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Zabala J, Rodríguez-Jorquera I, Trexler JC, Orzechowski S, Garner L, Frederick P. Accounting for food availability reveals contaminant-induced breeding impairment, food-modulated contaminant effects, and endpoint-specificity of exposure indicators in free ranging avian populations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 791:148322. [PMID: 34412380 DOI: 10.1016/j.scitotenv.2021.148322] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/30/2021] [Accepted: 06/04/2021] [Indexed: 06/13/2023]
Abstract
It remains unclear how sub-lethal effects of contaminants play out in relation to other stressors encountered by free-ranging populations. Effects may be masked or influenced by interactions with field stressors such as food availability. We predicted that (1) including food availability, and particularly its interaction with Hg, would reveal or enhance associations between Hg and breeding endpoints. We further predicted that (2) breeding impairment associated with Hg would be higher under food stress conditions. We monitored Hg and nest success of great egrets (Ardea alba) in eight breeding colonies in the Florida Everglades over 11 years. We characterized variation in local food availability among colonies and years using fish biomass and recession range -a proxy to fish vulnerability. We used two Hg exposure indicators (egg albumen Hg and nestling feather Hg) and six breeding endpoints (clutch-size, brood-size, fledged-size, hatching success, post-hatching success and fledglings per egg) to assess whether variation in food availability influenced associations between Hg and these endpoints. Accounting for interactions between Hg and food availability, we identified statistically significant associations in all 12 indicator-endpoint combinations, while only three were detectable without food. Further, 10 combinations showed interactions between Hg and components of food availability. Our results also indicated an endpoint-specific affinity, with albumen [Hg] explaining more variation in hatching success while nestling feather [Hg] explained more variation in post-hatching survival. Both Hg indicators accounted for relevant (6-10%) amounts of variation in fledglings produced per egg laid, an integrative endpoint. Increased Hg exposure resulted in overall reduced reproductive success when food availability was low, but our models predicted low or no effects of increasing Hg exposure when food availability was high. Our results indicate that Hg induced impairment is strongly driven by food availability, providing a framework that accommodates previously contradictory results in the literature.
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Affiliation(s)
- Jabi Zabala
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA; Department of Zoology and Animal Cell Biology, University of the Basque Country, UPV/EHU, C/Paseo de la Universidad 7, 01006 Vitoria-Gasteiz, Araba, Basque Country, Spain.
| | - Ignacio Rodríguez-Jorquera
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA; Centro de Humedales Río Cruces (CEHUM), Universidad Austral de Chile, Valdivia, Chile
| | - Joel C Trexler
- Department of Biological Sciences, Florida International University, Miami, FL, USA; Coastal & Marine laboratory, Florida State University, St. Teresa, FL, USA
| | - Sophie Orzechowski
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
| | - Lindsey Garner
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
| | - Peter Frederick
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
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Jackson AK, Eagles-Smith CA, Emery C. Spatial variation in aquatic invertebrate and riparian songbird mercury exposure across a river-reservoir system with a legacy of mercury contamination. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1195-1204. [PMID: 31056730 DOI: 10.1007/s10646-019-02043-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Mercury (Hg) loading and methylation in aquatic systems causes a variety of deleterious effects for fish and wildlife populations. Relatively little research has focused on Hg movement into riparian food webs and how this is modulated by habitat characteristics. This study characterized differences in Hg exposure in aquatic invertebrates and riparian songbirds across a large portion of the Willamette River system in western Oregon, starting at a Hg-contaminated Superfund site in the headwaters (Black Butte Hg Mine) and including a reservoir known to methylate Hg (Cottage Grove Reservoir), all downstream reaches (Coast Fork and Willamette River) and off-channel wetland complexes (Willamette Valley National Wildlife Refuge Complex). After accounting for year, date, and site differences in a mixed effects model, MeHg concentrations in aquatic invertebrates varied spatially among habitat categories and invertebrate orders. Similarly, THg in songbird blood varied by among habitat categories and bird species. The highest Hg concentrations occurred near the Hg mine, but Hg did not decline linearly with distance from the source of contamination. Birds were consistently elevated in Hg in habitats commonly associated with enhanced MeHg production, such as backwater or wetlands. We found a positive but weak correlation between aquatic invertebrate MeHg concentrations and songbird THg concentrations on a site-specific basis. Our findings suggest that Hg risk to riparian songbirds can extend beyond point-source contaminated areas, highlighting the importance of assessing exposure in surrounding habitats where methylmercury production may be elevated, such as reservoirs and wetlands.
