Chelliah Devan S, Ray Angelique E, Zhang Eden, Terauds Aleks, Ferrari Belinda C
School of Biotechnology and Biomolecular Sciences, The University of NSW, Kensington, NSW, Australia.
Sydney Informatics Hub, Core Research Facility, University of Sydney, Sydney, NSW, Australia.
Front Microbiol. 2024 Sep 23;15:1443491. doi: 10.3389/fmicb.2024.1443491. eCollection 2024.
Old Wallow is an underexplored, hyper-arid coastal desert in Antarctica's Vestfold Hills. Situated near an elephant seal wallow, we examined how stochastic nutrient inputs from the seal wallow affect soil communities amid environmental changes along a spatially explicit sampling transect. We hypothesized that nutrient levels would be elevated due to proximity to the seal wallow, influencing community distributions. While the soil bacterial and eukaryotic communities at the phylum level were similar to other terrestrial environments, analysis at class and family levels revealed a dominance of unclassified taxa that are often linked to marine environments. Elevated nutrient concentrations (NO , SO , SO) were found at Old Wallow, with conductivity and Cl levels up to 10-fold higher at the lowest elevation soils, correlating with significantly ( < 0.05) higher abundances of halophilic () and uncultivated lineages ( Actinomarinales, unclassified and unclassified ). An improved Gradient Forest model was used to quantify microbial responses to 26 soil gradients at OW, revealing variable responses to environmental predictors and identifying critical environmental thresholds or drivers of community turnover. Major tipping points were projected for eukaryotes with SO , pH, and SO, and for bacteria with moisture, NaO, and Cl. Thus, the Old Wallow ecosystem is primarily shaped by salt, sulphate, and moisture and is dominated by uncultivated taxa, which may be sensitive to environmental changes once critical tipping points are reached. This study provides critical baseline data for future regional monitoring under threats of environmental change.
老沃洛是南极洲弗斯德山一片未被充分探索的极度干旱的沿海沙漠。它位于一个海象栖息地附近，我们沿着一条空间明确的采样样带，研究了来自海象栖息地的随机养分输入如何在环境变化中影响土壤群落。我们假设，由于靠近海象栖息地，养分水平会升高，从而影响群落分布。虽然土壤细菌和真核生物群落的门水平与其他陆地环境相似，但在纲和科水平的分析显示，未分类的分类群占主导地位，这些分类群通常与海洋环境有关。在老沃洛发现了升高的养分浓度（NO 、SO 、SO），最低海拔土壤的电导率和Cl水平高达10倍，与嗜盐菌（）和未培养谱系（放线菌目、未分类 和未分类 ）的丰度显著更高（<0.05）相关。使用改进的梯度森林模型来量化微生物对老沃洛26种土壤梯度的反应，揭示了对环境预测因子的可变反应，并确定了群落周转的关键环境阈值或驱动因素。预测真核生物的主要临界点为SO 、pH和SO，细菌的临界点为湿度、NaO和Cl。因此，老沃洛生态系统主要由盐、硫酸盐和水分塑造，且以未培养的分类群为主，一旦达到关键临界点，这些分类群可能对环境变化敏感。这项研究为未来在环境变化威胁下的区域监测提供了关键的基线数据。
