1. Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan;
2. Arctic Research Center, Hokkaido University, Sapporo, Japan;
3. Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan;
4. Institute for Biological Problems of Cryolithozone, Siberian Branch of Russian Academy of Sciences, Yakutsk, Russia;
5. Institute for Natural Sciences, North-Eastern Federal University, Yakutsk, Russia;
6. Global Station for Arctic Research, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan;
7. Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan