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Rasmus KA, Petticrew EL, Rex J. The seasonal movement of sediment-associated marine-derived nutrients in a morphologically diverse riverbed: the influence of salmon in an Interior British Columbia river. JOURNAL OF SOILS AND SEDIMENTS 2023; 23:3638-3657. [PMID: 37791373 PMCID: PMC10542299 DOI: 10.1007/s11368-023-03563-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 05/25/2023] [Indexed: 10/05/2023]
Abstract
Purpose This study (1) investigated the extent to which flocculation and the hydrological and morphological attributes of an interior salmon-bearing river regulate the seasonal storage of marine-derived nutrients (MDN) and (2) compared the contribution of MDN to the fine bed sediment relative to other nutrient sources to the river. Methods Previous research has determined that the co-existence of re-suspended fine sediment, generated by salmon redd construction, with salmonid excretion and decay products in the water column creates ideal conditions for the flocculation of these inorganic and organic particles. Stored and suspended fine bed sediment was sampled from seven sites with varying morphologies and bed substrate down the length of a large spawning river in the interior of British Columbia over a 12-month period. MDN contributions to the sediment was tracked using aggregated versus dispersed particle size, carbon-to-nitrogen ratios, stable carbon and nitrogen isotopes, and MixSIAR modeling. Results and discussion (1) There was a significant longitudinal spatial distinction of nutrient retention between sites upstream and downstream of a large seasonally inundated floodplain; (2) the MDN isotopic signal in the surficial stored bed sediment in this sample year was short term; and (3) upstream spawner numbers, substrate size, stream morphology, and discharge were relevant to both the magnitude and retention time of sediment-associated MDN. Conclusion A cumulative magnification of MDN was correlated with the distance from the headwaters and the number of upstream spawners. The relationship between MDN retention in interior rivers, and possible multi-year accumulation, was influenced by variability in channel morphology, substrate size, and the presence of an inundated floodplain halfway down the river.
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Affiliation(s)
- Kristy A. Rasmus
- Ministry of Environment and Climate Change Strategy, 3726 Alfred Street, Smithers, BC V0J 2N0 Canada
| | - Ellen L. Petticrew
- Department of Geography, Earth and Environmental Sciences, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 Canada
| | - John Rex
- Ministry of Forests Omineca Region, Research and Forest Health, 5th Flr. 499 George St., Prince George, BC V2L 1R5 Canada
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2
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Walsh JC, Pendray JE, Godwin SC, Artelle KA, Kindsvater HK, Field RD, Harding JN, Swain NR, Reynolds JD. Relationships between Pacific salmon and aquatic and terrestrial ecosystems: implications for ecosystem-based management. Ecology 2020; 101:e03060. [PMID: 32266971 PMCID: PMC7537986 DOI: 10.1002/ecy.3060] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/10/2020] [Accepted: 02/24/2020] [Indexed: 11/18/2022]
Abstract
Pacific salmon influence temperate terrestrial and freshwater ecosystems through the dispersal of marine‐derived nutrients and ecosystem engineering of stream beds when spawning. They also support large fisheries, particularly along the west coast of North America. We provide a comprehensive synthesis of relationships between the densities of Pacific salmon and terrestrial and aquatic ecosystems, summarize the direction, shape, and magnitude of these relationships, and identify possible ecosystem‐based management indicators and benchmarks. We found 31 studies that provided 172 relationships between salmon density (or salmon abundance) and species abundance, species diversity, food provisioning, individual growth, concentration of marine‐derived isotopes, nutrient enhancement, phenology, and several other ecological responses. The most common published relationship was between salmon density and marine‐derived isotopes (40%), whereas very few relationships quantified ecosystem‐level responses (5%). Only 13% of all relationships tended to reach an asymptote (i.e., a saturating response) as salmon densities increased. The number of salmon killed by bears and the change in biomass of different stream invertebrate taxa between spawning and nonspawning seasons were relationships that usually reached saturation. Approximately 46% of all relationships were best described with linear or curved nonasymptotic models, indicating a lack of saturation. In contrast, 41% of data sets showed no relationship with salmon density or abundance, including many of the relationships with stream invertebrate and biofilm biomass density, marine‐derived isotope concentrations, or vegetation density. Bears required the highest densities of salmon to reach their maximum observed food consumption (i.e., 9.2 kg/m2 to reach the 90% threshold of the relationship’s asymptote), followed by freshwater fish abundance (90% threshold = 7.3 kg/m2 of salmon). Although the effects of salmon density on ecosystems are highly varied, it appears that several of these relationships, such as bear food consumption, could be used to develop indicators and benchmarks for ecosystem‐based fisheries management.
