2004年春季长江口海域甲藻孢囊的分布研究

Distribution of dinoflagellate cysts from Changjiang River Estuary in the spring of 2004

于2004年4月初,采集长江口(E122°～123°30′,N29°～32°)10个站点0～15cm底泥样品,研究甲藻孢囊在这10个站点的水平和垂直分布情况。在30个样品中共鉴定出6大类24种甲藻孢囊。孢囊组成以异养型原多甲藻类孢囊为主,有13种,平均密度为157cysts·g-1DW,为调查海域的最优势种群。两种产麻痹性贝类毒素(Paralyticshellfishpoisoning,PSP)的孢囊,塔玛亚历山大藻和链状裸甲藻,在海区分布广泛但数量较低。10个站点甲藻孢囊的种类数在11～18种之间,平均密度为189～846cysts·g-1DW,在远离河口的D6站点有一个明显的最高峰,位于最北部的D1站点孢囊密度最低。与其它海湾相比,属于孢囊密度较低的海区。Shannon-Weaver生物多样性指数(H’)变化范围在2.57～3.27之间。甲藻孢囊的密度分布与生物多样性相关系数r=-0.72。3个不同深度的甲藻孢囊密度分别为351cysts·g-1DW、412cysts·g-1DW、432cysts·g-1DW;生物多样性指数分别为3.22、2.95、2.98。

The sediments of 10 sites （E 122°～123°30′, N 29°～32° ） about 15cm in length were collected from Changjiang River Estuary during April, 2004 to investigate the horizontal and vertical distribution of dinoflagellate cysts in this area. Twenty-four dinoflagellate species were identified in the sediments from 30 samples of which 13 heterotrophic protoperidinium cysts dominated in the cyst assemblages with the average concentration of 157 cysts·g^-1 DW. Two Paralytic Shellfish Poisoning （PSP） producing toxic species, Alexandrium tarnarense （Lebour） Balech and Gyrnnodiniurn catenatum Graham were found, which distributed in a large range but the concentration was low. Cyst species richness in each sample varied from 11 to 18, and the concentrations rage from 189-846 cysts·g^-1 DW. The highest cysts concentration was obtained at D6, a site which is far from estuary, and the lowest was D1 that located in the northernmost. Compared with other sea areas, the cysts concentration of Changjiang River Estuary was low. The value of Shannon-Weaver diversity index （H＇）varied between 2.57-3.27, which had a high relative index with the concentration of the cysts, negatively r=-0.72. Results of vertical distribution of dinoflagellate cysts showed that cysts concentration from three different depth of sediment layers were 351 cysts·g^-1 DW, 412 cysts·g^-1 DW, 432 cysts·g^-1 DW, and the values of Shannon-Weaver diversity index were 3.22、2.95 、 2.98.