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Ivanova ES, Belova MA, Rumiantseva OY, Zudilova AA, Kopylov DS, Borisov MY, Komov VT. Effects of lipid extraction on stable isotope ratios of carbon and nitrogen in muscles of freshwater fish. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2024; 60:162-173. [PMID: 38353149 DOI: 10.1080/10256016.2024.2317379] [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: 01/16/2024] [Accepted: 01/28/2024] [Indexed: 03/20/2024]
Abstract
The extraction of lipids by the Folch method from the muscles of all the fish studied led to statistically significant differences in the values of δ15N. At the same time, lipid extraction led to a statistically significant increase in δ13C in pike and roach, and to a statistically insignificant decrease in δ13C in perch and bream. Thus, lipid extraction cannot serve as a universal method of sample preparation for the analysis of the isotopic composition of carbon (13C/12C) and nitrogen (15N/14N) in fish muscles. The differences between the δ13C values in the samples before and after lipid extraction were statistically investigated by different models. It is shown that mathematical correction method models can be used, but the results are depending on the fish types.
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Affiliation(s)
- Elena S Ivanova
- Department of Biology, Cherepovets State University, Cherepovets, Russia
| | - Maria A Belova
- Department of Biology, Cherepovets State University, Cherepovets, Russia
| | | | - Alena A Zudilova
- Department of Biology, Cherepovets State University, Cherepovets, Russia
| | - Dmitry S Kopylov
- Department of Biology, Cherepovets State University, Cherepovets, Russia
- Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, Russia
| | - Michael Y Borisov
- Vologda Branch of the Federal State Budget Scientific Institution «Russian Federal Research Institute of Fisheries and Oceanography», Vologda, Russia
| | - Viktor T Komov
- Department of Biology, Cherepovets State University, Cherepovets, Russia
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Russia
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2
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Sardenne F, Raynon T, Munaron JM, van der Lingen CD, Sadio O, Diop K, Brosset P, Lebigre C, Soudant P, Vagner M, Pecquerie L. Lipid-correction models for δ 13C values across small pelagic fishes (Clupeiformes) from the Atlantic Ocean. MARINE ENVIRONMENTAL RESEARCH 2023; 192:106213. [PMID: 37783159 DOI: 10.1016/j.marenvres.2023.106213] [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: 07/25/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/04/2023]
Abstract
The interpretation of δ13C values in trophic ecology requires standardization of the lipid content of organisms estimated through their C:N ratio. To avoid time-consuming lipid extractions, the use of mathematical corrections has been developed for many years, and the conclusions generally point in the direction of species-specific adjustment of the models. This study aimed at defining the maximum taxonomic level required to obtain the best corrected δ13C values in small pelagic fish of the order Clupeiformes. δ13C values of six species were analyzed bulk and lipid-free, and were used to fit and validate linear and mass-balance models at different taxonomic levels. Despite a species effect combined with the C:N ratio effect, the corrected δ13C values produced by a global model for the Clupeiformes were as good as or better when compared to lipid-free samples than those produced by species-specific models, paving the way for possible generalization to other species in this order. At the order level, the linear model outperformed the mass-balance model.
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Affiliation(s)
- Fany Sardenne
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280, Plouzané, France.
| | - Thomas Raynon
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280, Plouzané, France
| | | | - Carl D van der Lingen
- Department of Forestry, Fisheries and the Environment (DFFE), Cape Town, South Africa
| | - Oumar Sadio
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, Dakar, Senegal
| | - Khady Diop
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, Dakar, Senegal
| | - Pablo Brosset
- UMR DECOD, Ifremer, INRAE, L'Institut Agro, Plouzané, France
| | | | - Philippe Soudant
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280, Plouzané, France
| | - Marie Vagner
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280, Plouzané, France
| | - Laure Pecquerie
- IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280, Plouzané, France
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3
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Merquiol L, Romano G, Cutignano A, D'Ambra I. Chemical markers in marine food web: A simple workflow based on methyl tert-butyl ether extraction for fatty acids and stable isotopes assessment in plankton samples. MARINE ENVIRONMENTAL RESEARCH 2023; 190:106087. [PMID: 37473598 DOI: 10.1016/j.marenvres.2023.106087] [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: 03/26/2023] [Revised: 06/30/2023] [Accepted: 07/05/2023] [Indexed: 07/22/2023]
Abstract
Fatty acids (FAs) are used, often in combination with stable isotopes (SIs), as chemical biomarkers to assess the contribution of different prey to the diet of consumers and define food web structure and dynamics. Extraction of lipids is traditionally carried out using methanol (MeOH) combined with chloroform or dichloromethane, these latter being well-known environmental pollutant and potential carcinogenic agents. Recently, extraction protocols based on methyl tert-butyl ether (MTBE) and MeOH have been proposed as an alternative to halogenated solvents in lipidomic studies. However, no specific investigation has been performed to assess MTBE suitability in marine ecological studies including FA analysis together with SI measurements. We used an analytical workflow for qualitative and quantitative analysis of FAs and SIs in field samples of phytoplankton, zooplankton and the scyphomedusa Pelagia noctiluca, applying MTBE in comparison with chloroform- and dichloromethane-based protocols for total lipid extraction. Our analysis suggested that MTBE is a reliable substitute for lipid extraction in trophic ecology studies in marine planktonic organisms.
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Affiliation(s)
- Louise Merquiol
- Integrative Marine Ecology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy
| | - Giovanna Romano
- Ecosustainable Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, Via Acton 55, 80133, Napoli, Italy
| | - Adele Cutignano
- Ecosustainable Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, Via Acton 55, 80133, Napoli, Italy; Istituto di Chimica Biomolecolare (ICB), Consiglio Nazionale delle Ricerche, via Campi Flegrei 34, 80078, Pozzuoli, Italy.
| | - Isabella D'Ambra
- Integrative Marine Ecology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Napoli, Italy.
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Endo T, Kimura O, Terasaki M, Nakagun S, Kato Y, Fujii Y, Haraguchi K, Baker CS. Carbon, nitrogen, and oxygen stable isotope ratios of striped dolphins and short-finned pilot whales stranded in Hokkaido, northern Japan, compared with those of other cetaceans stranded and hunted in Japan. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2023; 59:230-247. [PMID: 37549039 DOI: 10.1080/10256016.2023.2234590] [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: 10/08/2022] [Accepted: 05/26/2023] [Indexed: 08/09/2023]
Abstract
Strandings of striped dolphins (SD) and short-finned pilot whales (PW) in Hokkaido, northern Japan, are rare but have recently increased, probably due to global warming. We quantified δ13C, δ15N, and δ18O in muscles of SD (n = 7) and PW (n = 3) stranded in Hokkaido and compared these values with those in muscles (red meat products) of hunted SD and PW in three areas of central and southern Japan. δ18O in stranded SD, except for the calf, decreased with increasing body length (BL), whereas δ13C increased, with no BL-related changes in δ15N. The variability of δ18O (range of maximum and minimum) was larger in the stranded SD (7.5 ‰) than of the hunted SD in three areas (0.9, 1.9, and 1.4 ‰), whereas that of δ15N was smaller in the stranded SD than in the hunted SD. Similarly, the variability of δ18O was larger in the stranded PW in Hokkaido (3.3 ‰) than in the hunted PW in central Japan (1.4 ‰). The larger variability of δ18O and smaller variability of δ15N in stranded SD imply long-term sojourning in coastal waters and feeding on small amounts of limited prey species at low trophic levels before death.
