LAUSR

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. *Correspondence: [email protected] Present address: The University of Basel, Department of Environmental Sciences, Basel, Switzerland Author Contributions Statement: ED conducted data collection, statistical analysis, and led manuscript preparation. SMB and GRB designed and supervised the study approach and field collection. All three authors contributed to the interpretation of data and preparation of the manuscript. Data Availability Statement: All data files and R scripts associated with this manuscript may be found at the FigShare digital repository under the address: https://doi.org/10.6084/m9.figshare.8289053. Associate editor: María González Additional Supporting Information may be found in the online version of this article. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.