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Determining the strength of exploitative competition from an introduced fish: roles of density, biomass and body size

Authors


Dr J. Robert Britton, Centre for Conservation Ecology & Environmental Change, Bournemouth University, Poole, Dorset BH12 5BB, UK; e-mail: rbritton@bournemouth.ac.uk

Abstract

Britton JR, Cucherousset J, Grey J, Gozlan RE. Determining the strength of exploitative competition from an introduced fish: roles of density, biomass and body size. Ecology of Freshwater Fish 2011: 20: 74–79. © 2010 John Wiley & Sons A/S

Abstract –  As species introductions can result in increased resource competition for coexisting species in the receiving ecosystems, the effects of increased exploitative competition for limited food resources from an introduced fish (Pseudorasbora parva) on a coexisting fish (Cyprinus carpio) were tested experimentally using a substitutive–additive design. Additive treatments revealed that the growth of Ccarpio was significantly suppressed following the introduction of Pparva with the magnitude of growth suppression directly proportional to P. parva density and biomass. A substitutive treatment that tested for the effect of intraspecific competition revealed that when Ccarpio were introduced at a similar biomass to Pparva, there was no significant difference in the extent of the suppressed growth. At the same density, however, the effect of Ccarpio (higher biomass) on growth was significantly above that of Pparva (lower biomass). This was independent of the initial body sizes of the introduced fishes. Thus, the interspecific competition imposed by P. parva was only as strong as the intraspecific competition of C. carpio when present at a similar biomass.

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