Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs

Martin Tsz-Ki Tsui; Songnian Liu; Rebecka L. Brasso; Joel D. Blum; Sae Yun Kwon; Yener Ulus; Yabing H. Nollet; Steven J. Balogh; Sue L. Eggert; Jacques C. Finlay

doi:10.1021/acs.est.8b06053

Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs

Martin Tsz-Ki Tsui, Songnian Liu, Rebecka L. Brasso, Joel D. Blum, Sae Yun Kwon, Yener Ulus, Yabing H. Nollet, Steven J. Balogh, Sue L. Eggert, Jacques C. Finlay

Ecology, Evolution and Behavior

Research output: Contribution to journal › Article › peer-review

39 Scopus citations

Abstract

Compared to the extensive research on aquatic ecosystems, very little is known about the sources and trophic transfer of methylmercury (MeHg) in terrestrial ecosystems. In this study, we examine energy flow and trophic structure using stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios, respectively, and MeHg levels in basal resources and terrestrial invertebrates from four temperate forest ecosystems. We show that MeHg levels in biota increased significantly (p < 0.01) with δ¹³C and δ¹⁵N at all sites, implying the importance of both microbially processed diets (with increased δ¹³C) and trophic level (with increased δ¹⁵N) at which organisms feed, on MeHg levels in forest floor biota. The trophic magnification slopes of MeHg (defined as the slope of log₁₀MeHg vs δ¹⁵N) for these forest floor food webs (0.20-0.28) were not significantly different (p > 0.05) from those observed for diverse temperate freshwater systems (0.24 ± 0.07; n = 78), demonstrating for the first time the nearly equivalent efficiencies with which MeHg moves up the food chain in these contrasting ecosystem types. Our results suggest that in situ production of MeHg within the forest floor and efficient biomagnification both elevate MeHg levels in carnivorous invertebrates in temperate forests, which can contribute to significant bioaccumulation of this neurotoxin in terrestrial apex predators.

Original language	English (US)
Pages (from-to)	2434-2440
Number of pages	7
Journal	Environmental Science and Technology
Volume	53
Issue number	5
DOIs	https://doi.org/10.1021/acs.est.8b06053
State	Published - Mar 5 2019

Bibliographical note

Funding Information:
This study was supported by a National Science Foundation award to M.T.K.T. (DEB-1354811) and J.D.B. (DEB-1353850), and funding from the University of North Carolina at Greensboro and the University of Michigan. We thank G. Woerndle, P. Blum, J. Alva, and G. Rios-Sotelo for assisting sample collection in the field. We appreciate the constructive comments from two anonymous reviewers. We also acknowledge the logistical support of research field stations for this study, including Angelo Coast Range Reserve, University of Michigan Biological Station, Hubbard Brook Ecosystem Study, and Coweeta LTER.

Publisher Copyright:
© 2019 American Chemical Society.

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title = "Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs",

abstract = "Compared to the extensive research on aquatic ecosystems, very little is known about the sources and trophic transfer of methylmercury (MeHg) in terrestrial ecosystems. In this study, we examine energy flow and trophic structure using stable carbon (δ13C) and nitrogen (δ15N) isotope ratios, respectively, and MeHg levels in basal resources and terrestrial invertebrates from four temperate forest ecosystems. We show that MeHg levels in biota increased significantly (p < 0.01) with δ13C and δ15N at all sites, implying the importance of both microbially processed diets (with increased δ13C) and trophic level (with increased δ15N) at which organisms feed, on MeHg levels in forest floor biota. The trophic magnification slopes of MeHg (defined as the slope of log10MeHg vs δ15N) for these forest floor food webs (0.20-0.28) were not significantly different (p > 0.05) from those observed for diverse temperate freshwater systems (0.24 ± 0.07; n = 78), demonstrating for the first time the nearly equivalent efficiencies with which MeHg moves up the food chain in these contrasting ecosystem types. Our results suggest that in situ production of MeHg within the forest floor and efficient biomagnification both elevate MeHg levels in carnivorous invertebrates in temperate forests, which can contribute to significant bioaccumulation of this neurotoxin in terrestrial apex predators.",

author = "{Tsz-Ki Tsui}, Martin and Songnian Liu and Brasso, {Rebecka L.} and Blum, {Joel D.} and Kwon, {Sae Yun} and Yener Ulus and Nollet, {Yabing H.} and Balogh, {Steven J.} and Eggert, {Sue L.} and Finlay, {Jacques C.}",

note = "Funding Information: This study was supported by a National Science Foundation award to M.T.K.T. (DEB-1354811) and J.D.B. (DEB-1353850), and funding from the University of North Carolina at Greensboro and the University of Michigan. We thank G. Woerndle, P. Blum, J. Alva, and G. Rios-Sotelo for assisting sample collection in the field. We appreciate the constructive comments from two anonymous reviewers. We also acknowledge the logistical support of research field stations for this study, including Angelo Coast Range Reserve, University of Michigan Biological Station, Hubbard Brook Ecosystem Study, and Coweeta LTER. Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

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AU - Finlay, Jacques C.

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Controls of Methylmercury Bioaccumulation in Forest Floor Food Webs

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