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Power M, Thorstad EB, Forseth T, Fiske P. Temporal shifts in the marine feeding of individual Atlantic salmon inferred from scale isotope ratios. Ecol Evol 2023; 13:e10656. [PMID: 37920771 PMCID: PMC10618632 DOI: 10.1002/ece3.10656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/10/2023] [Accepted: 09/27/2023] [Indexed: 11/04/2023] Open
Abstract
Given the limited information on prey use during the marine residency period for Atlantic salmon, scales were collected from salmon at return to the River Namsen (Norway) for spawning after 1 year at sea, and scale material from the first and second summer marine feeding periods was analysed using stable isotope methods to understand dynamics of their trophic ecology. As the salmon increased in size from the first to second summer, they reduced their feeding niche and specialised more (narrowed the δ13C range) and increased their dependency on higher tropic level (δ15N) prey, likely fish. Changes in δ13C indicated a consistent pattern of movement towards the north and west between summer feeding periods. Hence, salmon during their first year at sea may have a migration route roughly resembling that of previous spawners, as inferred from earlier tagging studies. Feeding conditions and nutrient composition during the last summer at sea, i.e. in the months before returning to the river for spawning, impacted final body size and within-season timing of return. Fish undergoing the largest trophic niche shift (δ13C and δ15N combined) between summer feeding periods, returned earliest. The earliest returning fish had the fastest specific growth rates at sea. Hence, salmon encountering abundant high-quality fish food during the marine migration, particularly during the last months, may reach a size and energetic state whereby it is better to return early to a safer environment in freshwater than risk being eaten by a big predator at sea. Both trophic status (δ15N), resource use (δ13C) and growth rates were significantly correlated between feeding periods. Nutrient composition during the first summer at sea did not impact the fish body length after the following winter, but growth conditions during the first summer evidenced carry-over effects from the first to the second summer of feeding.
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Affiliation(s)
- Michael Power
- Department of BiologyUniversity of WaterlooWaterlooOntarioCanada
| | - Eva B. Thorstad
- Aquatic Ecology DepartmentNorwegian Institute for Nature Research (NINA)TrondheimNorway
| | - Torbjørn Forseth
- Aquatic Ecology DepartmentNorwegian Institute for Nature Research (NINA)TrondheimNorway
| | - Peder Fiske
- Aquatic Ecology DepartmentNorwegian Institute for Nature Research (NINA)TrondheimNorway
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de la Vega C, Kershaw J, Stenson GB, Frie AK, Biuw M, Haug T, Norman L, Mahaffey C, Smout S, Jeffreys RM. Multi-decadal trends in biomarkers in harp seal teeth from the North Atlantic reveal the influence of prey availability on seal trophic position. GLOBAL CHANGE BIOLOGY 2023; 29:5582-5595. [PMID: 37477068 DOI: 10.1111/gcb.16889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/05/2023] [Accepted: 07/07/2023] [Indexed: 07/22/2023]
Abstract
Arctic food webs are being impacted by borealisation and environmental change. To quantify the impact of these multiple forcings, it is crucial to accurately determine the temporal change in key ecosystem metrics, such as trophic position of top predators. Here, we measured stable nitrogen isotopes (δ15 N) in amino acids in harp seal teeth from across the North Atlantic spanning a period of 60 years to robustly assess multi-decadal trends in harp seal trophic position, accounting for changes in δ15 N at the base of the food web. We reveal long-term variations in trophic position of harp seals which are likely to reflect fluctuations in prey availability, specifically fish- or invertebrate-dominated diets. We show that the temporal trends in harp seal trophic position differ between the Northwest Atlantic, Greenland Sea and Barents Sea, suggesting divergent changes in each local ecosystem. Our results provide invaluable data for population dynamic and ecotoxicology studies.
