INVESTIGADORES
VILLAFAÑE Virginia Estela
congresos y reuniones científicas
Título:
Photosynthetic activity under UVR exposure and nutrient addition of phytoplankton from coastal sites off São Francisco do Sul, Santa Catarina (Southern Brazil)
Autor/es:
ERZINGER, G. S.; VILLAFAÑE, V. E.; STRAUCH, S. M.; MACHADO, C. K.; HELBLING, E.W
Lugar:
Montreal
Reunión:
Congreso; 36th meeting of the American Society for Photobiology; 2012
Institución organizadora:
American Society for Photobiology
Resumen:
During March 2011 we carried out experiments to
evaluate the photosynthetic activity of phytoplankton collected from the area
of São Francisco do Sul, Santa Catarina, Brazil, when exposed to solar radiation and
nutrient addition. We collected samples from the
following sites: a) Prainha; b) Ubatuba; c) Babitonga Bay (both from the mouth
and inlet waters) and exposed them to three radiation conditions (PAB, 280-700
nm; PA, 320-700 nm and P, 400-700 nm, using cut-off filters) throughout a
daylight exposure; two nutrient treatments were implemented: Addition of f/2
medium the night previous of experimentation vs. natural concentration. Every
30-60 min measurements of various chlorophyll a (Chl a) fluorescence
parameters were done using a PAM fluorometer. At all sites, there were
significant effects of the different wavebands, as seen in the reduction of the
photochemical quantum yield (Y) values, especially in samples under the PAB
treatment. Nutrient addition however, was by far more important in counteracting
the UVR impact by increasing Y significantly as compared to samples under
natural nutrient levels. In spite of these general patterns of photosynthetic
responses under the treatments implemented, there was important variability
among the sites sampled. For example, while at Prainha there was a rather
smooth decrease of Y towards noon and partially recover in the afternoon,
samples from Ubatuba displayed variable responses, generally following
radiation patterns, but in any case, samples recovered only partially or did
not recover at all during afternoon hours. Samples from the mouth and inlet
waters of Babitonga Bay had similar photosynthetic responses (i.e., with a
significant decrease of Y towards noon and recovery in the afternoon). However,
samples from the inlet recovered faster and more complete than those from the
mouth. These variable responses among sites may be attributed not only to the
different radiation conditions throughout the experimental period (which ranged
in average from 0.33-1.17, 12.9-40.6 and 113-287 W m-2 for UV-B,
UV-A and PAR, respectively), but also to the differential taxonomic composition
of the communities sampled: Diatoms dominated at Prainha and Ubatuba (i.e., Asterionellopsis glacialis) whereas at
the mouth of Babitonga Bay dominated Leptocylindrus
sp.; however, at the inlet unidentified pico-nanoplankton flagellates were the
most abundant group.