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Affiliation(s)
- Allyson K Jackson
- Department of Environmental Studies, Purchase College SUNY, 735 Anderson Hill Road, Purchase, NY, 10577, USA.
- Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Colleen Emery
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
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Heddle C, Elliott JE, Brown TM, Eng ML, Perkins M, Basu N, Williams TD. Continuous exposure to mercury during embryogenesis and chick development affects later survival and reproduction of zebra finch (Taeniopygia guttata). ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1117-1127. [PMID: 31352572 DOI: 10.1007/s10646-019-02074-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/21/2019] [Indexed: 06/10/2023]
Abstract
Methylmercury (MeHg) is a global environmental contaminant that bioaccumulates and has multiple toxic modes of action. Aquatic species have traditionally been the focus of wildlife toxicological research on mercury, but terrestrial organisms, including passerine birds, can be exposed to similarly elevated levels of MeHg. In this study we exposed a model passerine, the zebra finch (Taeniopygia guttata), to MeHg in ovo, as chicks only, or with a combined 'in ovo + chick' treatment. We isolated exposure to specific developmental stages through the use of egg injections (3.2 µg Hg/g egg) and controlled oral dosing of chicks (0.24 µg Hg/g bw/day from day 1 to day 30). In ovo exposure to MeHg reduced hatching success, but there was no effect of MeHg on chick growth. We found that in ovo only or chick only exposure did not have long-term effects, but there was some evidence for longer-term effects of combined 'in ovo + chick' exposure on post-fledging survival and potentially sex-biased survival which resulted in very few 'in ovo + chick' exposed females surviving to breed. These females also had lower overall breeding productivity that was mainly due to lower hatching success of their offspring, not lower chick-rearing success. We found no effect of treatment on clutch size or latency to laying among females that did lay eggs. Our study suggests that combined embryonic and nestling MeHg exposure has compounding latent effects on productivity, likely through a mechanism that influences the ability of females to lay fertile eggs that hatch.
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Affiliation(s)
- Cybele Heddle
- Biological Sciences, Simon Fraser University, Biological Sciences, Burnaby, BC, V5A 1S6, Canada
| | - John E Elliott
- Biological Sciences, Simon Fraser University, Biological Sciences, Burnaby, BC, V5A 1S6, Canada.
- Environment and Climate Change Canada, Ecotoxicology and Wildlife Health Directorate, Delta, BC, V4K 3N2, Canada.
| | - Tanya M Brown
- Biological Sciences, Simon Fraser University, Biological Sciences, Burnaby, BC, V5A 1S6, Canada
| | - Margaret L Eng
- Biological Sciences, Simon Fraser University, Biological Sciences, Burnaby, BC, V5A 1S6, Canada
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3, Canada
| | - Marie Perkins
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, H9X 3V9, Canada
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, H9X 3V9, Canada
| | - Tony D Williams
- Biological Sciences, Simon Fraser University, Biological Sciences, Burnaby, BC, V5A 1S6, Canada
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Zabala J, Rodriguez-Jorquera IA, Orzechowski SC, Frederick P. Mercury Concentration in Nestling Feathers Better Predicts Individual Reproductive Success than Egg or Nestling Blood in a Piscivorous Bird. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:1150-1156. [PMID: 30626179 DOI: 10.1021/acs.est.8b05424] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Piscivorous birds are at high risk of mercury exposure in aquatic food webs, and their reproductive success is sensitive to methylmercury exposure. Although effects are convincingly shown in a handful of lab studies, sublethal effects at environmentally relevant concentrations in the field, where there is a range of other natural stressors, are not well delineated. Part of that uncertainty arises because mercury concentration (hereafter, [Hg]) in adult tissues used to assess Hg risk can be influenced by Hg values in wintering grounds or other nonrelated areas. Several studies have used nestling tissues under the assumption that they better represent local risk to breeding since nestlings consume locally derived food. However, the correlation between [Hg] in nestling tissues and local breeding success remains unassessed. We analyzed great egret ( Ardea alba) breeding parameters collected over 3 years (2015-2017) in the Everglades (Florida, USA). The Everglades is a large contiguous wetland with geographically dispersed wading bird breeding sites exposed to variable and biologically relevant ranges of mercury concentrations. We examined mercury concentrations in albumen and nestling blood and feathers as predictors of 6 measures of reproductive success at individual nests. Albumen [Hg] did not correlate with reproductive end points, and correlations with blood [Hg] were weak. Feather [Hg] correlated negatively with all of the posthatching endpoints and explained 8.3% of the variance in the probability of a laid egg resulting in a fledged chick. However, most of the observed failures were hatching failures, which were not explained by albumen [Hg], and other nestling tissues could therefore not be evaluated. While our results support the use of nestling feathers as indicators of site-specific mercury exposure, we discuss both advantages and possible limitations of using nestling feathers as indicators of local mercury exposure.
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Affiliation(s)
- Jabi Zabala
- Department of Wildlife Ecology and Conservation , University of Florida , Gainesville , Florida 32611 , United States
| | - Ignacio A Rodriguez-Jorquera
- Department of Wildlife Ecology and Conservation , University of Florida , Gainesville , Florida 32611 , United States
- Centro de Humedales Río Cruces (CEHUM) , Universidad Austral de Chile , Valdivia , Chile
| | - Sophia C Orzechowski
- Department of Wildlife Ecology and Conservation , University of Florida , Gainesville , Florida 32611 , United States
| | - Peter Frederick
- Department of Wildlife Ecology and Conservation , University of Florida , Gainesville , Florida 32611 , United States
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Eagles-Smith CA, Silbergeld EK, Basu N, Bustamante P, Diaz-Barriga F, Hopkins WA, Kidd KA, Nyland JF. Modulators of mercury risk to wildlife and humans in the context of rapid global change. AMBIO 2018; 47:170-197. [PMID: 29388128 PMCID: PMC5794686 DOI: 10.1007/s13280-017-1011-x] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Environmental mercury (Hg) contamination is an urgent global health threat. The complexity of Hg in the environment can hinder accurate determination of ecological and human health risks, particularly within the context of the rapid global changes that are altering many ecological processes, socioeconomic patterns, and other factors like infectious disease incidence, which can affect Hg exposures and health outcomes. However, the success of global Hg-reduction efforts depends on accurate assessments of their effectiveness in reducing health risks. In this paper, we examine the role that key extrinsic and intrinsic drivers play on several aspects of Hg risk to humans and organisms in the environment. We do so within three key domains of ecological and human health risk. First, we examine how extrinsic global change drivers influence pathways of Hg bioaccumulation and biomagnification through food webs. Next, we describe how extrinsic socioeconomic drivers at a global scale, and intrinsic individual-level drivers, influence human Hg exposure. Finally, we address how the adverse health effects of Hg in humans and wildlife are modulated by a range of extrinsic and intrinsic drivers within the context of rapid global change. Incorporating components of these three domains into research and monitoring will facilitate a more holistic understanding of how ecological and societal drivers interact to influence Hg health risks.
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Affiliation(s)
| | - Ellen K. Silbergeld
- Johns Hopkin Bloomberg School of Public Health, 615 N. Wolfe Street, E6644, Baltimore, MD 21205 USA
| | - Niladri Basu
- McGill University, 204-CINE Building, Montreal, QC H9X 3V9 Canada
| | - Paco Bustamante
- University of La Rochelle, laboratory of Littoral Environment and Societies, Littoral Environnement et Sociétés (LIENSs), LIENSs UMR 7266 CNRS-Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France
| | - Fernando Diaz-Barriga
- Center for Applied Research in Environment and Health at, Universidad Autonoma de San Luis Potosi, Avenida Venustiano Carranza No. 2405, Col Lomas los Filtros Código Postal, 78214 San Luis Potosí, SLP Mexico
| | - William A. Hopkins
- Department of Fish and Wildlife Conservation, 310 West Campus Drive Virginia Tech, Cheatham Hall, Room 106 (MC 0321), Blacksburg, VA 24061 USA
| | - Karen A. Kidd
- Department of Biology & School of Geography and Earth Sciences, McMaster University, 1280 Main Street W., Hamilton, ON L8S 4K1 Canada
| | - Jennifer F. Nyland
- Department of Biological Sciences, 1101 Camden Ave, Salisbury, MD 21801 USA
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Finger JW, Botero J, Zhang Y, Still SE, Hoffman AJ, Kavazis AN, Cristol DA, Wada H. No Effect of Lifelong Methylmercury Exposure on Oxidative Status in Zebra Finches (Taeniopygia guttata): A Demonstration of Methylmercury-Induced Selection? BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2017; 99:668-672. [PMID: 29080113 DOI: 10.1007/s00128-017-2202-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/25/2017] [Indexed: 06/07/2023]
Abstract
Songbirds exposed to methylmercury (MeHg) often exhibit reduced reproductive success and cognitive abilities. To better understand whether oxidative stress plays a role, we dosed zebra finches (Taeniopygia guttata) with a contaminated (1.2 ppm MeHg-cysteine) or control diet for their entire lives, including during development in the egg. Levels of antioxidant enzymes [superoxide dismutase (SOD1 and SOD2)], oxidative damage (4-hydroxynonenal; 4-HNE), and antioxidant transcription factors [nuclear factor (erythroid-derived 2)-like 2; Nrf2] were measured in the liver and pectoralis muscle of adults. MeHg treatment did not affect levels of 4-HNE or liver SOD2 or Nrf2. Birds in the MeHg treatment differed significantly from controls in pectoralis SOD1 and Nrf2, and tended to differ in liver SOD1 and pectoralis SOD2; however, we detected no overall pattern of effect of MeHg on oxidative status in dosed finches. We suspect that this is a consequence of the differential survival of MeHg-tolerant birds.
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Affiliation(s)
- John W Finger
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - Juan Botero
- Department of Biology, College of William & Mary, Williamsburg, VA, 23185, USA
| | - Yufeng Zhang
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Shelby E Still
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Alexander J Hoffman
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | | | - Daniel A Cristol
- Department of Biology, College of William & Mary, Williamsburg, VA, 23185, USA
| | - Haruka Wada
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
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Peterson EK, Buchwalter DB, Kerby JL, LeFauve MK, Varian-Ramos CW, Swaddle JP. Integrative behavioral ecotoxicology: bringing together fields to establish new insight to behavioral ecology, toxicology, and conservation. Curr Zool 2017; 63:185-194. [PMID: 29491976 PMCID: PMC5804166 DOI: 10.1093/cz/zox010] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 02/08/2017] [Indexed: 12/31/2022] Open
Abstract
The fields of behavioral ecology, conservation science, and environmental toxicology individually aim to protect and manage the conservation of wildlife in response to anthropogenic stressors, including widespread anthropogenic pollution. Although great emphasis in the field of toxicology has been placed on understanding how single pollutants affect survival, a comprehensive, interdisciplinary approach that includes behavioral ecology is essential to address how anthropogenic compounds are a risk for the survival of species and populations in an increasingly polluted world. We provide an integrative framework for behavioral ecotoxicology using Tinbergen’s four postulates (causation and mechanism, development and ontogeny, function and fitness, and evolutionary history and phylogenetic patterns). The aims of this review are: 1) to promote an integrative view and re-define the field of integrative behavioral ecotoxicology; 2) to demonstrate how studying ecotoxicology can promote behavior research; and 3) to identify areas of behavioral ecotoxicology that require further attention to promote the integration and growth of the field.