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Affiliation(s)
- Tetsuya Endo
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Osamu Kimura
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Masaru Terasaki
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - Shotaro Nakagun
- Laboratory of Veterinary Pathology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan
| | - Yoshihisa Kato
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
| | - Yukiko Fujii
- Department of Pharmaceutical Sciences, Daiichi University of Pharmacy, Fukuoka, Japan
| | - Koichi Haraguchi
- Department of Pharmaceutical Sciences, Daiichi University of Pharmacy, Fukuoka, Japan
| | - C Scott Baker
- Marine Mammal Institute and Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, USA
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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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Eggebo J, Groß J, Bengtson Nash S. Interpretation of southern hemisphere humpback whale diet via stable isotopes; implications of tissue-specific analysis. PLoS One 2023; 18:e0283330. [PMID: 37011067 PMCID: PMC10069779 DOI: 10.1371/journal.pone.0283330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 03/07/2023] [Indexed: 04/05/2023] Open
Abstract
Blubber and skin are commonly used tissues in stable isotope analysis for the purpose of investigating cetacean diet. Critical comparison of tissue-specific isotopic signals is, however, lacking resulting in uncertainty surrounding the representativeness and therefore utility of different tissues for accurate determination of recent foraging. This study used remotely biopsied blubber and skin tissues from southern hemisphere humpback whales for strategic comparison of δ13C and δ15N values. Samples were collected between 2008-2018 as part of long-term monitoring under the Humpback Whale Sentinel Program. Blubber tissues were lipid-extracted prior to analysis, whilst mathematical lipid-correction was performed on skin samples. Isotopic values from paired blubber and skin samples from the same individuals were compared to assess whether tissues could be used interchangeably for isotope analysis and dietary interpretation. Significant differences were observed for both δ13C and δ15N, flagging previously undocumented methodological considerations, and the need for method validation and standardisation in application of these approaches. This study therefore advances methodological aspects of cetacean dietary analysis. This is of elevated importance in the context of rapidly changing ocean ecosystems.
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Affiliation(s)
- June Eggebo
- Southern Ocean Persistent Organic Pollutants Program, Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - Jasmin Groß
- Southern Ocean Persistent Organic Pollutants Program, Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - Susan Bengtson Nash
- Southern Ocean Persistent Organic Pollutants Program, Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Nathan, QLD, Australia
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7
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Alvarez CD, Giussi AR, Botto F. Trophic variability of long tail hake Macruronus magellanicus in the Southwestern Atlantic: movements evidenced by stomach content and stable isotope analysis. Polar Biol 2022. [DOI: 10.1007/s00300-022-03063-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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8
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Kim D, Cho HE, Won EJ, Kim HJ, Lee S, An KG, Moon HB, Shin KH. Environmental fate and trophic transfer of synthetic musk compounds and siloxanes in Geum River, Korea: Compound-specific nitrogen isotope analysis of amino acids for accurate trophic position estimation. ENVIRONMENT INTERNATIONAL 2022; 161:107123. [PMID: 35147083 DOI: 10.1016/j.envint.2022.107123] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 01/23/2022] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Despite the extensive usage of synthetic musk compounds (SMCs) and siloxanes in various personal care products (PCPs), trophic magnification of such chemicals in aquatic environments remains unexplored. In June and September 2020, eleven SMCs and nineteen siloxanes were measured in water, sediments, and biota. Samples were collected from two sites where levels were expected to be influenced by the distance from the wastewater treatment plant (WWTP) in the Geum River, Republic of Korea, were expected. High concentrations of SMCs and siloxanes entered through WWTP were measured in water, sediment, and biota at the both sites and both seasons. The δ15N of amino acids provided a high-resolution food web and accurate trophic position (TP), which is an important factor for determining the trophic magnification factor (TMF). Among 24 TMFs, 19 of them were <1, ranging 0.7-0.8 for 1,3,4,6,7,8‑hexahydro‑4,6,6,7,8,8‑hexamethyl‑cyclopenta‑γ‑2‑benzopyran (HHCB), 0.6-0.8 for 6-Acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN), 0.7-0.8 for 4-tert-Butyl-3,5-dinitro-2,6-dimethylacetophenone (MK), 0.7-0.9 for octamethylcyclotetrasiloxane (D4), 0.1-0.4 for decamethylcyclopentasiloxane (D5), and 0.04-0.8 for dodecamethylcyclohexasiloxane (D6), and the remaining ones including HHCB, AHTN, MK, and D4 showed values close to 1 or slightly higher (TMF range: 1.0-2.3) indicating no or a little trophic magnification. The TMFs of these compounds were constant across sites and seasons. The TMF values of PCPs might be affected by species specificity and food web structure rather than by chemical properties such as log Kow, which describes a wide range of TMF values in various environments. This study presents valuable implications for assessing risk and managing environmental fate and trophic transfer of SMCs and siloxanes in freshwater environments.
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Affiliation(s)
- Dokyun Kim
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea
| | - Ha-Eun Cho
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea
| | - Eun-Ji Won
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea; Institute of Marine and Atmospheric Sciences, Hanyang University, Ansan 15588, Republic of Korea
| | - Hye-Jin Kim
- Department of Bioscience and Biotechnology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Sunggyu Lee
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea; Institute of Marine and Atmospheric Sciences, Hanyang University, Ansan 15588, Republic of Korea
| | - Kwang-Guk An
- Department of Bioscience and Biotechnology, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Hyo-Bang Moon
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea; Institute of Marine and Atmospheric Sciences, Hanyang University, Ansan 15588, Republic of Korea
| | - Kyung-Hoon Shin
- Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan 15588, Republic of Korea; Institute of Marine and Atmospheric Sciences, Hanyang University, Ansan 15588, Republic of Korea.
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9
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Groß J, Fry B, Burford MA, Bengtson Nash S. Assessing the effects of lipid extraction and lipid correction on stable isotope values (δ 13 C and δ 15 N) of blubber and skin from southern hemisphere humpback whales. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9140. [PMID: 34097783 DOI: 10.1002/rcm.9140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/26/2021] [Accepted: 06/04/2021] [Indexed: 06/12/2023]
Abstract
RATIONALE The coupled analysis of δ13 C and δ15 N stable isotope values of blubber and skin biopsy samples is widely used to study the diet of free-ranging cetaceans. Differences in the lipid content of these tissues can affect isotopic variability because lipids are depleted in 13 C, reducing the bulk tissue 13 C/12 C. This variability in carbon isotope values can be accounted for either by chemically extracting lipids from the tissue or by using mathematical lipid normalisation models. METHODS This study examines (a) the effects of chemical lipid extraction on δ13 C and δ15 N values in blubber and skin of southern hemisphere humpback whales, (b) whether chemical lipid extraction is more favourable than mathematical lipid correction and (c) which of the two tissues is more appropriate for dietary studies. Strategic comparisons were made between chemical lipid extraction and mathematical lipid correction and between blubber and skin tissue δ13 C and δ15 N values, as well as C:N ratios. Six existing mathematical normalisation models were tested for their efficacy in estimating lipid-free δ13 C for skin. RESULTS Both δ13 C and δ15 N values of lipid-extracted skin (δ13 C: -25.57‰, δ15 N: 6.83‰) were significantly higher than those of bulk skin (δ13 C: -26.97‰, δ15 N: 6.15‰). Five of the six tested lipid normalisation models had small error terms for predicting lipid-free δ13 C values. The average C:N ratio of lipid-extracted skin was within the lipid-free range reported in other studies, whereas the average C:N ratio of blubber was higher than previously reported. CONCLUSIONS These results highlight the need to account for lipids when analysing δ13 C and δ15 N values from the same sample. For optimised dietary assessments using parallel isotope analysis from a single sample, we recommend the use of unextracted skin tissue. δ15 N values should be obtained from unextracted skin, whereas δ13 C values may be adequately lipid corrected by a mathematical correction.
