Phyto- and zooplankton of the southeastern Barents Sea in April 2000

Spring bloom of cold-water centric and pennate diatoms was observed in two different areas of the southeastern Barents Sea in April 2000: ice-free waters off the Kolguev Island northern shelf and the eastern Pechora Sea near the Karskie Vorota (Kara Gate) Straight in polynyas and ice-free patches in one-year-old ice. Maximal values of phytoplankton abundance and biomass were found at the ice edge. The bloom was localized in shallow water areas with depths less than 50 m in mixing zones of waters of different origin: warm Atlantic, cold coastal, and Arctic (Litke current) waters. Ice melting was among factors inducing the phytoplankton bloom. Each area had a specific phytocoenosis, whose structure was determined by water origin and ice conditions. In the western Kara Sea, under a solid (up to 30 cm thick) ice cover (i.e., under conditions of a hydrological winter), a spring phytoplankton succession was observed from its initial stage. In areas located close to the ice-cover edge, simultaneously with the mass phytoplankton bloom, the early spring zoocoenosis development manifested itself in mass spawning of euphausiids and mass appearance of Cirripedia nauplii and bottom polychaete larvae.

2000年4月，研究人员在巴伦支海东南部的两个不同区域观测到冷水中心硅藻（centric diatoms）与羽纹硅藻（pennate diatoms）的春季水华：其一为科尔古耶夫岛北部陆架附近的无冰水域，其二为毗邻卡尔斯基沃罗塔（卡拉门，Karskie Vorota (Kara Gate)）海峡的伯朝拉海东部区域的冰间湖及一年冰中的无冰斑块。浮游植物丰度与生物量的峰值出现在冰缘区域。此次水华局限于水深不足50米的浅水区，该区域为不同来源水体的混合带：包括暖性大西洋水、冷性沿岸水以及北极（利特克海流，Litke Current）水。海冰融化是诱发此次浮游植物水华的关键因素之一。两个区域各有其独特的浮游植物群落（phytocoenosis），群落结构由水体来源与冰盖条件共同决定。在喀拉海西部，厚达30厘米的固定冰盖之下（即水文冬季环境），观测到了处于初始阶段的春季浮游植物群落演替过程。在靠近冰盖边缘的区域，伴随浮游植物的大规模水华，早春动物群落（zoocoenosis）的发育表现为磷虾类的大规模产卵，以及蔓足类无节幼体与底栖多毛类幼虫的大量出现。