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Bowen KR, Kurle CM. Effects of pre-treatment, historical age, and sample characteristics on the stable isotope analyses of killer whale (Orcinus orca) bone. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9874. [PMID: 39089821 DOI: 10.1002/rcm.9874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 06/05/2024] [Accepted: 07/03/2024] [Indexed: 08/04/2024]
Abstract
RATIONALE Stable isotope analysis of bone provides insight into animal foraging and allows for ecological reconstructions over time, however pre-treatment is required to isolate collagen. Pre-treatments typically consist of demineralization to remove inorganic components and/or lipid extraction to remove fats, but these protocols can differentially affect stable carbon (δ13C) and nitrogen (δ15N) isotope values depending on the chemicals, tissues, and/or species involved. Species-specific methodologies create a standard for comparability across studies and enhance understanding of collagen isolation from modern cetacean bone. METHODS Elemental analyzers coupled to isotope ratio mass spectrometers were used to measure the δ13C and δ15N values of powdered killer whale (Orcinus orca) bone that was intact (control) or subjected to one of three experimental conditions: demineralized, lipid-extracted, and both demineralized and lipid-extracted. Additionally, C:N ratios were evaluated as a proxy for collagen purity. Lastly, correlations were examined between control C:N ratios vs. historical age and control C:N ratios vs. sample characteristics. RESULTS No significant differences in the δ15N values were observed for any of the experimental protocols. However, the δ13C values were significantly increased by all three experimental protocols: demineralization, lipid extraction, and both treatments combined. The most influential protocol was both demineralization and lipid extraction. Measures of the C:N ratios were also significantly lowered by demineralization and both treatments combined, indicating the material was closer to pure collagen after the treatments. Collagen purity as indicated via C:N ratio was not correlated with historical age nor sample characteristics. CONCLUSIONS If only the δ15N values from killer whale bone are of interest for analysis, no pre-treatment seems necessary. If the δ13C values are of interest, samples should be both demineralized and lipid-extracted. As historical age and specimen characteristics are not correlated with sample contamination, all samples can be treated equally.
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Affiliation(s)
- Kelly R Bowen
- School of Biological Sciences, Department of Ecology, Behavior, and Evolution, University of California, San Diego, La Jolla, CA, USA
| | - Carolyn M Kurle
- School of Biological Sciences, Department of Ecology, Behavior, and Evolution, University of California, San Diego, La Jolla, CA, USA
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2
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Li S, Jiang D, Li J, Ma Y, Yao J, Du L, Xu Y, Qian Y. Geographical traceability of gelatin in China using stable isotope ratio analysis. Front Nutr 2023; 10:1116049. [PMID: 36875856 PMCID: PMC9978747 DOI: 10.3389/fnut.2023.1116049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 01/11/2023] [Indexed: 02/18/2023] Open
Abstract
Geographical traceability is crucial to the quality and safety control of gelatin. However, currently, methods for gelatin traceability have not been established anywhere in the world. This study aimed to investigate the possibility of differentiating the geographical origins of gelatin from different regions in China using stable isotope technology. To achieve this objective, 47 bovine stick bone samples from three different regions (Inner Mongolia, Shandong, and Guangxi, respectively) in China were collected, and gelatin was extracted from these bones using the enzymatic method. The fingerprint characteristics of stable isotopes of δ13C, δ15N, and δ2H of gelatin from different regions in China were studied. Moreover, isotopic changes from the bone to gelatin during the processing were examined to evaluate the effectiveness of these factors as origin indicators. The results of the one-way analysis of variance (ANOVA) showed that the δ13C, δ15N, and δ2H of gelatin from different regions display significant differences, and using the linear discriminant analysis (LDA), the correct differentiation of origin reached 97.9%. Certain differences in stable isotope ratios were observed during the processing of bone to gelatin samples. Nonetheless, the fractionation effect caused by the processing of bone to gelatin samples was not sufficient to influence the identification of gelatin from different origins, which proves that δ13C, δ15N, and δ2H are effective origin indicators of gelatin. In conclusion, the stable isotope ratio analysis combined with the chemometric analysis can be used as a reliable tool for identifying gelatin traceability.