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Affiliation(s)
- Jasmin Groß
- Centre for Planetary Health and Food Security, Southern Ocean Persistent Organic Pollutants Program, Griffith University, Nathan, Queensland, Australia
| | - Brian Fry
- Australian Rivers Institute, Griffith University, Nathan, Queensland, Australia
| | - Michele A Burford
- Australian Rivers Institute, Griffith University, Nathan, Queensland, Australia
| | - Susan Bengtson Nash
- Centre for Planetary Health and Food Security, Southern Ocean Persistent Organic Pollutants Program, Griffith University, Nathan, Queensland, Australia
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10
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Hayden B, Tongnunui S, Beamish F, Nithirojpakdee P, Soto D, Cunjak R. Functional and trophic diversity of tropical headwater stream communities inferred from carbon, nitrogen and hydrogen stable isotope ratios. FOOD WEBS 2021. [DOI: 10.1016/j.fooweb.2020.e00181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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11
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Effects of Tissue Preservation on Carbon and Nitrogen Stable Isotope Signatures in Syngnathid Fishes and Prey. Animals (Basel) 2020; 10:ani10122301. [PMID: 33291858 PMCID: PMC7762059 DOI: 10.3390/ani10122301] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 11/17/2022] Open
Abstract
Simple Summary Stable isotope analysis (SIA) was used to assess the influence of various preservation methods (freezing, ethanol and formaldehyde) on syngnathid (seahorses and pipefishes) fins, seahorse newborns (seahorses), and prey (copepods and Artemia). The first available conversion models for syngnathids are provided, enabling their application to isotopic studies in the field and in the laboratory. Abstract Isotopic stable analysis (SIA) is a powerful tool in the assessment of different types of ecological and physiological studies. For that, different preservation methods for sampled materials are commonly used prior to isotopic analysis. The effects of various preservation methods (freezing, ethanol and formaldehyde) were analyzed for C:N, and δ13C and δ15N signals on a variety of tissues including dorsal fins (three seahorse and two pipefish species), seahorse newborns (three seahorses species), and prey (copepods and different stages of Artemia) commonly used to feed the fishes under rearing conditions. The aims of the study were: (i) to evaluate isotopic effects of chemical preservation methods across different types of organisms and tissues, using frozen samples as controls, and (ii) to construct the first conversion models available in syngnathid fishes. The chemical preservation in ethanol and, to a lesser extent, in formaldehyde significantly affected δ13C values, whereas the effects on δ15N signatures were negligible. Due to their low lipid content, the isotopic signals in fish fins was almost unaffected, supporting the suitability of dorsal fins as the most convenient material in isotopic studies on vulnerable species such as syngnathids. The regression equations provided resulted convenient for the successful conversion of δ13C between preservation treatments. Our results indicate that the normalization of δ15N signatures in preserved samples is unnecessary. The conversion models should be applicable in isotopic field studies, laboratory experiments, and specimens of historical collections.
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Smith KJ, Trueman CN, France CAM, Peterson MJ. Evaluation of two lipid removal methods for stable carbon and nitrogen isotope analysis in whale tissue. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8851. [PMID: 32492222 DOI: 10.1002/rcm.8851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/30/2020] [Accepted: 06/02/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE The presence of lipids in animal tissues can influence the interpretation of stable isotope data, particularly in lipid-rich tissues such as the skin and muscle of marine mammals. The traditionally employed chloroform-methanol delipidation protocol has the potential to alter δ15 N values in proteinaceous tissues. Our objective was to determine whether the use of cyclohexane could be an alternative extraction method, effectively removing lipids without altering δ15 N values. METHODS Kidney, liver, muscle, and skin samples were collected from beach-cast Sowerby's beaked whales (Mesoplodon bidens). Control subsamples were processed without delipidation extraction, and duplicate subsamples were extracted with either chloroform-methanol or cyclohexane. δ13 C, δ15 N, and C:N values were determined by continuous-flow elemental analysis isotope ratio mass spectrometry. Paired Wilcoxon tests were used to evaluate the change in isotope ratios after extraction, and unpaired Wilcoxon tests were used to evaluate differences in isotope ratios between extractions. RESULTS Use of cyclohexane is an effective delipidation technique for tissues with low and moderate lipid content. Chemical delipidation influenced δ15 N values; extracted samples generally showed an increase in δ15 N values which varied from 0.0‰ to 1.7‰. Chloroform-methanol extraction resulted in alterations to δ15 N values greater than the analytical precision for all analyzed tissues. Changes to δ15 N values after cyclohexane extraction were at or near the analytical precision for liver and muscle but greater than the analytical precision for kidney and skin. CONCLUSIONS We recommend processing duplicate subsamples for stable isotope analysis, one with and one without extraction, in order to obtain accurate values for each isotope ratio. Prolonged chemical extractions are not necessary to effectively remove lipids. When samples are limited, we suggest using cyclohexane for tissues with low or moderate lipid content, and chloroform-methanol for lipid-rich tissues.
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Affiliation(s)
- Kerri J Smith
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
- Department of Vertebrate Zoology, National Museum of Natural History, Washington, DC, USA
| | - Clive N Trueman
- Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, SO45 4PJ, UK
| | - Christine A M France
- Museum Conservation Institute, Smithsonian Institution, Suitland, MD, 20746, USA
| | - Markus J Peterson
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
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Sturaro N, Hsieh YE, Chen Q, Wang PL, Denis V. Toward a standardised protocol for the stable isotope analysis of scleractinian corals. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8663. [PMID: 31802564 DOI: 10.1002/rcm.8663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE The stable isotope analysis of carbon and nitrogen is a powerful tool in many ecological studies, but different sample treatments may affect stable isotope ratios and hamper comparisons among studies. The goal of this study was to determine whether treatments that are commonly used to prepare scleractinian coral samples for stable isotope analysis yield different δ15 N and δ13 C values, and to provide guidelines toward a standardised protocol. METHODS The animal tissues and Symbiodiniaceae of two symbiotic scleractinian coral species (Stylophora pistillata and Porites lutea) were divided into subsamples to test the effects of the drying method, lipid extraction, acidification treatment and water washing. All the subsamples were analysed for their δ15 N and δ13 C values, using continuous flow elemental analyser/isotope ratio mass spectrometry. RESULTS The drying method and lipid extraction treatment had no substantial effects on the δ15 N and δ13 C values of Symbiodiniaceae and animal tissues. Acid treatment did cause significant differences in δ13 C values (mean differences ≤0.5‰, with individual samples becoming up to 2.0‰ more negative), whereas no ecologically significant differences were observed in δ15 N values. Animal tissue δ13 C values may vary depending on whether samples are washed or not. CONCLUSIONS To move towards a standardised protocol in coral research, we recommend using an available drying method (as they are equally acceptable) for the stable isotope analysis of scleractinian corals, examining the need for lipid extraction on a case-by-case basis, performing a direct acidification of Symbiodiniaceae and animal tissues, and avoiding washing animal tissue with distilled water.
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Affiliation(s)
- Nicolas Sturaro
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
| | - Yunli Eric Hsieh
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
| | - Qi Chen
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
| | - Pei-Ling Wang
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
- Research Center for Future Earth, National Taiwan University, Taipei, Taiwan
| | - Vianney Denis
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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14
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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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Wild LA, Mueter F, Witteveen B, Straley JM. Exploring variability in the diet of depredating sperm whales in the Gulf of Alaska through stable isotope analysis. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191110. [PMID: 32269781 PMCID: PMC7137980 DOI: 10.1098/rsos.191110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 01/27/2020] [Indexed: 06/11/2023]
Abstract
Sperm whales interact with commercially important groundfish fisheries offshore in the Gulf of Alaska (GOA). This study aims to use stable isotope analysis to better understand the trophic variability of sperm whales and their potential prey, and to use dietary mixing models to estimate the importance of prey species to sperm whale diets. We analysed tissue samples from sperm whales and seven potential prey (five groundfish and two squid species). Samples were analysed for stable carbon and nitrogen isotope ratios, and diet composition was estimated using Bayesian isotopic mixing models. Mixing model results suggest that an isotopically combined sablefish/dogfish group, skates and rockfish make up the largest proportion of sperm whale diets (35%, 28% and 12%) in the GOA. The top prey items of whales that interact more frequently with fishing vessels consisted of skates (49%) and the sablefish/dogfish group (24%). This is the first known study to provide an isotopic baseline of adult male sperm whales and these adult groundfish and offshore squid species, and to assign contributions of prey to whale diets in the GOA. This study provides information to commercial fishermen and fisheries managers to better understand trophic connections of important commercial species.
