我国长江口及邻近海域铜藻生长和金潮分布变化特征

为了解金潮源头,对枸杞岛附近贻贝(Mytilus edulis)养殖区固着褐藻进行了分布特征调查,并对长江口附近海域漂浮金潮进行月度监测。结果表明,枸杞岛附近贻贝养殖区设施上固着生长大量褐藻马尾藻,1—3月,藻体具有固着器,营固着快速生长,平均长度在3月可达3.45 m;同时海区巡航监测结果显示,1—2月枸杞岛附近海域无漂浮马尾藻,3月份只有单棵零星漂浮藻体; 4月份,贻贝养殖区马尾藻固着器逐渐萎缩消失,导致藻体大量脱落进入海区,由于马尾藻具有气囊结构,能够保障藻体长期漂浮在海表面形成金潮;大面监测结果显示,4—5月海区漂浮褐藻生物量与分布范围快速增加,分布面积可达27761 km^2。分子生物学检测结果显示,固着褐藻和海区漂浮褐藻均为铜藻(Sargassum horneri)。本研究结果表明,3—4月浙江沿岸固着铜藻在人为和海流的共同作用下从贻贝养殖设施上脱落后营漂浮生活,生长聚集,并可能在风和海流作用下向北至黄海海域形成金潮,黄海金潮可能具有多溯源性质。

Growth of Sargassum horneri distribution properties of golden tides in the Yangtze Estuary and adjacent waters

In recent years,macroalgal blooms have occurred in the coastal waters of China for several times,resulting in tremendous economic losses and damage to marine ecosystems. The golden tides caused by floating brown macroalgae are on the rapid rise in the Yellow Sea and the East China Sea. Locating the source of the golden tides has been one of the most important scientific issues. In this study,monthly shipboard monitoring of the floating golden tides was carried out in the Yangtze River Estuary and adjacent waters. The distribution characteristics of Sargassum in mussel culture area near Gouqi Island were also investigated. The results showed that attached Sargassum macroalgae grew rapidly on the infrastructures of mussel culture during January to March,and reached up to about 3.45 m in length at the end of March;whereas in April,a large amount of attached Sargassum on the infrastructures could be detached under the currents and human activities for harvesting mussel,then the detached Sargassum macroalgae could keep floating with the structure of air sacs,providing the initial biomass for the golden tides. Shipboard monitoring indicated that floating Sargassum macroalgae was not observed from January to February,individual and scattered floating Sargassum appeared on the sea surface in March,and the distribution range of floating Sargassum increased rapidly from April to May,the distribution area could reach 27761 km^2. Meanwhile,the attached and floating Sargassum showed similar morphological characteristics with the observation of blade,air sacs and branches,and they were all identified as Sargassum horneri by molecular methods with ITS-2 molecular marker. In conclusion,we inferred that the attached brown macroalgae in the mussel culture area would be cleaned up under the driving force of water currents or human impacts and became one of the sources of golden tides. Besides,multisources should be an important property for the blooms. This study increases our understanding of the importance of controlling the spread of macroalgae blooms.