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Berthelot F, Unnsteinsdóttir ER, Carbonell Ellgutter JA, Ehrich D. Long-term responses of Icelandic Arctic foxes to changes in marine and terrestrial ecosystems. PLoS One 2023; 18:e0282128. [PMID: 37792685 PMCID: PMC10550166 DOI: 10.1371/journal.pone.0282128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 09/03/2023] [Indexed: 10/06/2023] Open
Abstract
The long-term dynamics of predator populations may be driven by fluctuations in resource availability and reflect ecosystem changes such as those induced by climate change. The Icelandic Arctic fox (Vulpes lagopus) population has known major fluctuations in size since the 1950s. Using stable isotopes analysis of bone collagen over a long-time series (1979-2018), we aimed at identifying the main resources used by Icelandic Arctic foxes during periods of growth and decline to assess if the variations in their population size are linked to fluctuations in the availability of resources. We hypothesized that (1) the decline in Seabird abundance was responsible for the decrease in the fox population; and (2) that the growth in the fox population combined to fluctuations in main resources would lead to an increase in intra-specific competition, ultimately leading to variations in their isotopic niches at the population scale. The isotopic composition of Arctic fox bones differed clearly between inland and coast. Stable isotopes mixing models suggested that marine resources and rock ptarmigans were the most important food source and highlighted a rather stable diet in coastal habitats compared to inland habitats where more fluctuations in dietary composition were observed. Coastal foxes had a broader niche than inland foxes, and there was more variation in niche size in the inland habitat. Our results tend to confirm that a general decline in seabird populations drove the decline in Arctic foxes, especially in coastal habitats. For the inland foxes, our results suggest that the lack of marine resources might have led to an increased use of ptarmigans especially during the most recent period.
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Affiliation(s)
- Fanny Berthelot
- Department of Arctic and Marine Biology, UiT -The Arctic University of Norway, Tromsø, Norway
| | | | | | - Dorothee Ehrich
- Department of Arctic and Marine Biology, UiT -The Arctic University of Norway, Tromsø, Norway
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2
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Korobushkin DI, Gongalsky KB. Variability of Isotope Composition (15N/14N and 13С/12С) in Tissues and Organs of Mediterranean Soil Invertebrates. ARID ECOSYSTEMS 2022. [DOI: 10.1134/s207909612202007x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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3
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Rodríguez-Malagón MA, Speakman CN, Sutton GJ, Angel LP, Arnould JPY. Temporal and spatial isotopic variability of marine prey species in south-eastern Australia: Potential implications for predator diet studies. PLoS One 2021; 16:e0259961. [PMID: 34847167 PMCID: PMC8631622 DOI: 10.1371/journal.pone.0259961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 10/29/2021] [Indexed: 12/02/2022] Open
Abstract
Stable isotope analyses, particularly of carbon (δ13C) and nitrogen (δ15N), are used to investigate ecological relationships among species. For marine predators, research has shown the main factors influencing their intra-specific and intra-individual isotopic variation are geographical movements and changes in the composition of diet over time. However, as the differences seen may be the result of changes in the prey items consumed, a change in feeding location or the combination of both, knowledge of the temporal and spatial consistency in the isotopic values of prey becomes crucial for making accurate inferences about predator diets. This study used an abundant marine predator, the Australasian gannet (Morus serrator), as prey sampler to investigate the annual variation in fish and squid prey isotope values over a four-year period (2012–2015) and the geographic variation between two sites with contrasting oceanographic conditions. Significant inter-annual variation was observed in δ13C and/or δ15N values of five of the eight prey species analysed. The strongest inter-annual variation in both δ13C and δ15N values occurred in 2015, which coincided with a strong El Niño-Southern Oscillation (ENSO). This may suggest a temporal fluctuation in the geographic source of prey or the origin of their nutrients. These results suggest that it is important to consider the potential significant differences in isotopic values within the prey assemblages that predators consume. This is important to improve the interpretation of marine predator isotope results when determining the influence of environmental variability on their diets.
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Affiliation(s)
| | - Cassie N Speakman
- School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia
| | - Grace J Sutton
- School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia
| | - Lauren P Angel
- School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia
| | - John P Y Arnould
- School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia
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4
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Cecchetti M, Crowley SL, Goodwin CED, Cole H, McDonald J, Bearhop S, McDonald RA. Contributions of wild and provisioned foods to the diets of domestic cats that depredate wild animals. Ecosphere 2021. [DOI: 10.1002/ecs2.3737] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Martina Cecchetti
- Environment and Sustainability Institute University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Sarah L. Crowley
- Environment and Sustainability Institute University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Cecily E. D. Goodwin
- Environment and Sustainability Institute University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Holly Cole
- Centre for Ecology and Conservation University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Jennifer McDonald
- Centre for Ecology and Conservation University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Stuart Bearhop
- Centre for Ecology and Conservation University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
| | - Robbie A. McDonald
- Environment and Sustainability Institute University of Exeter Penryn Campus Penryn Cornwall TR10 9FE UK
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5
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Pereyra PER, Hallwass G, Poesch M, Silvano RAM. ‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.723026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.
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6
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Intra-Body Variations of Stable Isotope Ratios (δ13C, δ15N) and Influence of Storage Methods in Aquatic and Post-Aquatic Stages of the Common Toad, Bufo bufo. WATER 2021. [DOI: 10.3390/w13182544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Isotopic signatures of carbon and nitrogen are widely used for analysis of the structure of food webs in aquatic ecosystems. The study of animals raises a number of methodological questions, including choice of representative tissues and organs for sampling as well as storage of the studied organisms. Furthermore, the impacts of preservation methods can be tissue-specific, age-specific, and even taxon-specific; thus, studies of these impacts on particular taxa are necessary. We focused on the C and N isotope composition of the common toad (Bufo bufo), one of the most widespread European anuran amphibians. We hypothesized that its different tissues and organs may vary in isotopic composition, and ethanol and freezing may have different effects on isotopic values. Our results showed that both “tissue” and “storage method” factors significantly affected the δ13C values of tadpoles and postmetamorphic juveniles, whereas only the “tissue” factor had a significant effect on the δ15N values. The two stages, tadpoles and postmetamorphs, should be analyzed separately despite the brief postmetamorphic period of the juveniles. The skin, legs, muscles, and tail in tadpoles and legs, muscles and heart in juveniles can be used for δ13C and δ15N analysis regardless of the method of storage. The results will serve for the optimization of future study designs in isotopic ecology.
