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Chao L, Ni G, Ge Y, Zhang C, Chen J, Sun J. Occurrence, dietary influence and risks of selected trace metals in different coastal predatory species. ENVIRONMENTAL RESEARCH 2024; 245:117985. [PMID: 38123050 DOI: 10.1016/j.envres.2023.117985] [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: 10/06/2023] [Revised: 11/27/2023] [Accepted: 12/16/2023] [Indexed: 12/23/2023]
Abstract
The global issue of ongoing trace metal emissions and legacy accumulation from diverse sources is posing threats to coastal wildlife. This study characterized the distribution of five metals in relation to dietary ecology (carbon and nitrogen stable isotopes: δ15N and δ13C) in representative predatory species (starfish, fish, and seabird) collected from the coast of Qingdao, northeastern China. Zinc (Zn) was the most abundant metal across species, followed by copper (Cu), chromium (Cr), cadmium (Cd), total and methylated mercury (THg and MeHg). Among the studied species, black-tailed gulls (Larus crassirostris) occupied the highest trophic position, followed by three predatory fish species, whereas the northern Pacific seastar (Asterias amurensis) had the lowest trophic position. The starfish exhibited high capacity to accumulate Cd, Cr and Cu. Conversely, black-tailed gulls exhibited high levels of Zn, while Hg was highest in predatory fishes. Across species, Cr, MeHg, THg and MeHg:THg showed significant positive correlations with δ13C, suggesting the influence of inshore food sources on their accumulation. Both MeHg and THg were significantly and positively correlated with δ15N, with MeHg demonstrating a greater slope, indicating their potential trophic magnification. We assessed health risks from the studied metals using established toxicity reference thresholds. Elevated risks of Hg were identified in three predatory fish species, while other metals and species remain within safe limits. These findings emphasize the significance of foraging patterns in influencing trace metal accumulation in coastal predators and highlight the importance of further monitoring.
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Affiliation(s)
- Le Chao
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, Shandong, China
| | - Gang Ni
- Ministry of Education Key Laboratory of Mariculture, Ocean University of China, Qingdao, 266003, Shandong, China
| | - Yunfeng Ge
- College of Arts and Sciences, Washington University in St. Louis, St. Louis, 63130, Missouri, United States
| | - Chi Zhang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, Shandong, China
| | - Jingrui Chen
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, Shandong, China
| | - Jiachen Sun
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, Shandong, China.
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Han Y, Jiang Y, Xiong X, Sui X, Zhu R, Feng X, Li K, Jia Y, Chen Y. Mercury biomagnification at higher rates than the global average in aquatic ecosystems of the Qinghai-Tibet Plateau. JOURNAL OF HAZARDOUS MATERIALS 2023; 453:131408. [PMID: 37080022 DOI: 10.1016/j.jhazmat.2023.131408] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/16/2023] [Accepted: 04/11/2023] [Indexed: 05/03/2023]
Abstract
Mercury biomagnification in aquatic ecosystems is a global issue. Biomagnification patterns and drivers in alpine regions remain poorly understood. Hg biomagnification in the aquatic food web of the Qinghai-Tibetan Plateau (Q-T Plateau) was investigated. A total of 302 fish and macroinvertebrate tissue samples were analysed for total mercury (THg) and nitrogen (δ15N) stable isotope ratios. Overall, 26.75% of fish individuals exceeded the USFWS consumption guidelines. A total of 52.17% of the sampling sites covering different habitats exhibited a significantly positive THg-δ15N relationship, which confirmed the Hg biomagnification potential of Q-T Plateau aquatic ecosystems. The Q-T Plateau Hg biomagnification rates were generally far higher than global averages regardless of the habitat type. Hg in sediments, elevation and population density were positively related to the Hg biomagnification magnitude on the Q-T Plateau, which could be attributed to the disproportionate response of Hg concentrations in macroinvertebrates and fishes along environmental gradients. Our findings offer empirical evidence that fish consumption on the Q-T Plateau poses a substantial Hg exposure risk to people living along river and lake shores. Higher biomagnification rates could further disproportionately accelerate Hg pollution in Q-T Plateau aquatic ecosystems under future anthropogenic activities and climate warming trajectories.
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Affiliation(s)
- Yuzhu Han
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yihang Jiang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiong Xiong
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiaoyun Sui
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Ren Zhu
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiu Feng
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Kemao Li
- Qinghai Provincial Fishery Technology Extension Center, Xining 810012, China
| | - Yintao Jia
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
| | - Yifeng Chen
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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Lipid Extraction and Sample Preservation Techniques for Stable Isotope Analysis and Ecological Assays. Methods Mol Biol 2023; 2625:241-257. [PMID: 36653648 DOI: 10.1007/978-1-0716-2966-6_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Lipid extraction is an important component of many ecological and ecotoxicological measurements. For instance, percent lipid is often used as a measure of body condition, under the assumption that those individuals with higher lipid reserves are healthier. Likewise, lipids are depleted in 13C compared with protein, and it is consequently a routine to remove lipids prior to measuring carbon isotopes in ecological studies so that variation in lipid content does not obscure variation in diet. We provide detailed methods for two different protocols for lipid extraction: Soxhlet apparatus and manual distillation. We also provide methods for polar and non-polar solvents. Neutral (non-polar) solvents remove some lipids but few non-lipid compounds whereas polar solvents remove not only most lipids but also many non-lipid compounds. We discuss each of the methods and provide guidelines for best practices. We recommend that for stable isotope analysis, researchers test for a relationship between the change in the carbon stable isotope ratio and the amount of lipid extracted to see if the degree of extraction has an impact on isotope ratios. Stable isotope analysis is widely used by ecologists, and we provide a detailed methodology that minimizes known biases.
