In recent years, changes in the marine environment have been observed in the Arctic Ocean, such as earlier melting of sea ice and a decrease in sea ice extent, which are thought to be caused by climate change. There is concern about the impact of these changes on marine ecosystems, but knowledge on the life history of zooplankton, the main organisms that make up the Arctic marine ecosystem, is still scarce. One reason for this is that the Arctic Ocean freezes over during the winter, making it difficult to collect samples throughout the year. The time-series sampling at ice fixed stations on the sea ice overcomes this problem. The most successful time-series plankton sampling at a fixed station on ice in history was conducted by the U.S. and Canadian research project SHEBA, which used a Canadian icebreaker moored on ice in the western Arctic Ocean from October 1997 to October 1998 as an observation station, and time-series plankton samples were collected.
Using zooplankton samples collected at SHEBA, several analyses had been conducted by researchers at the Woods Hole Oceanographic Institution in the United States, but the life history of species distributed in the deep sea remained unresolved.