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Affiliation(s)
- Elizabeth K Peterson
- Department of Biological Sciences, State University of New York-Albany, Albany, NY 12222, USA
| | - David B Buchwalter
- Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Jacob L Kerby
- Department of Biology, University of South Dakota, Vermillion, SD 57069, USA
| | - Matthew K LeFauve
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA
| | | | - John P Swaddle
- Biology Department, Institute for Integrative Bird Behavior Studies, College of William & Mary, Williamsburg, VA 23187-8795, USA
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8
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Swaddle JP, Diehl TR, Taylor CE, Fanaee AS, Benson JL, Huckstep NR, Cristol DA. Exposure to dietary mercury alters cognition and behavior of zebra finches. Curr Zool 2017; 63:213-219. [PMID: 29491979 PMCID: PMC5804164 DOI: 10.1093/cz/zox007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/03/2017] [Indexed: 11/15/2022] Open
Abstract
Environmental stressors can negatively affect avian cognitive abilities, potentially reducing fitness, for example by altering response to predators, display to mates, or memory of locations of food. We expand on current knowledge by investigating the effects of dietary mercury, a ubiquitous environmental pollutant and known neurotoxin, on avian cognition. Zebra finches Taeniopygia guttata were dosed for their entire lives with sub-lethal levels of mercury, at the environmentally relevant dose of 1.2 parts per million. In our first study, we compared the dosed birds with controls of the same age using tests of three cognitive abilities: spatial memory, inhibitory control, and color association. In the spatial memory assay, birds were tested on their ability to learn and remember the location of hidden food in their cage. The inhibitory control assay measured their ability to ignore visible but inaccessible food in favor of a learned behavior that provided the same reward. Finally, the color association task tested each bird's ability to associate a specific color with the presence of hidden food. Dietary mercury negatively affected spatial memory ability but not inhibitory control or color association. Our second study focused on three behavioral assays not tied to a specific skill or problem-solving: activity level, neophobia, and social dominance. Zebra finches exposed to dietary mercury throughout their lives were subordinate to, and more active than, control birds. We found no evidence that mercury exposure influenced our metric of neophobia. Together, these results suggest that sub-lethal exposure to environmental mercury selectively harms neurological pathways that control different cognitive abilities, with complex effects on behavior and fitness.
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Affiliation(s)
- John P Swaddle
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Tessa R Diehl
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Capwell E Taylor
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Aaron S Fanaee
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Jessica L Benson
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
| | - Neil R Huckstep
- Biological Sciences, Virginia Tech, 1405 Perry Street, Blacksburg, VA 24061, USA
| | - Daniel A Cristol
- Biology Department, College of William and Mary, Institute for Integrative Bird Behavior Studies, Williamsburg, VA 23187-8795, USA
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9
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Fuchsman PC, Brown LE, Henning MH, Bock MJ, Magar VS. Toxicity reference values for methylmercury effects on avian reproduction: Critical review and analysis. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:294-319. [PMID: 27585374 DOI: 10.1002/etc.3606] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 05/28/2016] [Accepted: 08/29/2016] [Indexed: 06/06/2023]
Abstract
Effects of mercury (Hg) on birds have been studied extensively and with increasing frequency in recent years. The authors conducted a comprehensive review of methylmercury (MeHg) effects on bird reproduction, evaluating laboratory and field studies in which observed effects could be attributed primarily to Hg. The review focuses on exposures via diet and maternal transfer in which observed effects (or lack thereof) were reported relative to Hg concentrations in diet, eggs, or adult blood. Applicable data were identified for 23 species. From this data set, the authors identified ranges of toxicity reference values suitable for risk-assessment applications. Typical ranges of Hg effect thresholds are approximately 0.2 mg/kg to >1.4 mg/kg in diet, 0.05 mg/kg/d to 0.5 mg/kg/d on a dose basis, 0.6 mg/kg to 2.7 mg/kg in eggs, and 2.1 mg/kg to >6.7 mg/kg in parental blood (all concentrations on a wet wt basis). For Hg in avian blood, the review represents the first broad compilation of relevant toxicity data. For dietary exposures, the current data support TRVs that are greater than older, commonly used TRVs. The older diet-based TRVs incorporate conservative assumptions and uncertainty factors that are no longer justified, although they generally were appropriate when originally derived, because of past data limitations. The egg-based TRVs identified from the review are more similar to other previously derived TRVs but have been updated to incorporate new information from recent studies. While important research needs remain, a key recommendation is that species not yet tested for MeHg toxicity should be evaluated using toxicity data from tested species with similar body weights. Environ Toxicol Chem 2017;36:294-319. © 2016 SETAC.
