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Ma Y, Choi CY, Shang L, Klaassen M, Ma Z, Chang Q, Jaspers VLB, Bai Q, He T, Leung KKS, Hassell CJ, Jessop R, Gibson L. Mercury contamination is an invisible threat to declining migratory shorebirds along the East Asian-Australasian Flyway. Commun Biol 2024; 7:585. [PMID: 38755288 PMCID: PMC11098816 DOI: 10.1038/s42003-024-06254-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 04/26/2024] [Indexed: 05/18/2024] Open
Abstract
Exposure to pollutants is a potentially crucial but overlooked driver of population declines in shorebirds along the East Asian-Australasian Flyway. We combined knowledge of moult strategy and life history with a standardised sampling protocol to assess mercury (Hg) contamination in 984 individuals across 33 migratory shorebird species on an intercontinental scale. Over one-third of the samples exceeded toxicity benchmarks. Feather Hg was best explained by moulting region, while habitat preference (coastal obligate vs. non-coastal obligate), the proportion of invertebrates in the diet and foraging stratum (foraging mostly on the surface vs. at depth) also contributed, but were less pronounced. Feather Hg was substantially higher in South China (Mai Po and Leizhou), Australia and the Yellow Sea than in temperate and Arctic breeding ranges. Non-coastal obligate species (Tringa genus) frequently encountered in freshwater habitats were at the highest risk. It is important to continue and expand biomonitoring research to assess how other pollutants might impact shorebirds.
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Affiliation(s)
- Yanju Ma
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
- Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection (Guangxi Normal University), Ministry of Education, Guilin, 541006, Guangxi, China
- Guangxi Key Laboratory of Rare and Endangered Animal Ecology, College of Life Sciences, Guangxi Normal University, Guilin, 541006, Guangxi, China
| | - Chi-Yeung Choi
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
- Environmental Research Center, Duke Kunshan University, Kunshan, 215316, Jiangsu, China.
| | - Lihai Shang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, Guizhou, China
| | - Marcel Klaassen
- School of Life and Environmental Sciences, Deakin University, Geelong, VIC, Australia
| | - Zhijun Ma
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Coastal Ecosystems Research Station of the Yangtze River Estuary, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Qing Chang
- Nanjing Normal University, Nanjing, 210024, Jiangsu, China
| | - Veerle L B Jaspers
- Department of Biology, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway
| | - Qingquan Bai
- Dandong Forestry and Grassland Development Service Center, Dandong, 118000, Liaoning, China
| | - Tao He
- Zhanjiang Mangrove National Nature Reserve Bureau, Zhangjiang, Guangdong, 524000, China
| | - Katherine K-S Leung
- Hong Kong Waterbirds Ringing Group, Mai Po Nature Reserve, Mai Po, Hong Kong, China
| | - Chris J Hassell
- Australian Wader Studies Group, Curtin, ACT, 2605, Australia
| | - Roz Jessop
- Victorian Wader Study Group, Thornbury, VIC, 3071, Australia
| | - Luke Gibson
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China.
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Evers DC, Ackerman JT, Åkerblom S, Bally D, Basu N, Bishop K, Bodin N, Braaten HFV, Burton MEH, Bustamante P, Chen C, Chételat J, Christian L, Dietz R, Drevnick P, Eagles-Smith C, Fernandez LE, Hammerschlag N, Harmelin-Vivien M, Harte A, Krümmel EM, Brito JL, Medina G, Barrios Rodriguez CA, Stenhouse I, Sunderland E, Takeuchi A, Tear T, Vega C, Wilson S, Wu P. Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework. ECOTOXICOLOGY (LONDON, ENGLAND) 2024:10.1007/s10646-024-02747-x. [PMID: 38683471 DOI: 10.1007/s10646-024-02747-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/06/2024] [Indexed: 05/01/2024]
Abstract
An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.
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Affiliation(s)
- David C Evers
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA.
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA, 95620, USA
| | | | - Dominique Bally
- African Center for Environmental Health, BP 826 Cidex 03, Abidjan, Côte d'Ivoire
| | - Nil Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada
| | - Kevin Bishop
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Upsalla, Sweden
| | - Nathalie Bodin
- Research Institute for Sustainable Development Seychelles Fishing Authority, Victoria, Seychelles
| | | | - Mark E H Burton
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Paco Bustamante
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
| | - Celia Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - John Chételat
- Environment and Cliamte Change Canada, National Wildlife Research Centre, Ottawa, ON, K1S 5B6, Canada
| | - Linroy Christian
- Department of Analytical Services, Dunbars, Friars Hill, St John, Antigua and Barbuda
| | - Rune Dietz
- Department of Ecoscience, Aarhus University, Arctic Research Centre (ARC), Department of Ecoscience, P.O. Box 358, DK-4000, Roskilde, Denmark
| | - Paul Drevnick
- Teck American Incorporated, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Collin Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Luis E Fernandez
- Sabin Center for Environment and Sustainability and Department of Biology, Wake Forest University, Winston-Salem, NC, 29106, USA
- Centro de Innovación Científica Amazonica (CINCIA), Puerto Maldonado, Madre de Dios, Peru
| | - Neil Hammerschlag
- Shark Research Foundation Inc, 29 Wideview Lane, Boutiliers Point, NS, B3Z 0M9, Canada
| | - Mireille Harmelin-Vivien
- Aix-Marseille Université, Université de Toulon, CNRS/INSU/IRD, Institut Méditerranéen d'Océanologie (MIO), UM 110, Campus de Luminy, case 901, 13288, Marseille, cedex 09, France
| | - Agustin Harte
- Basel, Rotterdam and Stockholm Conventions Secretariat, United Nations Environment Programme (UNEP), Chem. des Anémones 15, 1219, Vernier, Geneva, Switzerland
| | - Eva M Krümmel
- Inuit Circumpolar Council-Canada, Ottawa, Canada and ScienTissiME Inc, Barry's Bay, ON, Canada
| | - José Lailson Brito
- Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, Sala 4002, CEP 20550-013, Maracana, Rio de Janeiro, RJ, Brazil
| | - Gabriela Medina
- Director of Basel Convention Coordinating Centre, Stockholm Convention Regional Centre for Latin America and the Caribbean, Hosted by the Ministry of Environment, Montevideo, Uruguay
| | | | - Iain Stenhouse
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Elsie Sunderland
- Harvard University, Pierce Hall 127, 29 Oxford Street, Cambridge, MA, 02138, USA
| | - Akinori Takeuchi
- National Institute for Environmental Studies, Health and Environmental Risk Division, 16-2 Onogawa Tsukuba, Ibaraki, 305-8506, Japan
| | - Tim Tear
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Claudia Vega
- Centro de Innovaccion Cientifica Amazonica (CINCIA), Jiron Ucayali 750, Puerto Maldonado, Madre de Dios, 17001, Peru
| | - Simon Wilson
- Arctic Monitoring and Assessment Programme (AMAP) Secretariat, N-9296, Tromsø, Norway
| | - Pianpian Wu
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
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Ackerman JT, Peterson SH, Herzog MP, Yee JL. Methylmercury Effects on Birds: A Review, Meta-Analysis, and Development of Toxicity Reference Values for Injury Assessment Based on Tissue Residues and Diet. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024. [PMID: 38682592 DOI: 10.1002/etc.5858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/08/2023] [Accepted: 02/20/2024] [Indexed: 05/01/2024]
Abstract
Birds are used as bioindicators of environmental mercury (Hg) contamination, and toxicity reference values are needed for injury assessments. We conducted a comprehensive review, summarized data from 168 studies, performed a series of Bayesian hierarchical meta-analyses, and developed new toxicity reference values for the effects of methylmercury (MeHg) on birds using a benchmark dose analysis framework. Lethal and sublethal effects of MeHg on birds were categorized into nine biologically relevant endpoint categories and three age classes. Effective Hg concentrations where there was a 10% reduction (EC10) in the production of juvenile offspring (0.55 µg/g wet wt adult blood-equivalent Hg concentrations, 80% credible interval: [0.33, 0.85]), histology endpoints (0.49 [0.15, 0.96] and 0.61 [0.09, 2.48]), and biochemical markers (0.77 [<0.25, 2.12] and 0.57 [0.35, 0.92]) were substantially lower than those for survival (2.97 [2.10, 4.73] and 5.24 [3.30, 9.55]) and behavior (6.23 [1.84, >13.42] and 3.11 [2.10, 4.64]) of juveniles and adults, respectively. Within the egg age class, survival was the most sensitive endpoint (EC10 = 2.02 µg/g wet wt adult blood-equivalent Hg concentrations [1.39, 2.94] or 1.17 µg/g fresh wet wt egg-equivalent Hg concentrations [0.80, 1.70]). Body morphology was not particularly sensitive to Hg. We developed toxicity reference values using a combined survival and reproduction endpoints category for juveniles, because juveniles were more sensitive to Hg toxicity than eggs or adults. Adult blood-equivalent Hg concentrations (µg/g wet wt) and egg-equivalent Hg concentrations (µg/g fresh wet wt) caused low injury to birds (EC1) at 0.09 [0.04, 0.17] and 0.04 [0.01, 0.08], moderate injury (EC5) at 0.6 [0.37, 0.84] and 0.3 [0.17, 0.44], high injury (EC10) at 1.3 [0.94, 1.89] and 0.7 [0.49, 1.02], and severe injury (EC20) at 3.2 [2.24, 4.78] and 1.8 [1.28, 2.79], respectively. Maternal dietary Hg (µg/g dry wt) caused low injury to juveniles at 0.16 [0.05, 0.38], moderate injury at 0.6 [0.29, 1.03], high injury at 1.1 [0.63, 1.87], and severe injury at 2.4 [1.42, 4.13]. We found few substantial differences in Hg toxicity among avian taxonomic orders, including for controlled laboratory studies that injected Hg into eggs. Our results can be used to quantify injury to birds caused by Hg pollution. Environ Toxicol Chem 2024;00:1-52. Published 2024. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Joshua T Ackerman
- US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, California, USA
| | - Sarah H Peterson
- US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, California, USA
| | - Mark P Herzog
- US Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, California, USA
| | - Julie L Yee
- US Geological Survey, Western Ecological Research Center, Santa Cruz Field Station, Santa Cruz, California, USA
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4
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Luo K, Yuan W, Lu Z, Xiong Z, Lin CJ, Wang X, Feng X. Unveiling the Sources and Transfer of Mercury in Forest Bird Food Chains Using Techniques of Vivo-Nest Video Recording and Stable Isotopes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6007-6018. [PMID: 38513264 DOI: 10.1021/acs.est.3c10972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Knowledge gaps in mercury (Hg) biomagnification in forest birds, especially in the most species-rich tropical and subtropical forests, limit our understanding of the ecological risks of Hg deposition to forest birds. This study aimed to quantify Hg bioaccumulation and transfer in the food chains of forest birds in a subtropical montane forest using a bird diet recorded by video and stable Hg isotope signals of biological and environmental samples. Results show that inorganic mercury (IHg) does not biomagnify along food chains, whereas methylmercury (MeHg) has trophic magnification factors of 7.4-8.1 for the basal resource-invertebrate-bird food chain. The video observations and MeHg mass balance model suggest that Niltava (Niltava sundara) nestlings ingest 78% of their MeHg from forest floor invertebrates, while Flycatcher (Eumyias thalassinus) nestlings ingest 59% from emergent aquatic invertebrates (which fly onto the canopy) and 40% from canopy invertebrates. The diet of Niltava nestlings contains 40% more MeHg than that of Flycatcher nestlings, resulting in a 60% higher MeHg concentration in their feather. Hg isotopic model shows that atmospheric Hg0 is the main Hg source in the forest bird food chains and contributes >68% in most organisms. However, three categories of canopy invertebrates receive ∼50% Hg from atmospheric Hg2+. Overall, we highlight the ecological risk of MeHg exposure for understory insectivorous birds caused by atmospheric Hg0 deposition and methylation on the forest floor.
