Abstract: To determine the abundance and diversity of archaea in Prydz Bay, Antarctica, summer sea-ice and seawater samples were collected during the 26th Chinese National Antarctic Research Expedition. Fluorescence in situ hybridization (FISH) was applied to determine the proportions of different archaea. Community composition was analyzed by constructing a 16S rRNA gene clone library. Finally, correlation analyses were performed to assess links between physicochemical parameters and archaeal diversity and abundance within the sea-ice. The FISH found that archaea was abundant in the top section of sea-ice, with the concentration of NH₄⁺ identified as a major driver of this distribution pattern. Using 16S rRNA gene libraries, archaea were not detected in the top and middle sections of the sea-ice. Overall, the diversity of archaea in sea-ice was low; all archaeal clones obtained from the bottom section of the sea-ice were grouped into the Marine Group I Crenarchaeota, while the archaeal clones from seawater were grouped into Marine Group I Crenarchaeota, Marine Group II and III of Euryarchaeote.

Key words: Antarctic, Prydz Bay, summer sea ice, archaea, 16S rRNA, abundance