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Buck KA, Varian-Ramos CW, Cristol DA, Swaddle JP. Blood Mercury Levels of Zebra Finches Are Heritable: Implications for the Evolution of Mercury Resistance. PLoS One 2016; 11:e0162440. [PMID: 27668745 PMCID: PMC5036838 DOI: 10.1371/journal.pone.0162440] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 08/23/2016] [Indexed: 11/18/2022] Open
Abstract
Mercury is a ubiquitous metal contaminant that negatively impacts reproduction of wildlife and has many other sub-lethal effects. Songbirds are sensitive bioindicators of mercury toxicity and may suffer population declines as a result of mercury pollution. Current predictions of mercury accumulation and biomagnification often overlook possible genetic variation in mercury uptake and elimination within species and the potential for evolution in affected populations. We conducted a study of dietary mercury exposure in a model songbird species, maintaining a breeding population of zebra finches (Taeniopygia guttata) on standardized diets ranging from 0.0-2.4 μg/g methylmercury. We applied a quantitative genetics approach to examine patterns of variation and heritability of mercury accumulation within dietary treatments using a method of mixed effects modeling known as the 'animal model'. Significant variation in blood mercury accumulation existed within each treatment for birds exposed at the same dietary level; moreover, this variation was highly repeatable for individuals. We observed substantial genetic variation in blood mercury accumulation for birds exposed at intermediate dietary concentrations. Taken together, this is evidence that genetic variation for factors affecting blood mercury accumulation could be acted on by selection. If similar heritability for mercury accumulation exists in wild populations, selection could result in genetic differentiation for populations in contaminated locations, with possible consequences for mercury biomagnification in food webs.
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Affiliation(s)
- Kenton A. Buck
- Institute for Integrative Bird Behavior Studies, College of William and Mary, Williamsburg, Virginia, United States of America
| | - Claire W. Varian-Ramos
- Biology Department, Colorado State University – Pueblo, Pueblo, Colorado, United States of America
| | - Daniel A. Cristol
- Institute for Integrative Bird Behavior Studies, College of William and Mary, Williamsburg, Virginia, United States of America
| | - John P. Swaddle
- Institute for Integrative Bird Behavior Studies, College of William and Mary, Williamsburg, Virginia, United States of America
- * E-mail:
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11
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Lei HL, Wei HJ, Chen PH, Hsi HC, Chien LC. Preliminary study of blood methylmercury effects on reproductive hormones and relevant factors among infertile and pregnant women in Taiwan. CHEMOSPHERE 2015; 135:411-417. [PMID: 26002048 DOI: 10.1016/j.chemosphere.2015.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 04/28/2015] [Accepted: 05/03/2015] [Indexed: 06/04/2023]
Abstract
Methylmercury (MeHg) is the most poisonous mercury species and an endocrine-disrupting chemical that could cause reproductive and developmental harm effects in animals. In this study, we recruited 310 infertile women and 57 pregnant women and investigated their blood MeHg levels. The distribution of blood reproductive hormone, selenium and zinc levels, and the difference of relevant factors by the reference level of blood MeHg (5.8 μg/L) of infertile women were further examined. Results showed that greater percentages of sashimi consumption, frequencies of Chinese herbal medicine use, alcohol consumption, and lack of physical activity were observed in infertile women than those for pregnant women. Blood MeHg concentration was significantly greater in infertile than that in pregnant women. Significant concentration differences for FSH and LH by the dichotomized reference level of blood MeHg (5.8 μg/L) in infertile women were not observed, which may stem from that these reproductive hormones in participated infertile women were mostly in the normal reference range. Consumption of fish and sashimi represented the major source of MeHg exposure in infertile women. MeHg levels were elevated in infertile women, and consistent with fish consumption frequency. Compared to the referent level of blood MeHg levels <5.8 μg/L, the elevated blood MeHg levels (⩾5.8 μg/L) in infertile women were 3.35 and 4.42 folds risk in categorized frequencies of fish consumption 1-2 meals per week and more than 3 meals per week, respectively. The obtained results provide evidences and help updating the advisory of fish consumption and improving women's reproductive health.
