Combined effects of solar radiation and nutrient addition on photosynthesis of phytoplankton communities from Ubatuba and Babitonga Bay (Santa Catarina, Brazil).

VILLAFAÑE, V. E.; STRAUCH, S. M.; ERZINGER, G. S.; HELBLING, E. W.

Camboriu

Congreso; XIV Congreso Latinoamericano de Ciencias del Mar; 2011

During March 2011 we carried out experiments to evaluate the photosynthetic responses ofphytoplankton from Santa Catarina, Brazil. We collected samples from Babitonga Bay (bothfrom the mouth and from inlet waters) and exposed them to two radiation conditions (PAB, 280-700 nm, and P, 400-700 nm) for 5 days; two nutrient treatments were implemented (addition off/2 vs natural concentration). During this incubation period, samples were taken and exposed tonoon solar radiation under three radiation treatments: PAB, PA (320-700 nm) and P, and then they were allowed to recover (under dim light); every 15-20 min measurements of various chlorophyll a (Chl a) fluorescence parameters were done. Additionally, we collected samples from Ubatuba beach; nutrients treatments were implemented as described before, and samples were exposed to solar radiation (i.e., under the PAB, PA and P treatments) from 8 am to 4 pm; for these samples, daily cycles of Chl a fluorescence parameters were done. There were significant effects of the different wavebands, as seen in the reduction of the photochemical quantum yield (Y) values. However, nutrient addition was by far more important in counteracting the UVR impact by increasing Y significantly as compared to samples under natural concentration conditions.