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Génier CSV, Guglielmo CG, Hobson KA. Combining bulk stable H isotope (δ2H) measurements with fatty acid profiles to examine differential use of aquatic vs. terrestrial prey by three sympatric species of aerial insectivorous birds. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1006928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aerial insectivorous songbirds such as swallows and martins have declined substantially in North America in recent decades. Aquatic-emergent insects provide more beneficial omega-3 fatty acids than terrestrial insects, and thus, diet quality is expected to vary among aerial insectivores with differential access to aquatic-emergent insects. We compared the stable hydrogen isotope (δ2H) values of feathers and bulk blood plasma fatty acids of nestling purple martins (Progne subis), tree swallows (Tachycineta bicolor), and barn swallows (Hirundo rustica), at lakeshore and inland sites near Lake Erie, Ontario, Canada. We found that diet quality differed between inland and lakeshore nesting habitats, but differences depended on species. Overall, purple martin and tree swallow nestlings had lower feather δ2H values, indicating a more aquatic-emergent diet, and lakeshore populations of both species had higher omega-3 fatty acid levels in their blood plasma compared to inland populations. Conversely, higher plasma levels of omega-6 fatty acids were found in inland birds. Tree swallows have a low omega-3 conversion efficiency from precursor substrates and so depend on aquatic subsidies to fulfill their nutritional needs. We suggest this may also be the case with purple martins. Barn swallows had the most positive feather δ2H values, regardless of proximity to the lakeshore, indicating a more terrestrial diet. However, barn swallow nestlings had consistently higher plasma omega-3 docosahexaenoic acid (DHA) regardless of nesting location, suggesting that barn swallows can efficiently convert omega-3 precursors into their beneficial elongated fatty acid chains. Our study indicates the benefit of combining plasma fatty acid compositional analyses with bulk feather δ2H values to decipher interspecific differences in adaptations to availability of aquatic-emergent insects.
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Kruszynski C, Bailey LD, Bach L, Bach P, Fritze M, Lindecke O, Teige T, Voigt CC. High vulnerability of juvenile Nathusius' pipistrelle bats (Pipistrellus nathusii) at wind turbines. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2513. [PMID: 34877754 DOI: 10.1002/eap.2513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/19/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
Large numbers of bats are killed by wind turbines globally, yet the specific demographic consequences of wind turbine mortality are still unclear. In this study, we compared characteristics of Nathusius' pipistrelles (Pipistrellus nathusii) killed at wind turbines (N = 119) to those observed within the live population (N = 524) during the summer migration period in Germany. We used generalized linear mixed-effects modeling to identify demographic groups most vulnerable to wind turbine mortality, including sex (female or male), age (adult or juvenile), and geographic origin (regional or long-distance migrant; depicted by fur stable hydrogen isotope ratios). Juveniles contributed with a higher proportion of carcasses at wind turbines than expected given their frequency in the live population suggesting that juvenile bats may be particularly vulnerable to wind turbine mortality. This effect varied with wind turbine density. Specifically, at low wind turbine densities, representing mostly inland areas with water bodies and forests where Nathusius' pipistrelles breed, juveniles were found more often dead beneath turbines than expected based on their abundance in the live population. At high wind turbine densities, representing mostly coastal areas where Nathusius' pipistrelles migrate, adults and juveniles were equally vulnerable. We found no evidence of increased vulnerability to wind turbines in either sex, yet we observed a higher proportion of females than males among both carcasses and the live population, which may reflect a female bias in the live population most likely caused by females migrating from their northeastern breeding areas migrating into Germany. A high mortality of females is conservation concern for this migratory bat species because it affects the annual reproduction rate of populations. A distant origin did not influence the likelihood of getting killed at wind turbines. A disproportionately high vulnerability of juveniles to wind turbine mortality may reduce juvenile recruitment, which may limit the resilience of Nathusius' pipistrelles to environmental stressors such as climate change or habitat loss. Schemes to mitigate wind turbine mortality, such as elevated cut-in speeds, should be implemented throughout Europe to prevent population declines of Nathusius' pipistrelles and other migratory bats.
