Abstract:

During the 6th Chinese Arctic Expedition in August 2014, samples from melting ponds, sea ice, and the
underlying sea water at seven ice camps in Canada Basin were collected, and the characteristics of the bacterial
and protist communities were analyzed using epifluorescence microscopy. The results showed the first and
second dominant groups were bacteria and heteroflagellates, respectively, with biomass percentages of 42.8%,
37.8%, 50.7%, 40.2%, 34.3%,37.5%, respectively (data from the ICE07 melting pond with an algal bloom were
not included). Heterotrophic organisms such as bacteria, heteroflagellates, and ciliates dominated within the
community, suggesting that the microbial loop might play an important role in the community of the pack ice
zone. Under the background of rapid melting of sea ice in austral summer, the environments of all three habitats
were unsuitable for rapid growth of the community and the biomass was very low. An autotrophic flagellate
bloom was observed in a melting pond and within the upper 20 cm of the ice column at ICE07. We suggest that
suitable quantities of both algal seed and nutrient supplement are essential for the occurrence of algal blooms on
surface ice.

Key words: Arctic, melting pond, sea ice, bacteria, protest, community