Oceanographic observations by USCGC Healy were safely conducted at a total 14 fixed points in the Chukchi Sea, though sea ice sometimes blocked our path. After finishing the work at the final observation point, Healy returned to the port of Seward Alaska.
During the cruise, vertical stratified zooplankton samples were collected from “Multinet” down to 2000 m depth, and I collected samples for stable isotope analysis. Stable isotope is a powerful tool to evaluate food web structure of ecosystem. After coming back to Japan, stable isotope analysis on these samples will be conducted. Feeding modes of zooplankton are species-specific and vary among herbivores and carnivores. Because of the sea ice, the temperature in the Arctic Ocean is generally low and homogenous throughout the water column. This special thermal condition allows the cold-water-adapted deep-sea zooplankton to extend their vertical habitat from the bottom to sea surface. By means of this stable isotope analysis, unique food web structure in the Arctic Ocean is expected to be uncovered.
During the cruise on the 28th of July, all the scientists and crews were awarded with the US Coast Guard Arctic Service Medal, after having worked in the Arctic Circle (>66°33’N) for over three weeks. The cruise was ended and we headed back to Seward, bringing with us various interesting experiences.
Atsushi Yamaguchi
(Faculty of Fisheries Sciences, Hokkaido University / A member of theme 6)
Zooplankton sampling by multinet and microscopic observation
Various zooplankton species collected in the Chukchi Sea
Group photo of scientists and crew of USCGC Healy
