Marine carbon and nitrogen in southeastern Alaska stream food webs: evidence from artificial and natural streams

Chaloner, Dominic T.; Martin, Kristine M.; Wipfli, Mark S.; Ostrom, Peggy H.; Lamberti, Gary A.

doi:10.1139/f02-084

Cited by 120 publications

(120 citation statements)

References 28 publications

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“…Also consistent with this mechanism were results from an experimental stream study in Alaska, where chironomids were the most isotopically enriched invertebrate in channels augmented with salmon tissue and likely a key pathway for the trophic transfer of marinederived nutrients delivered by spawning salmon (Chaloner et al 2002). 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).…”

Section: Methodssupporting

confidence: 57%

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: Methodssupporting

confidence: 57%

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

et al. 2014

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“…3, 4), responses of algae to N and P supplements from salmon are much less predictable on annual timescales (e.g., Mitchell and Lamberti 2005;Brock et al 2006). In streams, disturbance of the benthic environment by spawning salmon may restrict algal growth (Mitchell and Lamberti 2005) and can facilitate MDN export to coastal lakes and estuaries (Chaloner et al 2004). However, such nutrients are also attenuated slowly by algae in nursery lakes, possibly reflecting either rapid mixing throughout the basin or that N and P associated with organic matter must be mineralized before nutrients become available to primary producers (but see discussion of Mitchell and Lamberti 2005).…”

Section: Discussionmentioning

confidence: 99%

Variable effects of marine‐derived nutrients on algal production in salmon nursery lakes of Alaska during the past 300 years

Brock

Leavitt

Schindler

et al. 2007

Limnology & Oceanography

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We measured historical changes in sedimentary d 15 N and fossil pigments in four lakes with anadromous semelparous salmon and two reference lakes to quantify the degree to which the flux of marine-derived nutrients (MDNs as N isotopes) regulate algal production (as pigments). During the past 300 yr, production of the predominant algae (diatoms) was positively correlated (r 5 0.42-0.93, p , 0.02) with sedimentary d 15 N in nursery lakes of sockeye salmon (Oncorhynchus nerka) but was inversely correlated with sedimentary d 15 N (r 5 20.71 to 20.73, p , 0.0001) in reference lakes that lacked migratory fishes. Overall, the pigment-d 15 N correlation during the 20th century was strongly correlated with both mean densities of spawning sockeye salmon during 1956-2000 (r 5 0.97, p , 0.002) and the fraction of total ecosystem N derived from salmon during 1900-2000 (r 5 0.98, p , 0.001). Together these patterns suggest that the sign of the d 15 N-pigment correlation can be used to distinguish among lakes or periods of time in which algal production is regulated mainly by MDN influx (positive correlation) or other factors (negative correlation). Tests of this hypothesis revealed that the degree to which MDNs regulated algal production in nursery lakes varied greatly since 1700, with significant periods of weak control even in lakes with abundant salmon. Further, when considered at the landscape scale, the importance of MDNs to individual lakes varied substantially through time and in space, with little evidence of synchrony among sites or catchments.

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“…We measured nitrogen stable isotopes (d 15 N) in horsetail, scraper and generalist macroinvertebrates, and Dolly Varden, and additionally measured sulfur stable isotopes (d 34 S) and fatty acid composition in Dolly Varden. Delta 15 N has been used extensively to measure incorporation of MDN in freshwater food webs (e.g., Kline et al 1990, Bilby et al 1996, Chaloner et al 2002, Scheuerell et al 2007. Delta 15 N in adult salmon (typically 10-15%; reviewed in Johnson and Schindler 2009) is enriched v www.esajournals.org relative to freshwater sources (e.g., 0 to 9, depending on trophic level; Kline et al 1990), creating an isotopic disparity that can be used to measure the relative contribution of marine and freshwater nutrient pools.…”

Section: Laboratory Analysesmentioning

confidence: 99%

Seasonal persistence of marine‐derived nutrients in south‐central Alaskan salmon streams

Rinella

Wipfli

Walker³

et al. 2013

Ecosphere

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Abstract. Spawning salmon deliver annual pulses of marine-derived nutrients (MDN) to riverine ecosystems around the Pacific Rim, leading to increased growth and condition in aquatic and riparian biota. The influence of pulsed resources may last for extended periods of time when recipient food webs have effective storage mechanisms, yet few studies have tracked the seasonal persistence of MDN. With this as our goal, we sampled stream water chemistry and selected stream and riparian biota spring through fall at 18 stations (in six watersheds) that vary widely in spawner abundance and at nine stations (in three watersheds) where salmon runs were blocked by waterfalls. We then developed regression models that related dissolved nutrient concentrations and biochemical measures of MDN assimilation to localized spawner density across these 27 stations. Stream water ammonium-N and orthophosphate-P concentrations increased with spawner density during the summer salmon runs, but responses did not persist into the following fall. The effect of spawner density on d 15 N in generalist macroinvertebrates and three independent MDN metrics (d 15 N, d 34 S, and x3:x6 fatty acids) in juvenile Dolly Varden (Salvelinus malma) was positive and similar during each season, indicating that MDN levels in biota increased with spawner abundance and were maintained for at least nine months after inputs. Delta 15 N in a riparian plant, horsetail (Equisetum fluviatile), and scraper macroinvertebrates did not vary with spawner density in any season, suggesting a lack of MDN assimilation by these lower trophic levels. Our results demonstrate the ready assimilation of MDN by generalist consumers and the persistence of this pulsed subsidy in these organisms through the winter and into the next growing season.

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Marine carbon and nitrogen in southeastern Alaska stream food webs: evidence from artificial and natural streams

Cited by 120 publications

References 28 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

Variable effects of marine‐derived nutrients on algal production in salmon nursery lakes of Alaska during the past 300 years

Seasonal persistence of marine‐derived nutrients in south‐central Alaskan salmon streams

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