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Affiliation(s)
- Cecilia Kruszynski
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Liam D Bailey
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Lothar Bach
- Bach Freilandforschung, zoologische Gutachten, Bremen, Germany
| | - Petra Bach
- Bach Freilandforschung, zoologische Gutachten, Bremen, Germany
| | - Marcus Fritze
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Oliver Lindecke
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Tobias Teige
- Büro für faunistische Fachgutachten, Berlin, Germany
| | - Christian C Voigt
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Institute of Biology, Freie Universität Berlin, Berlin, Germany
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Brewer CT, Rauch-Davis WA, Fraser EE. The Use of Intrinsic Markers for Studying the Migratory Movements of Bats. Animals (Basel) 2021; 11:3477. [PMID: 34944252 PMCID: PMC8698158 DOI: 10.3390/ani11123477] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/26/2021] [Accepted: 12/01/2021] [Indexed: 11/30/2022] Open
Abstract
Mortality of migratory bat species at wind energy facilities is a well-documented phenomenon, and mitigation and management are partially constrained by the current limited knowledge of bat migratory movements. Analyses of biochemical signatures in bat tissues ("intrinsic markers") can provide information about the migratory origins of individual bats. Many tissue samples for intrinsic marker analysis may be collected from living and dead bats, including carcasses collected at wind energy facilities. In this paper, we review the full suite of available intrinsic marker analysis techniques that may be used to study bat migration, with the goal of summarizing the current literature and highlighting knowledge gaps and opportunities. We discuss applications of the stable isotopes of hydrogen, oxygen, nitrogen, carbon, sulfur; radiogenic strontium isotopes; trace elements and contaminants; and the combination of these markers with each other and with other extrinsic markers. We further discuss the tissue types that may be analyzed for each and provide a synthesis of the generalized workflow required to link bats to origins using intrinsic markers. While stable hydrogen isotope techniques have clearly been the leading approach to infer migratory bat movement patterns across the landscape, here we emphasize a variety of lesser used intrinsic markers (i.e., strontium, trace elements, contaminants) that may address new study areas or answer novel research questions.
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Affiliation(s)
| | | | - Erin E. Fraser
- School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, 20 University Drive, Corner Brook, NL A2H 5G4, Canada; (C.T.B.); (W.A.R.-D.)
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Recalde FC, Breviglieri CP, Kersch-Becker MF, Romero GQ. Contribution of emergent aquatic insects to the trophic variation of tropical birds and bats. FOOD WEBS 2021. [DOI: 10.1016/j.fooweb.2021.e00209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Kruszynski C, Bailey LD, Courtiol A, Bach L, Bach P, Göttsche M, Göttsche M, Hill R, Lindecke O, Matthes H, Pommeranz H, Popa-Lisseanu AG, Seebens-Hoyer A, Tichomirowa M, Voigt CC. Identifying migratory pathways of Nathusius' pipistrelles (Pipistrellus nathusii) using stable hydrogen and strontium isotopes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9031. [PMID: 33336436 DOI: 10.1002/rcm.9031] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/14/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
RATIONALE Identifying migratory corridors of animals is essential for their effective protection, yet the exact location of such corridors is often unknown, particularly for elusive animals such as bats. While migrating along the German coastline, Nathusius' pipistrelles (Pipistrellus nathusii) are regularly killed at wind turbines. Therefore, we explored the paths taken on their annual journey. METHODS We used isotope ratio mass spectrometry to measure stable hydrogen and strontium isotope ratios in fur keratin of 59 Nathusius' pipistrelles captured on three offshore islands. Samples were pre-treated before analysis to report exclusively stable isotope ratios of non-exchangeable hydrogen. We generated maps to predict summer origins of bats using isoscape models. RESULTS Bats were classified as long-distance migrants, mostly originating from Eastern Europe. Hydrogen analysis suggested for some bats a possible Fennoscandian origin, yet additional information from strontium analysis excluded this possibility. Instead, our data suggest that most Nathusius' pipistrelles migrating along the German coastline were of continental European summer origin, but also highlight the possibility that Nathusius' pipistrelles of Baltorussian origin may travel offshore from Fennoscandia to Germany. CONCLUSIONS Our findings demonstrate the benefit of using complementary isotopic tracers for analysing the migratory pathways of bats and also potentially other terrestrial vertebrate species. Furthermore, data from our study suggest an offset of fur strontium isotope ratios in relation to local bedrock.
