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Arai K, Castonguay M, Lyubchich V, Secor DH. Integrating machine learning with otolith isoscapes: Reconstructing connectivity of a marine fish over four decades. PLoS One 2023; 18:e0285702. [PMID: 37256866 DOI: 10.1371/journal.pone.0285702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/30/2023] [Indexed: 06/02/2023] Open
Abstract
Stable isotopes are an important tool to uncover animal migration. Geographic natal assignments often require categorizing the spatial domain through a nominal approach, which can introduce bias given the continuous nature of these tracers. Stable isotopes predicted over a spatial gradient (i.e., isoscapes) allow a probabilistic and continuous assignment of origin across space, although applications to marine organisms remain limited. We present a new framework that integrates nominal and continuous assignment approaches by (1) developing a machine-learning multi-model ensemble classifier using Bayesian model averaging (nominal); and (2) integrating nominal predictions with continuous isoscapes to estimate the probability of origin across the spatial domain (continuous). We applied this integrated framework to predict the geographic origin of the Northwest Atlantic mackerel (Scomber scombrus), a migratory pelagic fish comprised of northern and southern components that have distinct spawning sites off Canada (northern contingent) and the US (southern contingent), and seasonally overlap in the US fished regions. The nominal approach based on otolith carbon and oxygen stable isotopes (δ13C/δ18O) yielded high contingent classification accuracy (84.9%). Contingent assignment of unknown-origin samples revealed prevalent, yet highly varied contingent mixing levels (12.5-83.7%) within the US waters over four decades (1975-2019). Nominal predictions were integrated into mackerel-specific otolith oxygen isoscapes developed independently for Canadian and US waters. The combined approach identified geographic nursery hotspots in known spawning sites, but also detected geographic shifts over multi-decadal time scales. This framework can be applied to other marine species to understand migration and connectivity at a high spatial resolution, relevant to management of unit stocks in fisheries and other conservation assessments.
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Affiliation(s)
- Kohma Arai
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD, United States of America
| | - Martin Castonguay
- Fisheries and Oceans Canada, Institut Maurice-Lamontagne, Mont-Joli, QC, Canada
| | - Vyacheslav Lyubchich
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD, United States of America
| | - David H Secor
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD, United States of America
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Britton K, Crowley BE, Bataille CP, Miller JH, Wooller MJ. Silver Linings at the Dawn of a “Golden Age”. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.748938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nearly four decades after the first applications of strontium isotope analyses in archaeology and paleoecology research, it could be said that we are entering a “Golden Age”. Here, we reflect on major past developments and current strengths in strontium isotope research, as well as speculate on future directions. We review (1) the currently limited number of (but much needed) controlled feeding experiments, (2) recent advances in isoscape mapping and spatial assignment, and (3) the strength of multi-proxy approaches (including both the integration of strontium isotopes with other isotope systems and complementary techniques such as ancient DNA analyses). We also explore the integration of strontium isotope research with other types of paleoecological or archaeology data, as well as with evidence and interpretative frameworks from other fields (such as conservation ecology, conservation paleobiology or history). This blending is critical as we seek to advance the field beyond simply distinguishing local or relatively sedentary individuals from those that were non-local or highly mobile. We finish with a call for future research centered on balancing methodological developments and novel applications with critical self-reflection, deeper theoretical considerations and cross-disciplinarity.
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Winter ER, Hindes AM, Lane S, Britton JR. Dual‐isotope isoscapes for predicting the scale of fish movements in lowland rivers. Ecosphere 2021. [DOI: 10.1002/ecs2.3456] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Emily R. Winter
- Department of Life and Environmental Sciences Faculty of Science and Technology Institute of Aquatic Sciences Bournemouth University PooleBH12 5BBUK
| | | | - Steve Lane
- Fisheries, Biodiversity and Geomorphology Team Environment Agency Dragonfly House NorwichNR3 1UBUK
| | - J. Robert Britton
- Department of Life and Environmental Sciences Faculty of Science and Technology Institute of Aquatic Sciences Bournemouth University PooleBH12 5BBUK
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Brennan SR, Schindler DE, Cline TJ, Walsworth TE, Buck G, Fernandez DP. Shifting habitat mosaics and fish production across river basins. Science 2019; 364:783-786. [PMID: 31123135 DOI: 10.1126/science.aav4313] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 04/26/2019] [Indexed: 11/02/2022]
Abstract
Watersheds are complex mosaics of habitats whose conditions vary across space and time as landscape features filter overriding climate forcing, yet the extent to which the reliability of ecosystem services depends on these dynamics remains unknown. We quantified how shifting habitat mosaics are expressed across a range of spatial scales within a large, free-flowing river, and how they stabilize the production of Pacific salmon that support valuable fisheries. The strontium isotope records of ear stones (otoliths) show that the relative productivity of locations across the river network, as both natal- and juvenile-rearing habitat, varies widely among years and that this variability is expressed across a broad range of spatial scales, ultimately stabilizing the interannual production of fish at the scale of the entire basin.