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Affiliation(s)
- Lauren A. Wild
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 12101 Point Lena Loop, Juneau, AK 99801, USA
| | - Franz Mueter
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 12101 Point Lena Loop, Juneau, AK 99801, USA
| | - Briana Witteveen
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 12101 Point Lena Loop, Juneau, AK 99801, USA
| | - Janice M. Straley
- Department of Biology, University of Alaska Southeast, 1332 Seward Ave, Sitka, AK 99835, USA
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Kim D, Hong S, Choi H, Choi B, Kim J, Khim JS, Park H, Shin KH. Multimedia distributions, bioaccumulation, and trophic transfer of microcystins in the Geum River Estuary, Korea: Application of compound-specific isotope analysis of amino acids. ENVIRONMENT INTERNATIONAL 2019; 133:105194. [PMID: 31675558 DOI: 10.1016/j.envint.2019.105194] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/26/2019] [Accepted: 09/16/2019] [Indexed: 05/06/2023]
Abstract
To determine distributions, bioaccumulation, and trophic transfer of freshwater cyanobacterial toxins such as microcystins (MCs), surface water, suspended solids, sediments, and coastal organisms were collected from seven stations in inner and outer regions of the estuary dam in the Geum River Estuary in June and July 2017. Concentrations of MC variants (MC-LR, -RR, and -YR) in the multimedia samples were analyzed using a HPLC-MS/MS. Trophic position (TP) of organisms (fish, bivalve, gastropod, decapod, and polychaete) was determined by nitrogen stable isotope analyses of both bulk tissues and amino acids. From July to August 2017, great concentrations of MCs were detected in discharged freshwater ranging from 0.4 to 75 μg L-1. Considerable amounts of MCs are delivered to the Geum River Estuary in summer season. MCs spread far away as dissolved phases (18.7-49.5 ng L-1) in July when large amount of freshwater was discharged during the rainy season. Concentrations of MCs in marine organisms varied among species, ranging from 40 to 870 ng g-1 dw. Bioaccumulated MCs tend to decrease with increasing TP of organisms, suggesting that MCs are biodiluted through the marine food web. Compound-specific isotope analysis (nitrogen of amino acids) provides more reliable TPs compared with those by bulk isotope analysis in a closed estuary (such as the Geum River Estuary) with large fluctuations in the isotope ratio of primary producers.
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Affiliation(s)
- Dokyun Kim
- Department of Marine Science and Convergence Engineering, Hanyang University, Ansan, Republic of Korea
| | - Seongjin Hong
- Department of Ocean Environmental Sciences, Chungnam National University, Daejeon, Republic of Korea.
| | - Hyuntae Choi
- Department of Marine Science and Convergence Engineering, Hanyang University, Ansan, Republic of Korea
| | - Bohyung Choi
- Department of Marine Science and Convergence Engineering, Hanyang University, Ansan, Republic of Korea; Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Jaeseong Kim
- Water & Eco-Bio Co., Ltd., Jungboo Building, Miryong-dong, Kunsan, Republic of Korea
| | - Jong Seong Khim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul, Republic of Korea
| | - Hodong Park
- Department of Environmental Science, Faculty of Science, Shinshu University, Matsumoto, Japan
| | - Kyung-Hoon Shin
- Department of Marine Science and Convergence Engineering, Hanyang University, Ansan, Republic of Korea.
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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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Wang YV, Wan AH, Krogdahl Å, Johnson M, Larsen T. 13C values of glycolytic amino acids as indicators of carbohydrate utilization in carnivorous fish. PeerJ 2019; 7:e7701. [PMID: 31579597 PMCID: PMC6754727 DOI: 10.7717/peerj.7701] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Accepted: 08/19/2019] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Stable isotope analysis of single amino acids (AA) is usually applied in food web studies for tracing biosynthetic origins of AA carbon backbones and establishing trophic positions of consumers, but the method is also showing promise for characterizing quantity and quality of dietary lipids and carbohydrates. METHODS To investigate whether changes in high- and low-digestible carbohydrates affect δ 13C values of glycolytic AA, i.e., AA carbon backbones sourced from the glycolytic pathway, we compared Atlantic salmon (Salmo salar) from a feeding experiment with and without dietary inclusion of the red macroalga Palmaria palmata. The Control and experimental diets had similar relative proportions of macronutrients, but their ingredients differed; in the experimental treatment, 15% Palmaria inclusion substituted proteins from fishmeal and carbohydrates from corn starch. RESULTS We found that 13C values of the glycolytic AA were highly sensitive to substitution of corn starch with Palmaria. The δ 13C offsets of glycolytic AA between salmon and their diets were significantly greater in the Palmaria inclusion than Control treatment. This greater offset can be attributed to the different utilization of high- vs. low-digestible carbohydrate sources, i.e., corn starch vs. Palmaria, in the two treatments, and metabolic routing of dietary lipids. In addition, similar δ 13C values of essential AA between treatments indicate similar nutrient assimilation efficiency for all terrestrial (pea protein concentrate and wheat gluten meal) and marine (fishmeal and red alga) derived protein sources. These results show that δ 13CAA analysis is a promising tool for improving our understanding of how carnivorous fish utilize macronutrient and route metabolic intermediates to tissue.
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Affiliation(s)
- Yiming V. Wang
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
| | - Alex H.L. Wan
- Aquaculture Nutrition and Aquafeed Research Unit and Irish Seaweed Research Group, Ryan Institute, National University of Ireland, Galway, Ireland
| | - Åshild Krogdahl
- Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Mark Johnson
- Aquaculture Nutrition and Aquafeed Research Unit and Irish Seaweed Research Group, Ryan Institute, National University of Ireland, Galway, Ireland
| | - Thomas Larsen
- Department of Archaeology, Max Planck Institute for the Science of Human History, Jena, Germany
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Wild LA, Chenoweth EM, Mueter FJ, Straley JM. Evidence for dietary time series in layers of cetacean skin using stable carbon and nitrogen isotope ratios. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:1425-1438. [PMID: 29777550 PMCID: PMC6097889 DOI: 10.1002/rcm.8168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 05/05/2018] [Accepted: 05/06/2018] [Indexed: 05/22/2023]
Abstract
RATIONALE Stable isotope analysis integrates diet information over a time period specific to the type of tissue sampled. For metabolically active skin of free-ranging cetaceans, cells are generated at the basal layer of the skin and migrate outward until they eventually slough off, suggesting potential for a dietary time series. METHODS Skin samples from cetaceans were analyzed using continuous-flow elemental analyzer isotope ratio mass spectrometry. We used ANOVAs to compare the variability of δ13 C and δ15 N values within and among layers and columns ("cores") of the skin of a fin, humpback, and sperm whale. We then used mixed-effects models to analyze isotopic variability among layers of 28 sperm whale skin samples, over the course of a season and among years. RESULTS We found layer to be a significant predictor of δ13 C values in the sperm whale's skin, and δ15 N values in the humpback whale's skin. There was no evidence for significant differences in δ15 N or δ13 C values among cores for any species. Mixed-effects models selected layer and day of the year as significant predictors of δ13 C and δ15 N values in sperm whale skin across individuals sampled during the summer months in the Gulf of Alaska. CONCLUSIONS These results suggest that skin samples from cetaceans may be subsampled to reflect diet during a narrower time period; specifically different layers of skin may contain a dietary time series. This underscores the importance of selecting an appropriate portion of skin to analyze based on the species and objectives of the study.
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Affiliation(s)
- Lauren A. Wild
- University of Alaska Fairbanks, Juneau, AK 99801 USA
- Corresponding author;
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Seabirds fighting for land: phenotypic consequences of breeding area constraints at a small remote archipelago. Sci Rep 2018; 8:665. [PMID: 29330422 PMCID: PMC5766501 DOI: 10.1038/s41598-017-18808-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/16/2017] [Indexed: 11/08/2022] Open
Abstract
Identifying associations between phenotypes and environmental parameters is crucial for understanding how natural selection acts at the individual level. In this context, genetically isolated populations can be useful models for identifying the forces selecting fitness-related traits. Here, we use a comprehensive dataset on a genetically and ecologically isolated population of the strictly marine bird, the brown booby Sula leucogaster, at the tropical and remote Saint Peter and Saint Paul Archipelago, mid-Atlantic Ocean, in order to detect phenotypic adjustments from interindividual differences in diet, foraging behaviour, and nest quality. For this, we took biometrics of all individuals of the colony breeding in 2014 and 2015 and tested their associations with nest quality, diet parameters, and foraging behaviour. While body size was not related to the foraging parameters, the body size of the females (responsible for nest acquisition and defence) was significantly associated with the nest quality, as larger females occupied high-quality nests. Our findings suggest that the small breeding area, rather than prey availability, is a limiting factor, emphasizing the role of on-land features in shaping phenotypic characteristics and fitness in land-dependent marine vertebrates.
