Temperature acclimation of respiration and photosynthesis in the brown alga Laminaria saccharina

Sporophytes of the brown alga Laminaria saccharina (L.) Lamour grown at 15 degree C contained significantly more chlorophyll a (chl a) than did similar plants grown at 5 degree C. The increase in chl a in 15 degree C plants was due to increased numbers of photosystem II reaction centes, and possibly to increased photosynthetic unit size, compared with 5 degree C plants. These changes were associated with increased alpha values (photosynthetic efficiencies) in 15 degree C-grown L. saccharina relative to 5 degree C-grown plants. The changes in alpha together with reduced respiration rates allowed 15 degree C-grown L. saccharina to achieve net photosynthesis and light-saturated photosynthesis at a lower photon fluence rate (PFR) than 5 degree C plants when both groups were assayed at the same temperature (15 degree C).