Seasonal variation exceeds effects of salmon carcass additions on benthic food webs in the Elwha River

Morley, Sarah A.; Coe, Holly J.; Duda, Jeffrey J.; Dunphy, L. S.; McHenry, Michael L.; Beckman, Brian R.; Elofson, Mel; Sampson, Earnest M.; Ward, Larry G.

doi:10.1002/ecs2.1422

Cited by 13 publications

(13 citation statements)

References 64 publications

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“…In a carcass addition experiment, Morley et al. (2016) seeded a 100‐m portion of an Elwha side channel for a food web study with 0.75 kg/m 2 of salmon carcasses that were completely removed within 1 week by animal scavengers. Other cases could occur when mammalian scavengers like racoon or bears feed on salmon carcasses.…”

Section: Discussionmentioning

confidence: 99%

Environmental DNA is an effective tool to track recolonizing migratory fish following large‐scale dam removal

et al. 2020

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Environmental DNA (eDNA) has emerged as a potentially powerful tool for use in conservation and resource management, including for tracking the recolonization dynamics of fish populations. We used eDNA to assess the effectiveness of dam removal to restore fish passage on the Elwha River in Washington State (USA). Using a suite of 11 species‐specific eDNA polymerase chain reaction (PCR) assays, we showed that most targeted anadromous species (five Pacific Salmon species and Pacific Lamprey) were able to pass upstream of both former dam sites. Multiscale occupancy modeling showed that the timing and spatial extent of recolonization differed among species during the four years of post‐dam removal monitoring. More abundant species like Chinook Salmon and Coho Salmon migrated farther into the upper portions of the watershed than less abundant species like Pink Salmon and Chum Salmon. Sampling also allowed assessment of potamodromous fish species. Bull Trout and Rainbow Trout, ubiquitous species in the watershed, were detected at all sampling locations. Environmental DNA from Brook Trout, a non‐native species isolated between the dams prior to dam removal, was detected downstream of Elwha dam but rarely upstream of the Glines Canyon Dam suggested that the species has not expanded its range appreciably in the watershed following dam removal. We found that eDNA was an effective tool to assess the response of fish populations to large‐scale dam removal on the Elwha River.

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Section: Discussionmentioning

confidence: 99%

Environmental DNA is an effective tool to track recolonizing migratory fish following large‐scale dam removal

et al. 2020

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“…In turn, enhanced productivity may increase the rate of colonization and success of colonizers. This feedback may be particularly important when upstream habitats are recolonized by keystone species that strongly affect aquatic or riparian communities and food webs, such as anadromous salmonids (Gende et al 2002, Morley et al 2016) and amphidromous fishes and shrimp in tropical rivers (Pringle et al 1999). Second, increased life-history diversity promotes species persistence and colonization.…”

Section: Upstream Of the Former Reservoir: Going Against The Flowmentioning

confidence: 99%

Conceptualizing Ecological Responses to Dam Removal: If You Remove It, What's to Come?

et al. 2019

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One of the desired outcomes of dam decommissioning and removal is the recovery of aquatic and riparian ecosystems. To investigate this common objective, we synthesized information from empirical studies and ecological theory into conceptual models that depict key physical and biological links driving ecological responses to removing dams. We define models for three distinct spatial domains: upstream of the former reservoir, within the reservoir, and downstream of the removed dam. Emerging from these models are response trajectories that clarify potential pathways of ecological transitions in each domain. We illustrate that the responses are controlled by multiple causal pathways and feedback loops among physical and biological components of the ecosystem, creating recovery trajectories that are dynamic and nonlinear. In most cases, short-term effects are typically followed by longer-term responses that bring ecosystems to new and frequently predictable ecological condition, which may or may not be similar to what existed prior to impoundment.

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“…Taken together, these results suggest that stream fertilization or food augmentation will only be an efficient mechanism for increasing the density of stream salmonid populations in nutrient‐poor streams, where space is not limiting (e.g. Collins et al., ; Hyatt & Stockner, ; Morley et al., ; Stockner, Rydin, & Hyenstrand, ).…”

Section: Discussionmentioning

confidence: 91%

“…These results have important implications for salmonid restoration projects, which often attempt to increase juvenile recruitment by increasing the productivity of freshwater ecosystems (Johnston, Perrin, Slaney, & Ward, ; Mason, ). While the fertilization of freshwater ecosystems has dramatic effects on the growth and survival of individual fish, the effects on population density remain equivocal (Collins, Baxter, Marcarelli, & Wipfli, ; Deegan & Peterson, ; Grant, Steingrímsson, Keeley, & Cunjak, ; Johnston et al., ; Morley et al., ). An informal analysis based on a small sample size suggested that territory size was relatively insensitive to changes in food abundance (Grant et al., ).…”

Section: Introductionmentioning

confidence: 99%

Territory size decreases minimally with increasing food abundance in stream salmonids: Implications for population regulation

Grant

Weir

Steingrímsson

2017

Journal of Animal Ecology

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How the local density of territorial animals responds to changes in food abundance will depend on the flexibility of territory size. Quantitative estimates of territory size over a broad range of food abundance are relatively rare because of the difficulty of measuring food abundance in the wild. Stream salmonids are an ideal model system for investigating flexibility in territory size, because food abundance can be quantified in the field and manipulated in the laboratory. We conducted a meta-analysis to test whether territory size decreases with increasing food abundance, and a mixed model analysis to test among three competing predictions: with increasing food abundance, territory size will be (1) fixed-the slope of a regression of log territory size vs. log food abundance = 0; (2) flexible and decreasing, as if individuals are defending a fixed amount of food-a slope = -1; and (3) initially compressible, but with an asymptotic minimum size-a slope between 0 and -1. We collected data from 16 studies that manipulated or measured food abundance while monitoring changes in territory size of young-of-the-year salmonids; 10 were experimental laboratory studies, whereas six were observational field studies. Overall, territory size decreased significantly with increasing food abundance; the weighted average correlation coefficient was -0.31. However, the estimated slope of the relationship between log territory size and log food abundance was only -0.23, significantly different from 0, and also significantly shallower than -1. Our estimated slope suggests that attempts to increase the density of territorial salmonids by increasing food abundance and reducing territory size will be inefficient; a 20-fold increase in food abundance would be required to double population density. Our analysis may also have implications for other species with a territorial mosaic social system-i.e. contiguous territories. In these social systems, social inertia will dampen any effects of changes in food abundance on the local density of settlers, compared to non-territorial species or those with non-contiguous territories.

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Seasonal variation exceeds effects of salmon carcass additions on benthic food webs in the Elwha River

Cited by 13 publications

References 64 publications

Environmental DNA is an effective tool to track recolonizing migratory fish following large‐scale dam removal

Environmental DNA is an effective tool to track recolonizing migratory fish following large‐scale dam removal

Conceptualizing Ecological Responses to Dam Removal: If You Remove It, What's to Come?

Territory size decreases minimally with increasing food abundance in stream salmonids: Implications for population regulation

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