Experimental Designmentioning

confidence: 96%

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

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Do effects of mercury in larval amphibians persist after metamorphosis?

et al. 2011

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Sublethal effects on wood frogs chronically exposed to environmentally relevant concentrations of two neonicotinoid insecticides

Robinson

Richardson

Dalton

et al. 2017

Enviro Toxic and Chemistry

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Neonicotinoids are prophylactically used globally on a variety of crops, and there is concern for the potential impacts of neonicotinoids on aquatic ecosystems. The intensive use of pesticides on crops has been identified as a contributor to population declines of amphibians, but currently little is known regarding the sublethal effects of chronic neonicotinoid exposure on amphibians. The objective of the present study was to characterize the sublethal effect(s) of exposure to 3 environmentally relevant concentrations (1 mg/L, 10 mg/L, and 100 mg/L) of 2 neonicotinoids on larval wood frogs (Lithobates sylvaticus) using outdoor mesocosms. We exposed tadpoles to solutions of 2 commercial formulations containing imidacloprid and thiamethoxam, and assessed survival, growth, and development. Exposure to imidacloprid at 10 mg/L and 100 mg/L increased survival and delayed completion of metamorphosis compared with controls. Exposure to thiamethoxam did not influence amphibian responses. There was no significant effect of any treatment on body mass or size of the metamorphs. The results suggest that current usage of imidacloprid and thiamethoxam does not pose a threat to wood frogs. However, further assessment of both direct and indirect effects on subtle sublethal endpoints, and the influence of multiple interacting stressors at various life stages, is needed to fully understand the effects of neonicotinoids on amphibians.

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