Salinity and light effects on growth, photosynthesis, and respiration of Grateloupia filicina

Effects of salinity and irradiance on growth, photosynthesis, and respiration of the commerŽ . cially important red alga Grateloupia filicina Lamouroux C. Agardh were examined in laboratory cultures. G. filicina thalli showed various degrees of growth over a broad range of experimental conditions, with a maximum growth rate of 13% d observed at 20‰ and 100 mmol photons m s. Salinity also altered parameters of the photosynthesis-irradiance relationŽ . y1 ship. Maximum photosynthetic capacity P reached a high value of 109.2 mmol O g fw max 2 h at 20‰ but decreased to much lower values toward 0‰ and 40‰. P at 0‰ was only 15.3 max mmol O g fw h. The respiration rate ranged between 3.0 and 9.6 mmol O g fw h. 2 2 Ž . The respiration-to-P ratio RrP ratio showed an inverse relationship with the growth rate max max and had a minimum value of 0.07 at 20‰. These results suggest that salinity and irradiance need to be carefully controlled during mass cultivation of G. filicina in order to maximize growth and yield. q 2000 Elsevier Science B.V. All rights reserved.