Potential impacts of a recent and rapidly spreading coloniser of Australian freshwaters:: Oriental weatherloach (Misgurnus anguillicaudatus)

Oriental weatherloach (Misgurnus anguillicaudatus), a benthic freshwater fish species native to East Asia, was first recorded in Australian freshwater systems in 1984. Although this species is widely established around the world, very little is known about its potential impacts as an invader. We gathered field data to parameterise a mesocosm experiment investigating the impacts of Oriental weatherloach in Southeastern Australia. During this experiment, Oriental weatherloach caused significant reductions in macroinvertebrate numbers and biomass. Additionally, Oriental weatherloach were associated with elevated ammonia, nitrate/nitrite (NOx), and turbidity levels. Because of issues involved in scaling up mesocosm experiments we are not able to conclusively determine that Oriental weatherloach are having large impacts in natural systems. Our results come from mesocosms designed to mimic natural conditions, however, and they thus indicate that ecological impacts may be occurring, and underline the need for further research and control.