Antarctic sympagic meiofauna in winter

This study of Antarctic sympagic meiofauna in pack ice during late winter compares communities between the perennially ice-covered western Weddell Sea and the seasonally ice-covered southern Indian Ocean. Sympagic meiofauna (proto- and metazoans > 20 µm) and eggs > 20 µm were studied in terms of diversity, abundance and carbon biomass, and with respect to vertical distribution. Metazoan meiofauna had significantly higher abundance and biomass in the western Weddell Sea (medians: 31.1 * 10**3/m**2 and 6.53 mg/m**2, respectively) than in the southern Indian Ocean (medians: 1.0 * 10**3 /m**2 and 0.06 mg/m**2, respectively). Metazoan diversity was also significantly higher in the western Weddell Sea. Furthermore, the two regions differed significantly in terms of meiofauna community composition, as revealed through multivariate analyses. The overall diversity of sympagic meiofauna was high, and integrated abundance and biomass of total meiofauna were also high in both regions (0.6 - 178.6 * 10**3/m**2 and 0.02 - 89.70 mg/m**2, respectively), mostly exceeding values reported earlier from the western Weddell Sea in winter. We attribute the differences in meiofauna communities between the two regions to the older first-year ice and multi-year ice that is present in the western Weddell Sea, but not in the southern Indian Ocean. Our study indicates the significance of perennially ice-covered regions for the establishment of diverse and abundant meiofauna communities. Furthermore, it highlights the potential importance of sympagic meiofauna for the organic matter pool and trophic interactions in sea ice.

本研究针对冬末浮冰群中的南极海冰共生小型底栖生物（Antarctic sympagic meiofauna）展开，对比了常年封冻的威德尔海西部与季节性封冻的南印度洋两地的群落差异。本研究针对体长大于20微米的原生动物与后生动物，以及粒径大于20微米的卵展开分析，探讨了其多样性、丰度与碳生物量特征，并研究了其垂直分布规律。结果显示，后生动物小型底栖生物在威德尔海西部的丰度与碳生物量中位数分别为31.1×10³个/平方米与6.53毫克/平方米，显著高于南印度洋的对应数值（中位数分别为1.0×10³个/平方米与0.06毫克/平方米）。威德尔海西部的后生动物多样性亦显著更高。此外，多元分析结果表明，两地的小型底栖生物群落组成存在显著差异。本研究涉及的海冰共生小型底栖生物总体多样性水平较高，两地小型底栖生物总丰度与总碳生物量均处于较高区间（分别为0.6~178.6×10³个/平方米与0.02~89.70毫克/平方米），多数数值均高于此前冬季威德尔海西部的相关报道值。我们将两地小型底栖生物群落的差异归因于威德尔海西部存在的老龄一年冰与多年冰，而南印度洋并无此类冰型。本研究揭示了常年封冻海域对于构建多样且丰富的小型底栖生物群落的重要意义，同时凸显了海冰共生小型底栖生物对于海冰有机质库与营养级相互作用的潜在重要性。