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Affiliation(s)
- Cecilia Kruszynski
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin, 14195, Germany
| | - Liam D Bailey
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
| | - Alexandre Courtiol
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
| | - Lothar Bach
- Freilandforschung, zoologische Gutachten, Hamfhofsweg 125b, Bremen, 28357, Germany
| | - Petra Bach
- Freilandforschung, zoologische Gutachten, Hamfhofsweg 125b, Bremen, 28357, Germany
| | | | - Michael Göttsche
- Faunistica - Büro für ökologische & faunistische Freilanduntersuchungen, Jaguarring 4, Bad Segeberg, 23795, Germany
| | | | - Oliver Lindecke
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin, 14195, Germany
| | | | | | - Ana G Popa-Lisseanu
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
| | | | - Marion Tichomirowa
- Institut für Mineralogie, Technische Universität Bergakademie Freiberg, Brennhausgasse 14, Freiberg, 09599, Germany
| | - Christian C Voigt
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, Berlin, 10315, Germany
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, Berlin, 14195, Germany
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Génier CSV, Guglielmo CG, Mitchell GW, Falconer M, Hobson KA. Nutritional consequences of breeding away from riparian habitats in Bank Swallows: new evidence from multiple endogenous markers. CONSERVATION PHYSIOLOGY 2021; 9:coaa140. [PMID: 33532072 PMCID: PMC7836397 DOI: 10.1093/conphys/coaa140] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/07/2020] [Accepted: 12/28/2020] [Indexed: 06/01/2023]
Abstract
The Bank Swallow (Riparia riparia), a threatened species in Canada, breeds primarily in banks at lakeshores and rivers and in artificial (typically inland) aggregate mining pits. Inland pits may be ecological traps for this species, but relative dietary trade-offs between these two nesting habitats have not been investigated. The availability of aquatic emergent insects at lakeshores may have associated nutritional benefits for growing nestlings due to increased omega-3 fatty acids (FAs) in prey. We compared the diets of juvenile swallows from lakeshore and inland pit sites using assays of stable isotope values (δ13C, δ15N, δ2H) of feathers, faecal DNA metabarcoding and blood plasma FAs. Colony proximity to Lake Erie influenced the use of aquatic versus terrestrial insects by Bank Swallow adults and juveniles. Feather δ2H was particularly useful as a tracer of aquatic emergent versus terrestrial prey, and inland juveniles had feathers enriched in 2H, reflective of diets composed of fewer aquatic emergent insects. DNA metabarcoding of juvenile and adult faecal material indicated that lakeshore birds consumed more aquatic-emergent chironomids than inland birds. Lakeshore juveniles had elevated plasma omega-3 eicosapentaenoic acid levels compared with inland pit-breeding birds. We discuss the need to consider 'nutritional landscapes' and the importance of this concept in conservation of declining species and populations.