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Affiliation(s)
- Shuang Li
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, China
- Department of Molten Salt Chemistry and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Di Jiang
- Department of Molten Salt Chemistry and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Jinglin Li
- Department of Tritium Science and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Yuhua Ma
- Department of Tritium Science and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Jian Yao
- Department of Molten Salt Chemistry and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Lin Du
- Department of Molten Salt Chemistry and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Yisheng Xu
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, China
| | - Yuan Qian
- Department of Molten Salt Chemistry and Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
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3
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Turner Tomaszewicz CN, Liles MJ, Avens L, Seminoff JA. Tracking movements and growth of post-hatchling to adult hawksbill sea turtles using skeleto+iso. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.983260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the eastern Pacific Ocean, hawksbill sea turtles (Eretmochelys imbricata) are adapted to use coastal habitats and ecosystems uncharacteristic of most other sea turtles. Once considered extirpated from this region, hawksbills had sought refuge in estuaries, nesting on muddy banks among the tangles of mangrove roots. This population is at high risk of bycatch during fishing efforts in the estuaries (blast fishing) and adjacent coastal rocky reefs (gillnets), and is further impacted by habitat degradation from coastal development and climate change. The conservation and population recovery of hawksbills in this region is highly dependent on management actions (e.g., nest relocation, habitat protection, bycatch mitigation), and a better understanding of how hawksbills use and move between distinct habitats will help prioritize conservation efforts. To identify multi-year habitat use and movement patterns, we used stable carbon (δ13C) and nitrogen (δ15N) isotope analysis of skin and bone growth layers to recreate movements between two isotopically distinct habitats, a nearshore rocky reef and a mangrove estuary, the latter distinguishable by low δ13C and δ15N values characteristic of a mangrove-based foodweb. We applied skeletochronology with sequential δ13C and δ15N analysis of annual growth layers, “skeleto+iso,” to a dataset of 70 hawksbill humeri collected from coastal El Salvador. The results revealed at least two unique habitat-use patterns. All turtles, regardless of stranding location, spent time outside of the mangrove estuaries during their early juvenile years (< 35 cm curved carapace length, CCL, age 0–5), showing that an oceanic juvenile stage is likely for this population. Juveniles ca. > 35 cm then began to recruit to nearshore areas, but showed divergent habitat-use as some of turtles occupied the coastal rocky reefs, while others settled into the mangrove estuaries. For turtles recruiting to the estuaries, settlement age and size ranged from 3 to 13 years and 35–65 cm CCL. For the adult turtles, age-at-sexual-maturity ranged from 16 to 26 years, and the maximum reproductive longevity observed was 33 years. The skeleto+iso also showed that adult hawksbills have long-term habitat fidelity, and the results demonstrate the importance of both mangrove estuary and nearshore rocky reefs to the conservation of hawksbills in the eastern Pacific.
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Wilson T, Szpak P. Acidification does not alter the stable isotope composition of bone collagen. PeerJ 2022; 10:e13593. [PMID: 35722259 PMCID: PMC9205305 DOI: 10.7717/peerj.13593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/25/2022] [Indexed: 01/17/2023] Open
Abstract
In this study, we compared the elemental and isotopic composition of modern and ancient bone samples pre-treated using different demineralization agents with acidic and neutral pH. The purpose of our research was to examine if demineralization using a mineral acid such as hydrochloric acid (HCl) significantly alters the δ 15N and δ 13C values of bone collagen. Evidence from the elemental and amino acid composition of the samples were incorporated alongside isotopic compositions to provide a holistic view of the effect of demineralization agents on the composition of bone collagen. The stable isotope compositions of collagen extracts were also compared against equivalent whole bone samples to assess whether whole bone has a stable isotope composition that is comparable to collagen demineralized with a neutral agent. Our results demonstrate that bone demineralization using either ethylenediaminetetraacetic acid (EDTA) or HCl yields collagen extracts with stable isotope compositions that are not significantly different, indicating that mineral acid does not alter δ 15N and δ 13C values of bone collagen. The results comparing whole bone and extracted collagen stable isotope compositions indicate that whole bone cannot be used as an effective replacement for bone collagen due to the significantly different stable isotope compositions between these sample materials. In ecological and archaeological studies performing stable isotope analysis on bone, sample pre-treatment to isolate collagen is a necessity to obtain the most reliable and reproducible isotopic measurements.
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Affiliation(s)
- Tess Wilson
- Department of Anthropology, Trent University, Peterborough, Ontario, Canada,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Paul Szpak
- Department of Anthropology, Trent University, Peterborough, Ontario, Canada
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5
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Campbell MA, Udyawer V, Jardine TD, Fukuda Y, Kopf RK, Bunn SE, Campbell HA. Dietary shifts may underpin the recovery of a large carnivore population. Biol Lett 2022; 18:20210676. [PMID: 35472283 PMCID: PMC9042529 DOI: 10.1098/rsbl.2021.0676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Supporting the recovery of large carnivores is a popular yet challenging endeavour. Estuarine crocodiles in Australia are a large carnivore conservation success story, with the population having extensively recovered from past heavy exploitation. Here, we explored if dietary changes had accompanied this large population recovery by comparing the isotopes δ13C and δ15N in bones of crocodiles sampled 40 to 55 years ago (small population) with bones from contemporary individuals (large population). We found that δ13C and δ15N values were significantly lower in contemporary crocodiles than in the historical cohort, inferring a shift in prey preference away from marine and into terrestrial food webs. We propose that an increase in intraspecific competition within the recovering crocodile population, alongside an increased abundance of feral ungulates occupying the floodplains, may have resulted in the crocodile population shifting to feed predominantly upon terrestrial food sources. The number of feral pigs consumed to sustain and grow crocodile biomass may help suppress pig population growth and increase the flow of terrestrially derived nutrients into aquatic ecosystems. The study highlights the significance of prey availability in contributing to large carnivore population recovery.
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Affiliation(s)
- Mariana A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Vinay Udyawer
- Australian Institute of Marine Science, Darwin, NT, Australia
| | - Timothy D Jardine
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK, Canada.,Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Yusuke Fukuda
- Department of Environment, Parks and Water Security, Darwin, NT, Australia
| | - R Keller Kopf
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
| | - Stuart E Bunn
- Australian Rivers Institute, Griffith University, Nathan, QLD, Australia
| | - Hamish A Campbell
- Research Institute for the Environment and Livelihoods, College of Engineering, IT and Environment, Charles Darwin University, Darwin, NT, Australia
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Procopio N, Hopkins RJ, Harvey VL, Buckley M. Proteome Variation with Collagen Yield in Ancient Bone. J Proteome Res 2021; 20:1754-1769. [PMID: 33529527 PMCID: PMC7944572 DOI: 10.1021/acs.jproteome.0c01014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Indexed: 11/30/2022]
Abstract
Isotope analyses are some of the most common analytical methods applied to ancient bone, aiding the interpretation of past diets and chronology. For this, the evaluation of "collagen yield" (as defined in radiocarbon dating and stable isotope research) is a routine step that allows for the selection of specimens that are deemed adequate for subsequent analyses, with samples containing less than ∼1% "collagen yield" normally being used for isotopic analysis but discounted for radiocarbon dating. The aims of this study were to use proteomic methods of MALDI-TOF (matrix assisted laser desorption ionization time-of-fligh mass spectrometry) and LC-ESI-MS/MS (liquid chromatography electrospray ionization tandem mass spectrometry) to investigate the endogeneity of the dominant proteinaceous biomolecules within samples that are typically considered to contain poorly preserved protein. Taking 29 archaeological samples, we evaluated the proteome variability between different acid-soluble fractions removed prior to protein gelatinization and considered waste as part of the radiocarbon dating process. We then correlated these proteomes against the commonly used "collagen yield" proxy for preservation. We found that these waste fractions contained a significant amount of both collagenous and noncollagenous proteins (NCPs) but that the abundance of these was not correlated with the acquired "collagen yield". Rather than a depleted protein load as would be expected from a low "collagen yield", the variety of the extracted NCPs was comparable with that commonly obtained from ancient samples and included informative proteins useful for species identification, phylogenetic studies, and potentially even for isotopic analyses, given further method developments. Additionally, we did not observe any correlation between "collagen yield" and peptide mass fingerprint success or between the different fractions taken from the same sample but at different radiocarbon pretreatment stages. Overall, these findings highlight the value in retaining and analyzing sample fractions that are otherwise discarded as waste during the radiocarbon dating process but more importantly, that low "collagen yield" specimens that are often misinterpreted by archaeologists as being devoid of protein can still yield useful molecular sequence-based information.
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Affiliation(s)
- Noemi Procopio
- Forensic
Science Research Group, Faculty of Health and Life Sciences, Northumbria University, Northumbria University Newcastle, Ellison Building, Newcastle Upon Tyne NE1 8ST, U.K.
