2012年夏季西北冰洋浮游动物群落特征

北冰洋夏季海冰覆盖面积在2012年达到低值。为了了解海冰变化对浮游动物群落的影响, 利用夏季西北冰洋22个站位的网采样品, 通过种类组成和丰度研究了群落的类型、结构和地理分布, 探讨了其分布特征与环境因子的关系。根据记录到的54种(类)浮游动物, 21站位可以划分成在地理上基本隔离的三个浮游动物群落: 楚科奇海南部群落, 藤壶幼体数量占优, 站位丰度百分比在56.6%—79.8%之间, 桡足类次之(18.0%—42.2%), 同时还含有少量的白令海种类；楚科奇海中北部群落以广布性桡足类占绝对优势(62.3%—96.8%), 藤壶幼体次之(0—30.9%)；深海群落浮游动物的丰度极低, 组成上以桡足类为主(71.6%—89.8%), 且多数是体型较大极地种。楚科奇海陆坡边缘的M06站丰度较高但是种类组成与深海站位相似, 没有归入任何群落。两个浅水群落优势种都是北极哲水蚤(Calanus glacialis)、伪哲水蚤类(Pseudocalanus sp.)、圆胃住囊虫(Oikopleur vanhoffeni)以及藤壶幼体(Barnacle larva), 但优势度各异。深海群落优势种较多, 北极哲水蚤(Calanus glacialis)、极北哲水蚤(Calanus hyperboreus)、细长长腹水蚤(Metridia longa)以及北极拟真刺水蚤(Paraeuchaeta glacialis)等体型较大的桡足类优势度较高, 体型较小的矮小微哲水蚤(Microcalanus pygmaeus)、长腹剑水蚤(Oithona similis)优势度相对较低。与群落类型按维度和深度的变化趋势一致, 统计分析显示表层温度和表层盐度是最重要的影响因子。与海冰覆盖面积较高的2003年相比, 群落类型和地理分布没有显著变化, 但是楚科奇海浮游动物丰度增加了1—2倍, 深海群落丰度降低而组成上大型种类比例升高。

Ecological characteristics of zooplankton communities in the Western Arctic Ocean in summer of 2012

Arctic Ocean sea ice coverage reached a record minimum of 3.41 million km2 in 2012. Zooplankton samples collected from 22 stations during summer 2012 were analyzed to determine the composition and geographic distribution of various Arctic Ocean communities, and to identify relationships to environmental conditions. Three geographically distinct communities were identified. The southern Chukchi Sea (CS) community was dominated by barnacle larvae (total abundance 56.6%–79.8%), followed by copepods (18.0%–42.2%). The central and northern CS community was dominated by copepods (62.3%–96.8%) followed by barnacle larvae (0%–30.9%). The deep-sea community was dominated by copepods (71.6%–89.8%) and characterized by extremely low abundance. The zooplankton community at Station M06, located at the edge of the CS slope, could not be classified into one of the three communities. Abundance was similar to CS communities but composition was similar to deep-sea communities. Calanus glacialis, Pseudocalanus sp., Oikopleura vanhoffeni, and barnacle larvae were dominant in the two shallow water communities. There were more dominant species in the deep-sea community, mostly large copepods including Calanus glacialis, Calanus hyperboreus, and Metridia longa. Surface temperature and salinity were the most important environmental factors determining the geographical distribution of communities. There was no significant change in community patterns and geographic distribution compared to 2003 results (when sea ice coverage was higher), but total abundance of zooplankton in the CS increased up to 2-fold and total abundance decreased in the deep-sea community with an increase in the percentage of large copepods.