Effect of CO2, nutrients and light on coastal plankton IV: Physiological Responses
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AuthorsSobrino, C.; Segovia, M.; Neale, P.J.; Mercado-Carmona, J.M. (Jesús Mariano); García-Gómez, C. (Candela); Kulk, G.; Lorenzo, M. Rosario; Camarena, Teresa; van de Poll, W. (Williem); Spilling, K.
We studied the physiological response of phytoplankton to the interacting effects of 3 factors affected by global climate change: CO2, nutrient loading and irradiance. Treatments had a high and low level for each factor: CO2 was bubbled at 1000 ppm by volume versus present atmo spheric values; high nutrient treatments had a combination of inorganic and organic nutrients; and light treatments were obtained by covering the tanks with a single or double layer of screen. We measured esterase activity, oxidative stress (ROS), cell death, DNA damage, photosynthetic efficiency and 14C assimilation as particulate or dissolved organic material (POC and DOC respectively). Conditions simulating future global change scenarios showed similar chlorophyllnormalized primary productivity as present conditions. The main effect driving phytoplankton physiology was the downregulation of the photosynthetic apparatus by elevated CO2, which decreased esterase activity, ROS, cell death and DNA damage. ...