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Affiliation(s)
- Corrine S V Génier
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Christopher G Guglielmo
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Greg W Mitchell
- Environment and Climate Change Canada, Wildlife Research Division, 1125 Colonel By Drive, Ottawa, Ontario K1A 0H3, Canada
| | - Myles Falconer
- Birds Canada, 115 Front Rd., P.O. Box 160, Port Rowan, Ontario N0E 1M0, Canada
| | - Keith A Hobson
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
- Environment and Climate Change Canada, Wildlife Research Division, 11 Innovation Blvd., Saskatoon, Saskatchewan S7N 3H5, Canada
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Kardynal KJ, Jardine TD, Génier CSV, Bumelis KH, Mitchell GW, Evans M, Hobson KA. Mercury exposure to swallows breeding in Canada inferred from feathers grown on breeding and non-breeding grounds. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:876-891. [PMID: 32656653 DOI: 10.1007/s10646-020-02249-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Aerial insectivorous birds such as swallows have been the steepest declining groups of birds in North America over the last 50 years but whether such declines are linked to contaminants has not been examined. We sampled feathers from five species of swallow at multiple locations to assess total mercury [THg] exposure for adults during the non-breeding season, and for juveniles on the breeding grounds. We assessed Hg exposure to juvenile birds in crop- and grass-dominated landscapes to determine if land-use practices influenced feather [THg]. We assayed feathers for stable isotopes (δ2H, δ13C, δ15N) as proxies for relative habitat use and diet to determine their potential influence on feather [THg]. Feather [THg] was highest in adult bank swallows (Riparia riparia) and purple martins (Progne subis) from Saskatchewan and adult cliff swallows (Petrochelidon pyrrhonota) from western regions, indicating differential exposure to Hg on the non-breeding grounds. Juvenile bank, barn (Hirundo rustica) and tree (Tachycineta bicolor) swallows had lower feather [THg] in crop-dominated landscapes than grass-dominated landscapes in Saskatchewan, potentially resulting from lower use of wetland-derived insects due to wetland drainage and intensive agriculture. Feather [THg] was related to juvenile feather stable isotopes for several species, suggesting complex interactions with diet and environmental factors. Many individuals had feather [THg] values >2 µg/g, a threshold at which deleterious effects may occur. Our findings indicate differential Hg exposure among species of swallow, regions and land-uses and highlight the need for additional research to determine dietary and finer-scale land-use impacts on individual species and populations.
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Affiliation(s)
- Kevin J Kardynal
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada.
| | - Timothy D Jardine
- School of Environment and Sustainability, Toxicology Centre, University of Saskatchewan, Saskatoon, SK, S7N 5B3, Canada
| | - Corrine S V Génier
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Kaelyn H Bumelis
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
| | - Greg W Mitchell
- Environment and Climate Change Canada, 1125 Colonel By Drive, Ottawa, ON, K1A 0H3, Canada
| | - Marlene Evans
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada
| | - Keith A Hobson
- Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, SK, S7N 3H5, Canada
- Department of Biology, University of Western Ontario, London, ON, N6A 3K7, Canada
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Moyo S, Jacobs DS. Faecal analyses and alimentary tracers reveal the foraging ecology of two sympatric bats. PLoS One 2020; 15:e0227743. [PMID: 31945139 PMCID: PMC6964858 DOI: 10.1371/journal.pone.0227743] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/28/2019] [Indexed: 12/02/2022] Open
Abstract
We used three complementary methods to assess the diet of two insectivorous bat species: one an obligate aerial hunter, Miniopterus natalensis, and the other Myotis tricolor whose morphology and taxonomic affiliation to other trawling bats suggests it may be a trawler (capturing insects from the water surface with its feet and tail). We used visual inspection, stable isotope values and fatty acid profiles of insect fragments in bat faeces sampled across five sites to determine the contribution of aquatic and terrestrial arthropods to the diets of the two species. The niche widths of M. tricolor were generally wider than those of Miniopterus natalensis but with much overlap, both taking aquatic and terrestrial insects, albeit in different proportions. The diet of M. tricolor had high proportions of fatty acids (20:5ω3 and 22:6ω3) that are only obtainable from aquatic insects. Furthermore, the diet of M. tricolor had higher proportions of water striders (Gerridae) and whirligig beetles (Gyrinidae), insects obtainable via trawling, than Miniopterus natalensis. These results suggest both species are flexible in their consumption of prey but that M. tricolor may use both aerial hawking and trawling, or at least gleaning, to take insects from water surfaces. The resultant spatial segregation may sufficiently differentiate the niches of the two species, allowing them to co-exist. Furthermore, our results emphasize that using a combination of methods to analyse diets of cryptic animals yields greater insights into animal foraging ecology than any of them on their own.