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Reum JCP, Williams GD, Harvey CJ. Stable Isotope Applications for Understanding Shark Ecology in the Northeast Pacific Ocean. ADVANCES IN MARINE BIOLOGY 2017; 77:149-178. [PMID: 28882213 DOI: 10.1016/bs.amb.2017.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e.g., change in δ15N between predator and prey), tissue sample preparation methods specific to elasmobranchs, and methodological considerations for the estimation of trophic level and diet composition. We suggest that stable isotopes are a potentially powerful tool for addressing basic questions about shark ecology and are perhaps most valuable when combined and analysed with other data types (e.g., stomach contents, tagging data, or other intrinsic biogeochemical markers).
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Affiliation(s)
- Jonathan C P Reum
- University of Washington, School of Aquatic and Fishery Sciences, Seattle, WA, United States.
| | | | - Chris J Harvey
- National Oceanic and Atmospheric Administration, Northwest Fisheries Science Center, Seattle, WA, United States
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Das K, Holleville O, Ryan C, Berrow S, Gilles A, Ody D, Michel LN. Isotopic niches of fin whales from the Mediterranean Sea and the Celtic Sea (North Atlantic). MARINE ENVIRONMENTAL RESEARCH 2017; 127:75-83. [PMID: 28390660 DOI: 10.1016/j.marenvres.2017.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 01/25/2017] [Accepted: 03/19/2017] [Indexed: 06/07/2023]
Abstract
The fin whale (Balaenoptera physalus) is the most abundant and widespread mysticete species in the Mediterranean Sea, found mostly in deep, offshore waters of the western and central portion of the region. In the Mediterranean, this species is known to feed mainly on krill, in contrast to its Atlantic counterpart, which displays a more diversified diet. The International Whaling Commission recognizes several managements units in the Atlantic and the Mediterranean Sea and the connectivity between these populations is still being debated. Questions remain about inter-individual feeding strategies and trophic ecology. The goal of this study was to compare isotopic niches of fin whales from the Mediterranean Sea and the Celtic Sea (North Atlantic). δ13C and δ15N values were analysed in 136 skin biopsies from free-ranging Mediterranean fin whales sampled in 2010 and 2011 during campaigns at sea. δ13C and δ15N values ranged from -20.4 to -17.1‰ and from 5.9 to 8.9‰, respectively. These values are in good agreement with those estimated previously from baleen plates from Mediterranean and North Atlantic fin whales. The narrow isotopic niche width of the Mediterranean fin whale (Standard Ellipses area SEAc) compared to the North Atlantic fin whale raises many concerns in the context of global changes and long-term consequences. One could indeed expect that species displaying narrow niches would be more susceptible to ecosystem fragmentation and other anthropogenic impacts.
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Affiliation(s)
- Krishna Das
- Laboratory of Oceanology-MARE, University of Liege, Belgium.
| | | | - Conor Ryan
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland; Irish Whale and Dolphin Group, Merchant's Quay, Kilrush, Co. Clare, Ireland
| | - Simon Berrow
- Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Galway, Ireland; Irish Whale and Dolphin Group, Merchant's Quay, Kilrush, Co. Clare, Ireland
| | - Anita Gilles
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstraße 6, D-25761 Büsum, Germany
| | - Denis Ody
- WWF-France, 6 Rue des Fabres, 13001 Marseille, France
| | - Loïc N Michel
- Laboratory of Oceanology-MARE, University of Liege, Belgium
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Sitnikova TY, Mekhanikova IV, Sideleva VG, Kiyashko SI, Naumova TV, Zemskaya TI, Khlystov OM. Trophic relationships between macroinvertebrates and fish in St. Petersburg methane seep community in abyssal zone of Lake Baikal. CONTEMP PROBL ECOL+ 2017. [DOI: 10.1134/s1995425517020123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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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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Endo T, Kimura O, Ohta C, Koga N, Kato Y, Fujii Y, Haraguchi K. Metal Concentrations in the Liver and Stable Isotope Ratios of Carbon and Nitrogen in the Muscle of Silvertip Shark (Carcharhinus albimarginatus) Culled off Ishigaki Island, Japan: Changes with Growth. PLoS One 2016; 11:e0147797. [PMID: 26859569 PMCID: PMC4747518 DOI: 10.1371/journal.pone.0147797] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/09/2016] [Indexed: 11/18/2022] Open
Abstract
We analyzed Hg, Cd, Zn, Cu and Fe concentrations in liver samples as well as the Hg concentration and stable isotope ratios of carbon and nitrogen (δ13C and δ15N) in muscle samples from silvertip sharks (Carcharhinus albimarginatus) in Japan. Muscular and hepatic Hg concentrations increased with increased body length. However, these increases were more prominent in the liver than in the muscle samples, and appeared to occur after maturation. Hepatic Zn and Cu concentrations decreased during the growth stage, and then increased concomitantly thereafter with increases in Cd burden. Hepatic Fe concentration from males increased proportionally with increases in body length, whereas no increase was observed in samples from females, probably due to the mother-to-embryo transfer of Fe. The δ13C values tended to decrease with increases in body length, whereas no decrease in the δ15N values was observed.
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Affiliation(s)
- Tetsuya Endo
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061–0293, Japan
- * E-mail:
| | - Osamu Kimura
- School of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061–0293, Japan
| | - Chiho Ohta
- Faculty of Nutritional Sciences, Nakamura Gakuen University, 5-7-1 Befu, Jonan-Ku, Fukuoka 814–0198, Japan
| | - Nobuyuki Koga
- Faculty of Nutritional Sciences, Nakamura Gakuen University, 5-7-1 Befu, Jonan-Ku, Fukuoka 814–0198, Japan
| | - Yoshihisa Kato
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314–1 Shido, Sanuki, Kagawa 769–2193, Japan
| | - Yukiko Fujii
- Daiichi College of Pharmaceutical Sciences, 22–1 Tamagawa-Cho, Minami-Ku, Fukuoka 815–8511, Japan
| | - Koichi Haraguchi
- Daiichi College of Pharmaceutical Sciences, 22–1 Tamagawa-Cho, Minami-Ku, Fukuoka 815–8511, Japan
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Li Y, Zhang Y, Hussey NE, Dai X. Urea and lipid extraction treatment effects on δ(15)N and δ(13)C values in pelagic sharks. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1-8. [PMID: 26661965 DOI: 10.1002/rcm.7396] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 05/13/2023]
Abstract
RATIONALE Stable isotope analysis (SIA) provides a powerful tool to investigate diverse ecological questions for marine species, but standardized values are required for comparative assessments. For elasmobranchs, their unique osmoregulatory strategy involves retention of (15)N-depleted urea in body tissues and this may bias δ(15)N values. This may be a particular problem for large predatory species, where δ(15)N discrimination between predator and consumed prey can be small. METHODS We evaluated three treatments (deionized water rinsing [DW], chloroform/methanol [LE] and combined chloroform/methanol and deionized water rinsing [LE+DW]) applied to white muscle tissue of 125 individuals from seven pelagic shark species to (i) assess urea and lipid effects on stable isotope values determined by IRMS and (ii) investigate mathematical normalization of these values. RESULTS For all species examined, the δ(15)N values and C:N ratios increased significantly following all three treatments, identifying that urea removal is required prior to SIA of pelagic sharks. The more marked change in δ(15)N values following DW (1.3 ± 0.4‰) and LE+DW (1.2 ± 0.6‰) than following LE alone (0.7 ± 0.4‰) indicated that water rinsing was more effective at removing urea. The DW and LE+DW treatments lowered the %N values, resulting in an increase in C:N ratios from the unexpected low values of <2.6 in bulk samples to ~3.1 ± 0.1, the expected value of protein. The δ(13)C values of all species also increased significantly following LE and LE+DW treatments. CONCLUSIONS Given the mean change in δ(15)N(1.2 ± 0.6‰) and δ(13)C values (0.7 ± 0.4‰) across pelagic shark species, it is recommended that muscle tissue samples be treated with LE+DW to efficiently extract both urea and lipids to standardize isotopic values. Mathematical normalization of urea and lipid-extracted δ(15)N(LE+DW) and δ(13)C(LE+DW) values using the lipid-extracted δ(15)N(LE) and δ(13)C(LE) data were established for all pelagic shark species.
