Effects of spawning salmon on dissolved nutrients and epilithon in coupled stream-estuary systems of southeastern Alaska

Cak, Anthony D.; Chaloner, Dominic T.; Lamberti, Gary A.

doi:10.1007/s00027-008-8090-5

Cited by 27 publications

(26 citation statements)

References 48 publications

(69 reference statements)

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“…However, export of nutrients and organic matter driven by this disturbance may lead to increased delivery of salmon nutrients to downstream river reaches (Albers and Petticrew 2012), rearing lakes (Moore et al 2007), and estuaries (Cak et al 2008), and in some cases, these exported nutrients have been linked to increased biofilm standing crop in these downstream ecosystems (Albers and Petticrew 2012). Therefore, the effects of salmon spawning may be more appropriately viewed at the scale of stream segments or watersheds, rather than reaches.…”

Section: Discussionmentioning

confidence: 99%

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

2014

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Abstract. Mitigation activities designed to supplement nutrient and organic matter inputs to streams experiencing decline or loss of Pacific salmon typically presuppose that an important pathway by which salmon nutrients are moved to fish (anadromous and/or resident) is via nutrient incorporation by biofilms and subsequent bottom-up stimulation of biofilm production, which is nutrient-limited in many ecosystems where salmon returns have declined. Our objective was to quantify the magnitude of nutrient incorporation and biofilm dynamics that underpin this indirect pathway in response to experimental additions of salmon carcasses and pelletized fish meal (a.k.a., salmon carcass analogs) to 500-m reaches of central Idaho streams over three years. Biofilm standing crops increased 2-8-fold and incorporated marinederived nutrients (measured using 15 N and 13 C) in the month following treatment, but these responses did not persist year-to-year. Biofilms were nitrogen (N) limited before treatments, and remained N limited in analog, but not carcass-treated reaches. Despite these biofilm responses, in the month following treatment total N load was equal to 33-47% of the N added to the treated reaches, and N spiraling measurements suggested that as much as 20%, but more likely 2-3% of added N was taken up by microbes. Design of biologically and cost-effective strategies for nutrient addition will require understanding the rates at which stream microbes take up nutrients and the downstream distance traveled by exported nutrients.

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Section: Discussionmentioning

confidence: 99%

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

2014

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“…However, the net effects of spawning salmon can vary (Harding et al 2014); salmon can subsidize freshwater and riparian habitats through excretion and egg and carcass deposition (Kline et al 1990, Cederholm et al 1999, Janetski et al 2009, and can export nutrients with juvenile emigration and disturbance as adults dig and defend nests (Moore et al 2007, Kohler et al 2013. Although considerable amounts of salmon-derived nutrients imported into coastal watersheds are retained, large proportions are also exported downstream to estuaries (Gende et al 2004, Mitchell and Lamberti 2005, Cak et al 2008. The influence of salmon nutrients in estuaries has received some mention (Reimchen 1994, Wipfli et al 1998, Cederholm et al 1999, Lessard and Merritt 2006, Field and Reynolds 2013, but research on the topic is limited (Fujiwara and Highsmith 1997, Jauquet et al 2003, Cak et al 2008.…”

Section: Introductionmentioning

confidence: 99%

“…Although considerable amounts of salmon-derived nutrients imported into coastal watersheds are retained, large proportions are also exported downstream to estuaries (Gende et al 2004, Mitchell and Lamberti 2005, Cak et al 2008. The influence of salmon nutrients in estuaries has received some mention (Reimchen 1994, Wipfli et al 1998, Cederholm et al 1999, Lessard and Merritt 2006, Field and Reynolds 2013, but research on the topic is limited (Fujiwara and Highsmith 1997, Jauquet et al 2003, Cak et al 2008. However, the potential for estuaries to be affected by salmon nutrient subsidies is considerable.…”

Section: Introductionmentioning

confidence: 99%

From earth and ocean: investigating the importance of cross‐ecosystem resource linkages to a mobile estuarine consumer