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Affiliation(s)
- Camille de la Vega
- School of Environmental Sciences, University of Liverpool, Liverpool, UK
- Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | - Joanna Kershaw
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, UK
| | - Garry B Stenson
- Science Branch, Northwest Atlantic Fisheries Centre, Fisheries & Oceans Canada, St. John's, Newfoundland and Labrador, Canada
- Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, Canada
| | | | - Martin Biuw
- Institute of Marine Research, Fram Centre, Tromsø, Norway
| | - Tore Haug
- Institute of Marine Research, Fram Centre, Tromsø, Norway
| | - Louisa Norman
- School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - Claire Mahaffey
- School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - Sophie Smout
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, UK
| | - Rachel M Jeffreys
- School of Environmental Sciences, University of Liverpool, Liverpool, UK
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Espinasse B, Sturbois A, Basedow SL, Hélaouët P, Johns DG, Newton J, Trueman CN. Temporal dynamics in zooplankton δ13C and δ15N isoscapes for the North Atlantic Ocean: Decadal cycles, seasonality, and implications for predator ecology. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.986082] [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
The limited amount of ecological data covering offshore parts of the ocean impedes our ability to understand and anticipate the impact of anthropogenic stressors on pelagic marine ecosystems. Isoscapes, i.e., spatial models of the distribution of stable isotope ratios, have been employed in the recent years to investigate spatio-temporal patterns in biogeochemical process and ecological responses. Development of isoscapes on the scale of ocean basins is hampered by access to suitable reference samples. Here we draw on archived material from long-running plankton survey initiatives, to build temporally explicit isoscape models for the North Atlantic Ocean (> 40°N). A total of 570 zooplankton samples were retrieved from Continuous Plankton Recorder archives and analysed for δ13C and δ15N values. Bayesian generalised additive models were developed to (1) model the relations between isotopic values and a set of predictors and (2) predict isotopic values for the whole of the study area. We produced yearly and seasonal isoscape models for the period 1998–2020. These are the first observation-based time-resolved C and N isoscapes developed at the scale of the North Atlantic Ocean. Drawing on the Stable Isotope Trajectory Analysis framework, we identify five isotopically distinct regions. We discuss the hydro-biogeochemical processes that likely explain theses modes, the differences in temporal dynamics (stability and cycles) and compare our results with previous bioregionalization efforts. Finally, we lay down the basis for using the isoscapes as a tool to define predator distributions and their interactions with the trophic environment. The isoscapes developed in this study have the potential to update our knowledge of marine predator ecology and therefore our capacity to improve their conservation in the future.
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Thomas DN, Arévalo-Martínez DL, Crocket KC, Große F, Grosse J, Schulz K, Sühring R, Tessin A. A changing Arctic Ocean. AMBIO 2022; 51:293-297. [PMID: 34843100 PMCID: PMC8692628 DOI: 10.1007/s13280-021-01677-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Affiliation(s)
- David N. Thomas
- University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014 Helsinki, Finland
| | | | | | - Fabian Große
- Department of Microbiology, Federal Institute of Hydrology, Am Mainzer Tor 1, 56068 Koblenz, Germany
| | | | - Kirstin Schulz
- 201 E. 24th Street, Stop C0200, Austin, TX 78712-1229 USA
| | - Roxana Sühring
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3 Canada
| | - Allyson Tessin
- Department of Geology, Kent State University, 800 E Summit St, Kent, OH 44240 USA
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Tuerena RE, Mahaffey C, Henley SF, de la Vega C, Norman L, Brand T, Sanders T, Debyser M, Dähnke K, Braun J, März C. Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean. AMBIO 2022; 51:355-369. [PMID: 34914030 PMCID: PMC8692559 DOI: 10.1007/s13280-021-01673-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/20/2021] [Accepted: 11/12/2021] [Indexed: 05/25/2023]
Abstract
Climate change is altering nutrient cycling within the Arctic Ocean, having knock-on effects to Arctic ecosystems. Primary production in the Arctic is principally nitrogen-limited, particularly in the western Pacific-dominated regions where denitrification exacerbates nitrogen loss. The nutrient status of the eastern Eurasian Arctic remains under debate. In the Barents Sea, primary production has increased by 88% since 1998. To support this rapid increase in productivity, either the standing stock of nutrients has been depleted, or the external nutrient supply has increased. Atlantic water inflow, enhanced mixing, benthic nitrogen cycling, and land-ocean interaction have the potential to alter the nutrient supply through addition, dilution or removal. Here we use new datasets from the Changing Arctic Ocean program alongside historical datasets to assess how nitrate and phosphate concentrations may be changing in response to these processes. We highlight how nutrient dynamics may continue to change, why this is important for regional and international policy-making and suggest relevant research priorities for the future.
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Affiliation(s)
| | - Claire Mahaffey
- Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, Liverpool, L69 3GP Merseyside UK
| | - Sian F. Henley
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh, EH9 3FE UK
| | - Camille de la Vega
- Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, Liverpool, L69 3GP Merseyside UK
| | - Louisa Norman
- Department of Earth, Ocean and Ecological Sciences, School of Environmental Sciences, University of Liverpool, 4 Brownlow Street, Liverpool, L69 3GP Merseyside UK
| | - Tim Brand
- Scottish Association for Marine Science, Oban, PA37 1QA UK
| | - Tina Sanders
- Institute for Carbon Cycles, Helmholtz-Zentrum Hereon, Max-Planck-Str. 1, 21502 Geesthacht, Germany
| | - Margot Debyser
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh, EH9 3FE UK
| | - Kirstin Dähnke
- Institute for Carbon Cycles, Helmholtz-Zentrum Hereon, Max-Planck-Str. 1, 21502 Geesthacht, Germany
| | - Judith Braun
- Scottish Association for Marine Science, Oban, PA37 1QA UK
| | - Christian März
- School of Earth & Environment, University of Leeds, Leeds, LS2 9JT UK
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