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7
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Travis SC, Pérez-Fuentetaja A, Aga DS. Evidence of continued exposure to legacy persistent organic pollutants in threatened migratory common terns nesting in the Great Lakes. ENVIRONMENT INTERNATIONAL 2020; 144:106065. [PMID: 32891920 DOI: 10.1016/j.envint.2020.106065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/13/2020] [Accepted: 08/16/2020] [Indexed: 06/11/2023]
Abstract
Persistent organic pollutants (POPs) accumulate in the food web of the Great Lakes ecosystem, causing concern that these chemicals play a role in the decline of avian species such as colonial-nesting waterbirds. In this study, samples from four life stages of the common tern (Sterna hirundo), a threatened species in New York State, were collected post-mortem in the Buffalo-Niagara region (United States). Brains (n = 26) and livers (n =27) were analyzed for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and the insecticide p,p'-dichlorodiphenyltrichloroethane (DDT) and its two metabolites p,p'-dichlorodiphenyldichloroethylene (DDE) and p,p'-dichlorodiphenyldichloroethane (DDD). Detectable concentrations of PCBs and PBDEs were observed in all samples; concentrations of total PCBs ranged from 5.59 to 2,490 ng/g wet weight (ww), total PBDEs ranged from 1.09 to 494 ng/g ww, and DDE metabolites ranged from 0.56 to 637 ng/g ww. Analysis of the primary food source for terns in the Buffalo-Niagara region, emerald shiners (Notropis atherinoides), revealed that all three classes of POPs had similar contaminant profiles in the fish to those in the brains and livers of tern samples. Overall, small chicks contained greater concentrations of pollutants than medium chicks and juveniles, likely from maternal loading to eggs. These results underline the persistence of these legacy contaminants in the Great Lakes, despite their banning, and their biomagnification in threatened species through food web interactions.
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Affiliation(s)
- Steven C Travis
- Department of Chemistry, University at Buffalo, The State University of New York Buffalo, New York, United States
| | - Alicia Pérez-Fuentetaja
- Department of Biology and Great Lakes Center, Buffalo State, The State University of New York, Buffalo, NY, United States
| | - Diana S Aga
- Department of Chemistry, University at Buffalo, The State University of New York Buffalo, New York, United States.
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8
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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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9
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Cloyed CS, DaCosta KP, Hodanbosi MR, Carmichael RH. The effects of lipid extraction on δ
13
C and δ
15
N values and use of lipid‐correction models across tissues, taxa and trophic groups. Methods Ecol Evol 2020. [DOI: 10.1111/2041-210x.13386] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Carl S. Cloyed
- University Programs Dauphin Island Sea Lab Dauphin Island AL USA
| | - Kayla P. DaCosta
- University Programs Dauphin Island Sea Lab Dauphin Island AL USA
- Department of Marine Sciences University of South Alabama Mobile AL USA
| | - Matthew R. Hodanbosi
- University Programs Dauphin Island Sea Lab Dauphin Island AL USA
- Department of Marine Sciences University of South Alabama Mobile AL USA
| | - Ruth H. Carmichael
- University Programs Dauphin Island Sea Lab Dauphin Island AL USA
- Department of Marine Sciences University of South Alabama Mobile AL USA
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10
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Carbonell Ellgutter JA, Ehrich D, Killengreen ST, Ims RA, Unnsteinsdóttir ER. Dietary variation in Icelandic arctic fox (Vulpes lagopus) over a period of 30 years assessed through stable isotopes. Oecologia 2019; 192:403-414. [PMID: 31865484 DOI: 10.1007/s00442-019-04580-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 12/13/2019] [Indexed: 12/21/2022]
Abstract
Identifying resources driving long-term trends in predators is important to understand ecosystem changes and to manage populations in the context of conservation or control. The arctic fox population in Iceland has increased steadily over a period of 30 years, an increase that has been attributed to an overall increase in food abundance. We hypothesized that increasing populations of geese or seabirds were driving this growth. We analyzed stable isotopes in a long-term series of collagen samples to determine the role of these different resources. The isotopic signatures of arctic foxes differed consistently between coastal and inland habitats. While δ15N displayed a non-linear change over time with a slight increase in the first part of the period followed by a decline in both habitats, δ13C was stable. Stable isotope mixing models suggested that marine resources and rock ptarmigan were the most important dietary sources, with marine resources dominating in coastal habitats and rock ptarmigan being more important inland. Our results suggest that seabirds may have been driving the arctic fox population increase. The rapidly increasing populations of breeding geese seem to have played a minor role in arctic fox population growth, as rock ptarmigan was the most important terrestrial resource despite a considerable decrease in their abundance during recent decades. This study shows that a long-term population trend in a generalist predator may have occurred without a pronounced change in main dietary resources, despite ongoing structural changes in the food web, where one species of herbivorous birds increased and another decreased.
