Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms Carrillo Lechuga, Presentación Medina Sánchez, Juan Manuel Herrera, Guillermo Durán, Cristina Segovia García, María del Carmen Cortés, Dolores Salles, Soluna Korbee, Nathalie Figueroa, Félix L. Mercado, Jesús M. Some of the most important effects of global change on coastal marine systems include increasing nutrient inputs and higher levels of ultraviolet radiation (UVR, 280–400 nm), which could affect primary producers, a key trophic link to the functioning of marine food webs. However, interactive effects of both factors on the phytoplankton community have not been assessed for the Mediterranean Sea. An in situ factorial experiment, with two levels of ultraviolet solar radiation (UVR+PAR vs. PAR) and nutrients (control vs. P-enriched), was performed to evaluate single and UVR×P effects on metabolic, enzymatic, stoichiometric and structural phytoplanktonic variables. While most phytoplankton variables were not affected by UVR, dissolved phosphatase (APAEX) and algal P content increased in the presence of UVR, which was interpreted as an acclimation mechanism of algae to oligotrophic marine waters. Synergistic UVR×P interactive effects were positive on photosynthetic variables (i.e., maximal electron transport rate, ETRmax), but negative on primary production and phytoplankton biomass because the pulse of P unmasked the inhibitory effect of UVR. This unmasking effect might be related to greater photodamage caused by an excess of electron flux after a P pulse (higher ETRmax) without an efficient release of carbon as the mechanism to dissipate the reducing power of photosynthetic electron transport. 2024-10-04T11:45:37Z 2024-10-04T11:45:37Z 2015-10-29 journal article Carrillo P, Medina-Sánchez JM, Herrera G, Durán C, Segovia M, Cortés D, et al. (2015) Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms. PLoS ONE 10(11): e0142987. doi:10.1371/journal.pone.0142987 https://hdl.handle.net/10481/95549 10.1371/journal.pone.0142987 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Plos One