R/V Mirai Cruise MR16-06

We conducted meteorological and hydrographic surveys including marine biogeochemical samplings in the northern Bering Sea and the Arctic Ocean on board the R/V Mirai from 22 August to 5 October 2016 under the Arctic Challenge for Sustainability (ArCS) Project. During the cruise, the above-mentioned 11 studies were carried out.
The planned activities in the northern Bering Sea and the Arctic Ocean were changed or canceled due to sea ice, weather and other conditions. However, we tried to complete the observations in some focused areas where physical, chemical, and biological processes are sustaining unique marine environment and ecosystem that might be influenced by the recent Arctic warming and sea ice reduction.
For example, a biological hotspot off Pt. Hope is maintained by nutrient supplies from the Bering Sea in spring blooms and by nutrient regeneration at the bottom in fall blooms. A new instrument deployed during Green Network of Excellence (GRENE) project off Pt. Hope indicated seasonal changes in zooplankton, and the changes might be associated with migration of sea birds. We have also reported aragonite undersaturation in the bottom water off Pt. Hope and anthropogenic CO2 has significant impact on the duration of undersaturation in the bottom water. For further studies, we carried out detailed hydrographic surveys and a mooring deployment off Pt. Hope in this year.
Another focused area is the Barrow Canyon, where we have deployed moorings to monitor the flux of warm water from the Pacific Ocean that may impact on the sea ice distribution in the Canada Basin. The water also plays an important role in the biogeochemical cycles, and therefore, we attached chemical and biological sensors to the mooring in this year.
Shelf slopes are important to understand the shelf-basin interaction and its impact on ecosystem in response to meteorological conditions. Thus, some hydrographic sections were provided in the slope area.
In the basin area, the sea ice has been decreasing drastically. We found that oceanographic and biological responses to the sea ice loss are quite different between the Alaskan and Siberian sides of the region. However, on the Siberian side, data are still lacking and many biogeochemical processes may remain unknown. Unfortunately, the planned experiments in the Siberia side were canceled due to a heavy sea ice condition.