Native and invasive zooplankton show differing responses to decadal‐scale increases in maximum temperatures in a large temperate river

It has been widely proposed that increasing global temperatures will promote the geographic spread of invasive species, yet few studies have examined the effects of increasing temperatures on existing populations of invaders. Here, we examine temperature trends across a 70‐year series of daily records from the lower Columbia River (Washington and Oregon), and assess the correlation between interannual water temperature variability and the abundance of several native and invasive zooplankton species using a 12‐year series of monthly zooplankton samples from a nearby station. Our results show a clear pattern of increasing temperatures in the river, with a negative correlation between elevated late summer temperatures and the abundance of all examined native taxa, but none of the examined invasive taxa. Our study supports the hypothesis that anthropogenic climate change may promote conditions more favorable to previously established populations of invasive zooplankton species.