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Too Close for Comfort? Isotopic Niche Segregation in New Zealand’s Odontocetes. BIOLOGY 2022; 11:biology11081179. [PMID: 36009806 PMCID: PMC9405429 DOI: 10.3390/biology11081179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022]
Abstract
Simple Summary We used carbon and nitrogen stable isotopes as ecological tracers to investigate isotopic niche overlap between 21 odontocete (toothed whale) species inhabiting neritic, mesopelagic, and bathypelagic waters. Results showed a clear niche separation for the bathypelagic Gray’s beaked whales (Mesoplodon grayi) and sperm whales (Physeter macrocephalus), but high isotopic niche overlap and potential interspecific competition for neritic and mesopelagic species. This study represents the first insights into the coexistence of odontocetes in a biodiverse hotspot and provides a critical baseline for a system already undergoing ecosystem changes via ocean warming and its subsequent effect on prey abundance and distribution. Abstract Species occurring in sympatry and relying on similar and limited resources may partition resource use to avoid overlap and interspecific competition. Aotearoa, New Zealand hosts an extraordinarily rich marine megafauna, including 50% of the world’s cetacean species. In this study, we used carbon and nitrogen stable isotopes as ecological tracers to investigate isotopic niche overlap between 21 odontocete (toothed whale) species inhabiting neritic, mesopelagic, and bathypelagic waters. Results showed a clear niche separation for the bathypelagic Gray’s beaked whales (Mesoplodon grayi) and sperm whales (Physeter macrocephalus), but high isotopic niche overlap and potential interspecific competition for neritic and mesopelagic species. For these species, competition could be reduced via temporal or finer-scale spatial segregation or differences in foraging behaviour. This study represents the first insights into the coexistence of odontocetes in a biodiverse hotspot. The data presented here provide a critical baseline to a system already ongoing ecosystem change via ocean warming and subsequent effects on prey abundance and distributions.
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Gao S, Zhang R, Zhang H, Zhang S. The seasonal variation in heavy metal accumulation in the food web in the coastal waters of Jiangsu based on carbon and nitrogen isotope technology. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 297:118649. [PMID: 34902527 DOI: 10.1016/j.envpol.2021.118649] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 12/03/2021] [Accepted: 12/05/2021] [Indexed: 06/14/2023]
Abstract
Research on food web structures in marine ecosystems is an important field in ecology where the interaction of structure and function contributes to understanding biodiversity. The coastal waters of Jiangsu are one of the important fishing bases in China. In recent years, with the development of industry in the coastal waters of Jiangsu, heavy metal (HM) pollution in this region has become more serious. In this study, all samples (including macroalgae, bivalves, cephalopods, gastropods, crustaceans and fish) were collected in the coastal waters of Jiangsu in spring, summer and autumn. Based on the construction of the food web structure using carbon and nitrogen isotope technology, the main methods of material circulation and energy flow were quantified, and the accumulation regularity and seasonal variation characteristics of HMs in the food web were analysed. The results showed that (1) among all the trophic groups, bivalves had the highest enrichment level of HMs, while fish had the lowest. However, fish have a strong ability to enrich Hg, and the main source of Hg enrichment in the human body is edible fish, so more attention should be given to Hg concentrations in fish. (2) In spring, the mean HM concentrations of marine organisms in the coastal waters of Jiangsu were Zn > Cu > As > Cd > Cr > Pb > Ni > Hg, and they were Zn > Cu > As > Pb > Cd > Ni > Cr > Hg in summer and Zn > Cu > As > Pb > Cd > Cr > Ni > Hg in autumn. In total, the concentrations of Zn, Cu and As were the highest, while the mean concentration of Hg in organisms was the lowest. (3) No significant biomagnification of HMs was found in the three seasons. We speculated that overfishing leads to miniaturization and a younger age of organisms, which makes the concentration of highly enriched HMs in organisms with high trophic levels (TLs) lower.
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Affiliation(s)
- Shike Gao
- College of Marine Sciences, Shanghai Ocean University, Shanghai, 201306, China
| | - Rui Zhang
- College of Marine Sciences, Shanghai Ocean University, Shanghai, 201306, China
| | - Hu Zhang
- Jiangsu Research Institute of Marine Fisheries, Nantong, 226007, Jiangsu, China
| | - Shuo Zhang
- College of Marine Sciences, Shanghai Ocean University, Shanghai, 201306, China; Joint Laboratory for Monitoring and Conservation of Aquatic Living Resources in the Yangtze Estuary, Shanghai, 200000, China.
