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dc.contributor.authorShelton, J.M.
dc.contributor.authorSamways, M.J.
dc.contributor.authorDay, J.A.
dc.contributor.authorWoodford, D.J.
dc.date.accessioned2016-11-02T08:01:38Z
dc.date.available2016-11-02T08:01:38Z
dc.date.issued2016
dc.identifier.citationShelton, J.M.; Samways, M.J.; Day, J.A.; Woodford, D.J. (2016) Are native cyprinids of introduced salmonids stronger regulators of benthic invertebrates in South African headwater streams? Austral Ecology, 41(6): 633-643en
dc.identifier.issn1442-9993en
dc.identifier.urihttp://hdl.handle.net/123456789/2109
dc.description.abstractThe introduction of nonnative salmonids in the Southern Hemisphere generally leads to a reduction in invertebrate abundance and changes in assemblage composition. In the Cape Floristic Region of South Africa, introduced rainbow trout Oncorhynchus mykiss is the dominant predator in many headwater streams, where they have replaced small-bodied native fishes such as Breede River redfin Pseudobarbus burchelli. To examine the consequences of this species replacement on food web structure, we used a month-long field experiment to compare the top-down effects of Breede River redfin and rainbow trout on benthic invertebrate assemblages (abundance and composition) and basal resources (periphyton and particulate organic matter) in 1×1.5m of plastic cages. Benthic invertebrate abundance was more strongly depleted in the cages with redfin than in the cages with trout, and redfin and trout had distinct effects on invertebrate assemblage composition. On the other hand, neither redfin nor trout had a significant influence over standing stocks of periphyton or organic matter, implying that their differential effects on benthic invertebrates did not cascade down to the base of the stream food web in our experiment. Gut content analysis showed that aquatic invertebrates contributed more to the diet of redfin, while terrestrial invertebrates contributed more to the diet of trout, which may be responsible for the relatively weak effect of trout on aquatic invertebrates. This pattern contrasts with nonnative salmonid impacts elsewhere in the Southern Hemisphere. That trout can strongly alter the structure of benthic invertebrate assemblages, in addition to severely depleting native fish abundance, in Cape Floristic Region headwater streams should be weighed into management decisions, and our findings highlight the need for a detailed understanding of species-specific top-down effects where native predators are replaced by invasive predators.en
dc.format.extent1350804 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherEcological Society of Australiaen
dc.subjectfield experimenten
dc.subjectinvertebrate assemblageen
dc.subjectperiphytonen
dc.subjectspecies replacementen
dc.subjectterrestrial subsidyen
dc.titleAre native cyprinids of introduced salmonids stronger regulators of benthic invertebrates in South African headwater streams?en
dc.typeJournalArticlesen
dc.cibjournalAustral Ecologyen
dc.cibprojectNAen


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