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Affiliation(s)
- Yunkai Li
- College of Marine Sciences, Shanghai Ocean University, 999 Huchenghuan Rd., Shanghai, 201306, China
- Marine Sciences Program, School of Environment, Arts and Society, Florida International University, 3000 NE 151st, North Miami, FL, 33181, USA
| | - Yuying Zhang
- Marine Sciences Program, School of Environment, Arts and Society, Florida International University, 3000 NE 151st, North Miami, FL, 33181, USA
| | - Nigel E Hussey
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, ON, N9B 3P4, Canada
| | - Xiaojie Dai
- College of Marine Sciences, Shanghai Ocean University, 999 Huchenghuan Rd., Shanghai, 201306, China
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Factors Controlling the Stable Nitrogen Isotopic Composition (δ15N) of Lipids in Marine Animals. PLoS One 2016; 11:e0146321. [PMID: 26731720 PMCID: PMC4701503 DOI: 10.1371/journal.pone.0146321] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 12/16/2015] [Indexed: 12/02/2022] Open
Abstract
Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N) of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete), as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰). Importantly, the total lipid extract (TLE) was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰). The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰) than the TLE (-7 ‰), possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms.
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Giraldo C, Stasko A, Choy ES, Rosenberg B, Majewski A, Power M, Swanson H, Loseto L, Reist JD. Trophic variability of Arctic fishes in the Canadian Beaufort Sea: a fatty acids and stable isotopes approach. Polar Biol 2015. [DOI: 10.1007/s00300-015-1851-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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de Lecea AM, de Charmoy L. Chemical lipid extraction or mathematical isotope correction models: should mathematical models be widely applied to marine species? RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:2013-2025. [PMID: 26443401 DOI: 10.1002/rcm.7310] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 08/05/2015] [Accepted: 08/07/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Chemical lipid extractions, as means of standardizing sample preparations, have been identified as important for comparability of studies. Unfortunately, these methods are expensive, because of the costly chemicals and the need to analyse two sets of samples, one for δ(13) C values (treated) and another for δ(15) N values (untreated). To avoid this, studies have suggested mathematical solutions to the problem. Our study intends to (i) determine the applicability of the five most common mathematical correction models and (ii) which of the widely applied chemical extraction methods is the most suitable for a variety of marine organisms. METHODS Muscle, heart and liver samples were collected from eight different species. The tissues were treated with Bligh and Dyer, Folch and Soxhlet extraction methods and analysed in a Europa 20-20 mass spectrometer. Predicted lipid-extracted δ(13) C values were calculated from untreated tissue values using the five most common mathematical models. RESULTS The results indicated that the mathematical methods could not be accurately applied to any of the eight species used in this study, highlighting current issues with accepted isotope methodologies. The Folch chemical extraction removed the highest amount of lipid, suggesting it is the most suitable delipidation method. CONCLUSIONS Analysing two samples, one treated one not, remains the best method to obtain accurate δ(13) C isotope values of muscle tissue. By using this approach every study will obtain two datasets, eventually providing a suitable collective dataset for determining how isotopic signatures are affected by delipidation and potentially producing better mathematical correction models in future.
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Affiliation(s)
- Ander M de Lecea
- School of Life Sciences, College of Engineering, Agricultural and Life Sciences, Westville Campus, University of KwaZulu-Natal, Durban, South Africa, 4001
- Department for Biodiversity & Conservation Biology, University of the Western Cape, Belville, Cape Town, South Africa, 7535
| | - Lisa de Charmoy
- School of Life Sciences, College of Engineering, Agricultural and Life Sciences, Westville Campus, University of KwaZulu-Natal, Durban, South Africa, 4001
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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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Montanari S, Amato G. Discrimination factors of carbon and nitrogen stable isotopes from diet to hair and scat in captive tigers (Panthera tigris) and snow leopards (Uncia uncia). RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:1062-1068. [PMID: 26044274 DOI: 10.1002/rcm.7194] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/04/2015] [Accepted: 03/06/2015] [Indexed: 06/04/2023]
Abstract
RATIONALE In order to use stable isotope ratio values obtained from wild animal tissues, we must accurately calculate the differences in isotope ratios between diet and consumer (δtissue - δdiet). These values, called trophic discrimination factors (TDFs, denoted with ∆), are necessary for stable isotope ecology studies and are best calculated in controlled environments. METHODS Scat, hair, and diet samples were collected from captive tigers (n = 8) and snow leopards (n = 10) at the Bronx Zoo. The isotope ratios of carbon and nitrogen, the two most commonly used in ecological studies, of the samples were measured by continuous-flow isotope ratio mass spectrometry. The trophic discrimination factors were calculated for both carbon (δ(13)C values) and nitrogen (δ(15)N values). RESULTS It was found that the only significant TDFs in this study were diet-hair, ∆(13)CHair, for snow leopards (5.97 ± 1.25‰) and tigers (6.45 ± 0.54‰), and diet-scat, ∆(15)NScat, in snow leopards (2.49 ± 1.30‰). The other mean isotope ratios were not significantly different from that of the premixed feline diet. The ∆(15)NHair values for both species were unusually low, potentially due to the protein content and quality of the feline diet. CONCLUSIONS The discrimination factors of the stable isotopes of carbon and nitrogen calculated in this study can be applied to ecological studies of wild, non-captive terrestrial mammals. The effect of protein quality in isotope discrimination is also worthy of further investigation to better understand variation in TDFs. Carnivore scat is shown to be a valuable material for isotopic analysis.
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Affiliation(s)
- Shaena Montanari
- Columbia University, Department of Ecology, Evolution, and Environmental Biology, 1200 Amsterdam Avenue, New York, NY, 10027, USA
- Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA
| | - George Amato
- Columbia University, Department of Ecology, Evolution, and Environmental Biology, 1200 Amsterdam Avenue, New York, NY, 10027, USA
- Sackler Institute for Comparative Genomics, American Museum of Natural History, Central Park West at 79th Street, New York, NY, 10024, USA
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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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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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Perkins MJ, McDonald RA, van Veen FJF, Kelly SD, Rees G, Bearhop S. Important impacts of tissue selection and lipid extraction on ecological parameters derived from stable isotope ratios. Methods Ecol Evol 2013. [DOI: 10.1111/2041-210x.12098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Matthew J. Perkins
- Centre for Ecology & Conservation; School of Biosciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
| | - Robbie A. McDonald
- Environment and Sustainability Institute; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
| | - F. J. Frank van Veen
- Centre for Ecology & Conservation; School of Biosciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
| | - Simon D. Kelly
- Food and Environment Research Agency; York; Sand Hutton; YO41 1LZ; UK
| | - Gareth Rees
- Food and Environment Research Agency; York; Sand Hutton; YO41 1LZ; UK
| | - Stuart Bearhop
- Centre for Ecology & Conservation; School of Biosciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
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Nakayama SMM, Ikenaka Y, Muzandu K, Choongo K, Yabe J, Muroya T, Ijiri S, Minagawa M, Umemura T, Ishizuka M. Geographic information system-based source estimation of copper pollution in Lake Itezhi-tezhi and metal-accumulation profiles in Oreochromis spp. from both field and laboratory studies. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2013; 64:119-129. [PMID: 23052357 DOI: 10.1007/s00244-012-9802-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 08/06/2012] [Indexed: 06/01/2023]
Abstract
The Copperbelt region, upstream of the Kafue River, including Lake Itezhi-tezhi (ITT), in Zambia has extensive copper (Cu) mines. In our field study, geographic information system analysis in lake sediment indicated that the northern part of the lake, i.e., the Copperbelt region, could be the source of Cu pollution. Concentrations of Cu in stomach contents between fish species were not significantly different. However, Oreochromis spp. liver showed significantly greater Cu concentrations than those in other fish species. Log liver [Cu], standard length, and nitrogen stable isotope ratio were positively correlated only in Oreochromis spp. In the laboratory study, O. niloticus and O. latipes were exposed to Cu for 4 days, and recovery phases ≤ 28 days were examined. O. niloticus showed significantly greater concentrations of Cu compared with O. latipes at all sampling points. Significantly greater concentrations of Hg in Schilbe intermedius liver than for other fish species were observed, whereas O. macrochir showed significantly greater concentrations of cadmium. In conclusion, the northern part of the lake could be the source of Cu pollution in Lake ITT. Diet may not be the reason for high Cu accumulation in Oreochromis spp. Results from both field and laboratory studies imply that Oreochromis spp. contain high concentrations of Cu under normal physiological conditions.
