Organism incorporation into newly forming arctic sea ice in the greenland sea

Abstract

New ice formation, protist incorporation and enrichment in different stages of young Arctic sea ice (grease, nilas and pancake ice) were studied in the Greenland Sea in autumn 1995. Nutrients (nitrite, nitrate, phosphate and silicate), salinity and abundance estimates of organisms were analysed from surface water and new ice samples. The abundances of bacteria, diatoms, and photo- and heterotrophic flagellates in the ice and water column were determined using epifluorescence microscopy. An enrichment index was calculated to compare the abundance of organisms in the water column with different stages of young sea ice. The results clearly show that (i) protist incorporation already begins during the first stages of new sea ice formation, (ii) incorporation of protists is selective, showing preference for diatoms with a relatively large cell size and (iii) enrichment of organisms, in particular diatoms, takes place in young sea ice in the Greenland Sea. The selectivity of the incorporation process and the evident preference for diatoms are presumably a result of the larger cell size and/or certain properties of the cell surface (e.g. stickiness) that enhance their incorporation. The calculated enrichment indices were relatively low for bacteria and flagellates.