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Affiliation(s)
| | - Dorothee Ehrich
- Department of Arctic Biology and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Siw T Killengreen
- Department of Teacher Education and Education, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Rolf A Ims
- Department of Arctic Biology and Marine Biology, UiT-The Arctic University of Norway, Tromsø, Norway
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11
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Stewart C, Garrick E, McAulay J. Do mallard ducks feature in the diet of stoats in an agricultural landscape? NEW ZEALAND JOURNAL OF ZOOLOGY 2019. [DOI: 10.1080/03014223.2019.1691019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Cohen Stewart
- Southland Fish and Game Council, Invercargill, New Zealand
| | - Erin Garrick
- Southland Fish and Game Council, Invercargill, New Zealand
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12
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Hallanger IG, Fuglei E, Yoccoz NG, Pedersen ÅØ, König M, Routti H. Temporal trend of mercury in relation to feeding habits and food availability in arctic foxes (Vulpes lagopus) from Svalbard, Norway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 670:1125-1132. [PMID: 31018428 DOI: 10.1016/j.scitotenv.2019.03.239] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 06/09/2023]
Abstract
We investigated the temporal trend of mercury (Hg) in arctic foxes from Svalbard, Norway sampled in the period 1997-2014 (n = 109, from 11 trapping seasons). We used linear models to investigate the effect of trapping season, feeding habits (δ13C), food availability from marine and terrestrial ecosystems (reindeer carcasses and sea ice cover), sex, age and body condition on liver total Hg (THg) levels. Liver THg levels increased in arctic foxes with 7.2% (95% CI: 2.3, 9.6) per year when the concentrations were adjusted for variation of δ13C, sea ice cover, and reindeer carcasses, whereas the raw annual trend was 3.5% (CI: -0.11, 7.2). However, the THg levels in arctic foxes from Svalbard are still lower than other marine mammals. We also demonstrate that arctic fox terrestrial food consumption is important for lowering the overall THg levels in this species.
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Affiliation(s)
- Ingeborg G Hallanger
- Norwegian Polar Institute, Fram Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway; UiT - The Arctic University of Norway, Dept. of Arctic & Marine Biology, NO-9037 Tromsø, Norway.
| | - Eva Fuglei
- Norwegian Polar Institute, Fram Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway.
| | - Nigel G Yoccoz
- UiT - The Arctic University of Norway, Dept. of Arctic & Marine Biology, NO-9037 Tromsø, Norway.
| | - Åshild Ø Pedersen
- Norwegian Polar Institute, Fram Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway.
| | - Max König
- Norwegian Polar Institute, Fram Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway
| | - Heli Routti
- Norwegian Polar Institute, Fram Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway.
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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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14
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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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15
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Javornik J, Hopkins JB, Zavadlav S, Levanič T, Lojen S, Polak T, Jerina K. Effects of ethanol storage and lipids on stable isotope values in a large mammalian omnivore. J Mammal 2019. [DOI: 10.1093/jmammal/gyy187] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jernej Javornik
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
| | - John B Hopkins
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
- School of Biodiversity Conservation, Unity College, Unity, ME, USA
| | - Saša Zavadlav
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
- Department of Yield and Silviculture, Slovenian Forestry Institute, Večna pot, Ljubljana, Slovenia
| | - Tom Levanič
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
- Department of Yield and Silviculture, Slovenian Forestry Institute, Večna pot, Ljubljana, Slovenia
| | - Sonja Lojen
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
- Department of Environmental Sciences, Jožef Stefan Institute, Jamova cesta, Ljubljana, Slovenia
- School of Environmental Sciences, University of Nova Gorica, Lanthieri mansion, Glavni,Vipava, Slovenia
| | - Tomaž Polak
- Biotechnical Faculty, Department of Food Science and Technology, University of Ljubljana, Jamnikarjeva, Ljubljana, Slovenia
| | - Klemen Jerina
- Biotechnical Faculty, Department of Forestry, University of Ljubljana, Večna pot, Ljubljana, Slovenia
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16
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Liu Y, Luo XJ, Huang LQ, Tao L, Zeng YH, Mai BX. Halogenated organic pollutants in aquatic, amphibious, and terrestrial organisms from an e-waste site: Habitat-dependent accumulation and maternal transfer in watersnake. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 241:1063-1070. [PMID: 30029314 DOI: 10.1016/j.envpol.2018.06.038] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 05/30/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
Dichlorodiphenyltrichloroethanes (DDTs), Polychlorinated biphenyls (PCBs), and halogenated flame retardants (HFRs) were measured in aquatic, amphibious, and terrestrial wildlife collected from an e-waste contaminated pond and its surrounding region. The species-specific bioaccumulation and maternal transfer of chemicals in the watersnake were investigated. Total concentrations of target chemicals ranged from 1.3 × 103 to 4.8 × 105 ng g-1 lipid weight. PCBs were the predominant (72-95%) contaminants, followed by polybrominated biphenyl ethers (PBDEs, 4-27%). The concentrations of PCBs and HFRs except decabromodiphenyl ethane (DBDPE) were higher in aquatic organisms and terrestrial birds than in amphibians and lizards. Relatively high DDT levels were observed in the terrestrial birds and toads, but high DBDPE was found in the aquatic species except for waterbird eggs. Species-specific congeners profiles for PCB and PBDE and isomeric composition for dechlorane plus were observed. These results indicated a habitat-dependent accumulation among different species. Maternal transfer examined by the ratio of egg to carcass for watersnakes indicated multi-linear correlations between maternal transfer potential and octanol-water partition coefficient (log KOW) of chemicals. The same maternal transfer efficiencies were found for chemicals with log KOW between 6 and 8, then the maternal transfer potential rapidly decreased with increasing of log KOW.
