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.