江苏如东近海绿潮藻分子检测与类群演替分析

Molecular detection and analysis of green seaweeds from Rudong coasts in Jiangsu Province

2007年以来,中国青岛、连云港、如东等黄海沿海连续4年爆发绿潮现象,尤其2008年青岛爆发了世界最大规模绿潮,造成了严重的生态危害.2009年,我们对江苏省如东海域绿潮藻进行了调查和监测,选取紫菜养殖架和防波堤坝上的11个固着样品以及海区15个漂浮样品,对其ITS及5.8S rDNA和叶绿体rbcL基因序列进行了分子系统发育和类群演替分析.结果显示,如东沿岸堤坝和紫菜养殖筏架具有大量固着生长的浒苔类绿潮藻,其海区漂浮绿潮藻团出现时间也最早,并逐渐北移;ITS序列分析将如东样品聚为5个类群,即Ulva compressa类群(6个样品)、Ulva linza-procera-prolifera(LPP)复合体类群(12个样品)、Ulva flexuosa类群(3个样品)、Blidingia sp.类群(3个样品)以及Urospora spp.类群(2个样品),而rbcL序列较为保守,26个样品只聚为4个类群.DNA序列分析表明,如东海区漂浮与固着绿潮藻类群构成相同,亲缘关系较近,漂浮绿潮藻优势类群先后出现次序为:U.compressa,U.flexuosa及LPP,最终漂浮种与2008年黄海绿潮优势种的ITS序列完全相同.本研究为今后黄海绿潮溯源及其预测防控奠定了重要基础.

Since 2007, massive green tides have occurred every year in the Yellow Sea in areas such as Qingdao, Lianyungang and Rudong. In 2008, Qingdao experienced the largest Ulva bloom in the world, which caused an ecological disaster. In 2009, survey and monitoring of green seaweeds was conducted in the Rudong sea area of Jiangsu Province. We sequenced and analyzed the nu- clear encoded internal transcribed spacer （ITS） and associated 5.8S rDNA regions as well as the chloroplast rbcL genes for 11 attached samples and 15 free-floating samples of green algae collected from Rudong coasts. The investigation showed that a large amount of sessile Ulva existed in Rudong coastal areas. In addition, the floating green algae clusters appeared earliest in Rudong, and gradually drifted northwards. The phylogenetic analysis of ITS sequences revealed that the samples fell into five distinct clades： the Ulva compressa clade （6 samples）, the Ulva linza-procera-prolifera （LPP） complex clade （12 samples）, the Ulvaflexuosa clade （3 samples）, the Blidingia sp. clade （3 samples） and the Urospora spp. clade （2 samples）. However, the 26 samples formed just four clades in the phylogenetic tree of rbcL sequences, which indicated the higher conservativeness of rbcL. DNA sequencing analysis implied there were Ulva compressa, Ulva flexuosa and LPP complex in both the free-floating Ulva and the attached species from Rudong coasts and that the final free-floating strain was the same as the dominant Ulva species （U. prolifera） of the 2008 bloom in the Yellow Sea. This study laid significant foundations for source-tracing and prevention of Ulva blooms in the Yellow Sea.