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Rachel J.A. Hopkins
- Department
of Anthropology, University of New Mexico, MSC01-1040, 1 University of New
Mexico, Albuquerque, New
Mexico 87131-0001, United States
- Research
Laboratory for Archaeology and the History of Art (RLAHA), School
of Archaeology, University of Oxford, 1 South Parks Road, Oxford OX1 3TG, U.K.
| | - Virginia L. Harvey
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
- Interdisciplinary
Centre for Ancient Life, School of Natural Sciences, University of Manchester, Manchester, U.K.
| | - Michael Buckley
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
- Interdisciplinary
Centre for Ancient Life, School of Natural Sciences, University of Manchester, Manchester, U.K.
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Rumolo P, Bonanno A, Genovese S, Romeo T, Mazzola S, Basilone G, Gherardi S, Battaglia P, Andaloro F, Barra M. Growth-related trophic changes of Thunnus thynnus as evidenced by stable nitrogen isotopic values in the first dorsal spine. Sci Rep 2020; 10:9899. [PMID: 32555204 PMCID: PMC7303187 DOI: 10.1038/s41598-020-66566-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 05/06/2020] [Indexed: 11/25/2022] Open
Abstract
The bluefin tuna, Thunnus thynnus, is a highly migratory and long-living fish at the top of the pelagic food web. As top predator, it plays a key role in the stability of marine food webs by exerting top-down control on its prey. The diet composition of bluefin tuna varies in relation to its growth, seasons and migratory patterns, making it difficult to evaluate spatial and temporal effects. This latter aspect is further complicated to be determined during the first months of life, when T. thynnus specimens have a rapid growth rate leading to changes in the trophic status. In this study, the potential collagen-related effects on δ15N and δ13C values were evaluated on the whole spine of adult tuna specimens collected in the central Mediterranean Sea. Obtained results showed non-significant differences between extracted and non-extracted collagen samples for δ15N in whole spine, allowing adopting the isotopic analysis both for annuli in the spine section of adults and for younger specimens, whose spine size does not permit the collagen extraction. Specifically, isotopic analysis of whole spine of the young of the year specimens, showed a rapid change in δ15N values with length, following an exponential model. For older specimens, δ15N values were higher and varied around a plateau, likely due to a higher specificity in the choice of prey and/or to change in the geographical location. Such variability was also mirrored in annuli of spines sections of adult tunas. As far as δ13C values are concerned, a strong collagen-related effect was evidenced, likely highlighting the influence of lipids. Consequently, δ13C analysis may be used only on adult specimens where collagen extraction is possible. This research also showed how isotopic analysis of both whole sample and sequence of annuli in the cross-section of dorsal spine might produce isotopic profiles useful to detect specific trophic dynamics along the bluefin tuna growth.
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Affiliation(s)
- Paola Rumolo
- CNR-ISMAR, Calata Porta di Massa (Interno Porto di Napoli), Naples, Italy.
| | - Angelo Bonanno
- CNR-IAS, Torretta Granitola, Campobello di Mazara (TP), Italy
| | - Simona Genovese
- CNR-IAS, Torretta Granitola, Campobello di Mazara (TP), Italy
| | - Teresa Romeo
- Stazione Zoologica Anton Dohrn, Centro Interdipartimentale della Sicilia, Milazzo (ME), Italy.,Istituto Superiore per la Protezione e la Ricerca Ambientale, ISPRA, Milazzo (ME), Italy
| | | | | | - Serena Gherardi
- CNR-ISMAR, Calata Porta di Massa (Interno Porto di Napoli), Naples, Italy
| | - Pietro Battaglia
- Stazione Zoologica Anton Dohrn, Centro Interdipartimentale della Sicilia, Milazzo (ME), Italy
| | - Franco Andaloro
- Stazione Zoologica Anton Dohrn, Centro Interdipartimentale della Sicilia, Milazzo (ME), Italy
| | - Marco Barra
- CNR-ISMAR, Calata Porta di Massa (Interno Porto di Napoli), Naples, Italy
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Reiss L, Häussermann V, Mayr C. Stable isotope records of sei whale baleens from Chilean Patagonia as archives for feeding and migration behavior. Ecol Evol 2020; 10:808-818. [PMID: 32015845 PMCID: PMC6988525 DOI: 10.1002/ece3.5939] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 09/27/2019] [Accepted: 11/09/2019] [Indexed: 12/03/2022] Open
Abstract
Carbon (δ13C) and nitrogen (δ15N) stable isotope variations in baleen plates of sei whales (Balaenoptera borealis) stranded after a mass mortality event in Chilean Patagonia were investigated to assess potential dietary and migratory patterns. Carbon and nitrogen isotope ratios of seven baleens from six individuals were analyzed. The δ13C values ranged from - 19.1 to - 15.9‰ and the δ15N values from 8.7 to 15.4‰. Variations of up to 2.9‰ for δ13C and 5.3‰ for δ15N were observed within one baleen. Carbon and nitrogen isotope records of each baleen were significantly correlated and showed recurring oscillations confirmed by wavelet analyses. Oscillations slightly differed in periodicity indicating variable baleen growth rates between 10.0 and 16.5 cm/year. Food sources of the whales are discussed in terms of available isotope data for potential prey taxa and potential migratory behavior on the basis of latitudinal isotope gradients of particulate organic matter. Cyclicity could be explained by regular migrations of the sei whales from subtropical calving areas to high-latitude foraging grounds. δ15N records of baleens differed between individuals eventually pointing to diverse feeding and migratory preferences among sei whale individuals.