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Affiliation(s)
- Hsiao-Ling Lei
- School of Public Health, Taipei Medical University, Taipei City 110, Taiwan
| | - Hsiao-Jui Wei
- Infertility Center, Taiwan Adventist Hospital, Taipei City 105, Taiwan; Xiamen EMBO Hospital, Fujian Province, China
| | - Po-Hsi Chen
- Institute of Environmental Engineering and Management, National Taipei University of Technology, Taipei City 106, Taiwan
| | - Hsing-Cheng Hsi
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei City 106, Taiwan.
| | - Ling-Chu Chien
- School of Public Health, Taipei Medical University, Taipei City 110, Taiwan.
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Ou L, Varian-Ramos CW, Cristol DA. Effect of laying sequence on egg mercury in captive zebra finches: an interpretation considering individual variation. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2015; 34:1787-1792. [PMID: 25760460 DOI: 10.1002/etc.2976] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 02/09/2015] [Accepted: 03/09/2015] [Indexed: 06/04/2023]
Abstract
Bird eggs are used widely as noninvasive bioindicators for environmental mercury availability. Previous studies, however, have found varying relationships between laying sequence and egg mercury concentrations. Some studies have reported that the mercury concentration was higher in first-laid eggs or declined across the laying sequence, whereas in other studies mercury concentration was not related to egg order. Approximately 300 eggs (61 clutches) were collected from captive zebra finches dosed throughout their reproductive lives with methylmercury (0.3 μg/g, 0.6 μg/g, 1.2 μg/g, or 2.4 μg/g wet wt in diet); the total mercury concentration (mean ± standard deviation [SD] dry wt basis) of their eggs was 7.03 ± 1.38 μg/g, 14.15 ± 2.52 μg/g, 26.85 ± 5.85 μg/g, and 49.76 ± 10.37 μg/g, respectively (equivalent to fresh wt egg mercury concentrations of 1.24 μg/g, 2.50 μg/g, 4.74 μg/g, and 8.79 μg/g). The authors observed a significant decrease in the mercury concentration of successive eggs when compared with the first egg and notable variation between clutches within treatments. The mercury level of individual females within and among treatments did not alter this relationship. Based on the results, sampling of a single egg in each clutch from any position in the laying sequence is sufficient for purposes of population risk assessment, but it is not recommended as a proxy for individual female exposure or as an estimate of average mercury level within the clutch.
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Affiliation(s)
- Langbo Ou
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing, China
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William & Mary, Williamsburg, Virginia, USA
| | | | - Daniel A Cristol
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William & Mary, Williamsburg, Virginia, USA
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Kobiela ME, Cristol DA, Swaddle JP. Risk-taking behaviours in zebra finches affected by mercury exposure. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.02.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Bouétard A, Côte J, Besnard AL, Collinet M, Coutellec MA. Environmental versus anthropogenic effects on population adaptive divergence in the freshwater snail Lymnaea stagnalis. PLoS One 2014; 9:e106670. [PMID: 25207985 PMCID: PMC4160221 DOI: 10.1371/journal.pone.0106670] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 07/07/2014] [Indexed: 12/11/2022] Open
Abstract
Repeated pesticide contaminations of lentic freshwater systems located within agricultural landscapes may affect population evolution in non-target organisms, especially in species with a fully aquatic life cycle and low dispersal ability. The issue of evolutionary impact of pollutants is therefore conceptually important for ecotoxicologists. The impact of historical exposure to pesticides on genetic divergence was investigated in the freshwater gastropod Lymnaea stagnalis, using a set of 14 populations from contrasted environments in terms of pesticide and other anthropogenic pressures. The hypothesis of population adaptive divergence was tested on 11 life-history traits, using Q(ST)-F(ST) comparisons. Despite strong neutral differentiation (mean F(ST) = 0.291), five adult traits or parameters were found to be under divergent selection. Conversely, two early expressed traits showed a pattern consistent with uniform selection or trait canalization, and four adult traits appeared to evolve neutrally. Divergent selection patterns were mostly consistent with a habitat effect, opposing pond to ditch and channel populations. Comparatively, pesticide and other human pressures had little correspondence with evolutionary patterns, despite hatching rate impairment associated with global anthropogenic pressure. Globally, analyses revealed high genetic variation both at neutral markers and fitness-related traits in a species used as model in ecotoxicology, providing empirical support for the need to account for genetic and evolutionary components of population response in ecological risk assessment.
