Nematode absolute densities and genus counts from four stations near the Antarctic Peninsula, collected with a multicorer device during POLARSTERN cruise ANT-XXIX/3 in January-March 2013

Marine free-living nematode communities were studied at similar depths (~500m) at two sides of the Antarctic Peninsula, characterised by different environmental and oceanographic conditions. At the Weddell Sea side, benthic communities are influenced by cold deep-water formation and seasonal sea-ice conditions, whereas the Drake Passage side experiences milder oceanic conditions and strong dynamics of the Antarctic Circumpolar Current. Surface primary productivity contrasted with observed benthic pigment patterns and varied according to the area studied: chlorophyll a concentrations (as a proxy for primary production) were high in the Weddell Sea sediments, but low in the surface waters above; this pattern was reversed in the Drake Passage. Differences between areas were largely mirrored by the nematode communities: nematode densities peaked in Weddell stations and showed deeper vertical occurrence in the sediment, associated with deeper penetration of chlorophyll a. Generic composition did not differ markedly between both areas, but rather showed distinct community shifts with depth in the sediment.

本研究针对南极半岛两侧水深相近（约500米）海域的海洋自由生活线虫（Marine free-living nematode）群落展开调查，两侧区域具有截然不同的环境与海洋学特征。其中，威德尔海（Weddell Sea）一侧的底栖群落受冷水深层水形成过程与季节性海冰条件调控，而德雷克海峡（Drake Passage）一侧则拥有更为温和的海洋环境，且受南极绕极流（Antarctic Circumpolar Current）的强烈动力作用影响。表层初级生产力与观测到的底栖色素分布模式存在显著差异，且随研究区域不同而呈现变化：作为初级生产力替代指标的叶绿素a（chlorophyll a）浓度在威德尔海沉积物中较高，但其上覆表层海水的叶绿素a浓度较低；这一分布模式在德雷克海峡区域恰好相反。两地的线虫群落结构大体反映了这一环境差异：威德尔海站位的线虫密度达到峰值，且在沉积物中垂直分布更深，这与叶绿素a的渗透深度更大密切相关。两类区域的线虫属组成并无显著差异，但沉积物不同深度的群落结构呈现出明显的垂直演替特征。