Sea ice colored by ice algae in a lagoon, Lake Saroma, Hokkaido, Japan

Abstract

The coloration of sea ice by the ice algae was studied at Mombetsu (44°20′N, 143°20′E) on the Okhotsk coast of Hokkaido and at Toetoko (44°11′N, 143°45′E) in a lagoon, Lake Saroma, which is also situated on the same coast, Hokkaido, Japan. Lake Saroma is usually covered with the ice between middle January and early April. A brown layer was found at the bottom of the sea ice in February from 1977 through 1980. The 1977's results showed that Fragilariopsis, Nitzschia, Thalassiosira and other pennate diatoms were dominant components of the ice algal community. Chlorophyll a and phaeopigment were detected from top to bottom of the sea ice of 20 to 40 cm thick and concentrated at the bottom part. The level of plant pigment concentration (25.88μg chl a/l) in the sea ice was higher than that of the sea water (0.09μg chl a/l). The increase of plant pigments with the lapse of time was observed, when the growth rate of the sea ice extremely decreased at ice thickness of 20 to 40cm. The present results agreed with the data obtained at Syowa Station, Antarctica, on the development of ice algal community.