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

本研究的目的是与中国学者合作，弄清中国沿海马尾藻群落的分布和生态，并通过对东中国海和日本周边海域的海藻群落和漂浮海藻的比较，验证东中国海藻是否起源于中国沿海的海藻群落。在前两个地点，除了2000年4月在东中国海区发现的大量漂浮海藻外，还发现了马尾藻。2004年5月，在马尾藻生长旺盛的季节，我们在嵊丝州沟旗岛进行了实地调查。采用海藻样方抽样方法，对马尾藻床面附着的动物和鱼类进行采样。在与样方一起种植的海藻中，霍尔纳氏杆菌占湿重的93.7%。这一事实表明，漂浮海藻的来源之一可能位于包括嵊丝群岛在内的若山群岛。2005年3月，白国丸号科考巡航发现，在东中国海区，黑潮与陆架水之间的锋面发现了由霍尔内氏螺旋藻组成的漂流海藻。2005年3月至6月，在浙江省近海马尾藻海床附近释放了10个浮标，这些浮标的位置被ORBCOM卫星跟踪。其中一次在两个月内到达九州岛东海岸，另一次到达济济岛南部。这些研究结果表明，从中国海岸分离出来的马尾藻物种不仅对东中国海区的浮游海藻有贡献，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.