scholarly journals Heterogeneity of riparian habitats mediates responses of terrestrial arthropods to a subsidy of Pacific salmon carcasses

Ecosphere ◽  
2014 ◽  
Vol 5 (11) ◽  
pp. art146 ◽  
Author(s):  
S. F. Collins ◽  
C. V. Baxter

<em>Abstract.</em>—Based on the information presented at the Restoring Nutrients to Salmonid Ecosystems conference in Eugene, Oregon, in April of 2001, it will be necessary to substantially increase and achieve salmon spawner escapement goals in order to meet ecosystem productivity potential. Modeling of recovery rates shows that achievement of even the currently identified spawner escapement goals (much less ecosystem recovery) in less than 50–100 years is unlikely, unless there are substantial shifts in management thought and practice. To speed recovery, it is necessary to achieve consistent rates of increase in spawning escapement not seen in current management activities. Until actual spawner escapements approach levels necessary to support ecosystem function, it will be necessary to utilize alternative methods such as the distribution of salmon carcasses, carcass analogs, or the use of fertilizer to provide the nutrients needed to assist its salmonid population recovery. In addition to restoring absolute numbers, the size and age structures of the fish populations need to be restored in order to successfully utilize the available environment. Simply increasing escapements and resultant nutrient levels, however, is insufficient. Stream flows, whether average, flood, or low, need to be stabilized. Instream and riparian habitats need to be stabilized and restored; this would include allowing normal flood paths to be followed.


2009 ◽  
Vol 24 (5) ◽  
pp. 1091-1100 ◽  
Author(s):  
Morgan D. Hocking ◽  
Richard A. Ring ◽  
Thomas E. Reimchen

Fisheries ◽  
1999 ◽  
Vol 24 (10) ◽  
pp. 6-15 ◽  
Author(s):  
C. Jeff Cederholm ◽  
Matt D. Kunze ◽  
Takeshi Murota ◽  
Atuhiro Sibatani

1997 ◽  
Vol 75 (5) ◽  
pp. 803-811 ◽  
Author(s):  
M. Ben-David ◽  
T. A. Hanley ◽  
D. R. Klein ◽  
D. M. Schell

Feeding niches of riverine and coastal mink (Mustela vison) in southeast Alaska differ in prey composition and abundance and diving medium during spring and summer. In autumn, however, the upstream migration of spawning Pacific salmon (Oncorhynchus sp.) creates a pulse of food for mink. We hypothesized that diets of coastal and riverine mink, and therefore their stable isotope ratios (δ13C, δ15N), would differ significantly during periods when salmon were absent, but that salmon carcasses would constitute a large portion of the diet of both groups during the salmon spawning season. Stable isotope analyses of clotted blood cells from 24 live-captured mink and muscle tissue from 25 mink carcasses were used to indicate the composition of diets of individual mink in 1992 and 1993. These isotope values were then compared with stable isotope ratios of prey, using a multiple-source mixing model. Our results indicate that riverine mink depended on salmon (carcasses and fry), with little seasonal or individual variation, whereas coastal mink relied on intertidal organisms in spring and summer, with measurable (<25%) consumption of salmon carcasses when they became available in autumn. Coastal and riverine mink in southeast Alaska differ strongly in their diets in spring and summer, with both groups relying on the abundant salmon carcasses during autumn.


2009 ◽  
Vol 87 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Thomas P. Quinn ◽  
Stephanie M. Carlson ◽  
Scott M. Gende ◽  
Harry B. Rich, Jr.

Predation on Pacific salmon by bears (genus Ursus L., 1758) can be an important ecosystem process because the spatial distribution of carcasses largely determines whether marine-derived nutrients cycle through aquatic or terrestrial pathways. Direct observations on three streams in southeastern Alaska indicated that 49% of the pink ( Oncorhynchus gorbuscha (Walbaum, 1792)) and chum ( Oncorhynchus keta (Walbaum in Artedi, 1792)) salmon killed by bears were carried into the forest. The tendency of bears to transport carcasses was independent of the sex and species of salmon, but unspawned fish were more often transported than fish that had completed spawning. Data on tagged sockeye salmon ( Oncorhynchus nerka (Walbaum in Artedi, 1792)) in one southwestern Alaska stream indicated that 42.6% of the killed salmon were transported, and that higher percentages were transported in years when salmon densities were greater. At six other streams, on average, 68.1% of the sockeye salmon killed were apparently transported away from the stream into the forest. Combining the data from all sites, the proportion of carcasses transported increased with water depth at the site. These results emphasize the role that bears play in mediating the interactions between nutrients from salmon and the terrestrial and aquatic ecosystems, and the variation in carcass distribution among streams and among years.


