Expansion of round gobies in a non-navigable river system

摘要

Highlights?Weirs not a barrier to upstream goby migration.?Tubenose goby negatively affected by later establishment of round goby.?Round gobies in rip-rap are utilizing a ‘vacant’ niche.?No sex or size bias observed at the invasion front.AbstractA number of Ponto-Caspian Gobiid species have greatly increased their geographical ranges over recent decades. Most expansion studies to date, however, have focused on navigable waterways. In this study, we present a summary of six-years (2008–2013) monitoring of round gobyNeogobius melanostomusexpansion along two connected non-navigable rivers. Contiguous range expansion was observed in both rivers, with dispersal rate ranging from 1.2 to 3.2km/year. Gobies at newly invaded sites ranged from 20 to 117mm, with both juveniles and adult fish observed. Though the data did not allow us to see any consistent pattern in the first years aft