BALSEIRO esteban Gabriel
Resource versus consumer regulation of phytoplankton: testing the role of UVR in a Southern and Northern hemisphere lake
VILLAR-ARGAIZ, M.; BALSEIRO, E. G.; MODENUTTI, B. E.; SOUZA, M. S.; BULLEJOS, F. J.; MEDINA-S?NCHEZ, J. M.; CARRILLO, P.
Lugar: Berlin; Año: 2018 vol. 816 p. 107 - 120
AbstractModels predict thatphytoplankton is bottom- up regulated by resources and top-down controlled byconsumers. However, how the strength of these controls varies with UV radiation(UVR) is not well known. In this study, we test the hypothesis that thephosphorus (P) content of phytoplankton affects the role that UVR exertsstrengthening or weakening the resource and consumer control on distinctstoichiometric and functional phytoplankton traits. To accomplish this, wecoupled field meso- and microcosms in a split-plot design using UVR treatmentsat the plot level and nutrients and zooplankton (presence/ absence) at thesubplot level, in two mountain lakes characterized by their P-sufficient (LaCaldera) and P-deficient phytoplankton (Los Ca´ntaros). We found that theaddition of nutrients decreased phytoplankton C:P in both lakes, but enhancedprimary production and chlorophyll a only under UVR in La Caldera. Also, the effects of zooplankton onphytoplankton varied between lakes and UVR conditions, and increased primaryproduction and chlorophyll a under UVR in LaCaldera, but not in Los Ca´ntaros. These results suggest that differences inthe stoichiometric aspects associated with the P content in phytoplankton playa key role in how UVR affects resource and consumer controls, with much weakereffects in P-deficient food webs.