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Affiliation(s)
- Jessica C Walsh
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jane E Pendray
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Sean C Godwin
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kyle A Artelle
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.,Raincoast Conservation Foundation, P.O. Box 2429, Sidney, British Columbia, V8L 3Y3, Canada
| | - Holly K Kindsvater
- Department of Ecology, Evolution and Natural Resources, Rutgers University, 14 College Farm Road, New Brunswick, New Jersey, 08908, USA
| | - Rachel D Field
- Department of Biology, The Okanagan Institute for Biodiversity, Resilience and Ecosystem Services (BRAES), Irving K. Barber School of Arts and Sciences, University of British Columbia, Okanagan, SCI 133, 1177 Research Road, Kelowna, British Columbia, V1V 1V7, Canada
| | - Jennifer N Harding
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Noel R Swain
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - John D Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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3
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Joy PJ, Stricker CA, Ivanoff R, Wipfli MS, Seitz AC, Tyers M. Bridging the Gap Between Salmon Spawner Abundance and Marine Nutrient Assimilation by Juvenile Salmon: Seasonal Cycles and Landscape Effects at the Watershed Scale. Ecosystems 2020. [DOI: 10.1007/s10021-019-00406-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Wagner MA, Reynolds JD. Salmon increase forest bird abundance and diversity. PLoS One 2019; 14:e0210031. [PMID: 30726212 PMCID: PMC6364887 DOI: 10.1371/journal.pone.0210031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/14/2018] [Indexed: 11/19/2022] Open
Abstract
Resource subsidies across ecosystems can have strong and unforeseen ecological impacts. Marine-derived nutrients from Pacific salmon (Onchorhycus spp.) can be transferred to streams and riparian forests through diverse food web pathways, fertilizing forests and increasing invertebrate abundance, which may in turn affect breeding birds. We quantified the influence of salmon on the abundance and composition of songbird communities across a wide range of salmon-spawning biomass on 14 streams along a remote coastal region of British Columbia, Canada. Point-count data spanning two years were combined with salmon biomass and 13 environmental covariates in riparian forests to test for correlates with bird abundance, foraging guilds, individual species, and avian diversity. We show that bird abundance and diversity increase with salmon biomass and that watershed size and forest composition are less important predictors. This work provides new evidence for the importance of salmon to terrestrial ecosystems and information that can inform ecosystem-based management.
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Affiliation(s)
- Marlene A. Wagner
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- Hakai Institute, Heriot Bay, British Columbia, Canada
- * E-mail:
| | - John D. Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- Hakai Institute, Heriot Bay, British Columbia, Canada
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5
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Kiffney PM, Naman SM, Cram JM, Liermann M, Burrows DG. Multiple pathways of C and N incorporation by consumers across an experimental gradient of salmon carcasses. Ecosphere 2018. [DOI: 10.1002/ecs2.2197] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- P. M. Kiffney
- Fish Ecology National Oceanic and Atmospheric Administration National Marine Fisheries Service Northwest Fisheries Science Center 2725 Montlake Boulevard East Seattle Washington 98112 USA
| | - S. M. Naman
- Department of Zoology University of British Columbia 4200‐6270 University Boulevard Vancouver British Columbia V6T 1Z4 Canada
| | - J. M. Cram
- Science Division, Fish Program Washington Department of Fish and Wildlife 3515 Chelan Highway 97A Wenatchee Washington 98801 USA
| | - M. Liermann
- Fish Ecology National Oceanic and Atmospheric Administration National Marine Fisheries Service Northwest Fisheries Science Center 2725 Montlake Boulevard East Seattle Washington 98112 USA
| | - D. G. Burrows
- Environmental and Fisheries Sciences National Oceanic and Atmospheric Administration National Marine Fisheries Service Northwest Fisheries Science Center 2725 Montlake Boulevard East Seattle Washington 98112 USA
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6
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Whigham DF, Walker CM, Maurer J, King RS, Hauser W, Baird S, Keuskamp JA, Neale PJ. Watershed influences on the structure and function of riparian wetlands associated with headwater streams - Kenai Peninsula, Alaska. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 599-600:124-134. [PMID: 28475906 DOI: 10.1016/j.scitotenv.2017.03.290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/30/2017] [Accepted: 03/31/2017] [Indexed: 06/07/2023]
Abstract
Riparian wetlands are dynamic components of landscapes. Located between uplands and aquatic environments, riparian habitats intercept sediments and nutrients before they enter aquatic environments. They are a source of organic matter and nutrients to aquatic systems, and they provide important habitat for animals, often serving as corridors for the movement of animals between habitats in fragmented landscapes. In this project, we focused on the structure and function of riparian wetlands associated with headwater streams in Alaska that serve as nursery habitats for juvenile salmonids. We asked whether or not the structure and function of headwater wetlands differed between watersheds with and without nitrogen-fixing Alder (Alnus spp.). We found that the aboveground biomass of riparian vegetation was higher in the watershed with Alder, but the largest differences were in the litter layer and belowground where vegetation in the watershed with no Alder had significantly higher root biomass. Interstitial water chemistry also differed between the study sites with significantly higher inorganic N and significantly different characteristics of colored dissolved organic matter at the site with Alder on the watershed. The biomass of litter that hung over the creek bank was less at the site with Alder on the watershed and an in situ decomposition experiment showed significant differences between the two systems. Results of the research demonstrates that watershed characteristics can impact the ecology of headwater streams in ways that had not been previously recognized.
