Comparisons of the food niches of three native and two introduced fish species in an Australian river

摘要: The breadth, correspondence and overlap of the diets small large size classes three native species (Galaxias occidentalis, Bostockia porosa Edelia vittata) two introduced (Gambusia holbrooki Perca fluviatilis) fishes found in shallows main channel tributary creeks a south-western Australian river have been compared each season. Classification ordination were used to examine overall interrelationships across species, groups, seasons location where fish caught (channel or creek). smaller had narrower dietary breadth than larger spring summer, presumably reflecting limit imposed on prey by their possession relatively mouth these seasons. Intraspecific between was usually high G. but generally low P. fluviatilis, also B. E. vittata when difference lengths groups greatest. Dietary least autumn taxa most abundant. During winter, tributaries converged, probably faunal diversity highly seasonal water bodies. only consistent interspecific diet vittata. samples separated occidentalis (which fed extensively terrestrial organisms from surface) fluviatilis (that concentrated copepods plankton) ingested primarily benthic organisms). Furthermore, tended ingest Gambusia is sometimes dominated insects at other times organisms, demonstrating that this an opportunistic carnivore. It concluded food partitioning Collie River likely be one principal factors facilitating coexistence substantial populations system.