海岸带生物学与生物资源保护实验室知识库

(1) 海岸带生物学与生物资源利用重点实验室中国科学院烟台海岸带研究所

Phytoplankton are the major primary producers in the ocean and play a crucial role in the marine food chain. Understanding the dynamics of the marine phytoplankton community can provide insights into the succession process and current status of marine fishery resources. Based on the net-phytoplankton samples collected from the Bohai Sea in the summer (June and August) of 2015, we studied the phytoplankton community composition, diversity, abundance, and dominant taxa in the Bohai Sea. Compared with historical data, the phytoplankton community structure in the Bohai Sea was changed markedly. The chlorophyll-a concentration had changed slightly during recent years, but was much higher than that in the 1980s and 1990s, and the regions with lower values (<1.0 g/L) were much smaller than those 20 years ago. In terms of the dominant taxa, the dominance of the genera Chaetoceros and Coscίnodiscus was found to be slightly decreased, whereas the species Skeletonema costatum, which had been an important dominant species in the Bohai Sea, was not observed in the two months of summer in 2015. In contrast, Paralia sulcata and Pyrrophyta (Noctiluca scientillans in June and Ceratium tripos in August) were still dominant in the Bohai Sea, and the abundance and dominance of Achnanthes brevipes and Pseudo-nitzschia pungens was higher than those in the years before 2015. The diversity indices (Shannon diversity and species richness and evenness) of phytoplankton were at a moderate level. Such a trend was mainly caused by the significant change of the nutrient structure in the Bohai Sea. This may change the structure of the marine food chain and influence the growth and reproduction of commercial fishes and shrimps (e.g., Konosirus punctatus, Liza haematocheila, and Acetes chinensis) that feed on phytoplankton. Consequently, this will have potential impacts on fishery production and the structure and function of the ecosystem in the Bohai Sea.

本研究基于2015年夏季(6、8月)渤海网采浮游植物和叶绿素a调查数据,对渤海浮游植物的种类组成、丰度、多样性以及优势类群的分布特征进行分析。通过与历史数据进行对比发现,渤海浮游植物群落具有以下变化趋势:叶绿素a浓度近年来未发生明显变化,但较20世纪80、90年代明显升高,且低值区(<1.0 g/L)较20年前明显缩小;就优势类群而言,6月角毛藻属(Chaetoceros)和圆筛藻属(Coscinodiscus)的优势较往年有所减弱,以往在渤海具有突出优势地位的中肋骨条藻(Skeletonema costotum)在2015年夏季6、8月均未检测到,甲藻(6月:夜光藻Noctiluca scientillans; 8月:三角角藻Ceratium tripos)、具槽帕拉藻(Paralia sulcata)继续占优,而短柄曲壳藻(Achnanthes brevipes)、尖刺伪菱形藻(Pseudo-nitzschia pungens)的优势地位较以往明显上升。浮游植物多样性(Shannon多样性、物种丰富度、均匀度)与往年相比处于适中的水平。渤海浮游植物群落结构的变化主要是由渤海营养盐结构改变引起的,这一变化趋势可能会对渤海食物链结构以及对具有浮游植物食性的经济鱼虾[如斑(鱼祭)(Konosirus punctatus)、(鱼夋)鱼(Liza haematocheila)、毛虾(Acetes chinensis)]的生长繁殖造成影响,进而影响到渤海渔业资源产量以及生态系统结构和功能。