摘要：We investigated the interspecific interactions between the amphipod, Gammarus lacustris (Sars) and the cosmopolitan caddisfly, Ceratopsyche oslari (Banks). We believe this is an example of interference competition and may be one of several factors that limits the distribution of C. oslari from the Colorado River below Glen Canyon Dam. Field observations indicated that C. oslari was associated with fewer food capture nets in the Colorado River than in the Paria River tributary. Laboratory experiments indicated the amphipod Gammarus lacustris, which is abundant in the Colorado River but absent from the Paria River, had a detrimental effect on net-building success by C. oslari. Net numbers in laboratory chambers declined significantly after 6 d due to destruction by the swimming and feeding activities of G. lacustris. Competition with the introduced, non-native G. lacustris for interstitial spaces along with several abiotic factors, may limit the distribution of C. oslari in the Colorado River.
