Publicaciones Científicas

Vulnerability of mixotrophic algae to nutrient pulses and UVR in an oligotrophic Southern and Northern Hemisphere lake

Carrillo P, JM Medina-Sánchez, M Villar-Argaiz, FJ Bullejos, C Durán, M Bastidas-Navarro, MS Souza, EG Balseiro, BE Modenutti - 2017

El aumento en la deposición de aerosoles saharianos está reduciendo la diversidad funcional en las lagunas, con el declive de los nanoflagelados mixotróficos. La desaparición de este eslabón clave podría alterar las redes tróficas y desviar el flujo de Energía desde el bucle microbiano hacia la cadena de los consumidores herbívoros.

Nutrient inputs and ultraviolet radiation (UVR) are global factors a ecting the structure and functioning of aquatic ecosystems, particularly clear-water ecosystems. We performed experiments in two model lakes highly exposed to UVR uxes in order to test the effect that future increases in mineral nutrients transported by dust aerosol might exert on primary producers depending on the likelihood of atmospheric inputs. Lake La Caldera (Northern Hemisphere) has been receiving recurrent dust inputs from the Sahara Desert while lake Los Cántaros (Southern Hemisphere) has been less a ected by dust aerosol. UVR × Nutrient synergistically stimulated primary production (PP), chlorophyll a (Chl a), with a smaller increase in phytoplanktonic biomass in La Caldera, but not in Los Cántaros, where nutrient addition unmasked the UVR inhibitory e ect on phytoplankton. The proportional decrease of mixotrophic nano agellates (MNFs) after the nutrient pulse (in Los Cántaros) and the long-term decline of MNFs in La Caldera associated with the increase in aerosol-dust intrusions from the Sahara during the last 40 years suggest that a future scenario of intensified aerosol events from desert and desertified areas would not only reduce functional diversity with the decline of MNFs, but would ultimately alter the C flux towards the grazing chain in oligotrophic ecosystems.