1997年底中国东南沿海大规模赤潮原因生物的形态分类与生态学特征

TAXONOMIC AND ECOLOGICAL STUDIES ON A LARGE SCALE PHAEOCYSTIS POUCHETII BLOOM IN THE SOUTHEAST COAST OF CHINA DURING LATE 1997

1997年11月底和12月19—25日对同年11月中旬至12月底发生于广东饶平县柘林湾及南澳岛周围海域的大规模赤潮的生物学、生态学及其危害进行了调查。研究表明，此次赤潮的原因生物是棕囊藻Phaeocystispouchetii。这种赤潮生物在其生活史中有游泳单细胞和群体胶质囊2个生活阶段。游泳单细胞为球形或卵圆形，大小为6．0—7．2μm，有2根不等长的鞭毛和1根定鞭丝。群体胶质囊为球形或近球形，直径为110μm—2．6cm。直径在150μm以下的小胶质囊呈略似实心的球体，细胞分布不均，大小只有3．1－5．2μm；当直径大于200μm后，胶质囊已呈中空状，细胞均匀地分布在胶质囊表面，细胞大小增至62－7．4μm，群体胶质囊细胞内的2个林状叶绿体沿着细胞周壁相向嵌合。在赤潮高峰期，棕囊藻胶质囊遍布柘林湾，湾外的赤潮带达十数公里长，细胞密度最高为25×108cells／L，占浮游植物总细胞数的99．7％。此次赤潮的诱因主要是受1997—1998年度史上最强的厄尔尼诺现象的影响，导致我国东南沿海冬季气候反常，气温升高，东南风频。

A large scale harmful marine Ancroalgal bloom occuered in the Southast Waters of China from the midddle of November to the end of December, 1997. In order to study the biology, ecology and daInage of the bloom, we carried out an inveshgation to fish culbors at the end of November and a sampling inveshgahon on 20-24th December, 1997, in the most hit area of the bloom-Zhelin Bay and its neighbouring open sea Guangdong. The causative orgedsm of the bloom was idenhfied to be Phaeocystis pouchetii (Hariot) Lagerheim It had tWo different stages in the life cycle, a colony and a unicellular stage. The colony was spherical in shape, and ranged from 110μm uP to 2.6 cm in diameter. The small colony Undr 150μm looked like a solid ball. The cell distributed in the colony was not uniform, and a part of cells was deeply embedded withen the gelatinous. When the colony increased to > 200μm, it became hollow, and the cells were distributed boformly aroUn the periphery of the colony. The cells of the small colony were smaller with a size of 3.1- 5.2μm and a density of ca. 2.5×104cells / mm2, while the laree colony increased their cell size up to 6.2-7.4μm with a mean density of 5.6 ×103 cells / mm2. The cells of a healthy,ripe colony looked angular slightly, with two palletally located chlorophasts, bu without flagella and haptonma. The whcellular stage was biflagellate, spherical or ovoidal with a size of 6.0-7.2μm, possessing two flagella and a haptnema. The nagellate could be uP to more than twice the cell size. Haptonema was short and not clear Undr usual light ndcroscope. The P pouchetii bloom covered an area of more than 1 000km2 from the Quanzhou Bay of Fujian in the north to Shanwei Coast of Guangdong in the south. The bloom reached a peak from the end of November to the beginning of December, and collapsed from 22nd of December. In the Present inveshgation,the P pouchetii abUnance in a convergent bloom band reashed to 2.5×108cells / L. The bloom was so dense that the seawarer was trmd oily, brown and fishy smelling, and the masses of foam appeared in the surface. That caused extensive killing of the cultured fish in the Zhelin Bay of Guandong only. The results showed tha the colohies of P pouchetii could only move totally depending on the wind, and its bloom occunnce was inihated by the abnormal climate in the Southast Coast of China Ans year owing to the globally abnonnal climate and the strongest El Mfio Event of all time, the tempeature in the Southast Coast has been often as high as 25℃since the beginning of late fall of 1997, and a southast wind occimd in the season when northwest seasonal wind should be. The P pouchetii colony originared in the open sea was driven into the coastal waters- Finally, a great scale of harmful bloom occond in the bays such as the Zhelin Bay. According to the fishermen, P pouchetii colony occurs around the Nanpeng Islands in the lat autumn every year bu the colonies are not so numerous as one in 1997 and usually cannot enter the Zhelin Bay due to the resistance of northwest monsoon. thee years ago, the colony also entered the Zhelin Bay driven by southeast winds, bot it did not make a nd bloom because the colony was not so numrous.