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Affiliation(s)
- D F Whigham
- Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, USA.
| | - C M Walker
- Kachemak Bay National Estuarine Research Reserve, University of Alaska, 2181 Kachemak Drive, Homer, AK 99603, USA.
| | - J Maurer
- Kachemak Bay National Estuarine Research Reserve, University of Alaska, 2181 Kachemak Drive, Homer, AK 99603, USA.
| | - R S King
- Baylor University, Department of Biology, One Bear Place #97388, Waco, TX 76798, USA.
| | - W Hauser
- Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, USA; Wabash College, Biology Department, Crawfordsville, IN 47933, USA.
| | - S Baird
- Kachemak Bay National Estuarine Research Reserve, University of Alaska, 2181 Kachemak Drive, Homer, AK 99603, USA.
| | - J A Keuskamp
- Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 59, 6700 AB Wageningen, The Netherlands; Ecology & Biodiversity Group, Department of Biology, Utrecht University, P.O. Box 80.056, 3508 TB Utrecht, The Netherlands.
| | - P J Neale
- Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, USA.
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Gratton C, Hoekman D, Dreyer J, Jackson RD. Increased duration of aquatic resource pulse alters community and ecosystem responses in a subarctic plant community. Ecology 2017; 98:2860-2872. [DOI: 10.1002/ecy.1977] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/18/2017] [Accepted: 07/12/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Claudio Gratton
- Department of Entomology University of Wisconsin–Madison Madison Wisconsin 53706 USA
- Department of Zoology University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - David Hoekman
- Department of Entomology University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - Jamin Dreyer
- Department of Zoology University of Wisconsin–Madison Madison Wisconsin 53706 USA
| | - Randall D. Jackson
- Department of Agronomy University of Wisconsin–Madison Madison Wisconsin 53706 USA
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8
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Hanley TC, Kimbro DL, Hughes AR. Stress and subsidy effects of seagrass wrack duration, frequency, and magnitude on salt marsh community structure. Ecology 2017; 98:1884-1895. [DOI: 10.1002/ecy.1862] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 03/09/2017] [Accepted: 04/05/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Torrance C. Hanley
- Department of Marine and Environmental Science Marine Science Center Northeastern University Nahant Massachusetts 01908 USA
| | - David L. Kimbro
- Department of Marine and Environmental Science Marine Science Center Northeastern University Nahant Massachusetts 01908 USA
| | - Anne Randall Hughes
- Department of Marine and Environmental Science Marine Science Center Northeastern University Nahant Massachusetts 01908 USA
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Cyr A, Sergeant CJ, Lopez JA, O'Hara T. Assessing the influence of migration barriers and feeding ecology on total mercury concentrations in Dolly Varden (Salvelinus malma) from a glaciated and non-glaciated stream. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 580:710-718. [PMID: 27979620 DOI: 10.1016/j.scitotenv.2016.12.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/02/2016] [Accepted: 12/02/2016] [Indexed: 06/06/2023]
Abstract
Assimilation of mercury (Hg) into food webs is directly influenced by ecological factors such as local habitat characteristics, species feeding behavior, and movement patterns. Total Hg concentrations ([THg]) in biota from Subarctic latitudes are driven both by broad spatial processes such as long-range atmospheric transport and more local influences such as biovectors and geology. Thus, even relatively pristine protected lands such as national parks are experiencing Hg accumulation. We analyzed [THg] and stable isotopes of carbon (δ13C) and nitrogen (δ15N) in 104 Dolly Varden (Salvelinus malma) collected from two rivers in southeastern Alaska, upstream and downstream of apparent anadromous migration barriers in watersheds with and without glacial coverage. To assess the potential magnitude of marine-derived THg returning to freshwater, we analyzed [THg] in ten adult pink salmon from each study system. There were no differences in Dolly Varden mean [THg] between sites after the data were standardized for fork length, but unadjusted [THg] varied relative to fish size and δ15N values. While previous studies generally show that [THg] increases with higher δ15N values, we found that Dolly Varden below migration barriers and foraging on salmon eggs had the highest δ15N values among all sampled individuals, but the lowest [THg]. Dolly Varden residing below anadromous barriers had δ13C values consistent with marine influence. Since salmon eggs typically have low [Hg], our results suggest that abundant salmon populations and the dietary subsidy they provide may reduce the annual exposure to [Hg] in egg-eating stream fishes such as Dolly Varden. In addition to identifying a suitable species for freshwater Hg monitoring in southeastern Alaska, our study more broadly implies that river characteristics, location within a river, fish size, and feeding ecology are important factors influencing Hg accumulation.
