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

本研究的目的是与中国科研人员合作，厘清中国沿海马尾藻床的分布和生态，并通过对比东海和日本周边的海藻床和浮藻，研究东海浮藻是否来源于中国沿海的海藻床。我们在浙江南部、中部和北部进行了实地调研。在前两个地方，我们可以找到马尾藻床，但马尾藻是2000年4月在东海大量发现的漂浮海藻。2004年5月，在马尾藻生长旺盛的季节，我们在嵊泗州沟岐岛进行了实地调查。采用样方取样法对马尾藻床中附着动物和鱼类进行取样。在样方种植的海藻中，霍氏单胞菌占湿重的比例为93.7%。这一事实表明，浮动海藻的来源之一可能位于包括嵊泗群岛在内的Zoshan群岛。2005年3月，“白丸”号考察船在东海黑潮与陆架水域之间发现了由褐藻组成的浮游海藻。2005年3月至6月，在浙江近海马尾藻床附近投放了10个浮标，浮标上系有马尾藻种类，并由ORBCOM卫星跟踪其位置。一个在两个月内到达了九州岛东海岸，另一个到达了车祖岛南部。这些研究结果表明，中国海岸分离的马尾藻物种不仅对东海的浮游海藻有贡献，而且对日本海和日本太平洋沿岸的浮游海藻也有贡献。

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.