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Affiliation(s)
- Lilian Reiss
- Institute of GeographyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
| | - Verena Häussermann
- Huinay Scientific Field StationEscuela de Ciencias del MarFacultad de Recursos NaturalesPontificia Universidad Católica de ValparaísoValparaísoChile
| | - Christoph Mayr
- Institute of GeographyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
- GeoBio‐CenterDepartment of Earth and Environmental SciencesLudwig‐Maximilians‐UniversitätMünchenGermany
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Potential Use of Stable Isotope and Multi-element Analyses for Regional Geographical Traceability of Bone Raw Materials for Gelatin Production. FOOD ANAL METHOD 2019. [DOI: 10.1007/s12161-019-01687-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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10
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Figgener C, Bernardo J, Plotkin PT. Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology. Biol Rev Camb Philos Soc 2019; 94:1947-1973. [PMID: 31338959 PMCID: PMC6899600 DOI: 10.1111/brv.12543] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 06/07/2019] [Accepted: 06/13/2019] [Indexed: 11/30/2022]
Abstract
The idea that interspecific variation in trophic morphology among closely related species effectively permits resource partitioning has driven research on ecological radiation since Darwin first described variation in beak morphology among Geospiza. Marine turtles comprise an ecological radiation in which interspecific differences in trophic morphology have similarly been implicated as a pathway to ecopartition the marine realm, in both extant and extinct species. Because marine turtles are charismatic flagship species of conservation concern, their trophic ecology has been studied intensively using stable isotope analyses to gain insights into habitat use and diet, principally to inform conservation management. This legion of studies provides an unparalleled opportunity to examine ecological partitioning across numerous hierarchical levels that heretofore has not been applied to any other ecological radiation. Our contribution aims to provide a quantitative analysis of interspecific variation and a comprehensive review of intraspecific variation in trophic ecology across different hierarchical levels marshalling insights about realised trophic ecology derived from stable isotopes. We reviewed 113 stable isotope studies, mostly involving single species, and conducted a meta-analysis of data from adults to elucidate differences in trophic ecology among species. Our study reveals a more intricate hierarchy of ecopartitioning by marine turtles than previously recognised based on trophic morphology and dietary analyses. We found strong statistical support for interspecific partitioning, as well as a continuum of intraspecific trophic sub-specialisation in most species across several hierarchical levels. This ubiquity of trophic specialisation across many hierarchical levels exposes a far more complex view of trophic ecology and resource-axis exploitation than suggested by species diversity alone. Not only do species segregate along many widely understood axes such as body size, macrohabitat, and trophic morphology but the general pattern revealed by isotopic studies is one of microhabitat segregation and variation in foraging behaviour within species, within populations, and among individuals. These findings are highly relevant to conservation management because they imply ecological non-exchangeability, which introduces a new dimension beyond that of genetic stocks which drives current conservation planning. Perhaps the most remarkable finding from our data synthesis is that four of six marine turtle species forage across several trophic levels. This pattern is unlike that seen in other large marine predators, which forage at a single trophic level according to stable isotopes. This finding affirms suggestions that marine turtles are robust sentinels of ocean health and likely stabilise marine food webs. This insight has broader significance for studies of marine food webs and trophic ecology of large marine predators. Beyond insights concerning marine turtle ecology and conservation, our findings also have broader implications for the study of ecological radiations. Particularly, the unrecognised complexity of ecopartitioning beyond that predicted by trophic morphology suggests that this dominant approach in adaptive radiation research likely underestimates the degree of resource overlap and that interspecific disparities in trophic morphology may often over-predict the degree of realised ecopartitioning. Hence, our findings suggest that stable isotopes can profitably be applied to study other ecological radiations and may reveal trophic variation beyond that reflected by trophic morphology.
