@misc{10481/35447,
year = {2015},
url = {http://hdl.handle.net/10481/35447},
abstract = {An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280–400 nm) and photosynthetically active radiation (PAR, 400–700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton–bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton–bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio < 100). This did not occur in the low-UVR lake (i.e., BCD : EOC(%) ratio > 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.},
organization = {This study was supported by the Ministerio
Español de Medio Ambiente, Rural y Marino (PN2009/067),
Ciencia e Innovación (CGL2011-23681), Junta de Andalucía
(Excelencia CVI-02598 and P09-RNM-5376), Consejo Nacional
de Investigaciones Científicas y Técnicas – CONICET (PIP
no. 112-201001-00228), and Fundación Playa Unión. G. Herrera
and C. Durán were supported by a Formación de Profesorado
Universitario grant from the Spanish government. The authors are
indebted to the staff of Sierra Nevada National Park and Lagunas
de Ruidera Natural Park for permission to work, to E. Jiménez-Coll
for the bacterial production analysis, and to D. Nesbitt for writing
assistance in English.},
publisher = {Copernicus Publications; European Geosciences Union (EGU)},
keywords = {UVR},
keywords = {Phytoplankton},
keywords = {Oligotrophic},
keywords = {Mediterranean lakes},
title = {Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton–bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes},
doi = {10.5194/bg-12-697-2015},
author = {Carrillo Lechuga, Presentación and Medina Sánchez, Juan Manuel and Durán, C. and Herrera, Guillermo and Villafañe, V. E. and Helbling, E. W.},
}