Thermal and PAR effects on the photosynthesis of Eucheuma denticulatum and Kappaphycus striatus (so-called Sacol strain) cultivated in shallow bottom of Bali, Indonesia

Photosynthetic responses to various temperature and PAR conditions of two carrageenophytes, Eucheuma denticulatum and Kappaphycus striatus (so-called Sacol strain), cultured in shallow areas of Bali, Indonesia, were examined using dissolved oxygen measurements and pulse-amplitude-modulated (PAM) fluorometry. Net photosynthesis-irradiance (P-E) curves at 26 A degrees C revealed that the values of P (max) for E. denticulatum and K. striatus were 13.76 and 5.02 mu g O-2 g(fw) (-1) min(-1) (12.38-15.12 and 4.55-5.50 mu g O-2 g(fw) (-1) min(-1), 95 % Bayesian prediction interval (BPI)), respectively. Photoinhibition was not observed even at 1000 mu mol photons m(-2) s(-1). Gross photosynthesis and respiration characteristics over a range of temperatures (8-36 A degrees C) revealed optimum temperature for photosynthesis to be 31.1 A degrees C for E. denticulatum, and 31.6 A degrees C for K. striatus. These characteristics of photosynthesis indicate that both farmed seaweeds are well adapted to the light and temperature conditions of the cultivation site. However, studies on longer timescales for photochemical efficiency, photosynthesis, and respiration are still needed to determine their limits of tolerance. We also hypothesize that higher values of photosynthetic parameters for E. denticulatum suggest that this species is relatively superior in productivity under optimal conditions, conditional on the farming method.