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Affiliation(s)
- Yu Liu
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Xiao-Jun Luo
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China.
| | - Li-Qian Huang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Lin Tao
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yan-Hong Zeng
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China
| | - Bi-Xian Mai
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, People's Republic of China
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17
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Curk T, McDonald T, Zazelenchuk D, Weidensaul S, Brinker D, Huy S, Smith N, Miller T, Robillard A, Gauthier G, Lecomte N, Therrien JF. Winter irruptive Snowy Owls (Bubo scandiacus) in North America are not starving. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Winter irruptions, defined as irregular massive movement of individuals over large distances, have been linked to food supply. Two hypotheses have been put forward: the “lack-of-food” suggests that a shortage of food forces individuals to leave their regular winter range and the “breeding output” suggests that unusually large food supplies during the preceding breeding season allows production of a large number of offspring dispersing in winter. According to the breeding output hypothesis, irruptive Snowy Owls (Bubo scandiacus (Linnaeus, 1758)) in eastern North America should not exhibit a lower body condition than individuals in regular wintering regions and individuals on the breeding grounds. Additionally, body condition of irruptive individuals should be unrelated to irruption intensity. Although body condition of juveniles was generally lower than that of adults and improved during the winter, we measured a fair body condition in both juvenile and adult irruptive Snowy Owls across North America. The results showed that Snowy Owls are not in a starving state during winter and that body condition of all age classes was not related to winter irruption intensity. Those results support the breeding output hypothesis suggesting that winter irruptions seem to be primarily the result of a large number of offspring produced when food availability on the breeding grounds is high.
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Affiliation(s)
- T. Curk
- Hawk Mountain Sanctuary, Orwigsburg, Pennsylvania, USA
- Max Planck Institute for Ornithology, Radolfzell, Germany
| | | | | | - S. Weidensaul
- Ned Smith Center for Nature and Art, Millersburg, Pennsylvania, USA
| | - D. Brinker
- Maryland Department of Natural Resources, Catonsville, Maryland, USA
| | - S. Huy
- Project Owlnet, Maryland, USA
| | - N. Smith
- Mass Audubon, Lincoln, Massachusetts, USA
| | - T. Miller
- Conservation Science Global, Inc., Cape May, New Jersey, USA
| | - A. Robillard
- Université Laval, Centre d’études nordiques, QC G1V 0A6, Canada
| | - G. Gauthier
- Université Laval, Centre d’études nordiques, QC G1V 0A6, Canada
| | - N. Lecomte
- Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - J.-F. Therrien
- Hawk Mountain Sanctuary, Orwigsburg, Pennsylvania, USA
- Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, NB E1A 3E9, Canada
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18
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Tarroux A, Lydersen C, Trathan PN, Kovacs KM. Temporal variation in trophic relationships among three congeneric penguin species breeding in sympatry. Ecol Evol 2018; 8:3660-3674. [PMID: 29686847 PMCID: PMC5901183 DOI: 10.1002/ece3.3937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 01/12/2018] [Accepted: 01/27/2018] [Indexed: 11/08/2022] Open
Abstract
Penguins are a monophyletic group in which many species are found breeding sympatrically, raising questions regarding how these species coexist successfully. Here, the isotopic niche of three sympatric pygoscelid penguin species was investigated at Powell Island, South Orkney Islands, during two breeding seasons (austral summers 2013–2014 and 2015–2016). Measurements of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios were obtained from blood (adults) or feather (chicks) samples collected from Adélie Pygoscelis adeliae, chinstrap P. antarctica, and gentoo P. papua penguins. Isotopic niche regions (a proxy for the realized trophic niches) were computed to provide estimates of the trophic niche width of the studied species during the breeding season. The isotopic niche regions of adults of all three species were similar, but gentoo chicks had noticeably wider isotopic niches than the chicks of the other two species. Moderate to strong overlap in isotopic niche among species was found during each breeding season and for both age groups, suggesting that the potential for competition for shared food sources was similar during the two study years, although the actual level of competition could not be determined owing to the lack of data on resource abundance. Clear interannual shifts in isotopic niche were seen in all three species, though of lower amplitude for adult chinstrap penguins. These shifts were due to variation in carbon, but not nitrogen, isotopic ratios, which could indicate either a change in isotopic signature of their prey or a switch to an alternative food web. The main conclusions of this study are that (1) there is a partial overlap in the isotopic niches of these three congeneric species and that (2) they responded similarly to changes that likely occurred at the base of their food chain between the 2 years of the study.
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Affiliation(s)
- Arnaud Tarroux
- Norwegian Polar Institute Fram Centre Tromsø Norway.,Norwegian Institute for Nature Research Fram Centre Tromsø Norway
| | | | | | - Kit M Kovacs
- Norwegian Polar Institute Fram Centre Tromsø Norway
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19
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Poisbleau M, Beaulieu M, Dehnhard N, Demongin L, Lepoint G, Sturaro N, Eens M. Extreme intra-clutch egg size dimorphism is not coupled with corresponding differences in antioxidant capacity and stable isotopes between eggs. Comp Biochem Physiol A Mol Integr Physiol 2017; 205:77-85. [PMID: 28062221 DOI: 10.1016/j.cbpa.2016.12.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/03/2016] [Accepted: 12/28/2016] [Indexed: 10/20/2022]
Abstract
Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isotopic compositions between eggs suggesting that resources were allocated similarly to each egg within the clutch. Overall, we found little evidence for a significant role of antioxidant and isotopic compositions to explain differences in terms of embryo/chick development between eggs in crested penguins. However, since our results suggest a constant rate of antioxidant transfer from females to eggs, limiting the mass of the first-laid egg might represent a strategy for females to spare antioxidant defences and preserve self-maintenance.
