长江口附近海域春季浮游硅藻的种类组成和生态分布

2002年春季，在长江口附近海域典型赤潮高发区28个大面站位采集了53个样品，从中共鉴定出隶属于31个硅藻属的80个种和变种；其中种类多样性较高的属为圆筛藻属(Coscinodiscus)，有17个种，斜纹藻属(Pleurosigma)，有8个种和变种；数量上较优势的种为柔弱拟菱形藻(pseudo-nitzschia delicatissma)，为3．48×10^3cells·L-1，占28．54％；具槽直链藻(Melosira sulcata)，为1．43×10^3cells·L-1，占16．98％；尖刺拟菱形藻(Pseudo-nitzschia pungens)，为0．71×10^3cells·L-1，占9．85％．它们在大部分站位中都有出现；柔弱拟菱形藻和尖刺拟菱形藻的高细胞密度区主要出现在1230E断面的站位，而具槽直链藻则主要出现在长江口的31～32°N断面的站位．浮游硅藻总细胞丰度变化于0．43×10^3～23．3×10^3cells·L-1，平均4．61×10^3cells·L-1；在123°E、30．5°N的DDl5站位，无论表层还是中层，浮游硅藻总细胞丰度均最高(表层，1．85×10^4cells·L-1；中层，2．33×10^4cells·L-1)．从水平分布看，浮游硅藻呈不均匀分布态势，从垂直分布看，大部分站位的表层浮游硅藻丰度高于中层．

Species composition and ecological distribution of planktonic diatoms in the Changjiang River estuary during Spring

53 water samples were collected from 28 stations in typical regions where redtide frequently occurred in the Changjiang River estuary during Spring, 2002. In total, 80 diatom species and varieties belonging to 31 genera were identified, among which, genera with high species biodiversity included Coscinodiscus which contained 17 species and Pleurosigma which contained 8 species and varieties. Quantitative analysis of diatom cell density showed that Pseudo-nitzschia delicatissma (3.48 x 10(3) cells.L-1, 28.54%), Melosira sulcata (1.43 x 10(3) cells.L-1, 16.98%) and Pseudo-nitzschia pungens (0.71 x 10(3) cells.L-1, 9.85%) were dominant species, which occurred at almost all stations. Higher cell density of Pseudo-nitzschia delicatissma and Pseudo-nitzschia pungens occurred at stations along 123 degrees E, while that of Melosira sulcata occurred at stations around Changjiang River at 31-32 degrees N. The total diatom cell density ranged from 0.43 x 10(3)-23.3 x 10(3) cells.L-1, with average of 4.61 x 10(3) cells.L-1. At station DD15 located at 123 degrees E and 30.5 degrees N, the highest diatom cell density was found, which was 1.85 x 10(4) cells.L-1 at surface water layer, and 2.33 x 10(4) cells.L-1 at middle water layer (30 m) respectively. Horizontally, the diatom cell density showed scattered distribution, while vertically, it was commonly higher at surface water layer than that at middle water layer.