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Affiliation(s)
- Sean R Brennan
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105, USA.
| | - Daniel E Schindler
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105, USA
| | - Timothy J Cline
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105, USA
| | - Timothy E Walsworth
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98105, USA
| | - Greg Buck
- Alaska Department of Fish and Game, Anchorage, AK 99518, USA
| | - Diego P Fernandez
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112, USA
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Complex life histories discovered in a critically endangered fish. Sci Rep 2019; 9:16772. [PMID: 31727901 PMCID: PMC6856525 DOI: 10.1038/s41598-019-52273-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 10/15/2019] [Indexed: 11/21/2022] Open
Abstract
Effective conservation of endangered species requires knowledge of the full range of life-history strategies used to maximize population resilience within a stochastic and ever-changing environment. California’s endemic Delta Smelt (Hypomesus transpacificus) is rapidly approaching extinction in the San Francisco Estuary, placing it in the crossfire between human and environmental uses of limited freshwater resources. Though managed as a semi-anadromous species, recent studies have challenged this lifecycle model for Delta Smelt, suggesting the species is an estuarine resident with several localized “hot-spots” of abundance. Using laser-ablation otolith strontium isotope microchemistry, we discovered three distinct life-history phenotypes including freshwater resident (FWR), brackish-water resident (BWR), and semi-anadromous (SA) fish. We further refined life-history phenotypes using an unsupervised algorithm and hierarchical clustering and found that in the last resilient year-class, the FWR (12%) and BWR (7%) comprised a small portion of the population, while the majority of fish were SA (81%). Furthermore, the semi-anadromous fish could be clustered into at least four additional life-history phenotypes that varied by natal origin, dispersal age and adult salinity history. These diverse life-history strategies should be incorporated into future conservation and management efforts aimed at preventing the extinction of Delta Smelt in the wild.
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Brennan SR, Cline TJ, Schindler DE. Quantifying habitat use of migratory fish across riverscapes using space‐time isotope models. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13191] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sean R. Brennan
- University of WashingtonSchool of Aquatic and Fishery SciencesSeattle Washington
| | - Timothy J. Cline
- University of WashingtonSchool of Aquatic and Fishery SciencesSeattle Washington
| | - Daniel E. Schindler
- University of WashingtonSchool of Aquatic and Fishery SciencesSeattle Washington
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Bataille CP, von Holstein ICC, Laffoon JE, Willmes M, Liu XM, Davies GR. A bioavailable strontium isoscape for Western Europe: A machine learning approach. PLoS One 2018; 13:e0197386. [PMID: 29847595 PMCID: PMC5976198 DOI: 10.1371/journal.pone.0197386] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 05/01/2018] [Indexed: 11/18/2022] Open
Abstract
Strontium isotope ratios (87Sr/86Sr) are gaining considerable interest as a geolocation tool and are now widely applied in archaeology, ecology, and forensic research. However, their application for provenance requires the development of baseline models predicting surficial 87Sr/86Sr variations (“isoscapes”). A variety of empirically-based and process-based models have been proposed to build terrestrial 87Sr/86Sr isoscapes but, in their current forms, those models are not mature enough to be integrated with continuous-probability surface models used in geographic assignment. In this study, we aim to overcome those limitations and to predict 87Sr/86Sr variations across Western Europe by combining process-based models and a series of remote-sensing geospatial products into a regression framework. We find that random forest regression significantly outperforms other commonly used regression and interpolation methods, and efficiently predicts the multi-scale patterning of 87Sr/86Sr variations by accounting for geological, geomorphological and atmospheric controls. Random forest regression also provides an easily interpretable and flexible framework to integrate different types of environmental auxiliary variables required to model the multi-scale patterning of 87Sr/86Sr variability. The method is transferable to different scales and resolutions and can be applied to the large collection of geospatial data available at local and global levels. The isoscape generated in this study provides the most accurate 87Sr/86Sr predictions in bioavailable strontium for Western Europe (R2 = 0.58 and RMSE = 0.0023) to date, as well as a conservative estimate of spatial uncertainty by applying quantile regression forest. We anticipate that the method presented in this study combined with the growing numbers of bioavailable 87Sr/86Sr data and satellite geospatial products will extend the applicability of the 87Sr/86Sr geo-profiling tool in provenance applications.
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Affiliation(s)
- Clement P. Bataille
- Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Canada
- Department of Geological Sciences, University of North Carolina, Chapel Hill, N.C., United States of America
- * E-mail:
| | | | - Jason E. Laffoon
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, The Netherlands
- Faculty of Archaeology, Leiden University, Leiden, The Netherlands
| | - Malte Willmes
- Department of Wildlife, Fish, and Conservation Biology, University of California Davis, Davis, C.A., United States of America
| | - Xiao-Ming Liu
- Department of Geological Sciences, University of North Carolina, Chapel Hill, N.C., United States of America
| | - Gareth R. Davies
- Department of Earth Sciences, Faculty of Science, Vrije Universiteit Amsterdam, The Netherlands
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