Kinetics of dissolved inorganic carbon acquisition by red seaweeds (Rhodophyta) with and without carbon-dioxide concentrating mechanisms
Bárbara S. Labbé, Damon Britton, Lennart T. Bach, John A. Raven, John Beardall, Catriona L. HurdAbstract
Seaweed responses to ocean acidification (OA) may depend on whether they possess a carbon dioxide (CO 2 ) concentrating mechanism (CCM). Using photosynthesis versus dissolved inorganic carbon (DIC) experiments, we determined the photosynthetic affinity ( K 0.5 (CO 2 )) for CO 2 for the red algae Pollexfenia lobata (CCM), and Callophyllis rangiferina , Delisea pulchra and Plocamium cirrhosum (non-CCM). K 0.5 (CO 2 ) was statistically similar for CCM and non-CCM species, but P. lobata had values lower than those published for isolated red algal Rubiscos. Maximum photosynthetic rates ( P max ) were 2.5 times higher for Pl . cirrhosum and D. pulchra . Non-CCM species may benefit from future OA because photosynthesis would be less limited by DIC.