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Affiliation(s)
- Kang Luo
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Wei Yuan
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Zhiyun Lu
- Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong, Yunnan 676200, China
| | - Zichun Xiong
- Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences, Jingdong, Yunnan 676200, China
| | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University, Beaumont, Texas 77710, United States
| | - Xun Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Xinbin Feng
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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5
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Pisconte JN, Vega CM, Sayers CJ, Sevillano-Ríos CS, Pillaca M, Quispe E, Tejeda V, Ascorra C, Silman MR, Fernandez LE. Elevated mercury exposure in bird communities inhabiting Artisanal and Small-Scale Gold Mining landscapes of the southeastern Peruvian Amazon. ECOTOXICOLOGY (LONDON, ENGLAND) 2024:10.1007/s10646-024-02740-4. [PMID: 38363482 DOI: 10.1007/s10646-024-02740-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
Artisanal and Small-Scale Gold Mining (ASGM) represents a significant source of anthropogenic mercury emissions to the environment, with potentially severe implications for avian biodiversity. In the Madre de Dios department of the southern Peruvian Amazon, ASGM activities have created landscapes marred by deforestation and post-mining water bodies (mining ponds) with notable methylation potential. While data on Hg contamination in terrestrial wildlife remains limited, this study measures Hg exposure in several terrestrial bird species as bioindicators. Total Hg (THg) levels in feathers from birds near water bodies, including mining ponds associated with ASGM areas and oxbow lakes, were analyzed. Our results showed significantly higher Hg concentrations in birds from ASGM sites with mean ± SD of 3.14 ± 7.97 µg/g (range: 0.27 to 72.75 µg/g, n = 312) compared to control sites with a mean of 0.47 ± 0.42 µg/g (range: 0.04 to 1.89 µg/g, n = 52). Factors such as trophic guilds, ASGM presence, and water body area significantly influenced feather Hg concentrations. Notably, piscivorous birds exhibited the highest Hg concentration (31.03 ± 25.25 µg/g, n = 12) exceeding known concentrations that affect reproductive success, where one measurement of Chloroceryle americana (Green kingfisher; 72.7 µg/g) is among the highest ever reported in South America. This research quantifies Hg exposure in avian communities in Amazonian regions affected by ASGM, highlighting potential risks to regional bird populations.
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Affiliation(s)
- Jessica N Pisconte
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú.
| | - Claudia M Vega
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
- Sabin Center for Environment and Sustainability, and Department of Biology, Wake Forest University, Winston-, Salem, NC, 27106, USA
| | - Christopher J Sayers
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, 90095, USA
| | | | - Martin Pillaca
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
| | - Edwin Quispe
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
| | - Vania Tejeda
- World Wildlife Fund-Peru, Trinidad Moran 853, Lima 14, Lima, Peru
| | - Cesar Ascorra
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
| | - Miles R Silman
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
- Sabin Center for Environment and Sustainability, and Department of Biology, Wake Forest University, Winston-, Salem, NC, 27106, USA
| | - Luis E Fernandez
- Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, Madre de Dios, 17000, Perú
- Sabin Center for Environment and Sustainability, and Department of Biology, Wake Forest University, Winston-, Salem, NC, 27106, USA
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, 94305, USA
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Schwantes U. Impact of anthropogenous environmental factors on the marine ecosystem of trophically transmitted helminths and hosting seabirds: Focus on North Atlantic, North Sea, Baltic and the Arctic seas. Helminthologia 2023; 60:300-326. [PMID: 38222492 PMCID: PMC10787638 DOI: 10.2478/helm-2023-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 09/21/2023] [Indexed: 01/16/2024] Open
Abstract
Alongside natural factors, human activities have a major impact on the marine environment and thus influence processes in vulnerable ecosystems. The major purpose of this review is to summarise the current understanding as to how manmade factors influence the marine biocenosis of helminths, their intermediate hosts as well as seabirds as their final hosts. Moreover, it highlights current knowledge gaps regarding this ecosystem, which should be closed in order to gain a more complete understanding of these interactions. This work is primarily focused on helminths parasitizing seabirds of the North Atlantic and the Arctic Ocean. The complex life cycles of seabird helminths may be impacted by fishing and aquaculture, as they interfere with the abundance of fish and seabird species, while the latter also affects the geographical distribution of intermediate hosts (marine bivalve and fish species), and may therefore alter the intertwined marine ecosystem. Increasing temperatures and seawater acidification as well as environmental pollutants may have negative or positive effects on different parts of this interactive ecosystem and may entail shifts in the abundance or regional distribution of parasites and/or intermediate and final hosts. Organic pollutants and trace elements may weaken the immune system of the hosting seabirds and hence affect the final host's ability to control the endoparasites. On the other hand, in some cases helminths seem to function as a sink for trace elements resulting in decreased concentrations of heavy metals in birds' tissues. Furthermore, this article also describes the role of helminths in mass mortality events amongst seabird populations, which beside natural causes (weather, viral and bacterial infections) have anthropogenous origin as well (e.g. oil spills, climate change, overfishing and environmental pollution).
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Affiliation(s)
- U. Schwantes
- Verein Jordsand zum Schutz der Seevögel und der Natur e.V., Ahrensburg, Germany
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Grunst ML, Grunst AS, Grémillet D, Kato A, Gentès S, Fort J. Keystone seabird may face thermoregulatory challenges in a warming Arctic. Sci Rep 2023; 13:16733. [PMID: 37794049 PMCID: PMC10550970 DOI: 10.1038/s41598-023-43650-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 09/26/2023] [Indexed: 10/06/2023] Open
Abstract
Climate change affects the Arctic more than any other region, resulting in evolving weather, vanishing sea ice and altered biochemical cycling, which may increase biotic exposure to chemical pollution. We tested thermoregulatory impacts of these changes on the most abundant Arctic seabird, the little auk (Alle alle). This small diving species uses sea ice-habitats for foraging on zooplankton and resting. We equipped eight little auks with 3D accelerometers to monitor behavior, and ingested temperature recorders to measure body temperature (Tb). We also recorded weather conditions, and collected blood to assess mercury (Hg) contamination. There were nonlinear relationships between time engaged in different behaviors and Tb. Tb increased on sea ice, following declines while foraging in polar waters, but changed little when birds were resting on water. Tb also increased when birds were flying, and decreased at the colony after being elevated during flight. Weather conditions, but not Hg contamination, also affected Tb. However, given our small sample size, further research regarding thermoregulatory effects of Hg is warranted. Results suggest that little auk Tb varies with behavior and weather conditions, and that loss of sea ice due to global warming may cause thermoregulatory and energic challenges during foraging trips at sea.
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Affiliation(s)
- Melissa L Grunst
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France.
| | - Andrea S Grunst
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
| | - David Grémillet
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa
| | - Akiko Kato
- Centre d'Etudes Biologiques de Chizé, CEBC, UMR 7372 CNRS-La Rochelle Université, La Rochelle, France
| | - Sophie Gentès
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
| | - Jérôme Fort
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, 17000, La Rochelle, France
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Sayers CJ, Evers DC, Ruiz-Gutierrez V, Adams E, Vega CM, Pisconte JN, Tejeda V, Regan K, Lane OP, Ash AA, Cal R, Reneau S, Martínez W, Welch G, Hartwell K, Teul M, Tzul D, Arendt WJ, Tórrez MA, Watsa M, Erkenswick G, Moore CE, Gerson J, Sánchez V, Purizaca RP, Yurek H, Burton MEH, Shrum PL, Tabares-Segovia S, Vargas K, Fogarty FF, Charette MR, Martínez AE, Bernhardt ES, Taylor RJ, Tear TH, Fernandez LE. Mercury in Neotropical birds: a synthesis and prospectus on 13 years of exposure data. ECOTOXICOLOGY (LONDON, ENGLAND) 2023; 32:1096-1123. [PMID: 37907784 PMCID: PMC10622370 DOI: 10.1007/s10646-023-02706-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/09/2023] [Indexed: 11/02/2023]
Abstract
Environmental mercury (Hg) contamination of the global tropics outpaces our understanding of its consequences for biodiversity. Knowledge gaps of pollution exposure could obscure conservation threats in the Neotropics: a region that supports over half of the world's species, but faces ongoing land-use change and Hg emission via artisanal and small-scale gold mining (ASGM). Due to their global distribution and sensitivity to pollution, birds provide a valuable opportunity as bioindicators to assess how accelerating Hg emissions impact an ecosystem's ability to support biodiversity, and ultimately, global health. We present the largest database on Neotropical bird Hg concentrations (n = 2316) and establish exposure baselines for 322 bird species spanning nine countries across Central America, South America, and the West Indies. Patterns of avian Hg exposure in the Neotropics broadly align with those in temperate regions: consistent bioaccumulation across functional groups and high spatiotemporal variation. Bird species occupying higher trophic positions and aquatic habitats exhibited elevated Hg concentrations that have been previously associated with reductions in reproductive success. Notably, bird Hg concentrations were over four times higher at sites impacted by ASGM activities and differed by season for certain trophic niches. We developed this synthesis via a collaborative research network, the Tropical Research for Avian Conservation and Ecotoxicology (TRACE) Initiative, which exemplifies inclusive, equitable, and international data-sharing. While our findings signal an urgent need to assess sampling biases, mechanisms, and consequences of Hg exposure to tropical avian communities, the TRACE Initiative provides a meaningful framework to achieve such goals. Ultimately, our collective efforts support and inform local, scientific, and government entities, including Parties of the United Nations Minamata Convention on Mercury, as we continue working together to understand how Hg pollution impacts biodiversity conservation, ecosystem function, and public health in the tropics.
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Affiliation(s)
- Christopher J Sayers
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, 90095, USA.
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA.
