Salmon egg subsidies and interference competition among stream fishes

Bailey, Colin J.; Andersson, Luke C.; Arbeider, Michael; Bradford, Kent J.; Moore, Jonathan W.

doi:10.1007/s10641-019-00880-9

Cited by 5 publications

(8 citation statements)

References 45 publications

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“…1). Juvenile salmonids are food limited in the wild, but aggression during territorial defense typically declines with increasing food availability (Slaney and Northcote 1974;Toobaie and Grant 2013;Bailey et al 2019). In addition, intraspecific resource competition occurs not just via interference but also exploitative mechanisms, notably, via shadow competition whereby fish defending upstream territories, simply by virtue of their position, have priority access to drifting prey and deplete the resources available to those farther downstream (Hughes 1992;Elliott 2002;Einum et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Metabolic Rate Interacts with Resource Availability to Determine Individual Variation in Microhabitat Use in the Wild

Auer

Bassar

Turek

et al. 2020

The American Naturalist

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Ecological pressures such as competition can lead individuals within a population to partition resources or habitats, but the underlying intrinsic mechanisms that determine an individual's resource use are not well understood. Here we show that an individual's own energy demand and associated competitive ability influence its resource use, but only when food is more limiting. We tested whether intraspecific variation in metabolic rate leads to microhabitat partitioning among juvenile Atlantic salmon (Salmo salar) in natural streams subjected to manipulated nutrient levels and subsequent per capita food availability. We found that individual salmon from families with a higher baseline (standard) metabolic rate (which is associated with greater competitive ability) tended to occupy fasterflowing water, but only in streams with lower per capita food availability. Faster-flowing microhabitats yield more food, but high metabolic rate fish only benefited from faster growth in streams with high food levels, presumably because in low-food environments the cost of a high metabolism offsets the benefits of acquiring a productive microhabitat. The benefits of a given metabolic rate were thus context dependent. These results demonstrate that intraspecific variation in metabolic rate can interact with resource availability to determine the spatial structuring of wild populations.

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Section: Introductionmentioning

confidence: 99%

Metabolic Rate Interacts with Resource Availability to Determine Individual Variation in Microhabitat Use in the Wild

Auer

Bassar

Turek

et al. 2020

The American Naturalist

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show abstract

“…Stream fish communities are typically structured by species‐influenced dominance hierarchies (Glova 1986, David et al 2007, Naman et al 2019). Indeed, Bailey et al (2019) observed size‐ and species‐specific patterns of competitive interactions in video analysis from a subset of this study. Yet here we found that the community composition per se did not influence individual consumption rates.…”

Section: Discussionmentioning

confidence: 67%

“…Sculpins are benthic predators that can consume salmon eggs directly from salmon nests by moving through interstitial spaces in the substrate (Foote and Brown 1998). This mode of foraging likely reduces the rate of interactions between sculpins and salmonids, and is supported by Bailey et al (2019) who observed that sculpins rarely interacted with salmonids during egg experiments. Collectively, these findings showcase the functional relationships between the abundance of a pulsed resource (salmon eggs) and their consumption by a community of consumers (stream fishes).…”

Section: Discussionmentioning

confidence: 69%

“…At higher egg availabilities, hurdle model prediction slopes of total eggs consumed by large and small fish became approximately parallel (Fig 2), suggesting that fish at the tops of their respective dominance hierarchies were either satiated or unable to monopolize the salmon eggs. Underwater video analysis from a subset of this study found that increasing egg availability reduced the frequency of interference competition behaviors among stream fishes (Bailey et al 2019), suggesting that dominance hierarchies were indeed eroded by increasing egg availability. Overall, while stream fish communities are generally considered to be highly size‐structured competitive hierarchies (Nakano 1995, David et al 2007, Naman et al 2019), this paradigm may shift during resource pulses.…”