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Kahma TI, Karlson AML, Liénart C, Mörth CM, Humborg C, Norkko A, Rodil IF. Food-web comparisons between two shallow vegetated habitat types in the Baltic Sea. MARINE ENVIRONMENTAL RESEARCH 2021; 169:105402. [PMID: 34246890 DOI: 10.1016/j.marenvres.2021.105402] [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: 03/11/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 06/13/2023]
Abstract
Coastal vegetated habitats maintain highly diverse communities, where the contribution of macrophyte production is significant for macroinvertebrate primary consumers. In the brackish-waters of the Baltic Sea, the taxonomical diversity of different macrophytes includes both marine and limnic species. To study the basal food-web differences of two key vegetated habitat types, either dominated by a perennial brown macroalgae (Fucus vesiculosus) or by angiosperm plants, 13C and 15N compositions of different primary producers and macroinvertebrate consumers were examined, and their diets were estimated by Bayesian mixing models. Carbon isotope diversity of primary producers was high especially in the hard-bottom Fucus-dominated habitats, which was also reflected in a larger consumer isotope niche. However, consumer isotope niche among sites was similar within the same habitat type. Our models indicated that the perennial macrophyte dietary median contribution was about 25% for deposit feeders and omnivores in both habitat types, while epigrazers preferred filamentous algae (30-60%). The niche positions of the abundant clams L. balthica, M. arenaria and C. glaucum differed between the two habitats, but they showed only small (<10% units) differences in their macrophyte dietary contributions. The isotopic compositions of the dominating primary producer assemblage reflected significantly in the isotope niche structure of the associated primary consumers.
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Affiliation(s)
- T I Kahma
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland.
| | - A M L Karlson
- Department of Ecology, Environment and Plant Science, Stockholm University, Stockholm, Sweden; Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
| | - C Liénart
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland; Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
| | - C-M Mörth
- Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
| | - C Humborg
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland; Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
| | - A Norkko
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland; Baltic Sea Centre, Stockholm University, Stockholm, Sweden.
| | - I F Rodil
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland; Baltic Sea Centre, Stockholm University, Stockholm, Sweden; Departamento de Biología, Instituto Universitario de Investigación Marina (INMAR), University of Cádiz, Spain.
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Gao Y, Wang R, Li Y, Ding X, Jiang Y, Feng J, Zhu L. Trophic transfer of heavy metals in the marine food web based on tissue residuals. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 772:145064. [PMID: 33770865 DOI: 10.1016/j.scitotenv.2021.145064] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/06/2021] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Trophic transfer of metals has been well researched in aquatic food webs; however, most studies have examined the presence of metal residuals in the entire body of marine organisms and but not in specific tissues. In this study, we determined the concentrations of Cu, Cr, Pb, Zn, Cd, and Ni in various organs of 17 marine species, including crustaceans, gastropods, bivalves, and fishes, with different trophic levels (TLs), which were collected from the Liaodong Bay, China, in July 2019. Results showed that the liver, gill, and muscle tissues of marine species are ideal indicators for analyzing Cu, Cr, Pb, Zn, Cd, and Ni contamination in marine environments. When the entire bodies of these marine species were considered, a bio-dilution in Cu, Cr, Pb, Zn, Cd, and Ni was observed in the studied food web. In contrast, the metal tissue-specific bio-magnification in the entire studied food web showed different results. In the liver and gill tissues, negative correlations were found between the concentrations of cadmium and TLs, while copper bio-dilution was also observed in gill tissue. In the muscle tissues, Cu, Pb, and Ni showed bio-dilution and trophic magnification factors of Cu, Pb, and Ni ranged from 0.44 to 0.73. This study highlights the importance of tissue-specific considerations to obtain further accurate information on metal trophodynamics and trophic transfers in marine food webs, thereby enhancing the risk assessment of many elements in wildlife and human health.
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Affiliation(s)
- Yongfei Gao
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Ruyue Wang
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yanyu Li
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xuebin Ding
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yueming Jiang
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Jianfeng Feng
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
| | - Lin Zhu
- Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
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Kahma TI, Karlson AML, Sun X, Mörth CM, Humborg C, Norkko A, Rodil IF. Macroalgae fuels coastal soft-sediment macrofauna: A triple-isotope approach across spatial scales. MARINE ENVIRONMENTAL RESEARCH 2020; 162:105163. [PMID: 33137597 DOI: 10.1016/j.marenvres.2020.105163] [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] [Received: 05/10/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 06/11/2023]
Abstract
Shallow coastal zones may provide cross-habitat nutrient subsidies for benthic communities offshore, as macrophyte matter can drift to deeper sediments. To study the relative importance of carbon and nutrient flows derived from different primary food sources in a coastal ecosystem, the diets of clam Macoma balthica, polychaete Marenzelleria spp. and mussel Mytilus trossulus were examined across environmental gradients in the northern Baltic Sea using a triple-isotope approach (i.e. 13C, 15N and 34S) and Bayesian mixing models (MixSIAR). Our results suggest that in shallow habitats, production from Fucus vesiculosus is the primary energy source for M. balthica. The proportion of macroalgae-derived matter in the diet of M. balthica and Marenzelleria spp. decreased following a depth gradient. Our models for M. trossulus indicate that the pelagic POM dominates its diet. Our results indicate a trophic connectivity between shallow macrophyte-dominated and deeper habitats, which receive significant amounts of nutrient subsidies from shallower areas.
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Affiliation(s)
- T I Kahma
- University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland.
| | - A M L Karlson
- Stockholm University, Department of Ecology, Environment and Plant Science, 106 91 Stockholm, Sweden; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden.
| | - X Sun
- Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden.
| | - C-M Mörth
- Stockholm University, Department of Geological Sciences, 106 91 Stockholm, Sweden.
| | - C Humborg
- University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden.
| | - A Norkko
- University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden.
| | - I F Rodil
- University of Helsinki, Tvärminne Zoological Station, J. A. Palménin Tie 260, 10900 Hanko, Finland; Stockholm University, Baltic Sea Centre, 106 91 Stockholm, Sweden.