- Centro de Innovación Científica Amazónica, Puerto Maldonado, Madre de Dios, 17000, Peru.
| | - David C Evers
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | | | - Evan Adams
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Claudia M Vega
- Centro de Innovación Científica Amazónica, Puerto Maldonado, Madre de Dios, 17000, Peru
- Department of Biology, Center for Energy, Environment and Sustainability, Wake Forest University, Winston-Salem, NC, 27106, USA
| | - Jessica N Pisconte
- Centro de Innovación Científica Amazónica, Puerto Maldonado, Madre de Dios, 17000, Peru
| | - Vania Tejeda
- Centro de Innovación Científica Amazónica, Puerto Maldonado, Madre de Dios, 17000, Peru
| | - Kevin Regan
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Oksana P Lane
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Abidas A Ash
- Environmental Research Institute, University of Belize, Price Center Road, P.O. Box 340, Belmopan, Cayo District, Belize
| | - Reynold Cal
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Stevan Reneau
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Wilber Martínez
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Gilroy Welch
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Kayla Hartwell
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Mario Teul
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - David Tzul
- Foundation for Wildlife Conservation, Tropical Education Center, 28 George Price Highway, P.O. Box 368, La Democracia, Belize District, Belize
| | - Wayne J Arendt
- International Institute of Tropical Forestry, USDA Forest Service, 1201 Calle Ceiba, Jardín Botánico Sur, San Juan, 00926-1119, Puerto Rico
| | - Marvin A Tórrez
- Instituto Interdisciplinario de Ciencias Naturales, Universidad Centroamericana, Managua, Nicaragua
| | - Mrinalini Watsa
- Beckman Center for Conservation Research, San Diego Zoo Wildlife Alliance, P.O. Box 120551, San Diego, CA, 92112, USA
- Field Projects International, Escondido, CA, 92029, USA
| | | | - Caroline E Moore
- Beckman Center for Conservation Research, San Diego Zoo Wildlife Alliance, P.O. Box 120551, San Diego, CA, 92112, USA
| | - Jacqueline Gerson
- Department of Earth & Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Victor Sánchez
- Instituto de Investigación en Ecología y Conservación, Trujillo, Peru
| | - Raúl Pérez Purizaca
- Universidad Nacional de Piura, Urb. Miraflores S/N, Castilla, 20002, Piura, Peru
| | - Helen Yurek
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Mark E H Burton
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Peggy L Shrum
- Department of Fisheries and Wildlife Biology, Clemson University, Clemson, SC, 29634, USA
| | | | - Korik Vargas
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Finola F Fogarty
- Department of Zoology, Faculty of Science, University of British Columbia, Vancouver, BC, Canada
- Toucan Ridge Ecology and Education Society, 27.5 Miles Hummingbird Hwy, Stann Creek, Belize
| | - Mathieu R Charette
- Toucan Ridge Ecology and Education Society, 27.5 Miles Hummingbird Hwy, Stann Creek, Belize
| | - Ari E Martínez
- Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA, 95064, USA
| | | | - Robert J Taylor
- Department of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Timothy H Tear
- Center for Mercury Studies, Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Luis E Fernandez
- Centro de Innovación Científica Amazónica, Puerto Maldonado, Madre de Dios, 17000, Peru
- Department of Biology, Center for Energy, Environment and Sustainability, Wake Forest University, Winston-Salem, NC, 27106, USA
- Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, 94305, USA
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9
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Aljohani ASM. Heavy metal toxicity in poultry: a comprehensive review. Front Vet Sci 2023; 10:1161354. [PMID: 37456954 PMCID: PMC10340091 DOI: 10.3389/fvets.2023.1161354] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 05/22/2023] [Indexed: 07/18/2023] Open
Abstract
Arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) have been recognized as most toxic heavy metals that are continuously released into the environment, both from natural sources and from anthropogenic production of fertilizers, industrial activities, and waste disposal. Therefore, As, Cd, Hg, and Pb are found in increasing concentrations in bodies of water, fodder, feed, and in the tissues of livestock, including poultry, in the surroundings of industrial areas, leading to metabolic, structural, and functional abnormalities in various organs in all animals. In poultry, bioaccumulation of As, Pb, Cd, and Hg occurs in many organs (mainly in the kidneys, liver, reproductive organs, and lungs) as a result of continuous exposure to heavy metals. Consumption of Cd lowers the efficiency of feed conversion, egg production, and growth in poultry. Chronic exposure to As, Pb, Cd, and Hg at low doses can change the microscopic structure of tissues (mainly in the brain, liver, kidneys, and reproductive organs) as a result of the increased content of these heavy metals in these tissues. Histopathological changes occurring in the kidneys, liver, and reproductive organs are reflected in their negative impact on enzyme activity and serum biochemical parameters. Metal toxicity is determined by route of exposure, length of exposure, and absorbed dosage, whether chronic and acute. This review presents a discussion of bioaccumulation of As, Cd, Pb, and Hg in poultry and the associated histopathological changes and toxic concentrations in different tissues.
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10
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Grunst AS, Grunst ML, Grémillet D, Kato A, Bustamante P, Albert C, Brisson-Curadeau É, Clairbaux M, Cruz-Flores M, Gentès S, Perret S, Ste-Marie E, Wojczulanis-Jakubas K, Fort J. Mercury Contamination Challenges the Behavioral Response of a Keystone Species to Arctic Climate Change. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2054-2063. [PMID: 36652233 DOI: 10.1021/acs.est.2c08893] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Combined effects of multiple, climate change-associated stressors are of mounting concern, especially in Arctic ecosystems. Elevated mercury (Hg) exposure in Arctic animals could affect behavioral responses to changes in foraging landscapes caused by climate change, generating interactive effects on behavior and population resilience. We investigated this hypothesis in little auks (Alle alle), a keystone Arctic seabird. We compiled behavioral data for 44 birds across 5 years using accelerometers while also quantifying blood Hg and environmental conditions. Warm sea surface temperature (SST) and low sea ice coverage reshaped time activity budgets (TABs) and diving patterns, causing decreased resting, increased flight, and longer dives. Mercury contamination was not associated with TABs. However, highly contaminated birds lengthened interdive breaks when making long dives, suggesting Hg-induced physiological limitations. As dive durations increased with warm SST, subtle toxicological effects threaten to increasingly constrain diving and foraging efficiency as climate change progresses, with ecosystem-wide repercussions.
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Affiliation(s)
- Andrea S Grunst
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
| | - Melissa L Grunst
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
| | - David Grémillet
- CEFE, UMR 5175, CNRS─Université de Montpellier─Université Paul-Valéry Montpellier─EPHE, Montpellier 34090, France
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
| | - Akiko Kato
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-La Rochelle Université, Villiers-en-Bois 79360, France
| | - Paco Bustamante
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
- Institut Universitaire de France (IUF), 1 rue Descartes, Paris 75005, France
| | - Céline Albert
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
| | - Émile Brisson-Curadeau
- McGill University─Macdonald Campus, 21111 Lakeshore Dr, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Manon Clairbaux
- School of Biological, Environmental and Earth Sciences, University College Cork, Cork T23 N73K, Ireland
- MaREI Centre for Energy, Climate and Marine, Environmental Research Institute, University College Cork, Cork P43 C573, Ireland
| | - Marta Cruz-Flores
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
| | - Sophie Gentès
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
| | - Samuel Perret
- CEFE, UMR 5175, CNRS─Université de Montpellier─Université Paul-Valéry Montpellier─EPHE, Montpellier 34090, France
| | - Eric Ste-Marie
- McGill University─Macdonald Campus, 21111 Lakeshore Dr, Sainte-Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | | | - Jérôme Fort
- Littoral, Environnement et Sociétés (LIENSs), UMR 7266 CNRS-La Rochelle Université, 2 Rue Olympe de Gouges, La Rochelle FR-17000, France
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11
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Picone M, Distefano GG, Benhene GA, Corami F, Basso M, Panzarin L, Carabelli C, Volpi Ghirardini A. Seabirds as Biomonitors of Mercury Bioavailability in the Venice Lagoon. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 110:2. [PMID: 36484834 DOI: 10.1007/s00128-022-03650-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
Seabirds accumulate mercury (Hg) due to their long-life span together with their high trophic position. A Hg monitoring in Venice's Lagoon using three seabird species occupying different trophic habitat (Thalasseus sandvicensis, Ichthyaetus melanocephalus, and Chroicocephalus ridibundus) confirmed that fledgelings might effectively be used as sentinels of Hg bioavailability. The significant differences in Hg residues in feathers observed among the species highlighted a possible differential exposure due to different diets, with C. ridibundus accumulating more Hg than the other species. Average residues in feathers were not above the threshold associated with adverse effects on birds (5 mg kg- 1). Nevertheless, a large part of the C. ridibundus individuals (58%) exceeded the adverse effect level, underlining the need for strengthening Hg monitoring. Seabirds indeed may provide relevant insight on Hg transfer in food webs and a better picture of the hazards to men when bird species forage on species exploited for human consumption.
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Affiliation(s)
- Marco Picone
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari, Campus Scientifico via Torino 155, I-30170, Mestre, Venezia, Italy.
| | - Gabriele Giuseppe Distefano
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari, Campus Scientifico via Torino 155, I-30170, Mestre, Venezia, Italy
| | - Godbless Adu Benhene
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari, Campus Scientifico via Torino 155, I-30170, Mestre, Venezia, Italy
| | - Fabiana Corami
- Istituto di Scienze Polari, Consiglio Nazionale delle Ricerche, Via Torino 155, I-30170, Mestre, Venezia, Italy
| | | | - Lucio Panzarin
- Associazione Naturalistica Sandonatese, c/o Centro Didattico Naturalistico il Pendolino, via Romanziol 130, 30020, Noventa di Piave, Venezia, Italy
| | - Caterina Carabelli
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari, Campus Scientifico via Torino 155, I-30170, Mestre, Venezia, Italy
| | - Annamaria Volpi Ghirardini
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari, Campus Scientifico via Torino 155, I-30170, Mestre, Venezia, Italy
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12
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Sebastiano M, Eens M, Bustamante P, Chastel O, Costantini D. Seabirds under environmental pressures: Food supplementation has a larger impact than selenium on chicks exposed to mercury and a viral disease. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.963512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Although infectious disease outbreaks represent a serious threat for wildlife population viability, the environmental factors that underlie such outbreaks are poorly investigated. The French Guiana breeding population of Magnificent frigatebird Fregata magnificens is subjected to recurrent episodes of chicks’ mortality likely caused by a viral disease. We hypothesized that high mercury (Hg) concentrations may be responsible for the emergence of clinical signs. We therefore investigated whether healthy and sick chicks show different Hg concentrations in blood. Because the essential element selenium (Se) may be highly depleted during Hg poisoning, we further experimentally tested whether an increased intake of dietary Se has an effect on blood levels of Hg, increases circulating Se, and improves the oxidative status of chicks. Finally, we compared the results of this experiment with a previous food supplementation experiment. Our results show similar Hg concentrations between healthy and sick chicks with visible clinical signs of the disease. Se concentrations were significantly depleted in sick chicks. Se concentrations increased while Hg concentrations simultaneously decreased in chicks that naturally recovered from the disease. Both the Se and fish supplementation experiments significantly increased Se concentrations in blood, while Hg levels were only modestly affected. Providing food to chicks appeared to have greater benefits than only supplementing chicks with Se pills as, although food supplementation had an impact on blood Se similar to that of supplementation with Se pills, it also reduced the vulnerability of chicks to the viral disease, possibly by reducing nutritional stress and providing essential nutrients.