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Affiliation(s)
- Andrew Cyr
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 905 N Koyukuk Dr, Fairbanks, AK 99775-7220, USA.
| | - Christopher J Sergeant
- National Park Service, Inventory and Monitoring Program, 3100 National Park Road, Juneau 99801, AK, USA
| | - Juan Andres Lopez
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 905 N Koyukuk Dr, Fairbanks, AK 99775-7220, USA; University of Alaska Museum of the North, University of Alaska Fairbanks, 907 Yukon Dr, Fairbanks, AK 99775-6960, USA
| | - Todd O'Hara
- Department of Veterinary Medicine, University of Alaska Fairbanks, 901 Koyukuk Dr, Fairbanks, AK 99775-7750, USA
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10
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Vizza C, Sanderson BL, Coe HJ, Chaloner DT. Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes. Ecol Evol 2017; 7:1313-1324. [PMID: 28261445 PMCID: PMC5330886 DOI: 10.1002/ece3.2697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/21/2016] [Accepted: 11/27/2016] [Indexed: 11/11/2022] Open
Abstract
Stable isotope ratios (δ13C and δ15N) have been used extensively to trace nutrients from Pacific salmon, but salmon transfer more than carbon and nitrogen to stream ecosystems, such as phosphorus, minerals, proteins, and lipids. To examine the importance of these nutrients, metrics other than isotopes need to be considered, particularly when so few studies have made direct links between these nutrients and how they affect riparian organisms. Our study specifically examined δ13C and δ15N of riparian organisms from salmon and non-salmon streams in Idaho, USA, at different distances from the streams, and examined whether the quality of riparian plants and the body condition of invertebrates varied with access to these nutrients. Overall, quality and condition metrics did not mirror stable isotope patterns. Most notably, all riparian organisms exhibited elevated δ15N in salmon streams, but also with proximity to both stream types suggesting that both salmon and landscape factors may affect δ15N. The amount of nitrogen incorporated from Pacific salmon was low for all organisms (<20%) and did not correlate with measures of quality or condition, probably due to elevated δ15N at salmon streams reflecting historical salmon runs instead of current contributions. Salmon runs in these Idaho streams have been declining, and associated riparian ecosystems have probably seen about a 90% reduction in salmon-derived nitrogen since the 1950s. In addition, our results support those of other studies that have cautioned that inferences from natural abundance isotope data, particularly in conjunction with mixing models for salmon-derived nutrient percentage estimates, may be confounded by biogeochemical transformations of nitrogen, physiological processes, and even historical legacies of nitrogen sources. Critically, studies should move beyond simply describing isotopic patterns to focusing on the consequences of salmon-derived nutrients by quantifying the condition and fitness of organisms putatively using those resources.
