1999年春季渤海中部及其邻近海域的网采浮游植物群落

The netz-phytoplankton community of the Central Bohai Sea and its adjacent waters in spring 1999

研究了 1999年春季覆盖渤海中部、渤海海峡及其邻近海域 30个测站两遍大面调查的浮游植物物种及其群落特征 ,共发现浮游植物 4门 33属 6 5种 (不包括未定名物种 ) ,以硅藻为主。优势种主要为 :冰河拟星杆藻 (Asterionellopsisglacialis)、虹彩圆筛藻 (Coscinodiscus oculus- iridis)、太阳双尾藻 (Ditylum sol)、刚毛根管藻 (Rhizosolenia setigera)、布氏双尾藻 (Ditylumbrightwellii)、中肋骨条藻 (Skeletonema costatum)、膜状缪氏藻 (Meuniera membranacea)、派格棍形藻 (Bacillaria paxillifera)、加拉星平藻 (Asteroplanus karianus)、圆海链藻 (Thalassiosira rotula)、卡氏角毛藻 (Chaetoceros castracanei)和尖刺伪菱形藻(Pseudo- nitzschia pungens)。细胞丰度的平面分布主要由浮游硅藻的分布所决定 ,其高值区分布在渤海中部靠近渤海海峡处。浮游甲藻在渤海海峡局部区域形成高值区。两遍大面站调查期间渤海浮游植物群落的结构变化较大 ,原因主要是春季以小细胞为主体的浮游植物群落物种演替较快 ,另外春季的大风过程对浮游植物的群落结构影响较大。两遍大面站调查期间浮游植物细胞丰度呈增长趋势 ,温度和硅酸盐浓度的增加是导致调查期浮游植物生长的重要因素。E5站浮游植物群落的分析表明

Features of the phytoplankton community were studied using the netz-phytoplankton data from the Sino-Germany Cooperative Project “Analysis and Modelling of the Bohai Sea Ecosystem”. Two station-grid-surveys were carried between 28^(th) April and 11^(th) May 1999 at 30 grid stations in the Bohai Sea to understand the ecosystem structure and functions. Phytoplankton was sampled using the standing net type III (mesh size 76μm, the standard sampling tool in Chinese marine phytoplankton studies) with a vertical haul at each grid stations. The phytoplankton samples were preserved in neutral formalin (2% final concentration of formaldehyde) and analysed in the laboratory using a microscope. A total 4 phyla, including 33 genera and 65 species of phytoplankton (not including unidentified taxa) were commonly found in the survey area. The main phytoplankton group was diatoms, but there were also some dinoflagellates, Chrysophyta and Cyanophyta, especially in the Bohai Strait. The dominant species were Asterionellopsis glacialis, Coscinodiscus oculus-iridis, Ditylum sol, Rhizosolenia setigera, Ditylum brightwellii, Skeletonema costatum, Meuniera membranacea, Bacillaria paxillifera, Asteroplanus karianus, Thalassiosira rotula, Chaetoceros castracanei and Pseudo-nitzschia pungens, etc. Most are neritic species in temperate coastal seas, with a few species belonging to oceanic warm water or oceanic species. Most of dominant phytoplankton species are autochthonous species, which occur mainly locally. Asteroplanus karianus and Chaetoceros castracanei are allochthonous species, coming via Huanghai Sea Warm Current and the Kuroshiro Current through the North Bohai Strait. Some of these dominant species mentioned above are big-celled with high-carbon-contents, and are key species in spring. in the Bohai Sea. A study of species population dynamics was necessary to understand the processes of Bohai Sea ecosystem. The dominant species of phytoplankton in the two station-grid-surveys were quite different. There were two possible explanations these phenomena: one is that the dominant phytoplankton species, such as, Asterionellopsis glacialis, Skeletonema costatum and Pseudo-nitzschia pungens, etc., were small-celled, grew faster and the phytoplankton community developed faster. The other reason was that windy events were frequent in Spring, thus the phytoplankton community changed rapidly because of mixing of tychopelagic species in the upper water layer. Phytoplankton cell abundance in the first station-grid-survey ranged from 0.18× 10~4 ind./m^3 to 391.15×10~4 ind./m^3, the average value was 33.08×10~4 ind./m^3; it was high in the East Central Bohai Sea close to the Bohai Strait. Phytoplankton cell abundance in the second station-grid-survey ranged from 0.17×10~4 ind./m^3 to 1068.79×10~4 ind./m^3, the average value was 73.57×10~4 ind./m^3; the horizontal distribution pattern was similar to the first station-grid-survey. Diatom cell abundance in the first station-grid-survey ranged from 0.18×10~4 ind./m^3 to 390.07×10~4 ind./m^3, the average value was 32.37×10~4 ind./m^3; it was also high in the East Central Bohai Sea close to the Bohai Strait. Diatom cell abundance in the second station-grid-survey ranged from 0.17×10~4 ind./m^3 to 1067.96×10~4 ind./m^3, the average value was 73×10~4 ind./m^3; a similar horizontal pattern to the phytoplankton distribution was determined. Dinoflagellate cell abundance in the first station-grid-survey ranged from 0 to 4.21×10~4 ind./m^3, the average value was 0.7×10~4 ind./m^3; it was high along the A section located in the Bohai Strait. Dinoflagellate cell abundance in the second station-grid-survey ranged from 0 to 5.54×10~4 ind./m^3, the average value was 0.58×10~4 ind./m^3; it was also high in the Bohai Strait. The horizontal distribution of phytoplankton was quite similar between the two station-grid-surveys, but the species composition and cell abundance changes were rather large. The horizontal distribution of phytoplankton was determined by the diatom distribution pattern. T