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13
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Costantini D, Blévin P, Bustnes JO, Esteve V, Gabrielsen GW, Herzke D, Humann-Guilleminot S, Moe B, Parenteau C, Récapet C, Bustamante P, Chastel O. Integument carotenoid-based colouration reflects contamination to perfluoroalkyl substances, but not mercury, in arctic black-legged kittiwakes. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.952765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Anthropogenic activities are introducing multiple chemical contaminants into ecosystems that act as stressors for wildlife. Perfluoroalkyl substances (PFAS) and mercury (Hg) are two relevant contaminants that may cause detrimental effects on the fitness of many aquatic organisms. However, there is a lack of information on their impact on the expression of secondary sexual signals that animals use for mate choice. We have explored the correlations between integument carotenoid-based colourations, blood levels of carotenoids, and blood levels of seven PFAS and of total Hg (THg) in 50 adult male black-legged kittiwakes (Rissa tridactyla) from the Norwegian Arctic during the pre-laying period, while controlling for other colouration influencing variables such as testosterone and body condition. Kittiwakes with elevated blood concentrations of PFAS (PFOSlin, PFNA, PFDcA, PFUnA, or PFDoA) had less chromatic but brighter bills, and brighter gape and tongue; PFOSlin was the pollutant with the strongest association with bill colourations. Conversely, plasma testosterone was the only significant correlate of hue and chroma of both gape and tongue, and of hue of the bill. Kittiwakes with higher concentrations of any PFAS, but not of THg, tended to have significantly higher plasma concentrations of the carotenoids astaxanthin, zeaxanthin, lutein, and cryptoxanthin. Our work provides the first correlative evidence that PFAS exposure might interfere with the carotenoid metabolism and the expression of integument carotenoid-based colourations in a free-living bird species. This outcome may be a direct effect of PFAS exposure or be indirectly caused by components of diet that also correlate with elevated PFAS concentrations (e.g., proteins). It also suggests that there might be no additive effect of THg co-exposure with PFAS on the expression of colourations. These results call for further work on the possible interference of PFAS with the expression of colourations used in mate choice.
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14
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Short-term mercury exposure disrupts muscular and hepatic lipid metabolism in a migrant songbird. Sci Rep 2022; 12:11470. [PMID: 35794224 PMCID: PMC9259677 DOI: 10.1038/s41598-022-15680-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/28/2022] [Indexed: 11/18/2022] Open
Abstract
Methylmercury (MeHg) is a global pollutant that can cause metabolic disruptions in animals and thereby potentially compromise the energetic capacity of birds for long-distance migration, but its effects on avian lipid metabolism pathways that support endurance flight and stopover refueling have never been studied. We tested the effects of short-term (14-d), environmentally relevant (0.5 ppm) dietary MeHg exposure on lipid metabolism markers in the pectoralis and livers of yellow-rumped warblers (Setophaga coronata) that were found in a previous study to have poorer flight endurance in a wind tunnel than untreated conspecifics. Compared to controls, MeHg-exposed birds displayed lower muscle aerobic and fatty acid oxidation capacity, but similar muscle glycolytic capacity, fatty acid transporter expression, and PPAR expression. Livers of exposed birds indicated elevated energy costs, lower fatty acid uptake capacity, and lower PPAR-γ expression. The lower muscle oxidative enzyme capacity of exposed birds likely contributed to their weaker endurance in the prior study, while the metabolic changes observed in the liver have potential to inhibit lipogenesis and stopover refueling. Our findings provide concerning evidence that fatty acid catabolism, synthesis, and storage pathways in birds can be dysregulated by only brief exposure to MeHg, with potentially significant consequences for migratory performance.
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15
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Bajracharya SS, Zahor DL, Glynn KJ, Gratz LE, Cornelius JM. Feather mercury concentrations in omnivorous and granivorous terrestrial songbirds in Southeast Michigan. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:797-807. [PMID: 35445955 DOI: 10.1007/s10646-022-02545-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Sublethal exposure to methylmercury (MeHg) can have consequences for the reproductive, neurological, and physiological health of birds. Songbirds, regardless of trophic position, are often exposed to mercury (Hg) and may be at risk for health effects - especially if they inhabit a place that is subject to high Hg atmospheric deposition and/or have local conditions that are prone to methylation. This study investigates Hg concentrations in terrestrial songbirds of Southeast Michigan, where historical and present-day anthropogenic emissions of heavy metals are elevated. We collected tail feather samples from 223 songbirds across four different species during summer and fall of 2018 and 2019. The mean (±SE) Hg concentration across all samples was 103 ± 3.43 ng/g of dry feather weight. Mercury concentration varied significantly among species, and by age and site in some species, but not by sex. Mean concentrations were nearly seven times higher in two omnivore species, American robin (Turdus migratorius) and European starling (Sturnus vulgaris), than in the two granivore species, American goldfinch (Spinus tristus) and house sparrow (Passer domesticus). Juveniles had higher feather Hg concentrations than adults in all species except American goldfinches - which feed their young primarily seeds, further supporting a role of diet in exposure. We also found a negative correlation between Hg concentration and body condition in American robins, but further research is needed to verify this relationship. While our sample concentrations do not exceed the threshold for sublethal effects, our findings provide insight into the patterns of Hg concentrations in terrestrial songbirds, which may help in understanding Hg exposure pathways, bioaccumulation and risks in terrestrial species.
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Affiliation(s)
| | - Dorothy L Zahor
- Eastern Michigan University Biology Department, Ypsilanti, MI, 48197, USA
| | - Kenneth J Glynn
- Eastern Michigan University Biology Department, Ypsilanti, MI, 48197, USA
| | - Lynne E Gratz
- Colorado College Environmental Studies Program, Colorado Springs, CO, 80907, USA
| | - Jamie M Cornelius
- Eastern Michigan University Biology Department, Ypsilanti, MI, 48197, USA.
- Oregon State University Department of Integrative Biology, Corvallis, OR, 97331, USA.
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16
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Nay C, Gelsleichter J, Hill SE, Hirons AC, Kerstetter DW. Accumulation of the Toxic Metal Mercury in Multiple Tissues of Marine-Associated Birds from South Florida. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 82:493-505. [PMID: 35460055 DOI: 10.1007/s00244-022-00932-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
One of the best studied global "hot spots" for ecological mercury (Hg) contamination is south Florida (USA), where elevated Hg concentrations in environmental media and regional wildlife were first described over thirty years ago. While Hg contamination has lessened in this region, it is still critical to monitor Hg uptake and potential risks in south Florida wildlife, especially in marine-associated birds, which are known to accumulate potentially toxic Hg levels. In this study, total Hg (THg) concentrations were measured in liver, kidney, muscle, and feathers of 101 individuals from seven species of south Florida birds: brown pelican Pelecanus occidentalis, double-crested cormorant Phalacrocorax auratus, herring gull Larus argentatus, laughing gull Leucophaeus atricilla, northern gannet Morus bassanus, royal tern Thalasseus maximus, and osprey Pandion halietus. A sizeable proportion of individuals (> 40%) were found to contain THg concentrations in internal tissues that exceeded estimated toxicity thresholds for Hg-related effects. Certain species, especially osprey, were found to exhibit a higher rate of threshold exceedances than others and should continue to be monitored for Hg-related effects in future studies. Feather THg concentrations exhibited a lower rate of toxicity threshold exceedances (12%) and were not significantly correlated with those in internal tissues in most cases, suggesting that they may not be well suited for monitoring Hg exposure in these species unless sources of data variation can be better understood. The results of the present study contribute significantly to our understanding of trends in Hg accumulation and Hg-related health risks in south Florida marine-associated birds.
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Affiliation(s)
- Caitlyn Nay
- Halmos College of Arts and Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
- School of Veterinary Medicine, St. George's University, University Centre, St. George's, Grenada
| | - James Gelsleichter
- Department of Biology, University of North Florida, 1 UNF Drive, Jacksonville, FL, 32224, USA.
| | - Sarah E Hill
- Department of Biology, University of North Florida, 1 UNF Drive, Jacksonville, FL, 32224, USA
| | - Amy C Hirons
- Halmos College of Arts and Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
| | - David W Kerstetter
- Halmos College of Arts and Sciences, Nova Southeastern University, 8000 North Ocean Drive, Dania Beach, FL, 33004, USA
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Mancuso K, Hodges KE, Grosselet M, Elliott JE, Alexander JD, Zanuttig M, Bishop CA. Mercury toxicity risk and corticosterone levels across the breeding range of the Yellow-breasted Chat. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:234-250. [PMID: 34973137 PMCID: PMC8901494 DOI: 10.1007/s10646-021-02510-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Mercury (Hg) is an environmental contaminant that can negatively impact human and wildlife health. For songbirds, Hg risk may be elevated near riparian habitats due to the transfer of methylmercury (MeHg) from aquatic to terrestrial food webs. We measured Hg levels in tail feathers sampled across the breeding range of the Yellow-breasted Chat (Icteria virens), a riparian songbird species of conservation concern. We assessed the risk of Hg toxicity based on published benchmarks. Simultaneously, we measured corticosterone, a hormone implicated in the stress response system, released via the hypothalamus-pituitary-adrenal axis. To better understand range-wide trends in Hg and corticosterone, we examined whether age, sex, subspecies, or range position were important predictors. Lastly, we examined whether Hg and corticosterone were correlated. Hg levels in chats were relatively low: 0.30 ± 0.02 µg/g dry weight. 148 out of 150 (98.6%) had Hg levels considered background, and 2 (1.6%) had levels considered low toxicity risk. Hg levels were similar between sexes and subspecies. Younger chats (<1 year) had higher Hg levels than older chats (>1 year). Hg levels were lowest in the northern and central portion of the eastern subspecies' range. Corticosterone concentrations in feathers averaged 3.68 ± 0.23 pg/mm. Corticosterone levels were similar between ages and sexes. Western chats had higher levels of corticosterone than eastern chats. Hg and corticosterone were not correlated, suggesting these low Hg burdens did not affect the activity of the hypothalamus-pituitary-adrenal axis. Altogether, the chat has low Hg toxicity risk across its breeding range, despite living in riparian habitats.