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Affiliation(s)
- Maud Poisbleau
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp (Wilrijk), Belgium.
| | - Michaël Beaulieu
- Zoological Institute and Museum, University of Greifswald, Johann-Sebastian Bach Str. 11/12, 17489 Greifswald, Germany
| | - Nina Dehnhard
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp (Wilrijk), Belgium
| | - Laurent Demongin
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp (Wilrijk), Belgium
| | - Gilles Lepoint
- Laboratory of Oceanology, FOCUS UR, University of Liège, B6C, 4000 Liège, Sart Tilman, Belgium
| | - Nicolas Sturaro
- Laboratory of Oceanology, FOCUS UR, University of Liège, B6C, 4000 Liège, Sart Tilman, Belgium
| | - Marcel Eens
- Behavioural Ecology & Ecophysiology Group, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp (Wilrijk), Belgium
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20
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Routti H, Andersen MS, Fuglei E, Polder A, Yoccoz NG. Concentrations and patterns of hydroxylated polybrominated diphenyl ethers and polychlorinated biphenyls in arctic foxes (Vulpes lagopus) from Svalbard. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 216:264-272. [PMID: 27267742 DOI: 10.1016/j.envpol.2016.05.056] [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] [Received: 02/02/2016] [Revised: 04/26/2016] [Accepted: 05/19/2016] [Indexed: 06/06/2023]
Abstract
Concentrations and patterns of hydroxylated (OH) polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were investigated in liver from arctic foxes (Vulpes lagopus) sampled from Svalbard 1997-2011 (n = 100). The most important OH-PBDE in the arctic foxes was 6-OH-BDE47 detected in 24% of the samples. Relationships between 6-OH-BDE47, δ(13)C and BDE47 suggest that 6-OH-BDE47 residues in arctic foxes are related to marine dietary input, while the relative importance of the metabolic/natural origin of this compound remains unclear. 4-OH-CB187 and 4-OH-CB146 were the main OH-PCBs among the analyzed compounds. The OH-PCB pattern in the present arctic foxes indicates that arctic foxes have a capacity to biotransform a wide range of PCBs of different structures. Formation and retention of OH-PCBs was tightly related to PCB exposure. Furthermore, ΣOH-PCB concentrations were four times higher in the leanest compared to the fattest foxes. Concentrations of 4-OH-CB187 and 4-OH-CB146 among the highest contaminated arctic foxes were similar to the previously reported concentrations for polar bears. Given the high endocrine disruptive potential of OH-PCBs, we suggest that endocrine system may be affected by the relatively high OH-PCB residues in the Svalbard arctic fox population.
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Affiliation(s)
- Heli Routti
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway.
| | - Martin S Andersen
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway; Department of Arctic and Marine Biology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Eva Fuglei
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
| | - Anuschka Polder
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway
| | - Nigel G Yoccoz
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
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21
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Dalerum F, Hellström P, Miranda M, Nyström J, Ekenstedt J, Angerbjörn A. Network topology of stable isotope interactions in a sub-arctic raptor guild. Oecologia 2016; 182:511-8. [PMID: 27209296 DOI: 10.1007/s00442-016-3658-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 05/11/2016] [Indexed: 11/25/2022]
Abstract
Predation is an ecologically important process, and intra-guild interactions may substantially influence the ecological effects of predator species. Despite a rapid expansion in the use of mathematical graph theory to describe trophic relations, network approaches have rarely been used to study interactions within predator assemblages. Assemblages of diurnal raptors are subject to substantial intra- and interspecific competition. Here we used the novel approach of applying analyzes based on network topology to species-specific data on the stable isotopes (13)C and (15)N in feathers to evaluate patterns of relative resource utilization within a guild of diurnal raptors in northern Sweden. Our guild consisted of the golden eagle (Aquila chrysaetos), the gyrfalcon (Falco rusticolus), the peregrine falcon (Falco peregrinus) and the rough-legged buzzard (Buteo lagopus). We found a modular trophic interaction structure within the guild, but the interactions were less nested than expected by chance. These results suggest low redundancy and hence a strong ecological importance of individual species. Our data also suggested that species were less connected through intra-guild interactions than expected by chance. We interpret our results as a convergence on specific isotope niches, and that body size and different hunting behaviour may mediate competition within these niches. We finally highlight that generalist predators could be ecologically important by linking specialist predator species with disparate dietary niches.
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Affiliation(s)
- F Dalerum
- Research Unit of Biodiversity (UO-CSIC-PA), University of Oviedo, Mieres Campus, 33600, Mieres, Spain.
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
- Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden.
| | - P Hellström
- Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden
- Department of Environmental Research and Monitoring, Swedish Museum of Natural History, Frescativägen 40, 114 18, Stockholm, Sweden
| | - M Miranda
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3 Wits 2050, Johannesburg, South Africa
- Department of Economics, University of Oviedo, 33203, Oviedo, Spain
| | - J Nyström
- Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden
| | - J Ekenstedt
- Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden
| | - A Angerbjörn
- Department of Zoology, Stockholm University, 106 91, Stockholm, Sweden
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22
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Tatsch ACC, Secchi ER, Botta S. Effects of acidification, lipid removal and mathematical normalization on carbon and nitrogen stable isotope compositions in beaked whale (Ziphiidae) bone. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:460-466. [PMID: 26754138 DOI: 10.1002/rcm.7457] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The analysis of stable isotopes in tissues such as teeth and bones has been used to study long-term trophic ecology and habitat use in marine mammals. However, carbon isotope ratios (δ(13) C values) can be altered by the presence of (12) C-rich lipids and carbonates. Lipid extraction and acidification are common treatments used to remove these compounds. The impact of lipids and carbonates on carbon and nitrogen isotope ratios (δ(15) N values), however, varies among tissues and/or species, requiring taxon-specific protocols to be developed. METHODS The effects of lipid extraction and acidification and their interaction on carbon and nitrogen isotope values were studied for beaked whale (Ziphiidae) bone samples. δ(13) C and δ(15) N values were determined in quadruplicate samples: control, lipid-extracted, acidified and lipid-extracted followed by acidification. Samples were analyzed by means of elemental analysis isotope ratio mass spectrometry. Furthermore, the efficiency of five mathematical models developed for estimating lipid-normalized δ(13) C values from untreated δ(13) C values was tested. RESULTS Significant increases in δ(13) C values were observed after lipid extraction. No significant changes in δ(13) C values were found in acidified samples. An interaction between both treatments was demonstrated for δ(13) C but not for δ(15) N values. No change was observed in δ(15) N values for lipid-extracted and/or acidified samples. Although all tested models presented good predictive power to estimate lipid-free δ(13) C values, linear models performed best. CONCLUSIONS Given the observed changes in δ(13) C values after lipid extraction, we recommend a priori lipid extraction or a posteriori lipid normalization, through simple linear models, for beaked whale bones. Furthermore, acidification seems to be an unnecessary step before stable isotope analysis, at least for bone samples of ziphiids. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Ana Carolina C Tatsch