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Rioux È, Pelletier F, St-Laurent MH. From diet to hair and blood: empirical estimation of discrimination factors for C and N stable isotopes in five terrestrial mammals. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractCarbon and nitrogen stable isotope ratios are used widely to describe wildlife animal diet composition and trophic interactions. To reconstruct consumer diet, the isotopic differences between consumers and their diet items—called the trophic discrimination factor (TDF)—must be known. Proxies of diet composition are sensitive to the accuracy of TDFs. However, specific TDFs are still missing for many species and tissues because only a few controlled studies have been carried out on captive animals. The aim of this study was to estimate TDFs for hair and blood for carbon and nitrogen stable isotopes for caribou, moose, white-tailed deer, eastern coyote, and black bear. We obtained stable isotope ratios for diet items, hair, and blood samples, of 21 captive adult mammals. Diet–tissue discrimination factors for carbon in hair (∆ 13CLE) ranged from 0.96‰ to 3.72‰ for cervids, 3.01‰ to 3.76‰ for coyote, and 5.15‰ to 6.35‰ for black bear, while nitrogen discrimination factors (∆ 15N) ranged from 2.58‰ to 5.95‰ for cervids, 2.90‰ to 3.13‰ for coyote, and 4.48‰ to 5.44‰ for black bear. The ∆ 13CLE values in coyote blood components ranged from 2.20‰ to 2.69‰ while ∆ 15N ranged from 3.30‰ to 4.41‰. In caribou serum, ∆ 13CLE reached 3.34 ± 1.28‰ while ∆ 15N reached 5.02 ± 0.07‰. The TDFs calculated in this study will allow the evaluation of diet composition and trophic relationships between these five mammal species and will have important implications for the study of endangered caribou populations for which the use of noninvasive tissue sampling is highly relevant.
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Affiliation(s)
- Ève Rioux
- Centre for Northern Studies & Centre for Forest Research, Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, allée des Ursulines, Rimouski, Québec, Canada
| | - Fanie Pelletier
- Centre for Northern Studies, Département de Biologie, Université de Sherbrooke, boul. de l’Université, Sherbrooke, Québec, Canada
| | - Martin-Hugues St-Laurent
- Centre for Northern Studies & Centre for Forest Research, Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, allée des Ursulines, Rimouski, Québec, Canada
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10
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Ogloff WR, Ferguson SH, Tallman RF, Davoren GK. Diet of capelin (Mallotus villosus) in the Eastern Canadian Arctic inferred from stomach contents and stable isotopes. Polar Biol 2020. [DOI: 10.1007/s00300-020-02707-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rioux È, Pelletier F, St‐Laurent M. Influence of lipids on stable isotope ratios in mammal hair: highlighting the importance of validation. Ecosphere 2019. [DOI: 10.1002/ecs2.2723] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Ève Rioux
- Centre for Forest Research Département de Biologie Chimie et Géographie Université du Québec à Rimouski 300 Allée des Ursulines Rimouski Québec G5L 3A1 Canada
| | - Fanie Pelletier
- Canada Research Chair in Evolutionary Demography and Conservation Centre for Northern Studies Département de biologie Université de Sherbrooke 2500 Boulevard de l'Université Sherbrooke Québec J1K 2R1 Canada
| | - Martin‐Hugues St‐Laurent
- Centre for Forest Research Département de Biologie Chimie et Géographie Université du Québec à Rimouski 300 Allée des Ursulines Rimouski Québec G5L 3A1 Canada
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Clark CT, Horstmann L, Misarti N. Lipid normalization and stable isotope discrimination in Pacific walrus tissues. Sci Rep 2019; 9:5843. [PMID: 30971722 PMCID: PMC6458160 DOI: 10.1038/s41598-019-42095-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 03/11/2019] [Indexed: 11/09/2022] Open
Abstract
Analysis of stable carbon and nitrogen isotope values (δ13C and δ15N) of animal tissues can provide important information about diet, physiology, and movements. Interpretation of δ13C and δ15N values, however, is influenced by factors such as sample lipid content, tissue-specific isotope discrimination, and tissue turnover rates, which are typically species- and tissue-specific. In this study, we generated lipid normalization models for δ13C and investigated the effects of chemical lipid extractions on δ13C and δ15N in Pacific walrus (Odobenus rosmarus divergens) muscle, liver, and skin. We also evaluated tissue-specific isotope discrimination in walrus muscle, liver, skin, and bone collagen. Mean δ13Clipid-free of skin and bone collagen were similar, as were mean δ15N of muscle and liver. All other tissues differed significantly for both isotopes. Differences in δ13Clipid-free and δ15N among tissues agreed with published estimates of marine mammal tissue-specific isotope discrimination factors, with the exception of skin. The results of this work will allow researchers to gain a clearer understanding of walrus diet and the structure of Arctic food webs, while also making it possible to directly compare the results of contemporary walrus isotope research with those of historic and paleoecological studies.
