Effects of Salmon-Derived Nitrogen on Riparian Forest Growth and Implications for Stream Productivity

Helfield, James M.; Naiman, Robert J.

doi:10.2307/2679924

Cited by 125 publications

(178 citation statements)

References 24 publications

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“…The Carex C:N ratios in our study were not different in salmon and non-salmon streams. This contrasts with Helfield and Naiman (2001) who found that southeast Alaskan riparian trees had lower C:N ratios adjacent to streams with salmon than those without salmon spawners. However, Carex spp.…”

Section: C:n Ratios and Invertebrate Body Conditioncontrasting

confidence: 91%

“…In contrast, invertebrates can obtain salmon-derived carbon and nitrogen by directly consuming salmon carcasses, and can also indirectly acquire salmon-derived nitrogen from isotopically enriched vegetation and herbivorous consumers (Hocking & Reimchen, 2002). Through these pathways, riparian plants and invertebrates alongside streams receiving salmon spawners often exhibit higher δ 15 N, but not necessarily higher δ 13 C (Ben- David et al, 1998;Bilby, Beach, Fransen, Walter, & Peter, 2003;Helfield & Naiman, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…This ratio reveals the relative nitrogen content of the foliage, with low C:N ratios generally indicating a faster turnover in primary producers and greater rates of herbivory (Cebrián, Williams, McClelland, & Valiela, 1998). Together, stable isotope and C:N ratios could indicate whether vegetation is of higher quality because of uptake of salmon-derived nitrogen (Helfield & Naiman, 2001). Similarly to plants, consumer C:N ratios can be indicators of food quality for the next trophic level (Elser et al, 2000), but consumer C:N ratios can also be correlated with lipid content, a relationship that is not consistently found in plants (Post et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes

Vizza

Sanderson

Coe

et al. 2017

Ecology and Evolution

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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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Section: C:n Ratios and Invertebrate Body Conditioncontrasting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes

Vizza

Sanderson

Coe

et al. 2017

Ecology and Evolution

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“…Seasonal migration has evolved as a complex behavior to enhance fitness and results from interactions between individuals (e.g., learned behavior), their genes, and the environment, notably spatiotemporal variation in resources and interspecific threats (e.g., predation; Dingle & Drake, 2007;Fryxell & Sinclair, 1988;Hebblewhite & Merrill, 2009). Migration is widespread across taxonomic groups and increasingly recognized as fundamental to maintaining populations and communities through effects on population productivity and the lateral transport of nutrients within and across ecosystems (Bolger, Newmark, Morrison, & Doak, 2008;Helfield & Naiman, 2001;Holdo, Holt, Sinclair, Godley, & Thirgood, 2011;Milner-Gulland, Fryxell, & Sinclair, 2011;Sawyer, Middleton, Hayes, Kauffman, & Monteith, 2016). Moreover, identifying and conserving migration corridors is an important management priority for state (WYGF, 2016) and federal (USDOI, 2018) agencies, and noted as one of the most difficult conservation challenges of the 21st century (Berger, 2004).…”

Section: Introductionmentioning

confidence: 99%

Characterizing population and individual migration patterns among native and restored bighorn sheep (Ovis canadensis)

Lowrey

Proffitt

McWhirter

et al. 2019

Ecology and Evolution

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Migration evolved as a behavior to enhance fitness through exploiting spatially and temporally variable resources and avoiding predation or other threats. Globally, landscape alterations have resulted in declines to migratory populations across taxa. Given the long time periods over which migrations evolved in native systems, it is unlikely that restored populations embody the same migratory complexity that existed before population reductions or regional extirpation. We used GPS location data collected from 209 female bighorn sheep ( Ovis canadensis ) to characterize population and individual migration patterns along elevation and geographic continuums for 18 populations of bighorn sheep with different management histories (i.e., restored, augmented, and native) across the western United States. Individuals with resident behaviors were present in all management histories. Elevational migrations were the most common population‐level migratory behavior. There were notable differences in the degree of individual variation within a population across the three management histories. Relative to native populations, restored and augmented populations had less variation among individuals with respect to elevation and geographic migration distances. Differences in migratory behavior were most pronounced for geographic distances, where the majority of native populations had a range of variation that was 2–4 times greater than restored or augmented populations. Synthesis and applications . Migrations within native populations include a variety of patterns that translocation efforts have not been able to fully recreate within restored and augmented populations. Theoretical and empirical research has highlighted the benefits of migratory diversity in promoting resilience and population stability. Limited migratory diversity may serve as an additional factor limiting demographic performance and range expansion. We suggest preserving native systems with intact migratory portfolios and a more nuanced approach to restoration and augmentation in which source populations are identified based on a suite of criteria that includes matching migratory patterns of source populations with local landscape attributes.

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“…One of the best-known examples of this is the large-scale transport of marine carbon to freshwater and terrestrial ecosystems by migrating Pacific salmon, Oncorhynchus spp. (Helfield and Naiman 2001;Hocking and Reynolds 2011;Holtgrieve and Schindler 2011). Fishes may have a dual role: they prey on aquatic stages of terrestrial insects and thereby limit the transport of aquatic carbon to riparian plants and animals (Knight et al 2005;Finlay and Vredenburg 2007;Epanchin et al 2010;Hoekman et al 2011) but at the same time fishes augment transfers of terrestrial carbon into aquatic ecosystems via predation of terrestrial vertebrates and invertebrates (Fig.…”

Section: Introductionmentioning

confidence: 99%

Terrestrial prey fuels the fish population of a small, high-latitude lake

et al. 2015

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The significance of terrestrial carbon subsidies in lake ecosystems has been under active research, but the contribution of terrestrial energy to the highest trophic levels has been explored less frequently. Here, we examined the terrestrial energy contribution to the ingested and assimilated diet of introduced brown trout (Salmo trutta) in a small, high-latitude lake using stomach content, stable isotope and fatty acid analyses. Stomach content analysis of brown trout indicated a terrestrial contribution of 29 % during the open-water season. Terrestrial prey was mainly composed of rodents (23 % in volume), but also amphibians and terrestrial insects. A longer term estimate, obtained with a mixing model (SIAR) for liver and dorsal muscle stable isotopes from 2010 and 2011, revealed a terrestrial contribution of 68.5 and 63.5 %, respectively. Through a similar model, fatty acid analysis on 2011 samples estimated a contribution of 71.5 %. Despite the relatively high proportion of rodents in the trout ingested diet, no correlation was evident between the long-term rodent cycles and terrestrial energy contribution estimated with stable isotopes of muscle. Terrestrial prey were an important long-term energy source for fish in small highlatitude lake, but its contribution was not directly dependent on the availability of pulsed resources such as small mammals.

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Effects of Salmon-Derived Nitrogen on Riparian Forest Growth and Implications for Stream Productivity

Cited by 125 publications

References 24 publications

Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes

Evaluating the consequences of salmon nutrients for riparian organisms: Linking condition metrics to stable isotopes

Characterizing population and individual migration patterns among native and restored bighorn sheep (Ovis canadensis)

Terrestrial prey fuels the fish population of a small, high-latitude lake

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