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Affiliation(s)
- Christine Figgener
- Marine Biology Interdisciplinary ProgramTexas A&M University3258 TAMU, College StationTX77843U.S.A.
- Department of BiologyTexas A&M University3258 TAMU, College StationTX77843U.S.A.
- Department of OceanographyTexas A&M University3146 TAMU, College StationTX77843U.S.A.
| | - Joseph Bernardo
- Marine Biology Interdisciplinary ProgramTexas A&M University3258 TAMU, College StationTX77843U.S.A.
- Department of BiologyTexas A&M University3258 TAMU, College StationTX77843U.S.A.
- Program in Ecology and Evolutionary BiologyTexas A&M University2475 TAMU, College StationTX77843U.S.A.
| | - Pamela T. Plotkin
- Marine Biology Interdisciplinary ProgramTexas A&M University3258 TAMU, College StationTX77843U.S.A.
- Department of OceanographyTexas A&M University3146 TAMU, College StationTX77843U.S.A.
- Texas Sea Grant, Texas A&M University4115 TAMU, College StationTX77843U.S.A.
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11
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Carrasco TS, Botta S, Machado R, Colares EP, Secchi ER. Effects of acidification on the isotopic ratios of Neotropical otter tooth dentin. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:784-788. [PMID: 29488256 DOI: 10.1002/rcm.8097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE Stable carbon and nitrogen isotope ratios are widely used in ecological studies providing important information on the trophic ecology and habitat use of consumers. However, some factors may lead to isotopic variability, which makes difficult the interpretation of data, such as the presence of inorganic carbon in mineralized tissues. In order to remove the inorganic carbon, acidification is a commonly used treatment. METHODS The effects of two methods of acidification were tested: (i) dentin acidification with 10% HCl using the 'drop-by-drop' technique, and (ii) dentin acidification in an 'HCl atmosphere', by exposing the dentin to vaporous 30% hydrochloric acid. Results were compared with untreated subsamples. The stable carbon and nitrogen ratios of untreated and acidified subsamples were measured using an elemental analyzer coupled to an isotope ratio mass spectrometer. RESULTS The nitrogen isotopic ratios were statistically different between the two acidification treatments, but no significant changes in carbon isotopic ratios were found in acidified and untreated samples. CONCLUSIONS The results indicated that acidification had no effect on carbon isotopic ratios of Neotropical otter tooth dentin, while introducing a source of error in nitrogen isotopic ratios. Therefore, we conclude that acidification is an unnecessary step for C and N stable isotope analysis.
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Affiliation(s)
- Thayara S Carrasco
- Programa de Pós-graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
| | - Silvina Botta
- Laboratório de Ecologia e Conservação da Megafauna Marinha - ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
| | - Rodrigo Machado
- Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS), 95560-000, Torres, RS, Brazil
| | - Elton P Colares
- Programa de Pós-graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
| | - Eduardo R Secchi
- Programa de Pós-graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
- Laboratório de Ecologia e Conservação da Megafauna Marinha - ECOMEGA, Instituto de Oceanografia, Universidade Federal do Rio Grande, 96203-900, Rio Grande, RS, Brazil
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Turner Tomaszewicz CN, Seminoff JA, Price M, Kurle CM. Stable isotope discrimination factors and between-tissue isotope comparisons for bone and skin from captive and wild green sea turtles (Chelonia mydas). RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1903-1914. [PMID: 28857312 PMCID: PMC5653449 DOI: 10.1002/rcm.7974] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/21/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE The ecological application of stable isotope analysis (SIA) relies on taxa- and tissue-specific stable carbon (Δ13 C) and nitrogen (Δ15 N) isotope discrimination factors, determined with captive animals reared on known diets for sufficient time to reflect dietary isotope ratios. However, captive studies often prohibit lethal sampling, are difficult