Niche differentiation among invasive crayfish and their impacts on ecosystem structure and functioning

dc.contributor.authorJackson, Michelle C.
dc.contributor.authorJones, Tabitha
dc.contributor.authorMilligan, Maaike
dc.contributor.authorSheath, Danny
dc.contributor.authorTaylor, Jeff
dc.contributor.authorEllis, Adam
dc.contributor.authorEngland, Judy
dc.contributor.authorGrey, Jonathan
dc.contributor.emailmjackson@zoology.up.ac.zaen_US
dc.date.accessioned2014-10-01T05:58:01Z
dc.date.issued2014-06
dc.description.abstract1. Many aquatic ecosystems sustain multiple invasive species and interactions among them have important implications for ecosystem structure and functioning. Here, we examine interactions among two pairs of invasive crayfish species because of their close proximity and thus chance of sympatric populations in the near future within the Thames catchment, U.K. (signal, Pacifastacus leniusculus and virile crayfish, Orconectes virilis within a river system; red swamp, Procambarus clarkii and Turkish crayfish, Astacus leptodactylus found within a suite of ponds). We address two questions: do sympatric invasive crayfish occupy a smaller niche than their allopatric counterparts due to potential resource competition? and do interactions among invasive species amplify or mitigate one another’s impacts on the ecosystem? 2. Two fully factorial mesocosm experiments (one for each crayfish pair) were used to investigate crayfish diet and their impact on benthic invertebrate community structure, benthic algal standing stock and leaf litter decomposition rates in allopatric and sympatric populations, compared with a crayfish-free control. We used stable isotope analysis to examine crayfish diet in the mesocosms and in allopatric populations of each species in the Thames catchment. 3. Isotopic niche width did not vary significantly between allopatric and sympatric populations of crayfish in the mesocosm experiments, and isotopic niche partitioning in all the wild populations suggests the invaders can coexist. 4. All four species altered benthic invertebrate community structure but with differing functional effects, often mediated via trophic cascades. Red swamp crayfish predation upon snails evidently promoted benthic algal standing stock via reduction in grazing pressure. However, a trophic cascade whereby the crayfish consumed native invertebrate shredders, causing a reduction in net leaf litter decomposition, was decoupled by red swamp and signal crayfish since they consumed leaf litter directly and thus moderated the cascade to a trickle when in sympatry with Turkish or virile crayfish, respectively. 5. Benthic invertebrate predator abundance was significantly reduced by sympatric red swamp and Turkish crayfish but not independently when in allopatry, indicating an amplified effect overall when in sympatry. 6. Our results suggest that the combined effect of multiple invasions on the ecosystem can reflect either an additive effect of their independent impacts or an amplified effect, which is greater than the sum of their independent impacts. A lack of general pattern in their effects makes any potential management strategy more complex.en_US
dc.description.embargo2015-06-30
dc.description.librarianhb2014en_US
dc.description.sponsorshipEnvironment Agencyen_US
dc.description.urihttp://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2427en_US
dc.identifier.citationJackson, MC, Jones, T, Milligan, M, Sheath, D, Taylor, J, Ellis, A, England, J & Grey, J 2014, 'Niche differentiation among invasive crayfish and their impacts on ecosystem structure and functioning', Freshwater Biology, vol. 59, no. 6, pp. 1123-1135.en_US
dc.identifier.issn0046-5070 (print)
dc.identifier.issn1365-2427 (online)
dc.identifier.other10.1111/fwb.12333
dc.identifier.urihttp://hdl.handle.net/2263/42168
dc.language.isoenen_US
dc.publisherWileyen_US
dc.rights© 2014 John Wiley and Sons Ltd. This is the pre-peer reviewed version of the following article : Niche differentiation among invasive crayfish and their impacts on ecosystem structure and functioning in Freshwater Biology, vol. 59, no.6, pp.1123-1135, 2014. doi : 10.1111/fwb.12333 which has been published in final form at : http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2427.en_US
dc.subjectCrayfishen_US
dc.subjectEcosystem functioningen_US
dc.subjectInvasive speciesen_US
dc.subjectStable isotopesen_US
dc.subjectTrophic cascadesen_US
dc.titleNiche differentiation among invasive crayfish and their impacts on ecosystem structure and functioningen_US
dc.typePostprint Articleen_US

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