Abiotic and biotic contributions to invasion resistance for ornamental fish in west-central Florida, USA

Explaining the varying success of invaders is a central question in invasion biology. Florida is a good region to test hypotheses related to invasion because of variation in invasion success where a few non-native fishes have established and spread and some have locally established, whereas many have failed to establish despite high propagule pressure. We sampled fish and habitat near ornamental fish aquaculture facilities, sources of propagules, to test hypotheses related to habitat suitability and biotic resistance, resistance either from strongly interacting species or due to diversity (diversity–invasibility). We found a dramatic decline in non-native richness and density with increasing distance from facility effluent (virtually absent > 1,000 m). Non-native and native species richness and density were positively correlated. Increased density and richness of non-natives was associated with higher temperatures and lower abundance of select native species, including predatory largemouth bass Micropterus salmoides , but little support was found for the influence of eastern mosquitofish Gambusia holbrooki . Overall, we found mixed support for the contribution of abiotic and biotic factors and no support for the diversity–invasibility hypothesis. Additional studies into species-specific traits and manipulative experiments will provide key data on the contribution of abiotic and biotic influences on invasion success.