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Affiliation(s)
- Casey T Clark
- Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska, 99775-5860, USA. .,College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, Alaska, 99775-7220, USA.
| | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, Alaska, 99775-7220, USA
| | - Nicole Misarti
- Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska, 99775-5860, USA
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Lewis MC, West AG, O'Riain MJ. Isotopic assessment of marine food consumption by natural-foraging chacma baboons on the Cape Peninsula, South Africa. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 165:77-93. [PMID: 29076130 DOI: 10.1002/ajpa.23332] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 08/14/2017] [Accepted: 09/18/2017] [Indexed: 11/10/2022]
Abstract
OBJECTIVES Stable isotope analysis has been used to investigate consumption of marine resources in a variety of terrestrial mammals, including humans, but not yet in extant nonhuman primates. We sought to test the efficacy of stable isotope analysis as a tool for such studies by comparing isotope- and observation-based estimates of marine food consumption by a troop of noncommensal, free-ranging chacma baboons. MATERIALS AND METHODS We determined δ13 C and δ15 N values of baboon hair (n = 9) and fecal samples (n = 144), and principal food items (n = 362). These values were used as input for diet models, the outputs of which were compared to observation-based estimates of marine food consumption. RESULTS Fecal δ13 C values ranged from -29.3‰ to -25.6‰. δ15 N values ranged from 0.9‰ to 6.3‰ and were positively correlated with a measure of marine foraging during the dietary integration period. Mean (± SD) δ13 C values of adult male and female baboon hairs were -21.6‰ (± 0.1) and -21.8‰ (± 0.3) respectively, and corresponding δ15 N values were 5.0‰ (± 0.3) and 3.9‰ (± 0.2). Models indicated that marine contributions were ≤10% of baboon diet within any season, and contributed ≤17% of dietary protein through the year. DISCUSSION Model output and observational data were in agreement, both indicating that despite their abundance in the intertidal region, marine foods comprised only a small proportion of baboon diet. This suggests that stable isotope analysis is a viable tool for investigating marine food consumption by natural-foraging primates in temperate regions.
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Affiliation(s)
- Matthew C Lewis
- Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa.,Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa.,Department of Archaeology, University of Cape Town, Rondebosch, 7701, South Africa
| | - Adam G West
- Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
| | - M Justin O'Riain
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, 7701, South Africa
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14
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Abstract
Lipid extraction is an important component of many ecological and ecotoxicological measurements. For instance, percent lipid is often used as a measure of body condition, under the assumption that those individuals with higher lipid reserves are healthier. Likewise, lipids are depleted in 13C compared with protein, and it is consequently a routine to remove lipids prior to measuring carbon isotopes in ecological studies so that variation in lipid content does not obscure variation in diet. We provide detailed methods for two different protocols for lipid extraction: Soxhlet apparatus and manual distillation. We also provide methods for polar and nonpolar solvents. Neutral (nonpolar) solvents remove some lipids but few non-lipid compounds, whereas polar solvents remove most lipids but also many non-lipid compounds. We discuss each of the methods and provide guidelines for best practices. We recommend that, for stable isotope analysis, researchers test for a relationship between the change in carbon stable isotope ratio and the amount of lipid extracted to see if the degree of extraction has an impact on isotope ratios. Stable isotope analysis is widely used by ecologists, and we provide a detailed methodology that minimizes known biases.
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Patterson HK, Carmichael RH. The effect of lipid extraction on carbon and nitrogen stable isotope ratios in oyster tissues: Implications for glycogen-rich species. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:2594-2600. [PMID: 27709696 DOI: 10.1002/rcm.7759] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/28/2016] [Accepted: 10/03/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Extraction of lipids from tissues prior to carbon stable isotope analysis (SIA) has become a common practice, despite a lack of species-specific data to indicate when lipid extraction is needed. Marine invertebrates, including bivalves, are known to store carbon as glycogen and less in the form of lipids than other species, potentially reducing the need for lipid extraction even when C:N values are above 3.5, a value that previous studies suggest indicates a need for lipid extraction of animal tissues. METHODS We investigated the need for lipid extraction on individual tissues (adductor muscle, gut gland, gill) and whole tissue of a glycogen-storing species, the oyster Crassostrea virginica. Bulk and lipid-extracted samples were analyzed for their C and N stable isotope ratios by continuous flow isotope ratio mass spectrometry (IRMS). Samples were analyzed on a 20-20 isotope ratio mass spectrometer (PDZ Europa) after combustion in an elemental analyzer (PDZ Europa Automatic Analyzer-Gas Solid Liquid). RESULTS Although the C:N values for most bulk (unextracted) tissue samples were greater than 3.5, the lipid-extracted δ13 C values did not differ from the bulk values. Lipid extraction, however, affected δ15 N values in all tissue types except adductor muscle, indicating that separate SIA may be required when tissues are lipid extracted. CONCLUSIONS These data demonstrate that it is not necessary to lipid extract oyster tissues in all cases, and that C:N thresholds for lipid extraction in other species may not be reliable for organisms such as oysters that store glycogen. Our data indicate that minimizing unnecessary lipid extraction through preliminary testing will save researchers time and expense by avoiding superfluous sample handling, reducing concern over secondary effects on data quality, and reducing the costs of reagents and additional separate stable isotope analysis to ensure analytical accuracy. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- H K Patterson
- Department of Marine Sciences, University of South Alabama, Mobile, AL, 36688, USA
- Dauphin Island Sea Lab, Dauphin Island, AL, 36528, USA
- Department of Biology, University of Alabama Birmingham, Birmingham, AL, 35294, USA
| | - R H Carmichael
- Department of Marine Sciences, University of South Alabama, Mobile, AL, 36688, USA
- Dauphin Island Sea Lab, Dauphin Island, AL, 36528, USA
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16
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Seasonal Change in Trophic Niche of Adfluvial Arctic Grayling (Thymallus arcticus) and Coexisting Fishes in a High-Elevation Lake System. PLoS One 2016; 11:e0156187. [PMID: 27205901 PMCID: PMC4874605 DOI: 10.1371/journal.pone.0156187] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 05/10/2016] [Indexed: 11/27/2022] Open
Abstract
Introduction of non-native species is a leading threat to global aquatic biodiversity. Competition between native and non-native species is often influenced by changes in suitable habitat or food availability. We investigated diet breadth and degree of trophic niche overlap for a fish assemblage of native and non-native species inhabiting a shallow, high elevation lake system. This assemblage includes one of the last remaining post-glacial endemic populations of adfluvial Arctic grayling (Thymallus arcticus) in the contiguous United States. We examined gut contents and stable isotope values of fish taxa in fall and spring to assess both short- (days) and long-term (few months) changes in trophic niches. We incorporate these short-term (gut contents) data into a secondary isotope analysis using a Bayesian statistical framework to estimate long-term trophic niche. Our data suggest that in this system, Arctic grayling share both a short- and long-term common food base with non-native trout of cutthroat x rainbow hybrid species (Oncorhynchus clarkia bouvieri x Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis). In addition, trophic niche overlap among Arctic grayling, hybrid trout, and brook trout appeared to be stronger during spring than fall. In contrast, the native species of Arctic grayling, burbot (Lota lota), and suckers (Catostomus spp.) largely consumed different prey items. Our results suggest strong seasonal differences in trophic niche overlap among Arctic grayling and non-native trout, with a potential for greatest competition for food during spring. We suggest that conservation of endemic Arctic grayling in high-elevation lakes will require recognition of the potential for coexisting non-native taxa to impede well-intentioned recovery efforts.
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Kaufman TJ, Pajuelo M, Bjorndal KA, Bolten AB, Pfaller JB, Williams KL, Vander Zanden HB. Mother-egg stable isotope conversions and effects of lipid extraction and ethanol preservation on loggerhead eggs. CONSERVATION PHYSIOLOGY 2014; 2:cou049. [PMID: 27293670 PMCID: PMC4806724 DOI: 10.1093/conphys/cou049] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 06/06/2023]
Abstract
Carbon and nitrogen stable isotope (δ(13)C and δ(15)N) analysis has been used to elucidate foraging and migration behaviours of endangered sea turtle populations. Isotopic analysis of tissue samples from nesting females can provide information about their foraging locations before reproduction. To determine whether loggerhead (Caretta caretta) eggs provide a good proxy for maternal isotope values, we addressed the following three objectives: (i) we evaluated isotopic effects of ethanol preservation and lipid extraction on yolk; (ii) we examined the isotopic offset between maternal epidermis and corresponding egg yolk and albumen tissue δ(13)C and δ(15)N values; and (iii) we assessed the accuracy of foraging ground assignment using egg yolk and albumen stable isotope values as a proxy for maternal epidermis. Epidermis (n = 61), albumen (n = 61) and yolk samples (n = 24) were collected in 2011 from nesting females at Wassaw Island, GA, USA. Subsamples from frozen and ethanol-preserved yolk samples were lipid extracted. Both lipid extraction and ethanol preservation significantly affected yolk δ(13)C, while δ(15)N values were not altered at a biologically relevant level. The mathematical corrections provided here allow for normalization of yolk δ(13)C values with these treatments. Significant tissue conversion equations were found between δ(13)C and δ(15)N values of maternal epidermis and corresponding yolk and albumen. Finally, the consistency in assignment to a foraging area was high (up to 84%), indicating that these conversion equations can be used in future studies where stable isotopes are measured to determine female foraging behaviour and trophic relationships by assessing egg components. Loggerhead eggs can thus provide reliable isotopic information when samples from nesting females cannot be obtained.