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Affiliation(s)
- Kristen Mancuso
- Department of Biology, University of British Columbia Okanagan, Kelowna, BC, Canada.
| | - Karen E Hodges
- Department of Biology, University of British Columbia Okanagan, Kelowna, BC, Canada
| | | | - John E Elliott
- Science and Technology Branch, Environment and Climate Change Canada, Delta, BC, Canada
| | | | - Michelle Zanuttig
- Science and Technology Branch, Environment and Climate Change Canada, Delta, BC, Canada
| | - Christine A Bishop
- Science and Technology Branch, Environment and Climate Change Canada, Delta, BC, Canada
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18
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Flores-Santin J, Burggren WW. Beyond the Chicken: Alternative Avian Models for Developmental Physiological Research. Front Physiol 2021; 12:712633. [PMID: 34744759 PMCID: PMC8566884 DOI: 10.3389/fphys.2021.712633] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/13/2021] [Indexed: 12/23/2022] Open
Abstract
Biomedical research focusing on physiological, morphological, behavioral, and other aspects of development has long depended upon the chicken (Gallus gallus domesticus) as a key animal model that is presumed to be typical of birds and generally applicable to mammals. Yet, the modern chicken in its many forms is the result of artificial selection more intense than almost any other domesticated animal. A consequence of great variation in genotype and phenotype is that some breeds have inherent aberrant physiological and morphological traits that may show up relatively early in development (e.g., hypertension, hyperglycemia, and limb defects in the broiler chickens). While such traits can be useful as models of specific diseases, this high degree of specialization can color general experimental results and affect their translational value. Against this background, in this review we first consider the characteristics that make an animal model attractive for developmental research (e.g., accessibility, ease of rearing, size, fecundity, development rates, genetic variation, etc.). We then explore opportunities presented by the embryo to adult continuum of alternative bird models, including quail, ratites, songbirds, birds of prey, and corvids. We conclude by indicating that expanding developmental studies beyond the chicken model to include additional avian groups will both validate the chicken model as well as potentially identify even more suitable avian models for answering questions applicable to both basic biology and the human condition.
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Affiliation(s)
- Josele Flores-Santin
- Facultad de Ciencias, Biologia, Universidad Autónoma del Estado de Mexico, Toluca, Mexico
| | - Warren W Burggren
- Developmental Integrative Biology Research Group, Department of Biological Sciences, University of North Texas Denton, Denton, TX, United States
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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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Han B, García‐Mendoza D, van den Berg H, van den Brink NW. Modulatory Effects of Mercury (II) Chloride (HgCl 2 ) on Chicken Macrophage and B-Lymphocyte Cell Lines with Viral-Like Challenges In Vitro. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:2813-2824. [PMID: 34288095 PMCID: PMC9291928 DOI: 10.1002/etc.5169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 06/28/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg) is a toxic trace metal ubiquitously distributed in the environment. Inorganic mercury (as HgCl2 ) can cause immunotoxicity in birds, but the mechanisms of action are still not fully resolved, especially with respect to responses to viral infections. To investigate the potential immunomodulatory effects of Hg2+ on specific cell types of the avian immune system, chicken macrophage (HD-11) and B-lymphocyte (DT40) cell lines were applied as in vitro models for the innate and adaptive immune systems, respectively. The cells were stimulated with synthetic double-stranded RNA, which can be recognized by toll-like receptor-3 to mimic a viral infection. The Hg2+ showed concentration-dependent cytotoxicity in both cell lines, with similar median effect concentrations at 30 µM. The cytotoxicity of Hg2+ was closely related to glutathione (GSH) depletion and reactive oxygen species induction, whereas the de novo synthesis of GSH acted as a primary protective strategy. Nitric oxide produced by activated macrophages was strongly inhibited by Hg2+ , and was also influenced by cellular GSH levels. Cell proliferation, gene expression of microRNA-155, and cellular IgM levels in B cells were decreased at noncytotoxic Hg2+ concentrations. The secretion of antiviral interferon-α was induced by Hg2+ in both cell lines. Overall, our results suggest that Hg2+ exposure can cause immunomodulatory effects in birds by disrupting immune cell proliferation and cytokine production, and might result in disorders of the avian immune system. Environ Toxicol Chem 2021;40:2813-2824. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Biyao Han
- Division of Toxicology, Wageningen University and ResearchWageningenThe Netherlands
| | - Diego García‐Mendoza
- Division of Toxicology, Wageningen University and ResearchWageningenThe Netherlands
| | - Hans van den Berg
- Division of Toxicology, Wageningen University and ResearchWageningenThe Netherlands
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21
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Blood Toxic Elements and Effects on Plasma Vitamins and Carotenoids in Two Wild Bird Species: Turdus merula and Columba livia. TOXICS 2021; 9:toxics9090219. [PMID: 34564370 PMCID: PMC8473200 DOI: 10.3390/toxics9090219] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/30/2021] [Accepted: 09/02/2021] [Indexed: 12/14/2022]
Abstract
Birds have historically suffered adverse effects by toxic elements, such as As, Pb, Hg, and Cd. However, reports on exposure to a wide range of elements, including rare earth elements and other minor elements of emerging concern, and the potential consequences for wildlife are still scarce. This study evaluates blood concentrations of 50 elements and their related effects on lutein and vitamin levels in the Eurasian blackbird (Turdus merula) and wild rock pigeon (Columba livia), inhabiting different scenarios of contaminant exposure. Blood concentrations of As, Cd, and Pb (and Mn in T. merula) were increased in both species captured in the mining area, compared to the control site. T. merula also showed increased As, Cd, and Pb concentrations in blood in the agricultural–urban area, as compared to the control area, together with the highest Hg levels, which could be related to agricultural practices and industrial activities. Decreases of 33 and 38% in the plasma retinol levels in T. merula inhabiting the mining and the agricultural–urban areas, respectively, as compared to the control site, were associated with increased Pb, As, and Cd exposure. This could be due to a metal-driven suppressive effect in retinol metabolism and/or its over-use for coping with metal-related oxidative stress.
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22
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Mercury contamination of seabird and sea duck eggs from high Arctic Greenland. Polar Biol 2021. [DOI: 10.1007/s00300-021-02864-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Louzon M, Devalloir Q, Gimbert F, Pauget B, Rieffel D, de Vaufleury A. From bioavailability to risk assessment of polluted soil using snails: link between excess transfer and inhibition of sexual maturation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:17343-17354. [PMID: 33398759 DOI: 10.1007/s11356-020-11556-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
An accurate assessment of the environmental risk of soils contaminated by metal(loid)s (MEs) requires quantifying exposure and knowing the toxicity of contaminants transferred to biota. For this purpose, two indices have been developed with the bioindicator Cantareus aspersus to assess exposure (SET: sum of the excess of transfer) and risk (ERITME: evaluation of the risk of the transferred metal elements) of multi-contaminated soils. If the SET and ERITME indices allow characterization of exposure and risk based on unspecific toxicity points, then the link between these indices and real effects on some toxicological endpoints, such as growth or sexual maturation, remains to be demonstrated. For this purpose, sub-adult snails were exposed for 28 days to 38 ME-contaminated soils. Relationships between the SET and/or ERITME indices and health alterations in C. aspersus were determined using Spearman correlations, linear regressions, univariate regression trees, and kinetic models. Relationships were determined between the values of the SET and ERITME indices, bioaccumulation as an indicator of ME bioavailability, and the alteration in physiological endpoints, such as the shell development used as a non-invasive indicator of sexual maturation. The results enabled the determination of three levels of risk according to the differences in reaching sexual maturity: no risk, uncertain, and proven risk depended on whether the value of ERITME was below, in, or beyond the interval [2574-22720], respectively. This study provides the first benchmarks with the SET and ERITME indices to interpret the risk of contaminated soils to snails and to relate the environmental and toxicological bioavailability of ME mixtures.
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Affiliation(s)
- Maxime Louzon
- UMR CNRS 6249 Chrono-Environment, University of Franche-Comté, 16 route de Gray, 25030, Besançon Cedex, France.
| | - Quentin Devalloir
- UMR CNRS 6249 Chrono-Environment, University of Franche-Comté, 16 route de Gray, 25030, Besançon Cedex, France
| | - Frédéric Gimbert
- UMR CNRS 6249 Chrono-Environment, University of Franche-Comté, 16 route de Gray, 25030, Besançon Cedex, France
| | - Benjamin Pauget
- TESORA, Le Visium, 22 avenue Aristide Briand, 94110, Arcueil, France
| | - Dominique Rieffel
- UMR CNRS 6249 Chrono-Environment, University of Franche-Comté, 16 route de Gray, 25030, Besançon Cedex, France
| | - Annette de Vaufleury
- UMR CNRS 6249 Chrono-Environment, University of Franche-Comté, 16 route de Gray, 25030, Besançon Cedex, France
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24
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Ma Y, Hobson KA, Kardynal KJ, Guglielmo CG, Branfireun BA. Inferring spatial patterns of mercury exposure in migratory boreal songbirds: Combining feather mercury and stable isotope (δ 2H) measurements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 762:143109. [PMID: 33162143 DOI: 10.1016/j.scitotenv.2020.143109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 06/11/2023]
Abstract
Migratory songbirds breeding in the Canadian Boreal forest are exposed to mercury (Hg), a potent neurotoxin that impairs avian health, however, the degree of exposure depends on many factors. As breeding grounds are geographically remote and vast, the measurement of Hg in individual birds is impractical particularly at large spatial scales. Here, we present a Canada-wide dataset of nearly 2000 migratory songbirds that were used to assess summer Hg exposure of 15 songbird species sampled during fall migration. We measured Hg concentrations in tail feathers and related those to dietary guild, geographic capture location, age, sex and probable breeding ground locations using feather δ2H. Overall mean (±SE) feather Hg concentration was 1.49 ± 0.03 μg/g (N = 1946): however, a clear geographic gradient in feather Hg concentrations emerged being highest in East and lowest in West. Dietary guild was the next strongest predictor of feather Hg with insectivorous songbirds in Eastern Canada at particular risk due to Hg exposure on summer breeding grounds. This broad-scale assessment of Hg exposure in migratory songbirds in Canada can be used to guide future studies on finer-scale determinants of Hg exposure in birds.
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Affiliation(s)
- Yanju Ma
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Keith A Hobson
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Science and Technology Branch, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Kevin J Kardynal
- Science and Technology Branch, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Christopher G Guglielmo
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Advanced Facility for Avian Research, University of Western Ontario, London, Ontario, Canada
| | - Brian A Branfireun
- Department of Biology, University of Western Ontario, London, Ontario, Canada; Centre for Environment and Sustainability, University of Western Ontario, London, Ontario, Canada.
