Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels
1. Predators can impact competition among prey by altering prey density via consumption or by causing prey to modify their traits or foraging behavior. Yet, differences between these two mechanisms may lead to different cascading impacts on lower trophic levels. 2. Using a crab-snail-barnacle rocky...
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ftdryad:oai:v1.datadryad.org:10255/dryad.178504 2023-05-15T17:45:47+02:00 Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels Matassa, Catherine M. Ewanchuk, Patrick J. Trussell, Geoffrey C. Northwest Atlantic 2018-05-14T19:55:27Z http://hdl.handle.net/10255/dryad.178504 https://doi.org/10.5061/dryad.gf13b2m unknown doi:10.5061/dryad.gf13b2m/1 doi:10.1111/1365-2435.13131 doi:10.5061/dryad.gf13b2m Matassa CM, Ewanchuk PJ, Trussell GC (2018) Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels. Functional Ecology 32(9): 2241-2252. http://hdl.handle.net/10255/dryad.178504 hummock nonconsumptive effect rocky intertidal trait-mediated indirect interaction predation risk Article 2018 ftdryad https://doi.org/10.5061/dryad.gf13b2m https://doi.org/10.5061/dryad.gf13b2m/1 https://doi.org/10.1111/1365-2435.13131 2020-01-01T16:08:29Z 1. Predators can impact competition among prey by altering prey density via consumption or by causing prey to modify their traits or foraging behavior. Yet, differences between these two mechanisms may lead to different cascading impacts on lower trophic levels. 2. Using a crab-snail-barnacle rocky intertidal food chain, we tested the effects of predation risk from crabs (top predators) on intraspecific competition among snails (intermediate consumers) and emergent indirect effects on the density of and competition between barnacles (basal resources). 3. The per capita foraging and growth rates of snails declined with high conspecific density. Predation risk from crabs, which caused even larger reductions in snail foraging and growth, weakened competition among snails, whereas a 45% increase in barnacle density had no detectable effect on snail competition. 4. Intraspecific competition between barnacles, however, depended on the interactive effects of barnacle density, snail density, and crab predation risk. Barnacles developed hummocking morphologies as they grew and competed for space. Hummock formation (a proxy for competition) increased as a result of either greater initial barnacle density or reduced snail foraging pressure, but these effects depended on predation risk. 5. The effects of crab predation risk on snail foraging behavior weakened an otherwise strong relationship between barnacle density and hummock development: hummocking increased with barnacle density in the absence of crabs but remained relatively high when crabs were present. In communities with similar final barnacle densities, hummocking was more common in those with crabs than those without crabs. 6. The extent to which predators can drive trophic cascades by suppressing the foraging rates of their prey is highly context-dependent: the positive trait-mediated indirect effect of predators on basal resource abundance is stronger when many prey respond simultaneously to the threat of predation. However, our results demonstrate that top predators can also enhance competition among basal resources even when their indirect effect on resource abundance is relatively weak. Hence, the cascading effects of predators on competition within lower trophic levels may play an important but underappreciated role in the dynamics of basal resource populations and the communities they support. Article in Journal/Newspaper Northwest Atlantic Dryad Digital Repository (Duke University) |
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Open Polar |
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Dryad Digital Repository (Duke University) |
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ftdryad |
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unknown |
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hummock nonconsumptive effect rocky intertidal trait-mediated indirect interaction predation risk |
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hummock nonconsumptive effect rocky intertidal trait-mediated indirect interaction predation risk Matassa, Catherine M. Ewanchuk, Patrick J. Trussell, Geoffrey C. Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
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hummock nonconsumptive effect rocky intertidal trait-mediated indirect interaction predation risk |
description |
1. Predators can impact competition among prey by altering prey density via consumption or by causing prey to modify their traits or foraging behavior. Yet, differences between these two mechanisms may lead to different cascading impacts on lower trophic levels. 2. Using a crab-snail-barnacle rocky intertidal food chain, we tested the effects of predation risk from crabs (top predators) on intraspecific competition among snails (intermediate consumers) and emergent indirect effects on the density of and competition between barnacles (basal resources). 3. The per capita foraging and growth rates of snails declined with high conspecific density. Predation risk from crabs, which caused even larger reductions in snail foraging and growth, weakened competition among snails, whereas a 45% increase in barnacle density had no detectable effect on snail competition. 4. Intraspecific competition between barnacles, however, depended on the interactive effects of barnacle density, snail density, and crab predation risk. Barnacles developed hummocking morphologies as they grew and competed for space. Hummock formation (a proxy for competition) increased as a result of either greater initial barnacle density or reduced snail foraging pressure, but these effects depended on predation risk. 5. The effects of crab predation risk on snail foraging behavior weakened an otherwise strong relationship between barnacle density and hummock development: hummocking increased with barnacle density in the absence of crabs but remained relatively high when crabs were present. In communities with similar final barnacle densities, hummocking was more common in those with crabs than those without crabs. 6. The extent to which predators can drive trophic cascades by suppressing the foraging rates of their prey is highly context-dependent: the positive trait-mediated indirect effect of predators on basal resource abundance is stronger when many prey respond simultaneously to the threat of predation. However, our results demonstrate that top predators can also enhance competition among basal resources even when their indirect effect on resource abundance is relatively weak. Hence, the cascading effects of predators on competition within lower trophic levels may play an important but underappreciated role in the dynamics of basal resource populations and the communities they support. |
format |
Article in Journal/Newspaper |
author |
Matassa, Catherine M. Ewanchuk, Patrick J. Trussell, Geoffrey C. |
author_facet |
Matassa, Catherine M. Ewanchuk, Patrick J. Trussell, Geoffrey C. |
author_sort |
Matassa, Catherine M. |
title |
Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
title_short |
Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
title_full |
Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
title_fullStr |
Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
title_full_unstemmed |
Data from: Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
title_sort |
data from: cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels |
publishDate |
2018 |
url |
http://hdl.handle.net/10255/dryad.178504 https://doi.org/10.5061/dryad.gf13b2m |
op_coverage |
Northwest Atlantic |
genre |
Northwest Atlantic |
genre_facet |
Northwest Atlantic |
op_relation |
doi:10.5061/dryad.gf13b2m/1 doi:10.1111/1365-2435.13131 doi:10.5061/dryad.gf13b2m Matassa CM, Ewanchuk PJ, Trussell GC (2018) Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels. Functional Ecology 32(9): 2241-2252. http://hdl.handle.net/10255/dryad.178504 |
op_doi |
https://doi.org/10.5061/dryad.gf13b2m https://doi.org/10.5061/dryad.gf13b2m/1 https://doi.org/10.1111/1365-2435.13131 |
_version_ |
1766149052048605184 |