Photoadaptation of an ice algal community in thin sea ice, Saroma-Ko Lagoon, Hokkaido, Japan

Abstract

We investigated the shade adaptation of a seasonally well-developed ice algal community in thin sea ice at Saroma-Ko Lagoon, Hokkaido, Japan on 3–4 March 2006 and 4–5 March 2007, by examining photosynthetic pigment concentrations, the chlorophyll a-specific light-absorption coefficient (aph*), and the light-saturation index (Ek). The high proportions of photosynthetic pigments, including chlorophyll a, fucoxanthin, and chlorophyll c, and the low values of aph*(440) and aph*(675) suggested that the lagoon’s ice algal community was shade-adapted. The high ratio of Ek to total photosynthetically active radiation (PAR) in the ice algal habitat suggested that the degree of shade adaptation is weak. Scaling of Ek to total PAR could be extended to studies of the degree of photoadaptive succession of ice algal communities in the Northern Hemisphere. The degree of shade adaptation of ice algal communities in the Northern Hemisphere might be related to ice thickness, regardless of latitude.