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Affiliation(s)
- Sydney Moyo
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - David S. Jacobs
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
- * E-mail:
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Soto DX, Decru E, Snoeks J, Verheyen E, Van de Walle L, Bamps J, Mambo T, Bouillon S. Terrestrial contributions to Afrotropical aquatic food webs: The Congo River case. Ecol Evol 2019; 9:10746-10757. [PMID: 31624578 PMCID: PMC6787788 DOI: 10.1002/ece3.5594] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/08/2019] [Accepted: 07/26/2019] [Indexed: 12/13/2022] Open
Abstract
Understanding the degree to which aquatic and terrestrial primary production fuel tropical aquatic food webs remains poorly understood, and quantifying the relative contributions of autochthonous and allochthonous inputs is methodologically challenging. Carbon and nitrogen stable isotope ratios (δ 13C, δ 15N) can provide valuable insights about contributions of terrestrial resources and trophic position, respectively, but this approach has caveats when applied in typical complex natural food webs.Here, we used a combination of C, N, and H (δ 2H) stable isotope measurements and Bayesian mixing models to estimate the contribution of terrestrial (allochthonous) and aquatic (autochthonous) inputs to fish and invertebrate communities in the Congo River (and some tributaries).Overall, our results show that we gained power to distinguish sources by using a multiple tracer approach and we were able to discriminate aquatic versus terrestrial sources (esp. including hydrogen isotopes). Fish δ 2H values were clearly correlated with their food preferences and revealed a high level of variation in the degree of allochthony in these tropical aquatic communities.At the community level, it is clear that terrestrial C3 plants are an important source fueling the Congo River food web. However, in order to better constrain source contribution in these complex environments will require more robust constraints on stable isotope values of algal and methane-derived C sources.
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Affiliation(s)
- David X. Soto
- Department of Earth and Environmental SciencesKU LeuvenLeuvenBelgium
| | - Eva Decru
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Jos Snoeks
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
- Laboratory of Biodiversity and Evolutionary GenomicsKU LeuvenLeuvenBelgium
| | - Erik Verheyen
- OD Taxonomy and PhylogenyRoyal Belgian Institute of Natural SciencesBrusselsBelgium
- Department Biology, Evolutionary EcologyUniversity of AntwerpAntwerpenBelgium
| | - Lora Van de Walle
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Jolien Bamps
- Section Vertebrates, IchthyologyRoyal Museum for Central AfricaTervurenBelgium
| | - Taylor Mambo
- Centre de Surveillance de la BiodiversitéUniversité de KisanganiKisanganiDemocratic Republic of Congo
| | - Steven Bouillon
- Department of Earth and Environmental SciencesKU LeuvenLeuvenBelgium
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Roeleke M, Johannsen L, Voigt CC. How Bats Escape the Competitive Exclusion Principle—Seasonal Shift From Intraspecific to Interspecific Competition Drives Space Use in a Bat Ensemble. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00101] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Soto DX, Hobson KA, Wassenaar LI. Using hydrogen isotopes of freshwater fish tissue as a tracer of provenance. Ecol Evol 2016; 6:7776-7782. [PMID: 30128127 PMCID: PMC6093159 DOI: 10.1002/ece3.2519] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/27/2016] [Accepted: 09/06/2016] [Indexed: 11/06/2022] Open
Abstract