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Affiliation(s)
- Carmella Vizza
- National Marine Fisheries Service Northwest Fisheries Science Center Seattle WA USA; Department of Biological Sciences University of Notre Dame Notre Dame IN USA
| | - Beth L Sanderson
- National Marine Fisheries Service Northwest Fisheries Science Center Seattle WA USA
| | - Holly J Coe
- National Marine Fisheries Service Northwest Fisheries Science Center Seattle WA USA
| | - Dominic T Chaloner
- Department of Biological Sciences University of Notre Dame Notre Dame IN USA
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11
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Morley SA, Coe HJ, Duda JJ, Dunphy LS, McHenry ML, Beckman BR, Elofson M, Sampson EM, Ward L. Seasonal variation exceeds effects of salmon carcass additions on benthic food webs in the Elwha River. Ecosphere 2016. [DOI: 10.1002/ecs2.1422] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- S. A. Morley
- Fish Ecology Division Northwest Fisheries Science Center National Marine Fisheries Service, NOAA Seattle Washington 98112 USA
| | - H. J. Coe
- Ocean Associates Arlington Virginia 22207 USA
| | - J. J. Duda
- Western Fisheries Research Center U.S. Geological Survey Seattle Washington 98115 USA
| | - L. S. Dunphy
- School of Aquatic and Fishery Sciences University of Washington Seattle Washington 98105 USA
| | - M. L. McHenry
- Natural Resources Department Lower Elwha Klallam Tribe Port Angeles Washington 98363 USA
| | - B. R. Beckman
- Environmental and Fisheries Sciences Division Northwest Fisheries Science Center National Marine Fisheries Service, NOAA Seattle Washington 98112 USA
| | - M. Elofson
- Natural Resources Department Lower Elwha Klallam Tribe Port Angeles Washington 98363 USA
| | - E. M. Sampson
- Natural Resources Department Lower Elwha Klallam Tribe Port Angeles Washington 98363 USA
| | - L. Ward
- Natural Resources Department Lower Elwha Klallam Tribe Port Angeles Washington 98363 USA
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12
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Jardine TD, Woods R, Marshall J, Fawcett J, Lobegeiger J, Valdez D, Kainz MJ. Reconciling the role of organic matter pathways in aquatic food webs by measuring multiple tracers in individuals. Ecology 2015; 96:3257-69. [DOI: 10.1890/14-2153.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Collins SF, Marcarelli AM, Baxter CV, Wipfli MS. A Critical Assessment of the Ecological Assumptions Underpinning Compensatory Mitigation of Salmon-Derived Nutrients. ENVIRONMENTAL MANAGEMENT 2015; 56:571-586. [PMID: 25968140 DOI: 10.1007/s00267-015-0538-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
We critically evaluate some of the key ecological assumptions underpinning the use of nutrient replacement as a means of recovering salmon populations and a range of other organisms thought to be linked to productive salmon runs. These assumptions include: (1) nutrient mitigation mimics the ecological roles of salmon, (2) mitigation is needed to replace salmon-derived nutrients and stimulate primary and invertebrate production in streams, and (3) food resources in rearing habitats limit populations of salmon and resident fishes. First, we call into question assumption one because an array of evidence points to the multi-faceted role played by spawning salmon, including disturbance via redd-building, nutrient recycling by live fish, and consumption by terrestrial consumers. Second, we show that assumption two may require qualification based upon a more complete understanding of nutrient cycling and productivity in streams. Third, we evaluate the empirical evidence supporting food limitation of fish populations and conclude it has been only weakly tested. On the basis of this assessment, we urge caution in the application of nutrient mitigation as a management tool. Although applications of nutrients and other materials intended to mitigate for lost or diminished runs of Pacific salmon may trigger ecological responses within treated ecosystems, contributions of these activities toward actual mitigation may be limited.
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Affiliation(s)
- Scott F Collins
- Stream Ecology Center, Department of Biological Sciences, Idaho State University, Pocatello, ID, USA,
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14
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Harding JN, Reynolds JD. Opposing forces: Evaluating multiple ecological roles of Pacific salmon in coastal stream ecosystems. Ecosphere 2014. [DOI: 10.1890/es14-00207.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Time-delayed subsidies: interspecies population effects in salmon. PLoS One 2014; 9:e98951. [PMID: 24911974 PMCID: PMC4049634 DOI: 10.1371/journal.pone.0098951] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/09/2014] [Indexed: 11/19/2022] Open
Abstract
Cross-boundary nutrient inputs can enhance and sustain populations of organisms in nutrient-poor recipient ecosystems. For example, Pacific salmon (Oncorhynchus spp.) can deliver large amounts of marine-derived nutrients to freshwater ecosystems through their eggs, excretion, or carcasses. This has led to the question of whether nutrients from one generation of salmon can benefit juvenile salmon from subsequent generations. In a study of 12 streams on the central coast of British Columbia, we found that the abundance of juvenile coho salmon was most closely correlated with the abundance of adult pink salmon from previous years. There was a secondary role for adult chum salmon and watershed size, followed by other physical characteristics of streams. Most of the coho sampled emerged in the spring, and had little to no direct contact with spawning salmon nutrients at the time of sampling in the summer and fall. A combination of techniques suggest that subsidies from spawning salmon can have a strong, positive, time-delayed influence on the productivity of salmon-bearing streams through indirect effects from previous spawning events. This is the first study on the impacts of nutrients from naturally-occurring spawning salmon on juvenile population abundance of other salmon species.
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