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Affiliation(s)
- Shouta M M Nakayama
- Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
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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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Tissue turnover rates and isotopic trophic discrimination factors in the endothermic teleost, pacific bluefin tuna (Thunnus orientalis). PLoS One 2012; 7:e49220. [PMID: 23145128 PMCID: PMC3492276 DOI: 10.1371/journal.pone.0049220] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 10/08/2012] [Indexed: 11/29/2022] Open
Abstract
Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver) and isotope- (nitrogen and carbon) specific turnover rates and trophic discrimination factors (TDFs) using archived tissues from captive Pacific bluefin tuna (PBFT), Thunnus orientalis, 1–2914 days after a diet shift in captivity. Half-life values for 15N turnover in white muscle and liver were 167 and 86 days, and for 13C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ15N and 1.8 and 1.2‰ for δ13C, respectively. Our results demonstrate that turnover of 15N and 13C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. 15N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ15N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology.
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Endo T, Hotta Y, Hisamichi Y, Kimura O, Sato R, Haraguchi K, Funahashi N, Baker CS. Stable isotope ratios and mercury levels in red meat products from baleen whales sold in Japanese markets. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2012; 79:35-41. [PMID: 22364843 DOI: 10.1016/j.ecoenv.2012.01.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 01/25/2012] [Accepted: 01/29/2012] [Indexed: 05/31/2023]
Abstract
We analyzed the δ(13)C, δ(15)N and δ(18)O values and Hg concentration in red meat products originating from the predominant types sold in Japan for human consumption: two populations of common minke (J- and O-types), Bryde's and sei whales in the western North Pacific Ocean, and fin and Antarctic minke whales in the Southern Ocean. The order of the trophic positions, evaluated by δ(15)N values and Hg concentrations, coincided with their known feeding habits: common minke (J-type)=common minke (O-type)> Bryde's ≥ sei ≥ Antarctic minke ≥ fin. The Hg concentrations in the combined samples from the six samples were significantly correlated with their δ(15)N values (γ=0.455, n=66, p<0.05), reflecting overall differences in the trophic level. This correlation was not significant for within-species comparison for the common minke (J- and O-types) or the Bryde's whale, probably reflecting the higher δ(15)N value and lower Hg concentration in the North Pacific Ocean around Japan. Determination of δ(13)C, δ(15)N and δ(18)O could be used to discriminate between the red meat products originating from the whale species in the North Pacific and Southern Oceans. However, the four whale species or populations in the Pacific Ocean could not be discriminated on basis of these values, nor could the two species in the Southern Ocean. Positive correlations between the δ(13)C and δ(15)N values and negative correlations between the δ(15)N and δ(18)O values and the δ(13)C and δ(18)O values, probably reflecting migration patterns, were found in some whale species in the North Pacific and Southern Oceans.
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Affiliation(s)
- Tetsuya Endo
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
| | - Yohei Hotta
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
| | - Yohsuke Hisamichi
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
| | - Osamu Kimura
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
| | - Rie Sato
- SI Science Co. Ltd., 473-3 Hongou, Sugito-machi, Kitakatsushika, Saitama 345-0023, Japan
| | - Koichi Haraguchi
- Daiichi College of Pharmaceutical Sciences, 22-1 Tamagawa-Cho, Minami-Ku, Fukuoka 815-8511, Japan
| | - Naoko Funahashi
- International Fund for Animal Welfare, NishiShinjuku Well BLDG 6F, 5-24-16 NishiShinjuku, Shinjuku-ku, Tokyo 160-0023, Japan
| | - C Scott Baker
- Marine Mammal Program and Department of Fisheries and Wildlife, Oregon State University, Newport, Oregon 97365, USA
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Inamura O, Zhang J, Minagawa M. δ13C and δ15N values in scales of Micropterus salmoides largemouth bass as a freshwater environmental indicator. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:17-24. [PMID: 22215573 DOI: 10.1002/rcm.5288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We have investigated the effectiveness of using the Micropterus salmoides largemouth bass, which is a top predator found throughout the world, as the index of a hydrosphere environment and its food chain. To this end, we used stable carbon and nitrogen isotope analysis (SIA). Largemouth bass were collected from eight dam reservoirs and two ponds in Toyama Prefecture, Japan. Toyama is located in central Japan and features a variety of distinct geographical environments, a result of the 3000-m elevation that changes over short distances, and abundant water systems. The mean δ(13)C and δ(15)N values for the lipid-extracted muscle of largemouth bass from all sampling locations showed large variability, but there were only small standard deviations at each sampling location. The isotope ratios for largemouth bass express the characteristics of each investigated hydrosphere environment and food chain. A very high correlation (δ(13)C: Y(scale) = 0.96 X(muscle) + 1.58, R(2) = 0.98, δ(15)N: Y(scale) = 0.92 X(muscle) - 1.15, R(2) = 0.95) of SIA values was found between largemouth bass scales and lipid-extracted muscles, which suggests that the more easily analyzed scales are useful as SIA samples for the monitoring and comparison of hydrosphere environments throughout the world.
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Affiliation(s)
- O Inamura
- Graduate School of Environmental Science, Hokkaido University, Sapporo, N10W5, Sapporo, Hokkaido 060-0810, Hokkaido, Japan.
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Reum JCP. Lipid correction model of carbon stable isotopes for a cosmopolitan predator, spiny dogfish Squalus acanthias. JOURNAL OF FISH BIOLOGY 2011; 79:2060-2066. [PMID: 22141905 DOI: 10.1111/j.1095-8649.2011.03120.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Three lipid correction models were evaluated for liver and white dorsal muscle from Squalus acanthias. For muscle, all three models performed well, based on the Akaike Information Criterion value corrected for small sample sizes (AIC(c) ), and predicted similar lipid corrections to δ(13) C that were up to 2.8 ‰ higher than those predicted using previously published models based on multispecies data. For liver, which possessed higher bulk C:N values compared to that of white muscle, all three models performed poorly and lipid-corrected δ(13) C values were best approximated by simply adding 5.74 ‰ to bulk δ(13) C values.
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Affiliation(s)
- J C P Reum
- School of Aquatic and Fisheries Sciences, University of Washington, Seattle, 1122 NE Boat St, Seattle, WA 98105, USA.
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Boecklen WJ, Yarnes CT, Cook BA, James AC. On the Use of Stable Isotopes in Trophic Ecology. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2011. [DOI: 10.1146/annurev-ecolsys-102209-144726] [Citation(s) in RCA: 623] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- William J. Boecklen
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
| | - Christopher T. Yarnes
- Stable Isotope Facility, Department of Plant Sciences, University of California, Davis, Davis, California 95616;
| | - Bethany A. Cook
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
| | - Avis C. James
- Laboratory of Ecological Chemistry, Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003; , ,
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Gillies CL, Stark JS, Smith SDA. Research article: small-scale spatial variation of δ13C and δ15N isotopes in Antarctic carbon sources and consumers. Polar Biol 2011. [DOI: 10.1007/s00300-011-1126-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Therrien JF, Fitzgerald G, Gauthier G, Bêty J. Diet–tissue discrimination factors of carbon and nitrogen stable isotopes in blood of Snowy Owl (Bubo scandiacus). CAN J ZOOL 2011. [DOI: 10.1139/z11-008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Analysis of carbon (13C/12C) and nitrogen (15N/14N) stable isotope ratios (hereafter δ13C and δ15N, respectively) in animal tissues is a powerful tool in food-web studies. However, isotopic ratios of prey are not transmitted directly to a consumer, as a diet–tissue discrimination factor (denoted Δ) occurs between sources and consumer’s tissues. An accurate assessment of the diet of a consumer with stable isotopes thus requires that the Δ13C and Δ15N of the studied species are known. Our aim was to establish Δ13C and Δ15N values in the Snowy Owl ( Bubo scandiacus (L., 1758)). Moreover, we assessed the potential effect of ethanol preservation of blood samples on δ13C and δ15N values. We kept four captive adult Snowy Owls on a pure diet of mice for ≥6 weeks. We then collected mouse muscle and blood samples from the owls and analyzed their δ13C and δ15N values. Δ13C and Δ15N values (mean ± SE) for owl blood were +0.3‰ ± 0.2‰ and +1.9‰ ± 0.1‰, respectively. These values are the first discrimination factors ever reported in Strigiformes and are lower, for Δ15N, than those obtained in terrestrial carnivores and other bird species, including falcons. Preservation in ethanol did not significantly affect δ13C and δ15N values.
