| 摘要: |
| 对1998年4月15日采集于广东珠江口万山群岛桂山岛网箱养殖区的赤潮新鲜水样和福尔马林固定样品进行赤潮原因生物的形态分类和生物学特征的研究。结果发现，此次赤潮共有7种原因生物，全部属于裸甲藻类，其中最占优种三宅裸甲藻（Gymnodinium mikimotoi）和优势种斯氏多沟藻（Polvkrikos schwartzii）、螺旋螺沟藻（ Gymnodinium spirale）的形态分类及生物学特征研究结果已在本系列论文的第一篇报道。本文报道其余4种红色裸甲藻（ Gym. sanguineum）、灰白下沟藻（ Katodinium glaucum）、螺沟藻98型（ Gyrodinium sp. type-98）和多环旋沟藻（Cochlodinium polykrikoides）的形态分类和生物学特征。其中，红色裸甲藻是此次赤潮的优势种之一，灰白下沟藻和多环旋沟藻在我国是新记录，螺沟藻98型则可能是新种。 |
| 关键词: 甲藻 裸甲藻 赤潮 分类 珠江口 |
| DOI：10.11693/hyhz200003001001 |
| 分类号: |
| 基金项目:国家自然科学基金九五重大资助项目，39790110号 |
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| TAXONOMIC AND BIOLOGICAL STUDIES ON CAUSATIVE ORGANISMS FROM A LARGE SCALE RED TIDE OCCURRING IN PEARL RIVER ESTUARY IN THE SPRING, 1998 Ⅱ |
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HUANG Chang-jiang, DONG Qiao-xiang
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Marine Biology Laboratory of Science Center, Shantou University, Shantou, 515063
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| Abstract: |
| A large scale harmful algal bloom occurred in the Zhujiang (Pearl River) River estuary on the South China Sea coast from March to April, 1998, and caused a severe economic loss on the local fish farming. By light microscope and scanning electron microscope, we studied morphological features of the causative organisms sampled from the most hit area—a tanked fish farm near Guishan Island located on the west side of the Zhujiang River estuary, on April 15th 1998 when the bloom was on its peak. At the same time, counting on the populations was made for the species which could be judged in the samples preserved by formalin. In our previous part, we described and discussed the taxonomic and biological features of the dominant causative organisms Gymnodinium mikimotoi, Polvkrikos schwartzii and Gymnodinium spirale. in the present paper, we describe and discuss the taxonomic and biological features of the other four species Gym. sanguineum Hirasaka, Katodinium glaucum (Lebour) Loeblich III, Gyrodinium sp. type-98 and Cochlodinium polykrikoides Margalef.
Gym. sanguineum had a length of 55–77μm and a width of 40–50μm. Cells were generally pentagonal with rounded corners, but variable in shape. The displacement of girdle was not so clear. Sulcus did not invade into the epicone and extended posteriorly, making the hypocone look like a W alphabet. A large number of yellowish chromatophores distributed radically from the center of the cell near periphery. A big nucleus located at the center of the cells. K. glaucum had a spindle-shape in dorso-ventral view, 25–35μm in length, and 14–16μm in width. Epicone was much larger than hypocone. Pigments of photosynthesis were lack, but there were often some yellowish brown particles concerned with feeding found in the epicone. C. polykrikoides had both unicellular and chain shapes. Solitary cell was 30–40μm long and 20–30μm wide, and had a stigma situated dorsally at epicone. A deep cingulum made nearly two turns around the cell. Gyrodinium sp. type-98 looked ovoid with a 35–50μm in length. A deep and narrow cingulum was equatorial or slightly pre-median, displaced 1/5–1/3 of the cell length. Sulcus did not invade into epicone, extending to the antapex. There were many greenish yellow pigments distributed round and a circle nucleus in the center of the cell.
Gym. sanguineum was also a dominant species in the bloom with a population density of 2.3×104 cells/L. K. glaucum and C. polykrikoides were first recorded in China. The morphological structures such as appearance, chloroplast, nucleus, colony and so on for Gym. sanguineum, K. glaucum and C. polykrikoides were highly similar to those found in other countries, but the size of organisms was slightly smaller than that of those distributed in the Japanese waters such as the other three species described in the previous paper. The cingulum of Gyrodinium sp. type-98 displaced about 1/3 of cell length, but we could not identify the species. So, it might be a new species. The causative organisms found in the bloom all belong to unarmored dinoflagellate, and at least 7 species. This indicates that with the increase of environmental pollution and the abnormality of global climate, the unarmored dinoflagellate bloom, which has done severe damage to social, economic and environmental conditions of many countries, may become a harmful bloom of frequent occurrence like Noctilluca bloom on the southeast coast of China and an unstable factor to the local fish farming. |
| Key words: Dinoflagellate, Unarmored dinoflagellate, Red tide, Taxonomy, Zhujiang River estuary |