- Programa de Pós-Graduação em Oceanografia Biológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
- Laboratório de Ecologia e Conservação da Megafauna Marinha - ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
| | - Eduardo R Secchi
- Programa de Pós-Graduação em Oceanografia Biológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
- Laboratório de Ecologia e Conservação da Megafauna Marinha - ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
| | - Silvina Botta
- Programa de Pós-Graduação em Oceanografia Biológica, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
- Laboratório de Ecologia e Conservação da Megafauna Marinha - ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
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23
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Sardenne F, Ménard F, Degroote M, Fouché E, Guillou G, Lebreton B, Hollanda SJ, Bodin N. Methods of lipid-normalization for multi-tissue stable isotope analyses in tropical tuna. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:1253-1267. [PMID: 26395609 DOI: 10.1002/rcm.7215] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/13/2015] [Accepted: 04/17/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The bias associated with lipid contents in fish tissues is a recalcitrant topic for trophic studies using stable isotopes. Lipids are depleted in the heavy carbon isotope ((13)C) and the lipid content varies considerably among species, tissues and in both time and space. We have applied and assessed different correction methods for tropical tuna tissues. METHODS We tested two types of normalization methods to deal with variable lipid content in liver, gonads, and white and red muscles of yellowfin, bigeye and skipjack tuna: a chemical extraction using dichloromethane and a mathematical correction based on three modeling approaches (linear, non-linear and mass balance models). We measured isotopic ratios of bulk and lipid-free tissues and assessed the predictive ability of the correction models with the lipid-free measurements. The parameters of the models were estimated from our dataset and from results from published studies on other species. RESULTS Comparison between bulk, lipid-free and lipid-corrected isotopic ratios demonstrated that (1) chemical extraction using dichloromethane did not affect δ(15)N values; (2) the change in δ(13)C values after extraction was tissue-specific; (3) lipid-normalization models using published parameter estimates failed to predict lipid-corrected δ(13)C values; and (4) linear and non-linear models using parameters estimated for each tissue from our dataset provided accurate δ(13)C predictions for all tissues, and mass balance model for white muscle only. CONCLUSIONS Models using published estimates for parameters from other species cannot be used. Based on a range of lipid content that do not exceed 45%, we recommend the linear model to correct the bulk δ(13)C values in the investigated tissues but the parameters have to be estimated from a proportion of the original data for which chemical extraction is required and the isotopic values of bulk and lipid-free tissues are measured.
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Affiliation(s)
- Fany Sardenne
- IRD, UMR MARine Biodiversity Exploitation and Conservation (MARBEC), Avenue Jean Monnet, Sète, France
- IRD, UMR MARine Biodiversity Exploitation and Conservation (MARBEC), Fishing Port, Victoria, Seychelles
| | - Frédéric Ménard
- IRD, Mediterranean Institute of Oceanography (MIO), Aix-Marseille Université/CNRS/IRD/Université de Toulon, 13288, Marseille, France
| | - Maxime Degroote
- IRD, UMR MARine Biodiversity Exploitation and Conservation (MARBEC), Avenue Jean Monnet, Sète, France
| | - Edwin Fouché
- IRD, UMR MARine Biodiversity Exploitation and Conservation (MARBEC), Avenue Jean Monnet, Sète, France
- INRA, UMR TOXALIM (Research Centre in Food Toxicology), Toulouse, France
| | - Gaël Guillou
- CNRS-Université de la Rochelle, UMR Littoral Environnement et Sociétés (LIENSs), 2 rue Olympe de Gouges, 17000, La Rochelle, France
| | - Benoit Lebreton
- CNRS-Université de la Rochelle, UMR Littoral Environnement et Sociétés (LIENSs), 2 rue Olympe de Gouges, 17000, La Rochelle, France
| | | | - Nathalie Bodin
- IRD, UMR MARine Biodiversity Exploitation and Conservation (MARBEC), Fishing Port, Victoria, Seychelles
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24
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Andersen MS, Fuglei E, König M, Lipasti I, Pedersen ÅØ, Polder A, Yoccoz NG, Routti H. Levels and temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard in relation to dietary habits and food availability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 511:112-122. [PMID: 25536177 DOI: 10.1016/j.scitotenv.2014.12.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/12/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
Temporal trends of persistent organic pollutants (POPs) in arctic foxes (Vulpes lagopus) from Svalbard, Norway, were investigated in relation to feeding habits and seasonal food availability. Arctic foxes from Svalbard forage in both marine and terrestrial ecosystems and the availability of their food items are impacted by climatic variability. Concentrations of polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs) and brominated flame retardants (polybrominated diphenyl ethers [PBDEs] and hexabromocyclododecane [HBCDD]) were analyzed in the liver of 141 arctic foxes collected between 1997 and 2013. Stable carbon isotope values (δ13C) were used as a proxy for feeding on marine versus terrestrial prey. The annual number of recovered reindeer carcasses and sea ice cover were used as proxies for climate influenced food availability (reindeers, seals). Linear models revealed that concentrations of PCBs, chlordanes, p,p'-DDE, mirex and PBDEs decreased 4-11% per year, while no trends were observed for hexachlorobenzene (HCB) or β-hexachlorocyclohexane (β-HCH). Positive relationships between POP concentrations and δ13C indicate that concentrations of all compounds increase with increasing marine dietary input. Increasing reindeer mortality was related to lower HCB concentrations in the foxes based on the linear models. This suggests that concentrations of HCB in arctic foxes may be influenced by high mortality levels of Svalbard reindeer. Further, β-HCH concentrations showed a positive association with sea ice cover. These results in addition to the strong effect of δ13C on all POP concentrations suggest that climate-related changes in arctic fox diet are likely to influence contaminant concentrations in arctic foxes from Svalbard.
