Abstract
Irradiance beneath the sea ice also changes diurnally. We investigated the photosynthetic response of ice algae in Saroma-ko lagoon to the change of irradiance. The photosynthetic properties were assessed by PAM.
The maximum electron transport rate (ETRmax) increased from sunrise until around noon and decreased toward sundown. The maximum efficiency of photosynthesis changed inversely. Under 350 μmol photons/m2/s, which was enough to saturate the electron transport in the subjective ice algae, the level of non-photochemical quenching showed the same variation pattern as ETRmax. This means that ice algae adjust their capacity to dissipate excess light energy according to the diurnal change of irradiance.
These results indicate that ice algae regulate photosynthetic system totally to achieve efficient photosynthesis according to the diurnal change of irradiance. This regulation system may be essential for the productive photosynthesis of ice algae to utilize the weak light avoiding damages to photosystems.
