Distribution and ecology of seaweed beds in China and their contribution to floating seaweeds

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Objective of the research is to clarify distribution and ecology of Sargassum beds along the Chinese coast with cooperation of Chinese researchers and to examine whether floating seaweeds in East China Sea is originated from seaweed beds in Chinese coast through comparing the seaweed beds and floating seaweeds in East China Sea and around Japan.We made field research in south, middle and north parts of Zejiang Province. In the first two places, we could find Sargassum beds but Sargassum horneri that was found massively in East China Sea in April 2000 as floating seaweeds. In May 2004 during the luxuriant growth season of Sargassum, we made a field survey in Gouqi Island, Shengsi Prefecture. Samplings of attached animals and fishes in Sargassum beds were conducted with quadrat sampling of seaweeds. The percentage of S. horneri occupied 93.7% in wet weight among seaweeds cropped with the quadrat. This fact shows that one of the sources of floating seaweeds is probably situated in the Zoshan Islands including Shengsi Islands. In March 2005, research cruise of R/V Hakuo-maru revealed that drifting seaweeds composed of S.horneri were found in front between Kuroshio and shelf water in East China Sea. Ten buoys tied with floating Sargassum species of which positions were tracked by ORBCOM satellites were released near Sargassum beds off Zhejiang Province from March to June of 2005. One reached to the east coast of Kyushu Island and other to south of Chezu Island in two months. These findings of this research show that Sargassum species detached from Chinese coast contribute to the floating seaweeds not only in East China Sea but also in the Japan Sea and Pacific coast of Japan.