Hydrogen isotope (δ2H) measurements of consumer tissues in aquatic food webs are useful tracers of diet and provenance and may be combined with δ13C and δ15N analyses to evaluate complex trophic relationships in aquatic systems. However, δ2H measurements of organic tissues are complicated by analytical issues (e.g., H exchangeability, lack of matrix-equivalent calibration standards, and lipid effects) and physiological mechanisms, such as H isotopic exchange with ambient water during protein synthesis and the influence of metabolic water. In this study, δ2H (and δ15N) values were obtained from fish muscle samples from Lake Winnipeg, Canada, 2007-2010, and were assessed for the effects of species, feeding habits, and ambient water δ2H values. After lipid removal, we used comparative equilibration to calibrate muscle δ2H values to nonexchangeable δ2H equivalents and controlled for H isotopic exchange between sample and laboratory ambient water vapor. We then examined the data for evidence of trophic δ2H enrichment by comparing δ2H values with δ15N values. Our results showed a significant logarithmic correlation between fork length and δ2H values, and no strong relationships between δ15N and δ2H. This suggests the so-called apparent trophic compounding effect and the influence of metabolic water into tissue H were the potential mechanisms for δ2H enrichment. We evaluated the importance of water in controlling δ2H values of fish tissues and, consequently, the potential of H isotopes as a tracer of provenance by taking account of confounding variables such as body size and trophic effects. The δ2H values of fish appear to be a good tracer for tracking provenance, and we present a protocol for the use of H isotopes in aquatic ecosystems, which should be applicable to a broad range of marine and freshwater fish species. We advise assessing size effects or working with fish of relatively similar mass when inferring fish movements using δ2H measurements.
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Affiliation(s)
| | | | - Leonard I Wassenaar
- Environment Canada Saskatoon SK Canada.,Present address: International Atomic Energy Agency Vienna Austria
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Voigt CC, Lindecke O, Schönborn S, Kramer-Schadt S, Lehmann D. Habitat use of migratory bats killed during autumn at wind turbines. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:771-783. [PMID: 27411249 DOI: 10.1890/15-0671] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The killing of large numbers of migratory bats at wind turbines is a pressing conservation problem. Even though avoidance and mitigation measures could benefit from a better knowledge of the species' migratory habits, we lack basic information about what habitats and corridors bats use during migration. We studied the isotopic niche dimensions of three bat species that are frequently killed at wind turbines in Germany: non-migratory Pipistrellus pipistrellus, mid-distance migratory Nyctalus noctula, and long- distance migratory Pipistrellus nathusii. We measured stable carbon and nitrogen isotope ratios (δ¹³C, δ¹⁵N) in five tissues that differed in isotopic retention time (fur, wing membrane tissue, muscle, liver, blood) to shed light on the species-specific habitat use during the autumn migration period using standard ellipse areas (SEAc). Further, we used stable isotope ratios of non-exchangeable hydrogen (δ²H(K)) in fur keratin to assess the breeding origin of bats. We inferred from isotopic composition (δ¹³C, δ¹⁵N) of fur keratin that isotopic niche dimensions of P. nathusii was distinct from that of N. noctula and P. pipistrellus, probably because P. nathusii was using more aquatic habitats than the other two species. Isoscape origin models supported that traveled distances before dying at wind turbines was largest for P. nathusii, intermediate for N. noctula, and shortest for P. pipistrellus. Isotopic niche dimensions calculated for each sample type separately reflected the species' migratory behavior. Pipistrellus pipistrellus and N. noctula showed similar isotopic niche breadth across all tissue types, whereas SEAc values of P. nathusii increased in tissues with slow turnaround time. Isotopic data suggested that P. nathusii consistently used aquatic habitats throughout the autumn period, whereas N. noctula showed a stronger association with terrestrial habitats during autumn compared to the pre-migration period.
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Vander Zanden HB, Soto DX, Bowen GJ, Hobson KA. Expanding the Isotopic Toolbox: Applications of Hydrogen and Oxygen Stable Isotope Ratios to Food Web Studies. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00020] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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