Rising nutrient-pulse frequency and high UVR strengthen microbial interactions Cabrerizo, Marco J. Medina Sánchez, Juan Manuel Dorado-García, Irene Villar Argáiz, Manuel Carrillo Lechuga, Presentación Solar radiation Nutrient Ecosystem Ultraviolet radiation Solar radiation and nutrient pulses regulate the ecosystem’s functioning. However, little is known about how a greater frequency of pulsed nutrients under high ultraviolet radiation (UVR) levels, as expected in the near future, could alter the responses and interaction between primary producers and decomposers. In this report, we demonstrate through a mesocosm study in lake La Caldera (Spain) that a repeated (press) compared to a one-time (pulse) schedule under UVR prompted higher increases in primary (PP) than in bacterial production (BP) coupled with a replacement of photoautotrophs by mixotrophic nanoflagellates (MNFs). The mechanism underlying these amplified phytoplanktonic responses was a dual control by MNFs on bacteria through the excretion of organic carbon and an increased top-down control by bacterivory. We also show across a 6-year whole-lake study that the changes from photoautotrophs to MNFs were related mainly to the frequency of pulsed nutrients (e.g. desert dust inputs). Our results underscore how an improved understanding of the interaction between chronic and stochastic environmental factors is critical for predicting ongoing changes in ecosystem functioning and its responses to climatically driven changes. 2017-03-30T09:01:39Z 2017-03-30T09:01:39Z 2017 info:eu-repo/semantics/article Cabrerizo, M.J.; et al. Rising nutrient-pulse frequency and high UVR strengthen microbial interactions. Scientific Reports, 7: 43615 (2017). [http://hdl.handle.net/10481/45609] 2045-2322 http://hdl.handle.net/10481/45609 10.1038/srep43615 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ info:eu-repo/semantics/openAccess Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Nature Publishing Group