with endangered species, and reflect conditions not experienced in the wild. METHODS We overcame these constraints and determined the Δ13 C and Δ15 N values for skin and cortical bone from green sea turtles (Chelonia mydas) that died in captivity and evaluated the utility of a mathematical approach to predict discrimination factors. Using stable carbon (δ13 C values) and nitrogen (δ15 N values) isotope ratios from captive and wild turtles, we established relationships between bone stable isotope (SI) ratios and those from skin, a non-lethally sampled tissue, to facilitate comparisons of SI ratios among studies using multiple tissues. RESULTS The mean (±SD) Δ13 C and Δ15 N values (‰) between skin and bone from captive turtles and their diet (non-lipid-extracted) were 2.3 ± 0.3 and 4.1 ± 0.4 and 2.1 ± 0.6 and 5.1 ± 1.1, respectively. The mathematically predicted Δ13 C and Δ15 N values were similar (to within 1‰) to the experimentally derived values. The mean δ15 N values from bone were higher than those from skin for captive (+1.0 ± 0.9‰) and wild (+0.8 ± 1.0‰) turtles; the mean δ13 C values from bone were lower than those from skin for wild turtles (-0.6 ± 0.9‰), but the same as for captive turtles. We used linear regression equations to describe bone vs skin relationships and create bone-to-skin isotope conversion equations. CONCLUSIONS For sea turtles, we provide the first (a) bone-diet SI discrimination factors, (b) comparison of SI ratios from individual-specific bone and skin, and (c) evaluation of the application of a mathematical approach to predict stable isotope discrimination factors. Our approach opens the door for future studies comparing different tissues, and relating SI ratios of captive to wild animals.
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Affiliation(s)
- Calandra N. Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, California 92093-0116, USA
- Southwest Fisheries Science Center, NOAA, National Marine Fisheries Service, La Jolla, California 92037, USA
| | - Jeffrey A. Seminoff
- Southwest Fisheries Science Center, NOAA, National Marine Fisheries Service, La Jolla, California 92037, USA
| | - Mike Price
- SeaWorld San Diego, San Diego, California 92109, USA
| | - Carolyn M. Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, San Diego, La Jolla, California 92093-0116, USA
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Ramirez MD, Avens L, Seminoff JA, Goshe LR, Heppell SS. Growth dynamics of juvenile loggerhead sea turtles undergoing an ontogenetic habitat shift. Oecologia 2017; 183:1087-1099. [PMID: 28210809 DOI: 10.1007/s00442-017-3832-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 01/29/2017] [Indexed: 11/29/2022]
Abstract
Ontogenetic niche theory predicts that individuals may undergo one or more changes in habitat or diet throughout their lifetime to maintain optimal growth rates, or to optimize trade-offs between mortality risk and growth. We combine skeletochronological and stable nitrogen isotope (δ15N) analyses of sea turtle humeri (n = 61) to characterize the growth dynamics of juvenile loggerhead sea turtles (Caretta caretta) during an oceanic-to-neritic ontogenetic shift. The primary objective of this study was to determine how ontogenetic niche theory extends to sea turtles, and to individuals with different patterns of resource use (discrete shifters, n = 23; facultative shifters n = 14; non-shifters, n = 24). Mean growth rates peaked at the start of the ontogenetic shift (based on change in δ15N values), but returned to pre-shift levels within 2 years. Turtles generally only experienced 1 year of relatively high growth, but the timing of peak growth relative to the start of an ontogenetic shift varied among individuals (before, n = 14; during, n = 12; after, n = 8). Furthermore, no reduction in growth preceded the transition, as is predicted by ontogenetic niche theory. Annual growth rates were similar between non-transitioning turtles resident in oceanic and neritic habitats and turtles displaying alternative patterns of resource use. These results suggest that factors other than maximization of size-specific growth may more strongly influence the timing of ontogenetic shifts in loggerhead sea turtles, and that alternative patterns of resource use may have limited influence on somatic growth and age at maturation in this species.
