西北冰洋2010年夏季浮游植物群落的物种多样性

Species diversity of phytoplankton communities in the Western Arctic Ocean during summer 2010

有关北冰洋尤其是西北冰洋浮游植物聚群的资料非常不足。本研究拟通过我国第四次北极科考期间(2010年7月20日至8月30日)在西北冰洋(67.0o–86.1oN,152.5o–169.0oW)调查得到的藻类物种组成及其分布资料,描述调查区表层浮游植物群落物种多样性特征,以便全面地了解陆架至深海盆的浮游植物对持续的海冰变化的响应以及北极生态系统的演变。浮游植物样品采集自我国第四次北极科考期间"雪龙"号船在西北冰洋的50个测站。结果表明:西北冰洋表层浮游植物物种丰富,共鉴定出浮游植物(>5μm)10个门类(纲)67属152种,可归为4个生态类群,即极地类群、北极北方类群、暖温带类群和世界性广布类群;在调查期内浮游植物多样性的空间差异显著,主要反映在不同海域群落组成的空间异质性和细胞丰度的变化方面。聚类分析显示本海区表层浮游植物聚群可划分为浅海陆架群落和深海大洋群落,前者平均丰度和物种丰富度指数分别为892.6×102cells/L和1.81,皆远高于后者(27.7×102cells/L和1.28)。两个群落的优势种组成不同,浅海陆架群落优势种丰富,由大洋舟形藻(Navicula pelagica)、诺登海链藻(Thalassiosira nordenskioeldii)、皇冠角毛藻(Chaetoceros diadema)、成列伪菱形藻(Pseudo-nitzschia seriata)、丹麦细柱藻(Leptocylindrus danicus)、长菱形藻(Nitzschia longissima)和海洋拟脆杆藻(Fragilariopsis oceanica)等种类组成,并在调查期间经历了从羽纹硅藻到中心硅藻的演替过程;深海大洋群落主要优势种为菱形海线藻(Thalassionema nitzschioides)。文中还讨论了表层浮游植物聚群的分布特征及其与若干环境因素的关系。

Phytoplankton assemblages in the Arctic Ocean, particularly in the Western Arctic Ocean, remain unclear due to limited long-term ecological investigation caused by the existing harsh environment. In the present study, we characterized summer phytoplankton assemblages in surface water in terms of species composition and spatial distribution in the Western Arctic Ocean in 2010. Phytoplankton samples were collected at 50 stations in the survey area （67.0o–86.1o N, 152.5 o–169.0 o W） from 20 July to 30 August 2010 during the CHINARE 2010 cruise aboard the Chinese icebreaker R/V “Xuelong”. Results showed that high species diversity was present in the surface water phytoplankton community. A total of 154 phytoplankton taxa （〉5 μm） distributed among 67 genera of 10 phyla （or class） were identified in the study, which could be divided into four ecological groups, namely Arctic species, Arctic-boreal species, Warm-temperate species and Cosmopolitan species. Phytoplankton diversity exhibited a significant spatial difference with regard to taxonomic composition and abundance during the investigation period. Two phytoplankton assemblages were present in the surface water comprising a shelf community and an open sea community. Average abundance and species richness of the shelf community were 892.6×102 cells/dm3 and 1.81, respectively, and the dominant species were Navicula pelagica, Thalassiosira nordenskioeldii, Chaetoceros diadema, Pseudo-nitzschia seriata, Leptocylindrus danicus, Nitzschia longissima and N. grunowii. A succession from pennate to centric diatoms was evident. The open sea community contained a far lower abundance and species richness （27.7×102 cells/dm3 and 1.28） than the community in the abysmal area and was mainly dominated by Thalassionema nitzschioides. The relationship between the distribution of surface water phytoplankton and several environmental factors were discussed.