Effect of time of day on the recovery from light exposure in ice algae from Saroma Ko lagoon, Hokkaido

The amount of prior light exposure an algal community receives is likely to determine its ability to recover from exposure to high light levels. Here we investigate the effect of time of day and light on the ability of ice algae to recover from variable light exposure. The ice algae were obtained from Saroma Ko lagoon, a temperate, perennially ice covered lagoon in northern Hokkaido, Japan. Under ice irradiance varied between 0 and 122 μmol photons m-2s-1. Algal biomass, which was dominated by Nitzschia firigida, was 272.8±20.2 mg Chl a m-2. There was no consistent relationship between ambient in situ irradiance and recovery rates. While the sea ice community showed mild inhibition at the highest irradiance used, 490 μmol photons m-2s-1, after 10 min the quantum yield had recovered to between 90.9% and 112% (average 99.5%) of the original measurement. It is likely that ambient under ice irradiances at Saroma Ko lagoon were never sufficient to cause photo-inhibition and consequently had little negative long term effect on photophysiology. The Rapid Light Curves, while providing irradiances of sufficient intensity to cause inhibition, were of too short a duration to cause anything but a short, transient effect. Therefore, it is unclear whether higher in situ irradiances would necessitate a longer period of recovery. © 2006 National Institute of Polar Research.