Biodiversity / Food / Water

December 2, 2011


Large Warm-Core Eddy Plays Crucial role in Arctic Marine Ecosystem

Keywords: Ecosystems / Biodiversity University / Research institute 

Researchers from the Japan Agency for Marine Earth Science and Technology identified a large warm-core eddy in the Canadian Basin of the Arctic Ocean during a research cruise with the research vessel (R/V) Mirai from September to October 2010. This is the first time such detailed observational data of a large warm-core eddy has been reported in the Arctic Ocean. The work was published in the American journal Geophysical Research Letters on August 26, 2011.

A warm-core eddy is a loop of currents whose center is warmer than the surrounding water. The data collected by R/V Mirai, which was carrying out oceanographic and meteorological observations in an open water area of the Pacific side of the Arctic Ocean, revealed that the warm-core eddy was unusually large (more than 100 km in diameter) and that its center was up to seven degrees Celsius warmer than the surroundings. The eddy also contained high ammonium concentrations. As ammonium is the result of deposition on the sea shelf during summer, the high-ammonium water in the eddy was believed to have originated from the Chukchi Sea shelf adjacent to the Canada Basin.

In the upper portion of the eddy, large numbers of picophytoplankton (< 2 μm, e.g., flagellates), which utilized the ammonium concentrations for growth, were observed. In recent years, sea ice melting has accelerated the freshening of the Arctic Ocean, reducing nutrient concentrations in the euphotic zone (a layer exposed to sufficient sun light for photosynthesis) and making it uninhabitable for large phytoplankton. The findings revealed that ammonium supplied by the large warm-core eddy affects phytoplankton production and the Arctic Ocean ecosystem.

Arctic Sea Ice Shows Striking Decline (Related JFS article)
Bottom Water Warming in Pacific Ocean--Less Bottom Water Formed around Antarctica? (Related JFS article)

Posted: 2011/12/02 06:00:15 AM



R/V Mirai Survey Reveals Features and Biological Impact of Large Warm-Core Eddy in the Arctic Ocean