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Affiliation(s)
- Temma J. Kaufman
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
| | - Mariela Pajuelo
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
| | - Karen A. Bjorndal
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
| | - Alan B. Bolten
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
| | - Joseph B. Pfaller
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
- Caretta Research Project, PO Box 9841, Savannah, GA 31412, USA
| | | | - Hannah B. Vander Zanden
- Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, FL 32611, USA
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18
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Yurkowski DJ, Hussey NE, Semeniuk C, Ferguson SH, Fisk AT. Effects of lipid extraction and the utility of lipid normalization models on δ13C and δ15N values in Arctic marine mammal tissues. Polar Biol 2014. [DOI: 10.1007/s00300-014-1571-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Elliott KH, Davis M, Elliott JE. Equations for lipid normalization of carbon stable isotope ratios in aquatic bird eggs. PLoS One 2014; 9:e83597. [PMID: 24465384 PMCID: PMC3898914 DOI: 10.1371/journal.pone.0083597] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 11/13/2013] [Indexed: 11/19/2022] Open
Abstract
Stable isotope ratios are biogeochemical tracers that can be used to determine the source of nutrients and contaminants in avian eggs. However, the interpretation of stable carbon ratios in lipid-rich eggs is complicated because (13)C is depleted in lipids. Variation in (13)C abundance can therefore be obscured by variation in percent lipids. Past attempts to establish an algebraic equation to correct carbon isotope ratios for lipid content in eggs have been unsuccessful, possibly because they relied partly on data from coastal or migratory species that may obtain egg lipids from different habitats than egg protein. We measured carbon, nitrogen and sulphur stable isotope ratios in 175 eggs from eight species of aquatic birds. Carbon, nitrogen and sulphur isotopes were enriched in lipid-extracted egg samples compared with non extracted egg samples. A logarithmic equation using the C∶N ratio and carbon isotope ratio from the non extracted egg tissue calculated 90% of the lipid-extracted carbon isotope ratios within ±0.5‰. Calculating separate equations for eggs laid by species in different habitats (pelagic, offshore and terrestrial-influenced) improved the fit. A logarithmic equation, rather than a linear equation as often used for muscle, was necessary to accurately correct for lipid content because the relatively high lipid content of eggs compared with muscle meant that a linear relationship did not accurately approximate the relationship between percent lipids and the C∶N ratio. Because lipid extraction alters sulphur and nitrogen isotope ratios (and cannot be corrected algebraically), we suggest that isotopic measurement on bulk tissue followed by algebraic lipid normalization of carbon stable isotope ratio is often a good solution for homogenated eggs, at least when it is not possible to complete separate chemical analyses for each isotope.
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Affiliation(s)
- Kyle H. Elliott
- Department of Biological Sciences, University of Manitoba, Winnipeg, Canada
| | - Mikaela Davis
- Department of Biological Sciences, Simon Fraser University, Burnaby, Canada
| | - John E. Elliott
- Science & Technology Branch, Environment Canada, Delta, Canada
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20
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Newsome SD, Yeakel JD, Wheatley PV, Tinker MT. Tools for quantifying isotopic niche space and dietary variation at the individual and population level. J Mammal 2012. [DOI: 10.1644/11-mamm-s-187.1] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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21
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Warren JM, Cutting KA. Breeding strategy and organochlorine contamination of eggs in lesser scaup (Aythya affinis). ECOTOXICOLOGY (LONDON, ENGLAND) 2011; 20:110-118. [PMID: 21080226 DOI: 10.1007/s10646-010-0561-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/27/2010] [Indexed: 05/30/2023]
Abstract
We explored relationships between breeding strategy and contaminant importation and depuration into lesser scaup (Aythya affinis) eggs. Our primary hypothesis was that females accumulate organochlorine (OC) contaminants in lipid reserves obtained on wintering and spring staging areas and depurate those contaminants into eggs on the breeding area proportional to the amount of endogenous reserves used for egg formation. Egg collection occurred at Red Rock Lakes National Wildlife Refuge, Montana, in 2006 for contaminant and stable isotope analysis. Eggs were assayed for 22 lipophilic OCs and endogenous lipid reserves for each egg were estimated using carbon (δ(13)C) stable isotope values. Of the 22 OC analytes tested for, only p,p'-DDE was detected in all samples, oxychlordane was detected in 56%, and no other OC analytes tested for were detected in >50% of samples. The mean percent contribution of endogenous reserves to egg lipids in scaup was 37.9 ± 0.05%, ranging from 0-88.2%. We found little support for the hypothesized relationship between breeding strategy and egg contaminant levels. No significant trend was observed for endogenous reserves and egg contaminant levels of p,p'-DDE or oxychlordane (R (2) < 0.01, P = 0.792; R (2) < 0.01, P = 0.674, respectively). Thus, our results did not indicate that breeding females are importing contaminants from wintering or spring staging areas and depurating those contaminants into their clutches.
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Affiliation(s)
- Jeffrey M Warren
- US Fish and Wildlife Service, Red Rock Lakes National Wildlife Refuge, 27650B South Valley Road, Lima, MT 59739, USA.
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Ehrich D, Tarroux A, Stien J, Lecomte N, Killengreen S, Berteaux D, Yoccoz NG. Stable isotope analysis: modelling lipid normalization for muscle and eggs from arctic mammals and birds. Methods Ecol Evol 2010. [DOI: 10.1111/j.2041-210x.2010.00047.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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23
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Tarroux A, Ehrich D, Lecomte N, Jardine TD, Bêty J, Berteaux D. Sensitivity of stable isotope mixing models to variation in isotopic ratios: evaluating consequences of lipid extraction. Methods Ecol Evol 2010. [DOI: 10.1111/j.2041-210x.2010.00033.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bond AL, Diamond AW. Mercury concentrations in seabird tissues from Machias Seal Island, New Brunswick, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:4340-7. [PMID: 19419752 DOI: 10.1016/j.scitotenv.2009.04.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 04/15/2009] [Accepted: 04/16/2009] [Indexed: 05/21/2023]
Abstract
Mercury is a pervasive environmental contaminant, the anthropogenic portion of which is increasing globally, and in northeastern North America in particular. Seabirds frequently are used as indicators of the marine environment, including mercury contamination. We analysed paired samples for total mercury (Hg) concentrations in feathers and blood from adult and chick, albumen, and lipid-free yolk of seven seabirds breeding on Machias Seal Island, New Brunswick, Canada - Arctic Tern (Sterna paradisaea), Atlantic Puffin (Fratercula arctica), Common Eider (Somateria mollissima), Common Murre (Uria aalge), Common Tern (Sterna hirundo), Leach's Storm-petrel (Oceanodroma leucorhoa), and Razorbill (Alca torda). We also used stable-isotope ratios of carbon (delta(13)C), and nitrogen (delta(15)N) to evaluate the relationship between carbon source and trophic position and mercury. We found high Hg concentrations across tissue types in Leach's Storm-petrels, and Razorbills, with lower concentrations in other species, the lowest being in Common Eiders. Storm-petrels prey on mesopelagic fish that accumulate mercury, and Razorbills feed on larger, older fish that bioaccumulate heavy metals. Biomagnification of Hg, or the increase in Hg concentration with trophic position as measured by delta(15)N, was significant and greater in albumen than other tissues, whereas in other tissues, delta(15)N explained little of the overall variation in Hg concentration. Hg concentrations in egg components are higher on Machias Seal Island than other sites globally and in the Gulf of Maine region, but only for some species. Further detailed investigations are required to determine the cause of this trend.