2012 ◽  
Vol 42 (5) ◽  
pp. 908-917 ◽  
Author(s):  
Morgan D. Hocking ◽  
John D. Reynolds

Bears ( Ursus spp.) and other predators can capture and transport large numbers of Pacific salmon ( Oncorhynchus spp.) to riparian areas beside small coastal streams, a process that may affect site productivity and local plant communities. We used a novel experimental manipulation of salmon carcasses to analyze understory plant uptake of salmon-derived N. A hierarchical before–after, control–impact design was used with the addition of chum salmon ( Oncorhynchus keta (Walbaum in Artedi, 1792)) carcasses to forest sites along 11 streams on the central coast of British Columbia, Canada. Eight months after carcass placement, the foliar %N and δ15N in three herbaceous and one moss species had increased by an average of 14%–60% (%N) and 0.5–3.3‰ (δ15N) at treatment carcass sites versus control sites. Treatment effects for %N were typically greater than for δ15N. Nitrogen isotope signatures at carcass sites were highly variable (δ15N range = 30.1‰) and were mediated by plant species, stream salmon density, carcass mass, and individual plant foliar %N. These results show that understory plants use N from salmon during an important period of plant growth many months after carcasses were deposited in riparian areas. However, they also indicate that habitat variation across spatial scales from individual plants to streams needs to be considered when estimating the contribution of salmon to plant nutrition.


2006 ◽  
Vol 63 (9) ◽  
pp. 2076-2086 ◽  
Author(s):  
Morgan D Hocking ◽  
Thomas E Reimchen

Anadromous Pacific salmon (Oncorhynchus spp.) subsidize terrestrial food webs with their nutrients and carcasses, a process driven largely by selective foraging by bears (Ursus spp.). We quantify wildlife transfer of salmon carcasses to riparian zones on two watersheds in coastal British Columbia and estimate total terrestrial fly production from remnant carcasses. Large-bodied chum salmon (Oncorhynchus keta) were transferred into the forest at a greater rate than were pink salmon (Oncorhynchus gorbuscha) (chum salmon mass = 6089–11 031 kg, 16%–48% of salmon run; pink salmon mass = 2266–2808 kg, 4%–6% of salmon run). Blow flies (genus Calliphora) and other Diptera dominated colonization (>90% of salmon carcasses). Between the two watersheds, 196 and 265 g of Calliphora larvae per metre of spawning length (4 and 7 million larvae for whole watersheds) were generated from salmon carcass transfer. Stable isotope analysis of δ15N and δ13C of spring-emerging adult Calliphora revealed that >80% of individuals had salmon-based signatures. Flies are a dominant consumer and vector of salmon nutrients in terrestrial habitats and supplement the diet of at least 16 vertebrate and 22 invertebrate species. Anticipated further declines of salmon in the North Pacific can be expected to further erode the complex associations coupling marine and terrestrial ecosystems.


2020 ◽  
Vol 77 (10) ◽  
pp. 1601-1611 ◽  
Author(s):  
Joseph R. Benjamin ◽  
J. Ryan Bellmore ◽  
Emily Whitney ◽  
Jason B. Dunham

Multiple restoration actions have been implemented in response to declining salmon populations. Among these is the addition of salmon carcasses or artificial nutrients to mimic marine-derived nutrients historically provided by large spawning runs of salmon. A key assumption in this approach is that increased nutrients will catalyze salmon population growth. Although effects on aquatic ecosystems have been observed during treatments, it is unclear whether permanent population increases for salmon will occur. To test this assumption and address associated uncertainties, we linked a food web model with a salmon life cycle model to examine whether carcass additions in a river reach would improve conditions for salmon in the long term. Model results confirmed immediate increases in the biomass of periphyton, macroinvertebrates, and fish during carcass additions. In turn, juvenile salmon grew larger and experienced improved freshwater and smolt survival, which translated to a greater number of adults returning to spawn. However, once additions ceased, salmon abundance returned to pretreatment levels, which, based on our model, is owing to a combination of instream and out-of-basin factors. Overall, results of this work suggest that benefits during carcass and nutrient additions may not translate into persistent productivity of salmon unless additions are sustained indefinitely or other limiting factors are addressed.


2002 ◽  
Vol 47 (2) ◽  
pp. 263-273 ◽  
Author(s):  
Dominic T. Chaloner ◽  
Mark S. Wipfli ◽  
John P. Caouette

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