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Affiliation(s)
- Martin S Andersen
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway; Department of Arctic and Marine Biology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Eva Fuglei
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
| | - Max König
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
| | - Inka Lipasti
- Department of Biology, University of Eastern Finland, FI-80101 Joensuu, Finland
| | | | - Anuschka Polder
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Ås, Norway
| | - Nigel G Yoccoz
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Heli Routti
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway.
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25
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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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Aas CB, Fuglei E, Herzke D, Yoccoz NG, Routti H. Effect of body condition on tissue distribution of perfluoroalkyl substances (PFASs) in Arctic fox (Vulpes lagopus). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11654-61. [PMID: 25215880 DOI: 10.1021/es503147n] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Arctic animals undergo large seasonal fluctuations in body weight. The effect of body condition on the distribution and composition of 16 perfluoroalkyl substances (PFASs) was investigated in liver, blood, kidney, adipose tissue, and muscle of Arctic foxes (Vulpes lagopus) from Svalbard (n = 18, age 1-3 years). PFAS concentrations were generally highest in liver, followed by blood and kidney, while lowest concentrations were found in adipose tissue and muscle. Concentrations of summed perfluorocarboxylic acids and perfluoroalkyl sulfonates were five and seven times higher, respectively, in adipose tissue of lean compared to fat foxes. In addition, perfluorodecanoate (PFDA) and perfluoroheptanesulfonate (PFHpS) concentrations in liver, kidney, and blood, and, perfluorononanoate (PFNA) in liver and blood, were twice as high in the lean compared to the fat foxes. The ratio between perfluorooctane sulfonamide (FOSA) and its metabolite perfluorooctanesulfonate (PFOS) was lowest in liver, muscle, and kidney, while significantly higher proportions of FOSA were found in adipose tissue and blood. The results of the present study suggest that toxic potential of exposure to PFAS among other pollutants in Arctic mammals may increase during seasonal emaciation. The results also suggest that body condition should be taken into account when assessing temporal trends of PFASs.
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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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The effect of acidification and the combined effects of acidification/lipid extraction on carbon stable isotope ratios for sub-arctic and arctic marine zooplankton species. Polar Biol 2014. [DOI: 10.1007/s00300-014-1540-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Soininen EM, Ehrich D, Lecomte N, Yoccoz NG, Tarroux A, Berteaux D, Gauthier G, Gielly L, Brochmann C, Gussarova G, Ims RA. Sources of variation in small rodent trophic niche: new insights from DNA metabarcoding and stable isotope analysis. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2014; 50:361-381. [PMID: 24830842 DOI: 10.1080/10256016.2014.915824] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Intraspecific competition for food is expected to increase the trophic niche width of consumers, defined here as their diet diversity, but this process has been little studied in herbivores. Population densities of small rodents fluctuate greatly, providing a good study model to evaluate effects of competition on trophic niche. We studied resource use in five arctic small rodent populations of four species combining DNA metabarcoding of stomach contents and stable isotope analysis (SIA). Our results suggest that for small rodents, the most pronounced effect of competition on trophic niche is due to increased use of secondary habitats and to habitat-specific diets, rather than an expansion of trophic niche in primary habitat. DNA metabarcoding and SIA provided complementary information about the composition and temporal variation of herbivore diets. Combing these two approaches requires caution, as the underlying processes causing observed patterns may differ between methodologies due to different spatiotemporal scales.
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Affiliation(s)
- Eeva M Soininen
- a Department of Arctic and Marine Biology , UiT The Arctic University of Norway , Tromsø , Norway
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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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Diet, nesting density, and breeding success of rough-legged buzzards (Buteo lagopus) on the Nenetsky Ridge, Arctic Russia. Polar Biol 2013. [DOI: 10.1007/s00300-013-1441-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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L'Hérault V, Franke A, Lecomte N, Alogut A, Bêty J. Landscape heterogeneity drives intra-population niche variation and reproduction in an arctic top predator. Ecol Evol 2013; 3:2867-79. [PMID: 24101979 PMCID: PMC3790536 DOI: 10.1002/ece3.675] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/14/2013] [Accepted: 06/06/2013] [Indexed: 11/06/2022] Open
Abstract
While intra-population variability in resource use is ubiquitous, little is known of how this measure of niche diversity varies in space and its role in population dynamics. Here we examined how heterogeneous breeding environments can structure intra-population niche variation in both resource use and reproductive output. We investigated intra-population niche variation in the Arctic tundra ecosystem, studying peregrine falcon (Falco peregrinus tundrius, White) breeding within a terrestrial-marine gradient near Rankin Inlet, Nunavut, Canada. Using stable isotope analysis, we found that intra-population niches varied at the individual level; we examined within-nest and among-nest variation, though only the latter varied along the terrestrial-marine gradient (i.e., increased among-nest variability among birds nesting within the marine environment, indicating higher degree of specialization). Terrestrial prey species (small herbivores and insectivores) were consumed by virtually all falcons. Falcons nesting within the marine environment made use of marine prey (sea birds), but depended heavily on terrestrial prey (up to 90% of the diet). Using 28-years of peregrine falcon nesting data, we found a positive relationship between the proportion of terrestrial habitat surrounding nest sites and annual nestling production, but no relationship with the likelihood of successfully rearing at least one nestling reaching 25 days old. Annually, successful inland breeders raised 0.47 more young on average compared to offshore breeders, which yields potential fitness consequences for this long-living species. The analyses of niche and reproductive success suggest a potential breeding cost for accessing distant terrestrial prey, perhaps due to additional traveling costs, for those individuals with marine nest site locations. Our study indicates how landscape heterogeneity can generate proximate (niche variation) and ultimate (reproduction) consequences on a population of generalist predator. We also show that within-individual and among-individual variation are not mutually exclusive, but can simultaneously arise and structure intra-population niche variation.
