Do fall additions of salmon carcasses benefit food webs in experimental streams?

Cram, Jeremy M.; Kiffney, Peter M.; Klett, Ryan S.; Edmonds, Robert L.

doi:10.1007/s10750-011-0819-9

Cited by 13 publications

(14 citation statements)

References 36 publications

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“…With this in mind, our research in the Cedar River highlights the potential importance of species composition, light availability, density-dependent interactions, and season in affecting the response of river food webs to nutrient enrichment (e.g., increasing adult salmon escapement). With respect to season, we observed strong bottom-up effects of enriching channels with salmon tissue on coho growth in summer, while there were no effects of adding up to 4 kg/m 2 of adult salmon tissue on juvenile coho in the same set of experimental channels during fall and early winter, which we attribute to cool water temperatures and low light flux limiting trophic production (Cram et al 2011).…”

Section: Synthesis and Implicationsmentioning

confidence: 69%

“…Moreover, in previous experiments and field observations in the Cedar River, this range of adult inputs had no detectable effect on nutrient chemistry, algal biomass, invertebrate population biomass, fish growth, and stable isotope ratios of d 13 C and d 15 N of invertebrates or fish (Cram et al 2011;P. M. Kiffney, unpublished data).…”

Section: Field Studymentioning

confidence: 76%

“…Direct consumption of analogs may also explain some of the variation in coho growth and isotopic enrichment, as analog fragments and adult salmon tissue and eggs are consumed by coho (Armstrong et al 2010, Cram et al 2011, Kohler et al 2012b). However, our diet analysis provided no evidence of direct consumption of analogs, although this may reflect the fact that coho diets were only sampled once and at a different time (day 45) than invertebrate flux (day 14)…”

Section: Methodsmentioning

confidence: 99%

“…brates from the Cedar River (see Cram et al 2011 for further details). Deposition of eggs by aerial adults may have also contributed to invertebrate populations, but this source of colonists was not quantified.…”

Section: Study Sitementioning

confidence: 99%

“…Deposition of eggs by aerial adults may have also contributed to invertebrate populations, but this source of colonists was not quantified. Water was turned on 60 days prior to the start of the experiment to allow the benthic food web to establish (Cram et al 2011).…”

Section: Study Sitementioning

confidence: 99%

See 4 more Smart Citations

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

et al. 2014

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An experiment and a mark‐recapture field study of juvenile coho salmon (Oncorhynchus kisutch) were conducted to identify controls of key energy flow chains in river food webs. In the small‐scale experiment, we investigated the individual and interactive effects of physical habitat structure (PHS) as small wood and resource availability (tissue of adult Chinook salmon, O. tshawytscha) on nutrients, algae, invertebrates, and fish predators including juvenile coho. In the field, we quantified the effects of natural variation in prey availability (invertebrate drift biomass), PHS (wood), and local fish density on summer growth of juvenile coho across multiple stream reaches. Adding salmon tissue to experimental channels resulted in strong bottom‐up effects on select invertebrates including increased population biomass of chironomids and baetids, the numerically dominant invertebrates, and faster growth of juvenile coho. We link the enhanced growth of coho to chironomid productivity: for instance, adult chironomid flux was 4.3× higher and coho consumption of these animals 3× higher in salmon‐subsidized channels. PHS in experimental channels was associated with reduced algal biomass, potentially in response to increased invertebrate consumption, and invertebrate flux or export. The field study revealed coho growth was negatively related to PHS and total fish density and positively related to Diptera drift biomass; however, the effects of fish density and drift biomass on coho growth were relatively weak. The field study also indicated that prey resource availability and coho growth were associated with differences in canopy cover, with prey biomass and coho growth 2–4× higher in reaches receiving more sunlight. As in the experiment, coho in natural stream reaches predominantly fed on adult chironomids and other Diptera, indicating that these taxa and life‐stages are a key link between the benthic food web and mobile vertebrate predators. Our study showed that bottom‐up processes initiated by salmon subsidies and possibly light flux determined key trophic interactions in the Cedar River food web. Moreover, we speculate that PHS may modify some of these interactions indirectly through its effects on the movement of organisms through the environment.

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Section: Synthesis and Implicationsmentioning

confidence: 69%

Section: Field Studymentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

See 3 more Smart Citations

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

et al. 2014

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Multiple pathways of C and N incorporation by consumers across an experimental gradient of salmon carcasses

et al. 2018

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Abstract. Numerous studies link resource subsidies to consumers, yet manipulations of subsidy gradients are rare, limiting our ability to predict their effects. We measured natural abundance levels of the stable isotopes of carbon (d 13 C) and nitrogen (d 15 N) in consumers representing two taxonomic (invertebrates, fish) and multiple trophic groups (primary, secondary, and tertiary consumers) exposed to a gradient of Pacific salmon carcasses (0-4 kg/m 2 , eight treatment levels) in 16 experimental streams from September to December. We hypothesized (1) that consumer among invertebrates. The only fish that responded positively to carcasses was a small benthic, secondary consumer, and only for d 13 C. Overall, benthic invertebrate primary consumers were the dominant pathway by which salmon organic matter entered the trophic system, followed by benthic secondary consumers, and then tertiary consumers (juvenile coho salmon and cutthroat trout) that occupy the water column. The attenuating response to subsidies at higher trophic levels was possibly due to a combination of low decomposition and metabolic rates during fall and winter, composition of the subsidy, and habitat use. Our results demonstrate that decomposing salmon carcasses provide variable but potentially important sources of C (range:~0-60%) and N (range:~0-35%) supporting benthic consumers during fall and winter, when environmental conditions constrain primary productivity, with some evidence of saturation at carcass loadings >0.1-0.6 kg/m 2 . Furthermore, stable isotope analysis showed that consumers exploited salmon organic matter in different ways, potentially alleviating competition and allowing for a more efficient processing of this resource subsidy.

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A Critical Assessment of the Ecological Assumptions Underpinning Compensatory Mitigation of Salmon-Derived Nutrients

Collins

Marcarelli

Baxter

et al. 2015

Environmental Management

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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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Do fall additions of salmon carcasses benefit food webs in experimental streams?

Cited by 13 publications

References 36 publications

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

Linking resource availability and habitat structure to stream organisms: an experimental and observational assessment

Multiple pathways of C and N incorporation by consumers across an experimental gradient of salmon carcasses

A Critical Assessment of the Ecological Assumptions Underpinning Compensatory Mitigation of Salmon-Derived Nutrients

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