Photosynthesis of the red alga Gracilaria chilensis under natural solar radiation in an estuary in southern Chile

The photosynthetic performance and pigment content of Gracilaria chilensis Bird, McLachlan, and Oliveira were measured under natural solar radiation in the Quempillen river estuary (southern Chile) in order to assess the short-term acclimation of this species to the current levels of ultraviolet (UV) radiation during midsummer. The effect of the tidal fluctuation was evaluated in algae exposed for 3 days to two light climates in cages suspended at two depths (0.5 and 1.5 m from the bottom). Responses to high solar radiation at noon were also assessed to gain insights into rapid photochemical kinetics and the degree of photoinhibition. Results indicated that G. chilensis is a shade-adapted s…