INVESTIGADORES
VILLAFAÑE virginia Estela
congresos y reuniones científicas
Título:
Interactive effects of UVR and mixing in aquatic environments
Autor/es:
WALTER HELBLING, E; VIRGINIA ESTELA VILLAFAÑE
Lugar:
Aix-les-Bains, Francia
Reunión:
Congreso; 11th European Society for Photobiology Congress; 2005
Resumen:
The irradiance received by phytoplankton in the water column is conditioned by vertical mixing, and thus the depth of the upper mixed layer (zUML) plays an important role at the time to assess the effects of solar radiation on these organisms.  With shallow UMLs, the mean irradiance received by cells is higher than that found in deep UMLs, providing that other variables are about the same.  Earlier studies have found variable effects of mixing on primary production, so that vertical mixing enhanced, decreased or even had no effects; however, these experimentation addressed only the effects of PAR (400-700 nm).  Experiments conducted in the Southern Ocean determined that phytoplankton photosynthesis was more inhibited by UVR (280-400 nm) due to mixing than samples exposed to fixed irradiances, with assemblages responding to dose rather than to irradiance.  Experiments conducted in mid latitudes in Patagonia and tropical areas of China highlighted the importance of not only zUML but also the speed of vertical mixing.  Shallow UML (0.6 of the euphotic zone, zEu) resulted in significant UVR-induced inhibition but the same assemblage was able to use UVR as source of energy for photosynthesis with deep UML (> 0.9 of zEu).  Fast mixing within the same UML, resulted in an enhancement of carbon incorporation in samples exposed to full solar radiation (UVR+PAR) as compared to that exposed to PAR only, suggesting also the use of UVR for photosynthesis.  Thus, experiments to evaluate the interactive effects of vertical mixing and UVR should be done to evaluate how much “standard’ fixed-depth incubations deviate from in situ primary production.