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Burbank J, Drake DAR, Power M. Field-based oxygen isotope fractionation for the conservation of imperilled fishes: an application with the threatened silver shiner Notropis photogenis. ENDANGER SPECIES RES 2020. [DOI: 10.3354/esr01040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Identifying the realized thermal habitat of animals is important for understanding life history and population processes, yet methods to estimate realized thermal use are lacking for many small-bodied organisms, including imperilled fishes. Analysis of oxygen isotopes provides one solution, but requires the development of species-specific fractionation equations. To date, such equations have generally been limited to commercial or game fish species. Here, we developed a field-based fractionation equation for the threatened silver shiner Notropis photogenis to better understand the thermal ecology of the species in an urban watershed. Archived otoliths were analyzed for oxygen isotope values (δ18O). There was a significant linear relationship between otolith isotope fractionation and water temperature, described by δ18Ootolith(VPBD) - δ18Owater(VPBD) = 32.03 - 0.21(°C). Results indicate that otolith isotope techniques can be used to identify the average relative temperature occupied by silver shiner, representing the first investigation of oxygen isotopes to understand thermal occupancy of the species. This field-based equation provides an opportunity to understand how silver shiner may respond to alterations in stream temperatures resulting from urbanization and climate effects and may be useful in identifying thermal refugia for the species. Field-based, species-specific fractionation equations can provide insights into the thermal ecology of many small-bodied fishes, which are increasingly imperilled due to thermal stressors.
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Affiliation(s)
- J Burbank
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
- Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, Ontario L7S 1A1, Canada
| | - DAR Drake
- Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, Ontario L7S 1A1, Canada
| | - M Power
- Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Willmes M, Lewis LS, Davis BE, Loiselle L, James HF, Denny C, Baxter R, Conrad JL, Fangue NA, Hung TC, Armstrong RA, Williams IS, Holden P, Hobbs JA. Calibrating temperature reconstructions from fish otolith oxygen isotope analysis for California's critically endangered Delta Smelt. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:1207-1220. [PMID: 30993783 DOI: 10.1002/rcm.8464] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/22/2019] [Accepted: 04/15/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE Oxygen isotope ratios (δ18 O values) of fish otoliths (ear bones) are valuable geochemical tracers of water conditions and thermal life history. Delta Smelt (Hypomesus transpacificus) are osmerid forage fish endemic to the San Francisco Estuary, California, USA, that are on the verge of extinction. These fish exhibit a complex life history that allows them to survive in a dynamic estuarine environment; however, a rapidly warming climate threatens this thermally sensitive species. Here we quantify the accuracy and precision of using δ18 O values in otoliths to reconstruct the thermal life histories of Delta Smelt. METHODS Delta Smelt were reared for 360 days using three different water sources with different ambient δ18 Owater values (-8.75‰, -5.28‰, and -4.06‰) and different water temperatures (16.4°C, 16.7°C, 18.7°C, and 20.5°C). Samples were collected after 170 days (n = 28) and 360 days (n = 14) post-hatch. In situ δ18 O values were measured from the core of the otolith to the dorsal edge using secondary ion mass spectrometry (SIMS) to reconstruct temporally resolved thermal life histories. RESULTS The δ18 Ootolith values for Delta Smelt varied as a linear inverse function of water temperature: 1000 ln α = 18.39 (±0.43, 1SE)(103 TK-1 ) - 34.56 (±1.49, 1SE) and δ18 Ootolith(VPDB) - δ18 Owater (VPDB) = 31.34(±0.09, 1SE) - 0.19(±0.01, 1SE) × T ° C. When the ambient δ18 Owater value is known, this species-specific temperature-dependent oxygen isotope fractionation model facilitated the accurate (0.25°C) and precise (±0.37°C, 2σ) reconstruction of the water temperature experienced by the fish. In contrast, the use of existing general fractionation equations resulted in inaccurate temperature reconstructions. CONCLUSIONS The species-specific δ18 Ootolith fractionation equation allowed for accurate and precise reconstructions of water temperatures experienced by Delta Smelt. Characterization of ambient δ18 Owater values remains a critical next step for reconstructing thermal life histories of wild Delta Smelt. This tool will provide new insights into habitat utilization, potential thermal refugia, and resilience to future warming for this critically endangered fish.
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Affiliation(s)
- Malte Willmes
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Levi S Lewis
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Brittany E Davis
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
- California Department of Water Resources, 1416 9th Street, Sacramento, CA, 95814, USA
| | - Liane Loiselle
- Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT, 2601, Australia
| | - Hannah F James
- Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT, 2601, Australia
| | - Christian Denny
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Randall Baxter
- California Department of Fish and Wildlife, 1416 9th Street, Sacramento, CA, 95814, USA
| | - J Louise Conrad
- California Department of Water Resources, 1416 9th Street, Sacramento, CA, 95814, USA
| | - Nann A Fangue
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Tien-Chieh Hung
- Biological and Agricultural Engineering, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Richard A Armstrong
- Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT, 2601, Australia
| | - Ian S Williams
- Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT, 2601, Australia
| | - Peter Holden
- Research School of Earth Sciences, Australian National University, Building 142 Mills Road, Acton, ACT, 2601, Australia
| | - James A Hobbs
- Wildlife, Fish and Conservation Biology, UC Davis, One Shields Avenue, Davis, CA, 95616, USA
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