Harding

Reynolds

2014

Ecosphere

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Abstract. Externally derived resources often contribute to the structuring of ecological communities.Estuaries are one of the most productive ecosystems in the world and provide an ideal system to test how communities may be shaped by resource subsidies because they occur at the intersection of marine, freshwater and terrestrial habitats. Here we tested the effects of both terrestrial-and salmon-derived subsidies, in addition to other factors such as habitat area, on the diet (inferred from stable isotopes), abundance and size of a mobile estuarine consumer, the Dungeness crab (Metacarcinus magister). Crab trap surveys encompassed 19 watersheds over two seasons in the central coast of British Columbia, Canada, which spanned natural gradients in estuary size, watershed size, riparian tree composition, and Pacific salmon spawning density. Stable isotope ratios of crab tissue confirmed the predictions that estuarine nutrient regimes can be strongly affected by upstream watershed size, salmon density, and the dominance of nitrogen-fixing red alder (Alnus rubra). There were more crabs in larger estuaries and the largest crabs were found in estuaries below the largest watersheds. The proportional contributions of terrestrial-and salmon-derived subsidies to the diet of Dungeness crabs increased with watershed size and salmon density, respectively. These results confirmed that resource subsidies can constitute large proportions of the Dungeness crab's diet, that crab abundance is determined by habitat size, but that crab size is affected by the magnitude of terrestrial resource influx.

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“…Enclosures were considered to be adequately independent to merit an ANOVA approach, although we acknowledge that some temporal dependence may exist (Cak et al 2008). The minimum adequate model for each parameter was determined by comparing the Fratio of a full and reduced ANOVA model (Whittingham et al 2006).…”

Section: Methodsmentioning

confidence: 99%

Ecosystem response to a salmon disturbance regime: Implications for downstream nutrient fluxes in aquatic systems

Albers

Petticrew

2011

Limnology & Oceanography

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Recent work in salmon spawning streams has shown that sediment resuspended during nest construction flocculates with salmon organic matter to form suspended composite particles characterized by increased size and settling velocities. In a river system, these flocs have the potential to interact with benthic biofilms, suggesting a mechanism for the incorporation of organic matter into aquatic food webs. Using the Horsefly River spawning channel in central British Columbia, the spatial scale of biofilm floc trapping was evaluated for a salmon disturbance regime, which consists of the active digging of redds, spawning, and carcass decay. We stocked two sequential enclosures in the spawning channel with sockeye salmon (Oncorhynchus nerka) and established one upstream control enclosure. Biofilms were sampled for chlorophyll a, trapped sediment, and marine isotope tracers (d 15 N and d 13 C). In the active-spawn period, biofilm abundance was reduced due to spawning disturbance, with isotope values indicating low utilization of marine-derived nutrients (MDNs). During the post-spawn period, downstream biofilm abundance exceeded pre-spawn values, indicating a near-field nutrient pulse with isotope values reflecting biofilm utilization of MDNs. At the same time, an increase in biofilm trapping efficiency occurred in concert with a significant increase in the in situ particle size of suspended sediment, suggesting that flocs were a temporary storage site of MDNs. The retention of MDNs over short spatial scales acts to retard the flushing of MDNs to downstream rearing lakes. The magnitude of these processes has ecological implications on the downstream lake's productivity, thereby influencing the success of future salmon stocks.

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Effects of spawning salmon on dissolved nutrients and epilithon in coupled stream-estuary systems of southeastern Alaska

Cited by 27 publications

References 48 publications

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

Nutrient additions to mitigate for loss of Pacific salmon: consequences for stream biofilm and nutrient dynamics

From earth and ocean: investigating the importance of cross‐ecosystem resource linkages to a mobile estuarine consumer

Ecosystem response to a salmon disturbance regime: Implications for downstream nutrient fluxes in aquatic systems

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