Trophic overlap between fish and riparian spiders : potential impacts of an invasive fish on terrestrial consumers

Show simple item record Jackson, Michelle C. Woodford, Darragh J. Bellingan, Terence A. Weyl, Olaf L.F. Potgieter, Michael J. Rivers-Moore, Nick A. Ellender, Bruce R. Fourie, Hermina E. Chimimba, Christian Timothy 2017-06-10T07:33:52Z 2017-06-10T07:33:52Z 2016
dc.description Table S1. Characteristics of the 12 sites during the month of sampling. en_ZA
dc.description Table S2. Invertebrate resource isotope values and results of ANOVA’s testing for differences between resources and sites. en_ZA
dc.description Table S3. Carbon and nitrogen stable isotope values of fish and spiders used in the study. en_ZA
dc.description.abstract Studies on resource sharing and partitioning generally consider species that occur in the same habitat. However, subsidies between linked habitats, such as streams and riparian zones, create potential for competition between populations which never directly interact. Evidence suggests that the abundance of riparian consumers declines after fish invasion and a subsequent increase in resource sharing of emerging insects. However, diet overlap has not been investigated. Here, we examine the trophic niche of native fish, invasive fish, and native spiders in South Africa using stable isotope analysis. We compared spider abundance and diet at upstream fishless and downstream fish sites and quantified niche overlap with invasive and native fish. Spider abundance was consistently higher at upstream fishless sites compared with paired downstream fish sites, suggesting that the fish reduced aquatic resource availability to riparian consumers. Spiders incorporated more aquatic than terrestrial insects in their diet, with aquatic insects accounting for 45–90% of spider mass. In three of four invaded trout rivers, we found that the average proportion of aquatic resources in web-building spider diet was higher at fishless sites compared to fish sites. The probability of web-building and ground spiders overlapping into the trophic niche of invasive brown and rainbow trout was as high as 26 and 51%, respectively. In contrast, the probability of spiders overlapping into the trophic niche of native fish was always less than 5%. Our results suggest that spiders share resources with invasive fish. In contrast, spiders had a low probability of trophic overlap with native fish indicating that the traits of invaders may be important in determining their influence on ecosystem subsidies. We have added to the growing body of evidence that invaders can have crossecosystem impacts and demonstrated that this can be due to niche overlap. en_ZA
dc.description.department Zoology and Entomology en_ZA
dc.description.librarian am2017 en_ZA
dc.description.sponsorship The DST-NRF Centre of Excellence in Invasion Biology en_ZA
dc.description.uri en_ZA
dc.identifier.citation Jackson, MC, Woodford, DJ, Bellingan, TA, Weyl, OLF, Potgieter, MJ, Rivers-Moore, NA, Ellender, BR, Fourie, HE & Chimimba, CT 2016, 'Trophic overlap between fish and riparian spiders : potential impacts of an invasive fish on terrestrial consumers', Ecology and Evolution, vol. 6, no. 6, pp. 1745-1752. en_ZA
dc.identifier.issn 2045-7758
dc.identifier.other 10.1002/ece3.1893
dc.language.iso en en_ZA
dc.publisher Wiley Open Access en_ZA
dc.rights © 2016 The Authors. Ecology and Evolution published by John Wiley and Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License. en_ZA
dc.subject Competition en_ZA
dc.subject Invasive species en_ZA
dc.subject Niche overlap en_ZA
dc.subject NicheROVER en_ZA
dc.subject Stable isotope en_ZA
dc.subject Trophic subsidies en_ZA
dc.title Trophic overlap between fish and riparian spiders : potential impacts of an invasive fish on terrestrial consumers en_ZA
dc.type Article en_ZA

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