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Interspecific competition and predation: relative effects on foragers and their densities

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Author

Summary, in English

Predation and competition are both strong structuring forces in community dynamics, but their relative importance is disputed. In a laboratory experiment, we evaluated the relative importance of competition and predation from juvenile and adult brown trout, respectively, on foraging performance of groups of three stone loaches. We observed loach consumption rate, time spent inactive, and aggressive interactions between juvenile trout and loach in artificial stream sections. The controlled experiments were complemented by examining stone loach population densities in natural systems as functions of juvenile and adult trout. In the laboratory experiments, increasing numbers of competitors decreased prey availability, which ultimately led to lower consumption rates for loach. Loach responded to predation risk by increasing time being inactive, thereby decreasing consumption rates. However, there were no effects of juvenile trout competitors on loach consumption rates in treatments with adult trout presence, suggesting no additive effect of predation and competition on loach foraging success. Partial regressions of loach and trout densities in natural streams revealed a positive relationship between juvenile trout and loach, and a negative relationship between adult trout and loach. Our laboratory and field data thus suggest that predation is a limiting factor for loach success, and predator presence could mediate species coexistence at high interspecific densities.

Publishing year

2010

Language

English

Pages

729-736

Publication/Series

Behavioral Ecology and Sociobiology

Volume

64

Issue

5

Document type

Journal article

Publisher

Springer

Topic

  • Ecology

Keywords

  • Salmo trutta
  • barbatula
  • Barbatula
  • Fish
  • Predation
  • Foraging
  • Interspecific competition

Status

Published

Research group

  • Aquatic Ecology

ISBN/ISSN/Other

  • ISSN: 1432-0762