东海水螅水母环境适应与生态类群

Water environment adaptability and ecological groups of Hydroidomedusae in East China Sea

根据1997—2000年东海23°30′—33°00′N、118°30′—128°00′E海域4个季节海洋调查资料,依据丰度和同步表层温、盐度数据,采用曲线拟合构造了数学模型,并结合地理分布分析对东海水螅水母最适温度、最适盐度和生态类群进行了研究.结果表明:东海水螅水母适温环境多样,最适温度低于20℃的有15种,在20℃～22.5℃之间的有8种,在22.5℃～25℃之间的有12种,超过25℃的有17种;大多数物种(32种)最适盐度为32～34,大于34的有13种,在30～32之间的有6种,低于30的仅出现2种.水螅水母大多数物种生存的盐度区间较窄,它们的数量和分布范围有限.嵊山秀氏水母等2种属暖温带近海种,八囊摇篮水母等13种属暖温带外海种,宽外肋水母等8种属亚热带近海种,半口壮丽水母等5种具有热带大洋种特征,四叶小舌水母等25种属亚热带外海种.东海水螅水母的许多物种可作为东海水团重要的指示种.

Based on the data of four seasonal oceanographic censuses in East China Sea （23°30′- 33 °00′ N, 118 °30′- 128 °00′ E） in 1997-2000, the optimal water temperature and salinity and the ecological groups of Hydroidomedusae were studied by curve fitting, mathematical model forming, and geographic distribution analyzing. The results showed that Hydroidomedusae could live in the waters with different temperature and salinity. 15 species of Hydroidomedusae had an optimal water temperature of 〈 20 ℃, 8 species at 20 ℃-25 ℃, 12 species at 22.5 ℃-25 ℃, and 17 species at ≥25 ℃. 32 species of Hydroidomedusae had an optimal salinity of 32-34, 13 species at 34, 6 species at 30-32, and only 2 species at 〈 30. The weak adaptability of most Hydroidomedusae species to the variation of water salinity made them have low density and limited distribution in East China Sea. Sugiura chengshanense and Clytia hemisphaerica were of nearshore warm temperate water species, Cunina octonaria and other 12 species were of offshore warm temperate water species, 8 species represented by Ectopleura latitaeniata were of nearshore subtropical water species, 5 species represented by Aglaura hemistoma showed some oceanic tropical features, while 25 species represented by Liriope tetraphylla were of offshore subtropical species. Some Hydroidomedusae species could be used as an important bioindicator of water mass in East China Sea.