摘要:为了解莱州湾金城海域浮游植物群落年际变化特征，在该海域设置了15个监测站位，于2009年和2010年采用浅水Ⅲ型浮游生物网逐月连续进行24个航次浮游植物调查，同步监测其他环境因子。浮游植物样品经鲁格氏溶液固定后在OLYMPUS BX₅₁显微镜下进行分类、鉴定、计数，共鉴定出浮游植物81种，隶属于硅藻门、甲藻门、黄藻门和金藻门4门25科43属。其中硅藻16科33属67种，占种类数的82.7%；甲藻6科7属11种，占种类数的13.6%；黄藻2科2属2种，占种类数的2.5%；金藻1科1属1种，占种类数的1.2%。2009年和2010年金城海域浮游植物种类组成和比例基本一致，浮游植物丰度年际变化和种类数年际变化均呈现明显的双峰模型，每年2月和9月为高峰期，5月为全年最低值。2009年和2010年细胞丰度均值分别为465×10⁴ （38.4×10⁴-1351×10⁴） 个/m³和457×10⁴ （41.8×10⁴-1380×10⁴） 个/m³，均低于1982-1983年平均水平。浮游植物群落年际相似性在60%水平聚类分为四个类群，其中Ⅰ类为5月份样品，优势种为夜光藻和洛氏角毛藻；Ⅱ类为11-4月份样品，优势种有中肋骨条藻、旋链角毛藻和夜光藻；Ⅲ类为8、9、10月份样品，优势种为洛氏角毛藻和丹麦细柱藻；Ⅳ类为6、7月份样品，优势种为洛氏角毛藻和尖刺拟菱形藻。浮游植物群落Shannon-Winner多样性指数平均2.715 （1.446-3.807），Margalef丰富度指数平均2.418 （1.545-3.153），Pielou均匀度指数平均0.523 （0.263-0.706）。2009年和2010年多样性指数和均匀度高峰值出现在3月和10月，低值出现在7月和9月；均匀度指数年际变化低值出现在6-9月。浮游植物群落结构主要受水温和盐度环境因素的影响，其中水温与洛氏角毛藻丰度呈极显著正相关（R=0.613，P<0.01），与旋链角毛藻、中肋骨条藻和夜光藻丰度呈极显著负相关（R=-0.662，-0.649，-0.649，P<0.01）；化学需氧量与旋链角毛藻和中肋骨条藻均呈显著负相关（R=-0.589，-0.480，P<0.05）；盐度与中肋骨条藻呈极显著负相关（R=-0.585，P<0.01）；其他环境因子与各优势种丰度相关性不明显。



Abstract:Based on 24 cruises at 15 stations from January 2009 to December 2010, interannual variations in the phytoplankton community and their relationship with other environmental factors in the Jincheng area of Laizhou Bay were studied. Phytoplankton were vertically hauled using a type-Ⅲ standing phytoplankton net and environmental factors were recorded in situ synchronously. A total of 81 species of phytoplankton belonging to 43 genera of 4 phyla were detected. Bacillariophyta and Pyrrophyta were dominant, accounting for 67 and 11 species reflecting 82.7% and 13.6% of the total taxa, respectively. Xanthophyta included 2 species, while Chrysophyta included 1 species, accounting for 2.5% and 1.2%, respectively. Both in 2009 and 2010, the phytoplankton species composition and proportion were very similar. Compared to 2009, the proportion of diatom showed a slight increase, while dinoflagellates decreased slightly in 2010. Leptocylindrus danicus, Pseudo-nitzschia pungens, Skeletonema costatum, Chaetoceros curvisetus, and Chaetoceros lorenzianus were the most abundant species in Bacillariophyta, while Noctiluca scintillans was most abundant in Pyrrophyta. Interannual variability of phytoplankton abundance and the number of species showed a clear bimodal distribution. In 2009 and 2010, the average cell abundance was 465×10⁴ (38.4×10⁴-1351×10⁴) and 457×10⁴ (41.8×10⁴-1380×10⁴) cells/m³ respectively, all of which were lower than the average values observed in 1982-1983. CUSTER and MDS ordination analyses showed that the phytoplankton community was divided into four groups at 60% similarity. Group I contained samples from May, in which Noctiluca scintillans and Chaetoceros lorenzianus were the most abundant species. Samples from November through April belonged to Group Ⅱ, in which Skeletonema costatum, Chaetoceros curvisetus, and Noctiluca scintillans were the most abundant species. Group Ⅲ included samples in August, September, and October, in which Chaetoceros lorenzianus and Leptocylindrus danicus were the most abundant species. Group IV included samples from June and July, in which Chaetoceros lorenzianus and Pseudo-nitzschia pungens were the most abundant species. The means of the Shannon-Winner diversity index, Margalef richness, and Pielou evenness were 2.715 (1.446-3.807), 2.418 (1.545-3.153), and 0.523 (0.263-0.706), respectively. Both the diversity index and evenness of phytoplankton reached a maximum in March and October, while the minimum value was observed in July. The minimum value of the evenness index of phytoplankton was detected in June to September. Water temperature and salinity were the main environmental factors affecting the community structure of phytoplankton. Water temperature showed significantly positive correlations with Chaetoceros lorenzianus (R=0.613, P<0.01), but negatively correlated with Chaetoceros curvisetus, Skeletonema costatum, and Noctiluca scintillans (R=-0.662, -0.649, -0.649, P<0.01). There were negative correlations between the chemical oxygen demand and Chaetoceros curvisetus and Skeletonema costatum (R=-0.589, -0.480, P<0.05). Salinity was significantly negatively correlated with Skeletonema costatum (R=-0.585, P<0.01), whereas other environmental factors were not significantly correlated with the abundance of dominant species.





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