A recent study has revealed that certain species of zooplankton common in the North Pacific Ocean known as Neocalanus contribute significantly to the absorption of atmospheric carbon dioxide (CO2) in the ocean. This was found through a joint study by researchers from the Tohoku National Fisheries Research Institute (under Japan's Fisheries Research Agency) and Tokyo University. They estimated that Neocalanus absorb as much as 590 million tons of CO2 annually, equivalent to about half of the annual CO2 emissions from Japan, or 1.26 billion tons in fiscal 2003.

The system that enables Neocalanus to help absorb a huge amount of CO2 in the sea water is connected to its unique life history. During the spring, Neocalanus graze on phytoplankton that absorb CO2 through photosynthesis in the surface water, after which they migrate to deep water zones. They pass the winter, spawn, and end their lives there. Their excrement and carcasses, as well as those of their predators, are either deposited on the bottom of the sea, or decompose and dissolve in deep-sea water. It is through these processes that carbon is transferred from the upper to the deeper layers of the ocean.

It has been known for years that zooplankton contribute to the transport of carbon, but it was thought that their quantitative impacts were insignificant. The specific focus of this recent study on the life cycle of Neocalanus led to new discoveries regarding its substantial role in carbon transport.

According to Hiroaki Saito, chief researcher of the Biological Environment Research Laboratory at the Tohoku National Fisheries Research Institute, global warming has an impact on the amount of biomass of zooplankton, so fluctuations in zooplankton populations are assumed to influence their overall carbon transport capacity. This study is expected to contribute to a further understanding of the carbon cycle mechanisms, which are critical to global warming predictions.

http://tnfri.fra.affrc.go.jp/eindex.html

Posted: 2006/10/11 02:45:35 PM
Japanese version

TAG Ecosystem , Global warming , Government , University/Research institute