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25
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Sauer AK, Driscoll CT, Evers DC, Adams EM, Yang Y. Mercury exposure in songbird communities along an elevational gradient on Whiteface Mountain, Adirondack Park (New York, USA). ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1830-1842. [PMID: 32232628 DOI: 10.1007/s10646-020-02175-7] [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: 02/07/2020] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) is a potent neurotoxin that biomagnifies within food webs. Adverse effects have been documented for avian species related to exposure of elevated Hg levels. High elevation, boreal forests generally receive higher atmospheric Hg deposition and regional studies have subsequently identified elevated blood Hg concentrations in songbird species inhabiting these montane habitats. The overall goal of this study was to investigate spatial and seasonal Hg exposure patterns in songbird species along an elevational gradient on Whiteface Mountain in the Adirondack Park of New York State. Songbird blood samples were collected from June-July in 2009 and 2010 along an elevational gradient at 13 study plots (450-1400 m) with a focus on Catharus thrushes, including the hermit thrush, Swainson's thrush, and Bicknell's thrush. The main results of this study documented: (1) an overall linear pattern of increasing blood Hg concentrations with increasing elevation, with additional analysis suggesting a nonlinear elevational pattern of increasing blood Hg concentrations to 1075 m, followed by decreasing concentrations thereafter, for all Catharus thrush species across the elevational gradient; and (2) an overall nonlinear seasonal pattern of increasing, followed by decreasing blood Hg concentrations across target species. Avian exposure patterns appear driven by elevated atmospheric Hg deposition and increased methylmercury bioavailability within high elevation habitats as compared with low elevation forests. Seasonal patterns are likely influenced by a combination of complex and dynamic variables related to dietary selection and annual molting cycles. Considering that few high elevation analyses have been conducted within the context of regional songbird research, this project complements the results from similar studies and highlights the need for further monitoring efforts to investigate environmental Hg contamination within avian communities.
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Affiliation(s)
- Amy K Sauer
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA.
- Department of Biology, Syracuse University, Syracuse, NY, 13244, USA.
| | - Charles T Driscoll
- Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - David C Evers
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Evan M Adams
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Yang Yang
- Department of Forest and Natural Resources Management, State University of New York College of Environmental Science and Forestry, Syracuse, NY, 13210, USA
- Sierra Nevada Research Institute, University of California Merced, Merced, CA, 95340, USA
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Sauer AK, Driscoll CT, Evers DC, Adams EM, Yang Y. Mercury exposure in songbird communities within Sphagnum bog and upland forest ecosystems in the Adirondack Park (New York, USA). ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1815-1829. [PMID: 32037482 DOI: 10.1007/s10646-019-02142-x] [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: 11/24/2019] [Indexed: 06/10/2023]
Abstract
Mercury (Hg) is a potent neurotoxin that biomagnifies within both aquatic and terrestrial food webs resulting in adverse physiological and reproductive effects on impacted wildlife populations, including songbird communities. Due to reducing conditions, wetland ecosystems promote the formation of methylmercury. Regional studies have documented elevated blood mercury concentrations in songbird species within these habitat types. The overall goal of this research was to examine spatial and seasonal patterns of Hg exposure for targeted songbird species within Sphagnum bog wetland systems and compare these patterns with adjacent upland forests in the Adirondack Park of New York State. Project sampling was conducted at study plots within four Sphagnum bog and associated upland forest sites from May - August during the 2008, 2009, and 2011 field seasons. The overall results documented: (1) blood Hg concentrations were elevated in songbird species inhabiting Sphagnum bog habitats as compared to nearby upland forest species; (2) target species within each habitat type exhibited consistent species-level patterns in blood Hg concentrations at each study site; and (3) no seasonal change in blood Hg concentrations within Sphagnum bog habitats was documented, but an increasing, followed by a decreasing seasonal pattern in mercury exposure was detected for upland forest species. Habitat type was demonstrated to influence avian Hg exposure levels. Moreover, Sphagnum bog ecosystems may be contributing to elevated Hg concentrations in biota within the surrounding environment. Seasonal patterns for blood Hg concentrations were found to vary between habitat type and are likely related to a combination of variables including habitat-driven Hg concentrations in prey items, seasonal dietary shifts, and annual molting cycles. This project emphasizes the importance of prioritizing future research efforts within identified high Hg habitat types, specifically wetland systems, to better characterize associated avian exposure levels, estimate the spatial extent of wetland systems on the surrounding environment, and identify locations of potential biological hotspots across the Adirondack Park.
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Affiliation(s)
- Amy K Sauer
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA.
- Department of Biology, Syracuse University, Syracuse, NY, 13244, USA.
| | - Charles T Driscoll
- Department of Civil and Environmental Engineering, Syracuse University, Syracuse, NY, 13244, USA
| | - David C Evers
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Evan M Adams
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Yang Yang
- Department of Forest and Natural Resources Management, State University of New York College of Environmental Science and Forestry, Syracuse, NY, 13210, USA
- Sierra Nevada Research Institute, University of California Merced, Merced, CA, 95340, USA
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Zabala J, Trexler JC, Jayasena N, Frederick P. Early Breeding Failure in Birds Due to Environmental Toxins: A Potentially Powerful but Hidden Effect of Contamination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:13786-13796. [PMID: 33103894 DOI: 10.1021/acs.est.0c04098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Toxin emissions and legacies are major global issues affecting many species through, among other effects, endocrine disruption and reproductive impairment. Assessment of toxin risk to wildlife focuses mostly on offspring-related metrics, while the lack of breeding initiation or early breeding failure has received less attention. We tested whether exposure to methyl mercury (MeHg) results in early breeding failure and reduced number of breeding birds using observational and experimental data. We used 21 years of numbers of breeding pairs of colonially breeding wild Great Egrets (Ardea alba) in response to annual and geographical variation upon exposure to environmental MeHg. After controlling for food availability, we found a strong negative association between MeHg exposure and the number of breeding Great Egrets. We report reductions of >50% in breeding numbers under exposure levels otherwise associated with <20% reduction in post-egg-laying breeding success. Experimental exposure of White Ibises (Eudocimus albus) to MeHg also caused early breeding failure and a ∼20% reduction in breeding numbers at environmentally relevant exposures. The demographic consequences of reductions in breeding pairs are additive to known and typically studied impairments in postlaying reproductive success. Net demographic effects of exposure to endocrine disruptors may often be strongly underestimated if early breeding failure is not measured.
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Affiliation(s)
- Jabi Zabala
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, United States
| | - Joel C Trexler
- Department of Biological Sciences, Florida International University, North Miami, Florida 33181, United States
| | - Nilmini Jayasena
- Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya 20400, Sri Lanka
| | - Peter Frederick
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611, United States
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28
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Scoville SA, Varian-Ramos CW, Adkins GA, Swaddle JP, Saha MS, Cristol DA. Mercury delays cerebellar development in a model songbird species, the zebra finch. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1128-1137. [PMID: 32827288 DOI: 10.1007/s10646-020-02270-9] [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: 08/11/2020] [Indexed: 06/11/2023]
Abstract
Mercury exposure can disrupt development of the cerebellum, part of the brain essential for coordination of movement through a complex environment, including flight. In precocial birds, such as fowl, the cerebellum develops embryonically, and the chick is capable of leaving the nest within hours of hatching. However, most birds, including all songbirds, are altricial, and spend weeks in the nest between hatching and fledging. The objective of this study was to describe the normal development of the cerebellum in a model altricial songbird so as to determine the effect of exposure to mercury on cerebellar maturation. Adult zebra finch (Taeniopygia guttata) pairs were fed either a control diet, or a diet augmented with one of four treatment-levels of methylmercury (0.3-2.4 μg/g wet weight), and their offspring, the subjects of this study, were fed the same diet by parents. We documented, for the first time, the schedule of cerebellar development in an altricial bird, and compared stages of development among methylmercury-exposed groups. For all treatments of methylmercury, the age of completion of cellular migration was later than for control zebra finches, indicating a delay in cerebellar maturation. Displaced (heterotopic) Purkinje neurons, a pathology typical of methylmercury exposure in developing vertebrate brains, were more numerous in methylmercury-exposed birds, and persisted at least until the age of independence. Delays in maturation of the cerebellum could delay fledging in altricial bird species, with potential serious implications for the fitness of exposed individuals, as predation rates in the nest are often very high.
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Affiliation(s)
- Sheila A Scoville
- Department of Pathology and Anatomy, Eastern Virginia Medical School, Norfolk, VA, 23507, USA
| | - Claire W Varian-Ramos
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
- Biology Department, Colorado State University - Pueblo, Pueblo, CO, 81001, USA
| | - G Alden Adkins
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
- University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - John P Swaddle
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
| | - Margaret S Saha
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA
| | - Daniel A Cristol
- Department of Biology, William & Mary, Williamsburg, VA, 23185, USA.
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29
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Kardynal KJ, Jardine TD, Génier CSV, Bumelis KH, Mitchell GW, Evans M, Hobson KA. Mercury exposure to swallows breeding in Canada inferred from feathers grown on breeding and non-breeding grounds. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:876-891. [PMID: 32656653 DOI: 10.1007/s10646-020-02249-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Aerial insectivorous birds such as swallows have been the steepest declining groups of birds in North America over the last 50 years but whether such declines are linked to contaminants has not been examined. We sampled feathers from five species of swallow at multiple locations to assess total mercury [THg] exposure for adults during the non-breeding season, and for juveniles on the breeding grounds. We assessed Hg exposure to juvenile birds in crop- and grass-dominated landscapes to determine if land-use practices influenced feather [THg]. We assayed feathers for stable isotopes (δ2H, δ13C, δ15N) as proxies for relative habitat use and diet to determine their potential influence on feather [THg]. Feather [THg] was highest in adult bank swallows (Riparia riparia) and purple martins (Progne subis) from Saskatchewan and adult cliff swallows (Petrochelidon pyrrhonota) from western regions, indicating differential exposure to Hg on the non-breeding grounds. Juvenile bank, barn (Hirundo rustica) and tree (Tachycineta bicolor) swallows had lower feather [THg] in crop-dominated landscapes than grass-dominated landscapes in Saskatchewan, potentially resulting from lower use of wetland-derived insects due to wetland drainage and intensive agriculture. Feather [THg] was related to juvenile feather stable isotopes for several species, suggesting complex interactions with diet and environmental factors. Many individuals had feather [THg] values >2 µg/g, a threshold at which deleterious effects may occur. Our findings indicate differential Hg exposure among species of swallow, regions and land-uses and highlight the need for additional research to determine dietary and finer-scale land-use impacts on individual species and populations.
