Laboratory of Microbial Ecology, Department of Ecological Sciences, Faculty of Sciences, Universidad de Chile, Santiago, Chile.
Centre for Genomics, Ecology and Environment (GEMA), Faculty of Sciences, Universidad Mayor, Santiago, Chile.
PLoS One. 2019 Jan 9;14(1):e0209887. doi: 10.1371/journal.pone.0209887. eCollection 2019.
Seabirds and pinnipeds play an important role in biogeochemical cycling by transferring nutrients from aquatic to terrestrial environments. Indeed, soils rich in animal depositions have generally high organic carbon, nitrogen and phosphorus contents. Several studies have assessed bacterial diversity in Antarctic soils influenced by marine animals; however most have been conducted in areas with significant human impact. Thus, we chose Cape Shirreff, Livingston Island, an Antarctic Specially Protected Area designated mainly to protect the diversity of marine vertebrate fauna, and selected sampling sites with different types of animals coexisting in a relatively small space, and where human presence and impact are negligible. Using 16S rRNA gene analyses through massive sequencing, we assessed the influence of animal concentrations, via their modification of edaphic characteristics, on soil bacterial diversity and composition. The nutrient composition of soils impacted by Antarctic fur seals and kelp gulls was more similar to that of control soils (i.e. soils without visible presence of plants or animals), which may be due to the more active behaviour of these marine animals compared to other species. Conversely, the soils from concentrations of southern elephant seals and penguins showed greater differences in soil nutrients compared to the control. In agreement with this, the bacterial communities of the soils associated with these animals were most different from those of the control soils, with the soils of penguin colonies also possessing the lowest bacterial diversity. However, all the soils influenced by the presence of marine animals were dominated by bacteria belonging to Gammaproteobacteria, particularly those of the genus Rhodanobacter. Therefore, we conclude that the modification of soil nutrient composition by marine vertebrates promotes specific groups of bacteria, which could play an important role in the recycling of nutrients in terrestrial Antarctic ecosystems.
海鸟和鳍足类动物通过将营养物质从水生环境转移到陆地环境，在生物地球化学循环中发挥着重要作用。事实上，富含动物沉积物的土壤通常具有较高的有机碳、氮和磷含量。已经有几项研究评估了受海洋动物影响的南极土壤中的细菌多样性；然而，大多数研究都是在人类影响较大的地区进行的。因此，我们选择了利文斯顿岛的谢雷夫角，这是一个南极特别保护区，主要目的是保护海洋脊椎动物区系的多样性，并选择了不同类型的动物共存于相对较小空间的采样点，且人类的存在和影响可以忽略不计。通过大规模测序的 16S rRNA 基因分析，我们评估了动物浓度（通过改变土壤特性）对土壤细菌多样性和组成的影响。受南极软毛海豹和巨藻鸥影响的土壤的养分组成与对照土壤（即没有可见的植物或动物存在的土壤）更为相似，这可能是由于这些海洋动物的行为比其他物种更为活跃。相反，来自南象海豹和企鹅聚居地的土壤的养分差异与对照土壤相比则更大。与此一致的是，与这些动物相关的土壤中的细菌群落与对照土壤的差异最大，企鹅聚居地的土壤的细菌多样性也最低。然而，所有受海洋动物存在影响的土壤都以属于γ-变形菌门的细菌为主，特别是罗丹杆菌属的细菌。因此，我们得出结论，海洋脊椎动物对土壤养分组成的改变促进了特定的细菌群，这些细菌群可能在南极陆地生态系统的养分循环中发挥重要作用。
