Effect of silicate enrichment on ice algae at low salinity in Saroma-ko Lagoon, Hokkaido, Japan

• Published in: Journal of marine systems Vol. 11; no. 1; pp. 45 - 52
• Main Authors: Taguchi, Satoru, Smith, Ralph E.H., Shirasawa, Kunio
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-1997
• Subjects: cell size; deficiency; less saline lenses; Marine; photosynthesis; salinity; silicate; less saline lenses; salinity; silicate; deficiency; photosynthesis; cell size
• ISSN: 0924-7963; 1879-1573
• DOI: 10.1016/S0924-7963(96)00026-7

The response of ice algae to low salinity was determined at three levels of silicate enrichment during the winter of 1992 in Saroma-ko Lagoon, Hokkaido, Japan. Regardless of the silicate concentration, the chlorophyll
a content decreased by 50% of its initial value within the first day of exposure to low salinity water (22 psu) and continued to decrease gradually thereafter. The degree of decrease after the first day was a function of silicate concentration. The size distribution of the ice algae at the beginning of the incubation was 52% in the size class > 10 μm, 39% in 10-2 μm and 9% in 2-0.2 μm. Within two weeks of silicate enrichment, the 2-0.2 μm fraction decreased to less than 1% while the > 10 μm fraction increased to more than 90%. Low salinity and low silicate concentrations reduced the chlorophyll
a biomass and photosynthetic activity. Silicate enrichments, even at the low salinity, enhanced photosynthetic activity and the relative abundance of the > 10 μm cells. Our results suggest that ice algae may not survive if trapped in the low salinity lens that is present immediately below the ice during melting because of possible osmotic damage associated with silicate deficiency. However, ice algal cells may recover from the damage when they sink into the high salinity and silicate-rich underlying water in Saroma-ko Lagoon. The ecological role of low salinity water is discussed in relation to vertical flux of ice algae.