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Affiliation(s)
- Vincent L'Hérault
- Université du Québec à Rimouski et Centre d'Études Nordiques300 Allée des Ursulines, Rimouski, Quebec, G5L 3A1, Canada
| | - Alastair Franke
- Canadian Circumpolar Institute, University of EdmontonEdmonton, Alberta, Canada
| | - Nicolas Lecomte
- Université du Québec à Rimouski et Centre d'Études Nordiques300 Allée des Ursulines, Rimouski, Quebec, G5L 3A1, Canada
- Government of Nunavut Department of EnvironmentP.O. Box 209, Igloolik, Nunavut, Canada
- Université de Moncton18 Avenue Antonine-Maillet Moncton, New Brunswick, E1A 3E9, Canada
| | - Adam Alogut
- Nunavut Arctic CollegeP.O. Box 187, Rankin Inlet, Nunavut, Canada
| | - Joël Bêty
- Université du Québec à Rimouski et Centre d'Études Nordiques300 Allée des Ursulines, Rimouski, Quebec, G5L 3A1, Canada
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Ryan C, McHugh B, Trueman CN, Harrod C, Berrow SD, O'Connor I. Accounting for the effects of lipids in stable isotope (δ13C and δ15N values) analysis of skin and blubber of balaenopterid whales. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:2745-2754. [PMID: 23124665 DOI: 10.1002/rcm.6394] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RATIONALE Stable isotope values (δ(13)C and δ(15)N) of darted skin and blubber biopsies can shed light on habitat use and diet of cetaceans, which are otherwise difficult to study. Non-dietary factors affect isotopic variability, chiefly the depletion of (13)C due to the presence of (12)C-rich lipids. The efficacy of post hoc lipid-correction models (normalization) must be tested. METHODS For tissues with high natural lipid content (e.g., whale skin and blubber), chemical lipid extraction or normalization is necessary. C:N ratios, δ(13)C values and δ(15)N values were determined for duplicate control and lipid-extracted skin and blubber of fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and minke whales (B. acutorostrata) by continuous-flow elemental analysis isotope ratio mass spectrometry (CF-EA-IRMS). Six different normalization models were tested to correct δ(13)C values for the presence of lipids. RESULTS Following lipid extraction, significant increases in δ(13)C values were observed for both tissues in the three species. Significant increases were also found for δ(15)N values in minke whale skin and fin whale blubber. In fin whale skin, the δ(15)N values decreased, with no change observed in humpback whale skin. Non-linear models generally out-performed linear models and the suitability of models varied by species and tissue, indicating the need for high model specificity, even among these closely related taxa. CONCLUSIONS Given the poor predictive power of the models to estimate lipid-free δ(13)C values, and the unpredictable changes in δ(15)N values due to lipid-extraction, we recommend against arithmetical normalization in accounting for lipid effects on δ(13)C values for balaenopterid skin or blubber samples. Rather, we recommend that duplicate analysis of lipid-extracted (δ(13)C values) and non-treated tissues (δ(15)N values) be used.
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Affiliation(s)
- Conor Ryan
- Marine and Freshwater Research Centre, Department of Life Science, Galway-Mayo Institute of Technology Galway, Dublin Road, Galway, Ireland.
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Graves GR, Newsome SD, Willard DE, Grosshuesch DA, Wurzel WW, Fogel ML. Nutritional stress and body condition in the Great Gray Owl (Strix nebulosa) during winter irruptive migrations. CAN J ZOOL 2012. [DOI: 10.1139/z2012-047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The largest irruptive migration of the Great Gray Owl ( Strix nebulosa Forster, 1772) recorded since 1831 occurred in Minnesota, USA, during the winter of 2004–2005. We tested the hypothesis that morphometric indicators of nutritional stress covary with stable isotope signatures in a sample of 265 owls killed by vehicle collisions. The ratio of carbon to nitrogen in muscle (C/Nmuscle) was shown to be a reliable proxy of nutritional stress. δ13C values for liver and muscle were significantly higher in owls in poor condition, reflecting the depletion of lipid reserves in fasting individuals. On the other hand, δ15N values for liver and muscle were marginally lower or unchanged in owls in poor condition. Stomachs of emaciated owls were less likely to contain prey, implying that many nutritionally stressed individuals were too weak to hunt and were near the tipping point of irreversible fasts. In a broader context, sexual differences in the correlative relationships between stable isotope signatures, C/N, and body condition suggest that the consequences of reversed sexual size dimorphism extend to physiological processes during the nonbreeding season.
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Affiliation(s)
- Gary R. Graves
- Department of Vertebrate Zoology, MRC-116, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, Washington, DC 20013-7012, USA; Center for Macroecology, Evolution and Climate, University of Copenhagen, DK-2100, Copenhagen Ø, Denmark
| | - Seth D. Newsome
- Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road Northwest, Washington, DC 20015, USA; Department of Zoology and Physiology, University of Wyoming, 1000 East University Avenue, Department 3166, Laramie, WY 82071, USA
| | - David E. Willard
- Zoology Department, Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA
| | | | - William W. Wurzel
- Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road Northwest, Washington, DC 20015, USA; State University of New York College of Environmental Science and Forestry, SUNY-ESF, 1 Forestry Drive, Syracuse, NY 13210, USA
| | - Marilyn L. Fogel
- Carnegie Institution of Washington, Geophysical Laboratory, 5251 Broad Branch Road Northwest, Washington, DC 20015, USA
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Pisanu B, Caut S, Gutjahr S, Vernon P, Chapuis JL. Introduced black rats Rattus rattus on Ile de la Possession (Iles Crozet, Subantarctic): diet and trophic position in food webs. Polar Biol 2010. [DOI: 10.1007/s00300-010-0867-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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