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Affiliation(s)
- Alexander L Bond
- Atlantic Cooperative Wildlife Ecology Research Network, University of New Brunswick, Fredericton, New Brunswick, Canada.
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25
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Rogers KM. Stable isotopes as a tool to differentiate eggs laid by caged, barn, free range, and organic hens. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:4236-4242. [PMID: 19358533 DOI: 10.1021/jf803760s] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Stable carbon and nitrogen isotope values of whole yolk, delipidized yolk, albumen, and egg membrane were analyzed from 18 different brands of chicken eggs laid under caged, barn, free range, and organic farming regimes. In general, free range and organic egg components showed enrichment of (15)N values up to 4‰ relative to caged and barn laid eggs, suggesting a higher animal protein (trophic) contribution to the chicken's diet than pure plant-based foods and/or that the feed was organically manufactured. One sample of free range and two samples of organic eggs had δ(15)N values within the range of caged or barn laid eggs, suggesting either that these eggs were mislabeled (the hens were raised under "battery" or "barn" conditions, and not permitted to forage outside) or that there was insufficient animal protein gained by foraging to shift the δ(15)N values of their primary food source. δ(13)C values of potential food sources are discussed with respect to dietary intake and contribution to the isotopic signature of the eggs to determine mixing of C(3) and C(4) diets, although they did not elucidate laying regimen. The study finds that stable nitrogen isotope analysis of egg components is potentially a useful technique to unravel dietary differences between caged or barn hens and free range hens (both conventional and organic) and could be further developed as an authentication tool in the egg industry.
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Affiliation(s)
- Karyne M Rogers
- National Isotope Centre, GNS Science, 30 Gracefield Road, Lower Hutt, New Zealand.
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Ricca MA, Keith Miles A, Anthony RG. Sources of organochlorine contaminants and mercury in seabirds from the Aleutian archipelago of Alaska: inferences from spatial and trophic variation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2008; 406:308-323. [PMID: 18692865 DOI: 10.1016/j.scitotenv.2008.06.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 06/18/2008] [Accepted: 06/19/2008] [Indexed: 05/26/2023]
Abstract
Persistent organochlorine compounds and mercury (Hg) have been detected in numerous coastal organisms of the Aleutian archipelago of Alaska, yet sources of these contaminants are unclear. We collected glaucous-winged gulls, northern fulmars, and tufted puffins along a natural longitudinal gradient across the western and central Aleutian Islands (Buldir, Kiska, Amchitka, Adak), and an additional 8 seabird species representing different foraging and migratory guilds from Buldir Island to evaluate: 1) point source input from former military installations, 2) westward increases in contaminant concentrations suggestive of distant source input, and 3) effects of trophic status (delta15N) and carbon source (delta13C) on contaminant accumulation. Concentrations of Sigma polychlorinated biphenyls (PCBs) and most chlorinated pesticides in glaucous-winged gulls consistently exhibited a 'U'-shaped pattern of high levels at Buldir and the east side of Adak and low levels at Kiska and Amchitka. In contrast, concentrations of Sigma PCBs and chlorinated pesticides in northern fulmars and tufted puffins did not differ among islands. Hg concentrations increased westward in glaucous-winged gulls and were highest in northern fulmars from Buldir. Among species collected only at Buldir, Hg was notably elevated in pelagic cormorants, and relatively high Sigma PCBs were detected in black-legged kittiwakes. Concentrations of Sigma PCBs, dichlorodiphenyldichloroethylene (p,p' DDE), and Hg were positively correlated with delta15N across all seabird species, indicating biomagnification across trophic levels. The east side of Adak Island (a former military installation) was a likely point source of Sigma PCBs and p,p' DDE, particularly in glaucous-winged gulls. In contrast, elevated levels of these contaminants and Hg, along with PCB congener and chlorinated pesticide compositional patterns detected at Buldir Island indicated exposure from distant sources influenced by a combination of atmospheric-oceanic processes and the migratory movements of seabirds.
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Affiliation(s)
- Mark A Ricca
- U.S. Geological Survey, Western Ecological Research Center - Davis Field Station, 1 Shields Avenue, University of California, Davis, Davis, CA 95616, USA.
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