南麂列岛海域沉积物中甲藻孢囊的多样性和分布

BIODIVERSITY AND DISTRIBUTION OF DINOFLAGELLATE RESTING CYSTS IN THE SEDIMENTS OF NANJI ISLAND, EAST CHINA SEA

南麂列岛地处亚热带海域,是台湾暖流和江浙沿岸流的交汇处,因而呈现出很好的生物多样性。据调查,南麂列岛附近海域已鉴定的浮游植物甲藻有53种,而到目前为止,对南麂列岛海域甲藻的休眠孢囊种类和分布的调查仍为空白。本文通过对2014年南麂列岛附近海域沉积物中甲藻孢囊的调查研究,在该海域共发现甲藻孢囊10属26种,其中,种类最多的是原多甲藻属(Protoperidinium),有10种;其次是斯氏藻属(Scrippsiella)和亚历山大藻属(Alexandrium),分别有4种,膝沟藻属(Gonyaulax)2种,舌甲藻属(Lingulodinium)、易碎藻属(Fragilidium)、扁甲藻属(Pyrophacus)、翼藻属(Diplopsalis)、裸甲藻属(Gymnodinium)和多沟藻属(Polykrikos)各1种。这些甲藻孢囊中,异养型和自养型甲藻孢囊各13种,自养型甲藻孢囊在数量上所占比例较大(79%)。2014年南麂列岛海域甲藻孢囊丰度较低,每毫升沉积物能检测出2—33个;夏、秋季的孢囊丰富度较高;岙口等相对开放海域的孢囊丰度明显高于岙内各站点。值得注意的是,三种有毒甲藻孢囊,塔玛/相似亚历山大藻(Alexandrium tamarense/affine),具刺膝沟藻(Gonyaulax spinifera)和多边舌甲藻(Lingulodinium polyedra)的孢囊也在样品中检出,并且分别占春季、夏季和秋季孢囊总丰度的37%、23%和27%。本研究为完善南麂列岛甲藻的物种多样性提供了依据。

A survey was conducted in 2014 on seasonal and special distributions of dinoflagellate cysts in sediment near Nanji Island off Wenzhou City, East China. High biological diversity was observed as the area is located between Taiwan Warm Current and Jiangsu / Zhejiang coastal current. Fifty-three species of dinoflagellates were identified microscopically, including 26 species and 10 genera. Among them, Protoperidinium dominated（10 species）, followed by Scrippsiella（4）, Alexandrium（4）, and Gonyaulax（2）; and only one species in Lingulodinium, Fragilidium, Pyrophacus, Diplopsalis, Gymnodinium, and Polykrikos. Of the 26 species, the numbers of autotrophic and heterotrophic species were equal; however, the autotrophic species were more abundant, taking up to 79% of all samples. In general, the cysts abundance was relatively low in 2014, ranging from 2 to 33 per m L sediment. Cysts were remarkably higher in summer and autumn, and in open waters than those in spring and the gulf area. Notably, cysts of three toxic dinoflagellates, Alexandrium tamarense/affine, Gonyaulax spinifera, and Lingulodinium polyedra were detected for the first time in the sediment, accounting for 37%, 23%, and 27% of the total cysts abundance in spring, summer and autumn, respectively. The presence of the toxic cysts indicates a potential outbreak risk of their vegetative cells in local coastal area. Our study provides background information for cysts diversity in the area and calls for detailed research in the future.