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Affiliation(s)
- Kevin J Kardynal
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada.
| | - Timothy D Jardine
- School of Environment and Sustainability, Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3, Canada
| | - Corrine S V Génier
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Kaelyn H Bumelis
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Greg W Mitchell
- Environment and Climate Change Canada, 1125 Colonel By Drive, Ottawa, ON, K1A 0H3, Canada
| | - Marlene Evans
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada
| | - Keith A Hobson
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
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Badry A, Krone O, Jaspers VLB, Mateo R, García-Fernández A, Leivits M, Shore RF. Towards harmonisation of chemical monitoring using avian apex predators: Identification of key species for pan-European biomonitoring. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 731:139198. [PMID: 32422436 DOI: 10.1016/j.scitotenv.2020.139198] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/01/2020] [Accepted: 05/01/2020] [Indexed: 05/09/2023]
Abstract
Biomonitoring in raptors can be used to study long-term and large-scale changes in environmental pollution. In Europe, such monitoring is needed to assess environmental risks and outcomes of chemicals regulation, which is harmonised across the European Union. To be effective, the most appropriate sentinels need to be monitored. Our aim was to identify which European raptor species are the likely most appropriate biomonitors when pollutant quantification is based on analysing tissues. Our current study was restricted to terrestrial exposure pathways and considered four priority pollutant groups: toxic metals (lead and mercury), anticoagulant rodenticides, pesticides and medicinal products. We evaluated information on the distribution and key ecological traits (food web, foraging trait, diet, preferred habitat, and migratory behaviour) of European raptors to identify the most appropriate sentinel species. Common buzzard (Buteo buteo) and/or tawny owl (Strix aluco) proved the most suitable candidates for many of the pollutants considered. Moreover, they are abundant in Europe, enhancing the likelihood that samples can be collected. However, other species may be better sentinels for certain pollutants, such as the golden eagle (Aquila chrysaetos) for lead, the northern goshawk (Accipiter gentilis) for mercury across areas including Northern Europe, and vultures (where they occur in Europe) are likely best suited for monitoring non-steroidal anti-inflammatory drugs (NSAIDs). Overall, however, we argue the selection of candidate species for widescale monitoring of a range of pollutants can be reduced to very few raptor species. We recommend that the common buzzard and tawny owl should be the initial focus of any pan-European raptor monitoring. The lack of previous widespread monitoring using these species suggests that their utility as sentinels for environmnetal pollution has not been widely recognised. Finally, although the current study focussed on Europe, our trait-based approach for identifying raptor biomonitors can be applied to other continents and contaminants.
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Affiliation(s)
- Alexander Badry
- Leibniz Institute for Zoo and Wildlife Research, Department of Wildlife Diseases, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany.
| | - Oliver Krone
- Leibniz Institute for Zoo and Wildlife Research, Department of Wildlife Diseases, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany
| | - Veerle L B Jaspers
- Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, 7491 Trondheim, Norway
| | - Rafael Mateo
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo s/n, 13071 Ciudad Real, Spain
| | - Antonio García-Fernández
- Toxicology and Risk Assessment Group, Department of Health Sciences, University of Murcia, Espinardo Campus, 30100 Murcia, Spain
| | - Madis Leivits
- Chair of Clinical Veterinary Medicine, Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, 51006 Tartu, Estonia
| | - Richard F Shore
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg LA1 4AP, UK
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Grieves LA, Bottini CLJ, Branfireun BA, Bernards MA, MacDougall-Shackleton SA, MacDougall-Shackleton EA. Food stress, but not experimental exposure to mercury, affects songbird preen oil composition. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:275-285. [PMID: 32036507 DOI: 10.1007/s10646-020-02171-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/28/2020] [Indexed: 06/10/2023]
Abstract
Mercury is a global pollutant and potent neurotoxic metal. Its most toxic and bioavailable form, methylmercury, can have both lethal and sublethal effects on wildlife. In birds, methylmercury exposure can disrupt behavior, hormones, the neuroendocrine system, and feather integrity. Lipid-rich tissues and secretions may be particularly susceptible to disruption by lipophilic contaminants such as methylmercury. One such substance is feather preen oil, a waxy secretion of the uropygial gland that serves multiple functions including feather maintenance, anti-parasitic defense, and chemical signaling. If methylmercury exposure alters preen oil composition, it could have cascading effects on feather quality, susceptibility to ectoparasites, and mate choice and other social behaviors. We investigated whether exposure to methylmercury, either alone or in association with other stressors, affects preen oil chemical composition. We used a two-factor design to expose adult song sparrows (Melospiza melodia) to an environmentally relevant dietary dose of methylmercury and/or to another stressor (unpredictable food supply) for eight weeks. The wax ester composition of preen oil changed significantly over the 8-week experimental period. This change was more pronounced in the unpredictable food treatment, regardless of dietary methylmercury. Contrary to our prediction, we found no main effect of methylmercury exposure on preen oil composition, nor did methylmercury interact with unpredictable food supply in predicting the magnitude of chemical shifts in preen oil. While it remains critical to study sublethal effects of methylmercury on wildlife, our findings suggest that the wax ester composition of preen oil is robust to environmentally relevant doses of this contaminant.
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Affiliation(s)
- L A Grieves
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada.
| | - C L J Bottini
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - B A Branfireun
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - M A Bernards
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
| | - S A MacDougall-Shackleton
- Department of Psychology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5C2, Canada
| | - E A MacDougall-Shackleton
- Department of Biology, The University of Western Ontario, 1151 Richmond St., London, ON, N6A 5B7, Canada
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32
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English MD, Robertson GJ, O’Driscoll NJ, Klapstein SJ, Peck LE, Mallory ML. Variation in isotopic niche, digestive tract morphology, and mercury concentrations in two sympatric waterfowl species wintering in Atlantic Canada. Facets (Ott) 2020. [DOI: 10.1139/facets-2019-0056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Sympatric communities of organisms may exploit different ecological niches to avoid intra- and interspecific competition. We examined the isotopic niches of American black ducks ( Anas rubripes) and mallards ( A. platyrhynchos) wintering in coastal and urban areas of Atlantic Canada and compared isotopic niche with digestive tract morphologies and blood mercury (Hg) concentrations. Isotopic niche width (for δ13C and δ15N) varied between the three groups of ducks studied, with coastally foraging black ducks exhibiting the widest isotopic niche, followed by coastal mallards, while urban feeding black ducks had a narrow isotopic niche. These niche differences had physical and chemical consequences: coastal black ducks had longer digestive tracts, a larger range in gizzard sizes, and higher and more variable Hg concentrations than urban black ducks and coastal mallards. This plasticity in ecological niche may reduce competition among and within species, and subsequently explain why winter numbers of black ducks and mallards have increased in Atlantic Canada.
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Affiliation(s)
| | - Gregory J. Robertson
- Wildlife Research Division, Environment and Climate Change Canada, 6 Bruce Street, Mount Pearl, NL A1N 4T3, Canada
| | - Nelson J. O’Driscoll
- Department of Earth and Environmental Sciences, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - Sara J. Klapstein
- Department of Earth and Environmental Sciences, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - Liam E. Peck
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - Mark L. Mallory
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
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33
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Zabala J, Rodriguez-Jorquera IA, Orzechowski SC, Frederick P. Non-lethal sampling of avian indicators reveals reliable geographic signals of mercury despite highly dynamic patterns of exposure in a large wetland. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 247:577-585. [PMID: 30708320 DOI: 10.1016/j.envpol.2019.01.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 01/10/2019] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Mercury is a global contaminant with special relevance for aquatic food webs, where biomagnification can result in strong effects on apex predators. Non-lethal sampling of tissues such as blood and feathers is often used to assess mercury risk and spatiotemporal variability of mercury exposure on avian populations. However, the assumption that samples from individuals within a population are representative of local mercury exposure underpins those approaches. While this assumption may be justified, it is rarely expressed quantitatively. Further, the stability of the tissue/exposure relationship over time or space may depend on the sampling medium used, since some tissues and age classes may be better at reflecting local or short-term changes in exposure. Here, we present analyses of mercury concentrations from three tissues (albumen, blood and feathers) of the same individual great egret (Ardea alba) nestlings from breeding colonies in the Florida Everglades collected over three consecutive years. The interaction of year and colony location explained at least 50% of the observed variation in mercury concentration in all the sampled tissues. Annual colony-wide average Hg concentrations in any of the sampled tissues correlated with average Hg concentrations in the other two tissues from the same colony (R2 > 0.53 in every case), while concentrations in albumen, blood and feathers from the same individual correlated poorly (R2 < 0.23 in every case). We suggest that despite high variation between and within individuals of the same colony, annual colony-averaged mercury concentrations in albumen, nestling blood or feathers can be representative indicators of annual geographic differences in mercury exposure. These results support the use of non-lethal sampling of nestling tissues to reflect local mercury exposure over large spatial scales.
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Affiliation(s)
- Jabi Zabala
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, USA
| | - Ignacio A Rodriguez-Jorquera
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, USA; 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, FL, 32611, USA
| | - Peter Frederick
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, 32611, USA.
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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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Scheiber IBR, Weiß BM, de Jong ME, Braun A, van den Brink NW, Loonen MJJE, Millesi E, Komdeur J. Stress behaviour and physiology of developing Arctic barnacle goslings ( Branta leucopsis) is affected by legacy trace contaminants. Proc Biol Sci 2018; 285:20181866. [PMID: 30963902 PMCID: PMC6304058 DOI: 10.1098/rspb.2018.1866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/12/2018] [Indexed: 11/23/2022] Open
Abstract
Natural populations are persistently exposed to environmental pollution, which may adversely impact animal physiology and behaviour and even compromise survival. Responding appropriately to any stressor ultimately might tip the scales for survival, as mistimed behaviour and inadequate physiological responses may be detrimental. Yet effects of legacy contamination on immediate physiological and behavioural stress coping abilities during acute stress are virtually unknown. Here, we assessed these effects in barnacle goslings ( Branta leucopsis) at a historical coal mine site in the Arctic. For three weeks we led human-imprinted goslings, collected from nests in unpolluted areas, to feed in an abandoned coal mining area, where they were exposed to trace metals. As control we led their siblings to feed on clean grounds. After submitting both groups to three well-established stress tests (group isolation, individual isolation, on-back restraint), control goslings behaved calmer and excreted lower levels of corticosterone metabolites. Thus, legacy contamination may decisively change stress physiology and behaviour in long-lived vertebrates exposed at a young age.
