Warming of shallow temperate lakes: consequences for rotifer community composition and population dynamics

Abstract Taxa specific responses to climate warming may shape aquatic communities, dominance patterns, biotic interactions, and related ecosystem processes and functions. As climate warming effects on smaller zooplankton are less understood than larger zooplankton, we focused on rotifers to study their response to a future climate warming scenario in outdoor mesocosms. Our year-long experiment (14 July 2020 to 13 July 2021) included present temperature conditions as controls and a treatment simulating a future warmer climate involving occasional heatwaves. Total rotifer abundance increased with warming, with Keratella spp. and Polyarthra spp. benefiting the most, while the Kellicottia spp. population collapsed. Filinia spp. were negatively affected by warming in the summer of 2020, but increased during winter and the following summer. Our findings suggest that thermophilic or eurytherm rotifers such as Keratella and Polyarthra may increase in a warmer future, while heat-sensitive Kellicottia may be negatively affected in the temperate region. Milder winters may allow some rotifer genera to proliferate while allowing others to recover from high summer temperatures, thereby considerably changing the composition and dominance patterns of rotifer assemblages.