Biotic Resistance to Survival and Recruitment of a Non-Native Fish Varies Across Predator Communities

Understanding factors that promote or impede establishment by non-natives is fundamental to development of management strategies for invasive species. West-central Florida is an ideal system to investigate non-native fish establishment because ornamental fish escape fish farms or are released by hobbyists into a mosaic of habitats that vary both in abiotic factors (e.g., temperature and hydrology) and in biotic communities (i.e., predators, competitors, and prey). In this study we focused on the role of native fishes in limiting the success of a non-native fish in experimental ponds. We evaluated whether Green Swordtails Xiphophorus hellerii can establish and recruit across a gradient of predation intensity as represented by native fish communities consisting of Eastern Mosquitofish Gambusia holbrooki, sunfish Lepomis spp., and Largemouth Bass Micropterus salmoides. Survival and recruitment were greatest without predators and nearly nonexistent in high predator communities. Body size of Green Swordtails was greater in the medium predator treatment, suggesting adult survival may be influenced by the gape of Lepomis spp. These results indicate survival and recruitment vary as a function of the predator community, suggesting biotic resistance may also vary across the landscape.