title: Rising nutrient-pulse frequency and high UVR strengthen microbial interactions.
abstract: 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.
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071, Granada España.|Instituto Universitario de Investigación del Agua, Universidad de Granada, C/Ramón y Cajal, 4, 18071, Granada España.
authors.forename: Marco J
authors.initials: MJ
authors.lastname: Cabrerizo
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071, Granada España.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Medina-Sánchez
authors.affiliation: Instituto Universitario de Investigación del Agua, Universidad de Granada, C/Ramón y Cajal, 4, 18071, Granada España.
authors.forename: Irene
authors.initials: I
authors.lastname: Dorado-García
authors.affiliation: Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071, Granada España.
authors.forename: Manuel
authors.initials: M
authors.lastname: Villar-Argaiz
authors.affiliation: Instituto Universitario de Investigación del Agua, Universidad de Granada, C/Ramón y Cajal, 4, 18071, Granada España.
authors.forename: Presentación
authors.initials: P
authors.lastname: Carrillo
mesh_terms: D002980:Climate; D017753:Ecosystem; D004783:Environmental Microbiology; D056265:Microbial Interactions / Q000528:radiation effects*; D064307:Microbiota; D010839:Phytoplankton; D014466:Ultraviolet Rays; D014867:Water / Q000032:analysis / Q000737:chemistry
chemical_list: D014867:Water