Section: Discussionmentioning

confidence: 83%

“…Salmon‐bearing streams are a classic example of ecosystems that can experience resource pulses (Schindler et al 2003, Moore et al 2008, Walsh et al 2020). Salmon spawn and die in streams annually, producing carcass tissues and eggs that are consumed by a variety of predators and scavengers (Naiman et al 2002, Deacy et al 2016) such as stream fishes (Lang et al 2006, Bailey et al 2019). Energy acquired during the brief salmon spawning period can dominate the annual energy budget for stream fish consumers (Scheuerell et al 2007, Moore et al 2008, Armstrong and Bond 2013); for example, through bioenergetic simulations, Moore et al (2008) predicted that resident rainbow trout ( Oncorhynchus mykiss ) in their study would run an energetic deficit during the summer without salmon subsidies.…”

Section: Introductionmentioning

confidence: 99%

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Resource pulses increase the diversity of successful competitors in a multi‐species stream fish assemblage

Bailey¹,

Moore²

2020

Ecosphere

Self Cite

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Food resources are often patchily distributed through space and time and are classified as resource pulses when hyperabundant. Resource pulses can benefit growth, reproduction, and abundance of various consumers. Yet, it is relatively unknown how such resources are partitioned among competing consumers and how this is influenced by the magnitude of the pulse. Here, we examined how the magnitude of a pulsed resource influences resource partitioning among diverse sizes and species of consumers in a natural setting over small spatial and temporal scales. We focused on salmon egg subsidies to stream fish consumers. We experimentally added different quantities of pink salmon eggs to five meter long experimental stream sections. Egg additions spanned three orders of magnitude from 6 to 3575 eggs. Stream fish (egg consumers) were captured and gastric lavaged at each experimental section to determine how many eggs each individual fish consumed. We modeled taxon‐specific individual egg consumption as a function of egg availability, individual mass, community composition, number of competitors, and stream velocity using hurdle models in a Bayesian framework. We found that there were diminishing returns for increasing egg abundance increasing egg consumption (i.e., type II functional response) for individual size classes of fish, but that higher egg numbers were needed to benefit diverse consumers. Top models indicated that egg availability and individual fish characteristics (size and taxon) drove egg consumption, while community characteristics (species composition and number of competitors) were not supported. Our results suggest that resource pulses can provide rare opportunities for less dominant sizes and species of fish to consume abundant resources. The current paradigm in the stream fish literature suggests that stream fish communities are structured by dominance hierarchies; however, dominance hierarchies may be less influential where pulsed resources comprise a large portion of the resource base.

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Flood-induced interspecific interactions in spring-fed tributary as an ecosystem function of heterogeneous river networks

2021

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Understanding the migratory community dynamics of river networks is important for maintaining lotic system integrity. River animals migrate to their preferred habitats in spatiotemporally heterogeneous river environments. Spring-fed habitats are uniquely characterized by stable temperature and flow regimes, which create suitable spawning habitats for the chum salmon Oncorhynchus keta. O. keta exhibits "run up" to its birthplace for spawning, especially during floods. Because the eggs deposited by this anadromous fish are nutritious and actively consumed by freshwater animals, the location and timing of O. keta spawning events affect the spatiotemporal accumulation of mobile consumers. In this study, we examined changes in temporal population density in spawning O. keta and a mobile consumer (juvenile O. masou masou) in a lowland, spring-fed tributary in northern Japan during a 48.5-mm autumn rainfall event.In both species, population density increased, and then decreased, after the rainfall event.In O. keta, these changes were closely associated with rainfall intensity, whereas in O. masou masou the peak was delayed until 3 days after the rainfall event. A comparison of the gut contents of O. masou masou sampled from a spring-fed tributary and an adjacent non-spring-fed tributary indicated greater consumption of O. keta eggs in the spring-fed tributary. These results suggested that preferential migration of O. keta into spring-fed tributaries for spawning induces subsequent accumulation of juvenile O. masou masou, in turn increasing O. keta egg consumption. These findings improve our understanding of community dynamics during floods in a heterogeneous river network environment.

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Salmon egg subsidies and interference competition among stream fishes

Cited by 5 publications

References 45 publications

Metabolic Rate Interacts with Resource Availability to Determine Individual Variation in Microhabitat Use in the Wild

Metabolic Rate Interacts with Resource Availability to Determine Individual Variation in Microhabitat Use in the Wild

Resource pulses increase the diversity of successful competitors in a multi‐species stream fish assemblage

Flood-induced interspecific interactions in spring-fed tributary as an ecosystem function of heterogeneous river networks

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