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Affiliation(s)
- Isabella B. R. Scheiber
- Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG Groningen, The Netherlands
- Department of Behavioural Biology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
| | - Brigitte M. Weiß
- Behavioural Ecology Research Group, University of Leipzig, 04103 Leipzig, Germany
- Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - Margje E. de Jong
- Arctic Centre, University of Groningen, 9718 CW Groningen, The Netherlands
| | - Anna Braun
- Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Nico W. van den Brink
- Department of Toxicology, Wageningen University, 6700 EA Wageningen, The Netherlands
| | | | - Eva Millesi
- Department of Behavioural Biology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria
| | - Jan Komdeur
- Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG Groningen, The Netherlands
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Chételat J, Hickey MBC, Poulain AJ, Dastoor A, Ryjkov A, McAlpine D, Vanderwolf K, Jung TS, Hale L, Cooke ELL, Hobson D, Jonasson K, Kaupas L, McCarthy S, McClelland C, Morningstar D, Norquay KJO, Novy R, Player D, Redford T, Simard A, Stamler S, Webber QMR, Yumvihoze E, Zanuttig M. Spatial variation of mercury bioaccumulation in bats of Canada linked to atmospheric mercury deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 626:668-677. [PMID: 29396333 DOI: 10.1016/j.scitotenv.2018.01.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/05/2018] [Accepted: 01/06/2018] [Indexed: 06/07/2023]
Abstract
Wildlife are exposed to neurotoxic mercury at locations distant from anthropogenic emission sources because of long-range atmospheric transport of this metal. In this study, mercury bioaccumulation in insectivorous bat species (Mammalia: Chiroptera) was investigated on a broad geographic scale in Canada. Fur was analyzed (n=1178) for total mercury from 43 locations spanning 20° latitude and 77° longitude. Total mercury and methylmercury concentrations in fur were positively correlated with concentrations in internal tissues (brain, liver, kidney) for a small subset (n=21) of little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus), validating the use of fur to indicate internal mercury exposure. Brain methylmercury concentrations were approximately 10% of total mercury concentrations in fur. Three bat species were mainly collected (little brown bats, big brown bats, and northern long-eared bats [M. septentrionalis]), with little brown bats having lower total mercury concentrations in their fur than the other two species at sites where both species were sampled. On average, juvenile bats had lower total mercury concentrations than adults but no differences were found between males and females of a species. Combining our dataset with previously published data for eastern Canada, median total mercury concentrations in fur of little brown bats ranged from 0.88-12.78μg/g among 11 provinces and territories. Highest concentrations were found in eastern Canada where bats are most endangered from introduced disease. Model estimates of atmospheric mercury deposition indicated that eastern Canada was exposed to greater mercury deposition than central and western sites. Further, mean total mercury concentrations in fur of adult little brown bats were positively correlated with site-specific estimates of atmospheric mercury deposition. This study provides the largest geographic coverage of mercury measurements in bats to date and indicates that atmospheric mercury deposition is important in determining spatial patterns of mercury accumulation in a mammalian species.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada.
| | | | - Alexandre J Poulain
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Ashu Dastoor
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Andrei Ryjkov
- Air Quality Research Division, Environment and Climate Change Canada, Dorval, Quebec H9P 1J3, Canada
| | - Donald McAlpine
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada
| | - Karen Vanderwolf
- New Brunswick Museum, Saint John, New Brunswick E2K 1E5, Canada; Canadian Wildlife Federation, Kanata, Ontario K2M 2W1, Canada
| | - Thomas S Jung
- Yukon Department of Environment, Whitehorse, Yukon Territory Y1A 2C6, Canada
| | - Lesley Hale
- Ontario Ministry of Natural Resources & Forestry, Peterborough, Ontario K9J 8M5, Canada
| | - Emma L L Cooke
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | - Dave Hobson
- Alberta Environment and Parks, Edson, Alberta T7E 1T2, Canada
| | - Kristin Jonasson
- Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Laura Kaupas
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Sara McCarthy
- Wildlife Division, Fisheries and Land Resources, Goose Bay, Newfoundland and Labrador A0P 1E0, Canada
| | - Christine McClelland
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
| | | | - Kaleigh J O Norquay
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Richard Novy
- Golder Associates Ltd., Calgary, Alberta T2A 7W5, Canada
| | | | - Tony Redford
- Animal Health Centre, BC Ministry of Agriculture, Abbotsford, British Columbia V3G 2M3, Canada
| | - Anouk Simard
- Direction de l'expertise sur la faune terrestre, l'herpétofaune et l'avifaune, Ministère des Forêts, de la Faune et des Parcs, Québec, Quebec G1S 4X4, Canada
| | - Samantha Stamler
- Alberta Environment and Parks, Edmonton, Alberta T6H 4P2, Canada
| | - Quinn M R Webber
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba R3B 2G3, Canada
| | - Emmanuel Yumvihoze
- Biology Department, Faculty of Science, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Michelle Zanuttig
- Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario K1A 0H3, Canada
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Morran SAM, Elliott JE, Young JML, Eng ML, Basu N, Williams TD. Ecologically-relevant exposure to methylmercury during early development does not affect adult phenotype in zebra finches (Taeniopygia guttata). ECOTOXICOLOGY (LONDON, ENGLAND) 2018; 27:259-266. [PMID: 29313303 DOI: 10.1007/s10646-017-1890-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/16/2017] [Indexed: 06/07/2023]
Abstract
Methylmercury causes behavioural and reproductive effects in adult mammals via early developmental exposure. Similar studies in birds are limited and mostly focussed on aquatic systems, but recent work has reported high blood mercury concentrations in terrestrial, passerine songbirds. We used the zebra finch (Taeniopygia guttata) as a model to explore the long-term effects of early developmental exposure to methylmercury exposure. Chicks were dosed orally with either the vehicle control, 0.0315 µg Hg/g bw/day, or 0.075 µg Hg/g bw/day throughout the nestling period (days 1-21 post-hatching). We then measured (a) short-term effects on growth, development, and behaviour (time to self-feeding, neophobia) until 30 days of age (independence), and (b) long-term effects on courtship behaviour and song (males) and reproduction (females) once methylmercury-exposed birds reached sexual maturity (90 days post-hatching). High methylmercury treated birds had mean blood mercury of 0.734 ± 0.163 µg/g at 30 days post-hatching, within the range of values reported for field-sampled songbirds at mercury contaminated sites. However, there were no short-term effects of treatment on growth, development, and behaviour of chicks, and no long-term effects on courtship behaviour and song in males or reproductive performance in females. These results suggest that the nestling period is not a critical window for sensitivity to mercury exposure in zebra finches. Growing nestlings can reduce blood mercury levels through somatic growth and depuration into newly growing feathers, and as a result they might actually be less susceptible compared to adult birds receiving the same level of exposure.
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Affiliation(s)
- Spencer A M Morran
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - John E Elliott
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- Environment and Climate Change Canada, Science & Technology Branch, Pacific Wildlife Research Centre, Delta, BC, Canada
| | - Jessica M L Young
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Margaret L Eng
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- University of Saskatchewan, Saskatoon, SK, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Ste. Anne de Bellevue, QC, Canada
| | - Tony D Williams
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
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Aazami J, KianiMehr N. Survey of heavy metals in internal tissues of Great cormorant collected from southern wetlands of Caspian Sea, Iran. ENVIRONMENTAL MONITORING AND ASSESSMENT 2017; 190:52. [PMID: 29288418 DOI: 10.1007/s10661-017-6433-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/19/2017] [Indexed: 06/07/2023]
Abstract
The level of mercury, iron, copper, and zinc was measured in 18 Great cormorants (Phalacrocorax carbo) collected from Anzali and Gomishan wetlands in the south of the Caspian Sea. The mean level of metals in dried tissues of the muscle, liver, and kidney was 2.26, 5.71, 3.79-Hg; 943.54, 379.97, 348.05-Fe; 42.64, 14.78, 60.79-Cu, and 71.97, 134.63, 77.82-Zn, respectively (mg/kg). There was no significant different between genders in terms of accumulation of metals, except for copper in the kidney. The results of Pearson correlation showed a positive and strong relationship between the fat in the liver and mercury (r = 0.95, R2 = 0.90). Also, there was a significant difference between the values of all metals with the allowable limits presented in EPA, WHO, and CCME, where all of values were above standard levels. Thus, as the muscles of the bird are sometimes eaten by humans, this result is a serious warning. Nevertheless, the relatively high levels of heavy metals accumulated in different tissues of Great cormorant at that time are a result of their high weight and nourishment they have at the terminal days of their migration due to lack of natural physical activity. Regarding to the importance of heavy metals in birds, we suggest the same study to be conducted on the species in other seasons and wetlands.
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Affiliation(s)
- Jaber Aazami
- Department of Environment Sciences, Faculty of Sciences, University of Zanjan, Zanjan, Iran.
| | - Naser KianiMehr
- Department of Environment Sciences, Faculty of Sciences, University of Zanjan, Zanjan, Iran
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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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Chin SY, Hopkins WA, Cristol DA. Mercury alters initiation and construction of nests by zebra finches, but not incubation or provisioning behaviors. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:1271-1283. [PMID: 29022240 DOI: 10.1007/s10646-017-1852-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
Mercury is an environmental contaminant that impairs avian reproduction, but the behavioral and physiological mechanisms underlying this effect are poorly understood. The objective of this study was to determine whether lifetime dietary exposure to mercury (1.2 µg/g wet weight in food) impacted avian parental behaviors, and how this might influence reproductive success. To distinguish between the direct effects of mercury on parents and offspring, we created four treatment groups of captive-bred zebra finches (Taeniopygia guttata), with control and mercury-exposed adults raising cross-fostered control or mercury-exposed eggs (from maternal transfer). Control parents were 23% more likely to fledge young than parents exposed to mercury, regardless of egg exposure. Mercury-exposed parents were less likely to initiate nests than controls and spent less time constructing them. Nests of mercury-exposed pairs were lighter, possibly due to an impaired ability to bring nest material into the nestbox. However, nest temperature, incubation behavior, and provisioning rate did not differ between parental treatments. Unexposed control eggs tended to have shorter incubation periods and higher hatching success than mercury-exposed eggs, but there was no effect of parental exposure on these parameters. We accidentally discovered that parent finches transfer some of their body burden of mercury to nestlings during feeding through secretion in the crop. These results suggest that, in mercury-exposed songbirds, pre-laying parental behaviors, combined with direct exposure of embryos to mercury, likely contribute to reduced reproductive success and should be considered in future studies. Further research is warranted in field settings, where parents are exposed to greater environmental challenges and subtle behavioral differences might have more serious consequences than were observed in captivity.
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Affiliation(s)
- Stephanie Y Chin
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, Williamsburg, VA, 23185, USA
| | - William A Hopkins
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Daniel A Cristol
- Institute for Integrative Bird Behavior Studies, Department of Biology, College of William and Mary, Williamsburg, VA, 23185, USA.
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Whitney M, Cristol D. Rapid depuration of mercury in songbirds accelerated by feather molt. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:3120-3126. [PMID: 28722762 DOI: 10.1002/etc.3888] [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: 01/31/2017] [Revised: 03/08/2017] [Accepted: 06/12/2017] [Indexed: 06/07/2023]
Abstract
Mercury (Hg) is a ubiquitous environmental contaminant that affects avian reproduction and condition, in both aquatic and terrestrial species. Because Hg binds strongly to the keratin of growing feathers, molt is an important avenue for Hg elimination. We investigated the rate of depuration of Hg from songbird blood and organs (brain, kidney, liver, muscle) as a function of molt. We exposed 2 species of captive songbirds, European starling (Sturnus vulgaris) and zebra finch (Taeniopygia guttata), to environmentally relevant dietary Hg (1.2-1.5 mg/kg wet wt) for extended periods of time and then allowed them to depurate on a Hg-free diet for 20 wk. Depuration occurred either while birds were regrowing new feathers or when there was little to no molt occurring. Both species quickly eliminated Hg from blood and reduced Hg concentrations in other tissues by more than 90% over 20 wk. The rate of depuration was more rapid than previously reported in the literature, but depuration in small-bodied songbirds has rarely been studied. Molting birds depurated Hg from their blood more rapidly than nonmolting birds. The effect of molt on Hg retention in other tissues was more difficult to resolve, because by the time we sampled organ tissue, depuration was nearly complete. Our results confirm that molting expedites depuration and raises mechanistic questions about how songbirds depurate Hg stored in their tissues. Environ Toxicol Chem 2017;36:3120-3126. © 2017 SETAC.
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