福建北部海域浙闽沿岸流消亡期浮游植物的种类组成与分布特征

根据2009年4月在福建北部海域(24°47’17.0"~26°48’02.9"N,119°29’36.0"~120°57’13.8"E)所获浮游植物网采样品和同步观测的理化参数,并结合2007年"908专项"春季航次相应范围的调查资料,分析该海域浮游植物种类组成、分布特点、年际变化及其与环境因子的关系.本航次共记录浮游植物3个门类85种,其中硅藻75种、甲藻9种、蓝藻1种.物种组成以广温种为主(占47.06%),其次为暖水种(占36.47%),温带种仅占7.06%.调查区浮游植物丰度平均为137.89×104cells m-3,其平面分布呈现从近岸往外海、从北往南递增的态势.聚类分析显示本海区浮游植物可划分为2个群落,群落Ⅰ主要由近岸低盐种组成,仅分布于受浙闽沿岸流影响较直接的闽江口以北的近岸测站;群落Ⅱ主要为外海高盐种和广温广盐种,广泛分布于受台湾暖流影响较大的闽江口以南及三沙湾外侧水域.主成分分析(PCA)表明,对本海区浮游植物的分布起主导作用的是温度和盐度,而与营养盐的关系不密切,反映调查期间浙闽沿岸流已基本退出本海区,浮游植物的分布主要受制于台湾暖流.浮游植物丰度的平面分布格局与以往的调查结果基本一致,但其群落结构存在年际变化,"908专项"春季航次的优势种为近岸低盐种和广温广盐种,优势种突出,多样性指数低;而本次调查外海性广温种成为优势种之一,多样性指数(H’)和均匀度(J’)均较高,这可能与考察期间受东北季风强度所左右的浙闽沿岸流强弱有关.

Species Composition and Distribution Characteristics of Phytoplankton in Northern Sea of Fujian, China During Withdraw of Zhe-Min Coastal Current

Based on the survey data of net-phytoplankton samples and simultaneously physic-chemical parameters in northern sea of Fujian,China in April 2009,the species composition,distribution characteristics of phytoplankton and their relationship to environmental factors were analyzed.Eighty-five species belonging to 3 phyla were recorded.Among them most were eurythermal species(47.06%),the next were warm-water species(36.47%) and temperate species only accounted for 7.06%.The average of phytoplankton abundance was 137.89×104 cells m-3,increasing from nearshore waters to the offshore and from the north to the south.Bray-Curtis similarity clusters showed that the phytoplankton community could be divided into two groups.The first group was inshore stations in the north of the Minjiang River,dominated by neritic species.The second cluster was offshore stations in the outer part of the Sansha Bay and in the south of the Minjiang River,dominated by hyperhaline species,eurythermal and euryhaline species.Principal components analysis(PCA) indicated that currents played an important role in the distribution of the phytoplankton in the study area,and the phytoplankton abundance was significantly positive correlation with water temperature and salinity.It suggested that the Zhe-Min coastal current had withdrew from the area during the survey time,and the phytoplankton distribution pattern was mainly influenced by the Taiwan warm current.Phytoplankton abundance and distribution were similar to those reported previously.However,the phytoplankton community structures showed quite differently.Besides neritic species and eurythermal and euryhaline species,oceanic eurythermal species was one of the dominant species.The diversity index and evenness index were relatively high compared with other studies,which might be the results of wax and wane of the Zhe-Min coastal current caused by prevailing NE monsoon.