Influence of variables associated with global change on photosynthesis of marine phytoplankton from Patagonia (Argentina).

VILLAFAÑE, V. E.; STRAUCH, S. M.; FIORDA GIORDANINO, MARÍA VALERIA; GUENDULAIN GARCIA, S. D.; HALAC, S.R.; BANASZAK, A. T.; HELBLING, E. W.

Camboriu

Congreso; XIV Congreso Latinoamericano de Ciencias del Mar; 2011

During February-March (mid summer) and May-June (late autumn) of 2011 we carried out experiments to evaluate the combined effects of temperature and solar radiation on photosynthesis of phytoplankton communities from Patagonia, Argentina. We collected samples from Bahía Engaño, Chubut, and exposed them to three solar radiation conditions (PAB, 280-700 nm, PA, 320-700 nm and P, 400-700 nm) under two temperatures: in situ (17 and 11°C, for summer and autumn, respectively) and increased (20 and 16°C, for summer and autumn, respectively), simulating a scenario of global warming as expected by the year 2100. Every hour, and throughout a daily cycle, measurements of various chlorophyll a (Chl a) fluorescence parameters were undertaken. A typical response of inhibition of photochemical quantum yield (Y) at noon and posterior recovery during the afternoon was observed, although the rates were different in summer and autumn. In general, solar ultraviolet radiation induced relatively small effects in both seasons. Increased temperature, on the other hand, did not affect photosynthetic performance of summer communities; however it benefited the autumn communities by decreasing photoinhibition. As phytoplankton blooms in the area occur in autumn-winter, increased temperatures might benefit their overall photosynthetic performance.