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Affiliation(s)
- Matthew D Ramirez
- Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA.
| | - Larisa Avens
- NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort Laboratory, 101 Pivers Island Road, Beaufort, NC, 28516, USA
| | - Jeffrey A Seminoff
- NOAA National Marine Fisheries Service, Southwest Fisheries Science Center, 8901 La Jolla Shores Drive, La Jolla, CA, 92037, USA
| | - Lisa R Goshe
- NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort Laboratory, 101 Pivers Island Road, Beaufort, NC, 28516, USA
| | - Selina S Heppell
- Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, USA
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Turner Tomaszewicz CN, Seminoff JA, Peckham SH, Avens L, Kurle CM. Intrapopulation variability in the timing of ontogenetic habitat shifts in sea turtles revealed using δ 15 N values from bone growth rings. J Anim Ecol 2017; 86:694-704. [PMID: 28075017 DOI: 10.1111/1365-2656.12618] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/24/2016] [Indexed: 11/29/2022]
Abstract
Determining location and timing of ontogenetic shifts in the habitat use of highly migratory species, along with possible intrapopulation variation in these shifts, is essential for understanding mechanisms driving alternate life histories and assessing overall population trends. Measuring variations in multi-year habitat-use patterns is especially difficult for remote oceanic species. To investigate the potential for differential habitat use among migratory marine vertebrates, we measured the naturally occurring stable nitrogen isotope (δ15 N) patterns that differentiate distinct ocean regions to create a 'regional isotope characterization', analysed the δ15 N values from annual bone growth layer rings from dead-stranded animals, and then combined the bone and regional isotope data to track individual animal movement patterns over multiple years. We used humeri from juvenile North Pacific loggerhead turtles (Caretta caretta), animals that undergo long migrations across the North Pacific Ocean (NPO), using multiple discrete regions as they develop to adulthood. Typical of many migratory marine species, ontogenetic changes in habitat use throughout their decades-long juvenile stage is poorly understood, but each potential habitat has unique foraging opportunities and spatially explicit natural and anthropogenic threats that could affect key life-history parameters. We found a bimodal size/age distribution in the timing that juveniles underwent an ontogenetic habitat shift from the oceanic central North Pacific (CNP) to the neritic east Pacific region near the Baja California Peninsula (BCP) (42·7 ± 7·2 vs. 68·3 ± 3·4 cm carapace length, 7·5 ± 2·7 vs. 15·6 ± 1·7 years). Important to the survival of this population, these disparate habitats differ considerably in their food availability, energy requirements and threats, and these differences can influence life-history parameters such as growth, survival and future fecundity. This is the first evidence of alternative ontogenetic shifts and habitat-use patterns for juveniles foraging in the eastern NPO. We combine two techniques, skeletochronology and stable isotope analysis, to reconstruct multi-year habitat-use patterns of a remote migratory species, linked to estimated ages and body sizes of individuals, to reveal variable ontogeny during the juvenile life stage that could drive alternate life histories and that has the potential to illuminate the migration patterns for other species with accretionary tissues.
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Affiliation(s)
- Calandra N Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, La Jolla, CA, 92093, USA.,Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, CA, 92037, USA
| | - Jeffrey A Seminoff
- Southwest Fisheries Science Center, NOAA-National Marine Fisheries Service, La Jolla, CA, 92037, USA
| | - S Hoyt Peckham
- Center for Ocean Solutions, Stanford University, Pacific Grove, CA, 93950, USA
| | - Larisa Avens
- Southeast Fisheries Science Center, NOAA-National Marine Fisheries Service, Beaufort, NC, 28516, USA
| | - Carolyn M Kurle
- Division of Biological Sciences, Ecology, Behavior, and Evolution Section, University of California, La Jolla, CA, 92093, USA
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Turner Tomaszewicz CN, Seminoff JA, Avens L, Kurle CM. Methods for sampling sequential annual bone growth layers for stable isotope analysis. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12522] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Calandra N. Turner Tomaszewicz
- Division of Biological Sciences, Ecology, Behavior and Evolution Section University of California San Diego La Jolla CA 92093‐0116 USA
- Southwest Fisheries Science Center NOAA, National Marine Fisheries Service La Jolla CA 92037 USA
| | - Jeffrey A. Seminoff
- Southwest Fisheries Science Center NOAA, National Marine Fisheries Service La Jolla CA 92037 USA
| | - Larisa Avens
- Southeast Fisheries Science Center NOAA, National Marine Fisheries Service Beaufort NC 28516 USA
| | - Carolyn M. Kurle
- Division of Biological Sciences, Ecology, Behavior and Evolution Section University of California San Diego La Jolla CA 92093‐0116 USA
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Ramirez MD, Avens L, Seminoff JA, Goshe LR, Heppell SS. Patterns of loggerhead turtle ontogenetic shifts revealed through isotopic analysis of annual skeletal growth increments. Ecosphere 2015. [DOI: 10.1890/es15-00255.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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