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Affiliation(s)
- J.-F. Therrien
- Département de biologie et Centre d’études nordiques, 1045 avenue de la Médecine, Université Laval, Québec, QC G1V 0A6, Canada
| | - G. Fitzgerald
- Faculté de médecine vétérinaire, Université de Montréal, 3200 rue Sicotte, C.P. 5000, Saint-Hyacinthe, QC J2S 7C6, Canada
| | - G. Gauthier
- Département de biologie et Centre d’études nordiques, 1045 avenue de la Médecine, Université Laval, Québec, QC G1V 0A6, Canada
| | - J. Bêty
- Département de biologie, chimie et géographie and Centre d’études nordiques, 300 Allée des Ursulines, Université du Québec à Rimouski, Rimouski, QC G5L 3A1, Canada
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Wyatt ASJ, Waite AM, Humphries S. Variability in isotope discrimination factors in coral reef fishes: implications for diet and food web reconstruction. PLoS One 2010; 5:e13682. [PMID: 21060681 PMCID: PMC2965116 DOI: 10.1371/journal.pone.0013682] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 09/30/2010] [Indexed: 11/25/2022] Open
Abstract
Interpretation of stable isotope ratios of carbon and nitrogen (δ(13)C and δ(15)N) is generally based on the assumption that with each trophic level there is a constant enrichment in the heavier isotope, leading to diet-tissue discrimination factors of 3.4‰ for (15)N (ΔN) and ∼0.5‰ for (13)C (ΔC). Diet-tissue discrimination factors determined from paired tissue and gut samples taken from 152 individuals from 26 fish species at Ningaloo Reef, Western Australia demonstrate a large amount of variability around constant values. While caution is necessary in using gut contents to represent diet due to the potential for high temporal variability, there were significant effects of trophic position and season that may also lead to variability in ΔN under natural conditions. Nitrogen enrichment increased significantly at higher trophic levels (higher tissue δ(15)N), with significantly higher ΔN in carnivorous species. Changes in diet led to significant changes in ΔN, but not tissue δ(15)N, between seasons for several species: Acanthurus triostegus, Chromis viridis, Parupeneus signatus and Pomacentrus moluccensis. These results confirm that the use of meta-analysis averages for ΔN is likely to be inappropriate for accurately determining diets and trophic relationships using tissue stable isotope ratios. Where feasible, discrimination factors should be directly quantified for each species and trophic link in question, acknowledging the potential for significant variation away from meta-analysis averages and, perhaps, controlled laboratory diets and conditions.
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Affiliation(s)
- Alex S J Wyatt
- The Oceans Institute, The University of Western Australia, Crawley, Australia.
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Pangallo KC, Reddy CM. Marine natural products, the halogenated 1'-methyl-1,2'-bipyrroles, biomagnify in a northwestern Atlantic food web. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:5741-7. [PMID: 20583784 DOI: 10.1021/es101039d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Halogenated 1'-methyl-1,2'-bipyrroles (MBPs) are putative marine natural products that accumulate in marine mammal blubber in similar concentrations and patterns to biomagnifying organic pollutants. Here we measure concentrations of MBPs and 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) in 40 samples composed of eight fish species, two squid species, and six species of marine mammals. To determine their trophic positions and to further investigate influence of prey preference, we also measured the stable carbon and nitrogen isotopic compositions of all samples. Our results show that lipid-normalized MBP concentrations increase with increasing trophic level; therefore, MBPs qualify as another class of biomagnifying marine natural products. The presence of MBPs in pinniped prey and absence in pinniped blubber suggests that these mammals share dietary exposure to MBPs with odontocetes but have an enhanced ability to metabolize these natural products.
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Affiliation(s)
- Kristin C Pangallo
- Department of Biochemistry and Microbiology, Rutgers, The State University of New Jersey, 76 Lipman Road, New Brunswick, New Jersey 08901, 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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Endo T, Hisamichi Y, Kimura O, Kotaki Y, Kato Y, Ohta C, Koga N, Haraguchi K. Contamination levels of mercury in the muscle of female and male spiny dogfishes (Squalus acanthias) caught off the coast of Japan. CHEMOSPHERE 2009; 77:1333-1337. [PMID: 19863992 DOI: 10.1016/j.chemosphere.2009.09.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2009] [Revised: 09/17/2009] [Accepted: 09/18/2009] [Indexed: 05/28/2023]
Abstract
We analyzed the total mercury (T-Hg) and stable isotopes of (13)C and (15)N in the muscle of spiny dogfish (Squalus acanthias) caught off the coast of Japan. The average body length of the female spiny dogfish sampled (94.9+/-20.2 cm, 50.5-131.0 cm, n=40) was significantly larger than that of the males sampled (77.8+/-10.8 cm, 55.5-94.0 cm, n=35), although the ages of the samples were unknown. The T-Hg concentration in the muscle samples rapidly increased after maturity in the females (larger than about 120 cm) and males (larger than about 90 cm), followed by a continued gradual increase. Contamination level of T-Hg in female muscle samples (0.387+/-0.378 microg(wet g)(-1), n=40) was slightly higher than that in male muscle samples (0.316+/-0.202 microg(wet g)(-1), n=35), probably due to the greater longevity of females. In contrast, the contamination level of T-Hg in females smaller than 94.0 cm in length (0.204+/-0.098 microg(wet g)(-1), n=20) was slightly lower than that in the males, probably due to the faster growth rate of females. Although the partial differential(13)C and partial differential(15)N values in the muscle samples increased with an increase in body length, there were no significant differences between the females (-17.2+/-0.4 per thousand and 12.4+/-0.9 per thousand, respectively) and males (-17.3+/-0.4 per thousand and 12.4+/-0.8 per thousand, respectively). A positive correlation was found between partial differential(13)C and partial differential(15)N values, suggesting trophic enrichment due to the growth.
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Affiliation(s)
- Tetsuya Endo
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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Bugoni L, McGill RAR, Furness RW. Effects of preservation methods on stable isotope signatures in bird tissues. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:2457-2462. [PMID: 18642324 DOI: 10.1002/rcm.3633] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Increasing use is being made of stable isotopes as indicators of habitat use and trophic ecology of animals. Preservation of tissues can alter stable isotope signatures. We investigated the effects of addition of ethanol and NaCl solution (hereafter 'salt'), and of freezing and drying, on carbon and nitrogen isotopic values in blood of the spectacled petrel Procellaria conspicillata, and compared these with those from simultaneously growing feathers. The mean delta(13)C values of blood preserved in ethanol was significantly higher, and of blood preserved in salt was significantly lower than that of dried or frozen samples. delta(13)C values in ethanol showed high variation according to brand and batch and could account for the differences found in delta(13)C ratios in ethanol-preserved blood samples. Mean delta(13)C and delta(15)N values in growing feathers were higher than in blood, suggesting tissue-specific fractionation. We conclude that different methods of preserving tissues such as blood may bias stable isotope values, and urge researchers to consider this issue. Air drying is proposed as a practical and unbiased method for blood preservation in field situations where freezing is not a practical option, and a mathematical approach is suggested to permit comparison between studies using different preservation methods or tissues.
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Affiliation(s)
- Leandro Bugoni
- Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK.
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