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Affiliation(s)
- Anthony Bouétard
- INRA, UMR 0985 ESE, Ecology and Ecosystem Health, INRA – Agrocampus Ouest, CS84215, Rennes Cedex, France
| | - Jessica Côte
- INRA, UMR 0985 ESE, Ecology and Ecosystem Health, INRA – Agrocampus Ouest, CS84215, Rennes Cedex, France
| | - Anne-Laure Besnard
- INRA, UMR 0985 ESE, Ecology and Ecosystem Health, INRA – Agrocampus Ouest, CS84215, Rennes Cedex, France
| | - Marc Collinet
- INRA, UMR 0985 ESE, Ecology and Ecosystem Health, INRA – Agrocampus Ouest, CS84215, Rennes Cedex, France
| | - Marie-Agnès Coutellec
- INRA, UMR 0985 ESE, Ecology and Ecosystem Health, INRA – Agrocampus Ouest, CS84215, Rennes Cedex, France
- * E-mail:
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Gillet AMTY, Seewagen CL. Mercury exposure of a wetland songbird, Agelaius phoeniceus, in the New York metropolitan area and its effect on nestling growth rate. ENVIRONMENTAL MONITORING AND ASSESSMENT 2014; 186:4029-4036. [PMID: 24526618 DOI: 10.1007/s10661-014-3677-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 01/29/2014] [Indexed: 06/03/2023]
Abstract
The potential for mercury accumulation in free-living passerine birds is now recognized to be much greater than previously assumed. However, lowest observable effect levels have yet to be well established for this taxonomic group and it is usually unknown whether levels observed in the wild are causing adverse effects. We measured total blood mercury (THg) levels and took repeated morphological measurements from nestling red-winged blackbirds (Agelaius phoeniceus; N = 39) in the New York metropolitan area to investigate whether mercury affected their growth rate. We also compared THg levels of nestlings (and parents; N = 14) between our two study sites, which included riparian habitats along a city river and surrounding ponds in a nearby suburb, to examine differences between birds within and beyond the urban core. THg levels ranged 0.009-0.284 ppm in nestlings and 0.036-0.746 ppm in adults. Adults and nestlings had significantly higher THg outside of the city than within, possibly due to the ability of rivers to flush contaminants and the higher methylation potential of ponds. Among our candidate sets, models containing THg had minimal support for explaining variation in nestling growth rate. Summed Akaike weights further showed that THg had little relative importance. Mercury pollution in our sites may be low, or feather growth may have been sufficient to protect nestlings from accumulating harmful mercury levels in living tissues.
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Varian-Ramos CW, Swaddle JP, Cristol DA. Mercury reduces avian reproductive success and imposes selection: an experimental study with adult- or lifetime-exposure in zebra finch. PLoS One 2014; 9:e95674. [PMID: 24759822 PMCID: PMC3997408 DOI: 10.1371/journal.pone.0095674] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 03/31/2014] [Indexed: 02/06/2023] Open
Abstract
Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 – 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success.
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Affiliation(s)
- Claire W. Varian-Ramos
- Biology Department, Colorado State University – Pueblo, Pueblo, Colorado, United States of America
- * E-mail:
| | - John P. Swaddle
- Institute for Integrative Bird Behavior Studies, Biology Department, The College of William and Mary, Williamsburg, Virginia, United States of America
| | - Daniel A. Cristol
- Institute for Integrative Bird Behavior Studies, Biology Department, The College of William and Mary, Williamsburg, Virginia, United States of America
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