Abstract
Since the early 21st century, global climate change has been inducing rapid glacier retreat at an unprecedented rate. In this context, the melt ponds impart increasing unique footprints on the periglacial rivers due to their hydrodynamic connection. Given that bacterial communities control numerous ecosystem processes in the glacial ecosystem, exploring the fate of bacterial communities from melt ponds to periglacial rivers yields key knowledge of the biodiversity and biogeochemistry of glacial ecosystems. Here, we analyzed the bacterial community structure, diversity, and co-occurrence network to reveal the community organization in the Zhuxi glacier in the Tibet Plateau. The results showed that the bacterial communities in melt ponds were significantly lower in alpha-diversity but were significantly higher in beta-diversity than those in periglacial rivers. The rare sub-communities significantly contributed to the stability of the bacterial communities in both habitats. The co-occurrence network inferred that the mutually beneficial relationships predominated in the two networks. Nevertheless, the lower ratio of positive to negative edges in melt ponds than periglacial rivers implicated fiercer competition in the former habitat. Based on the significantly higher value of degree, betweenness, and modules, as well as shorter average path length in melt ponds, we speculated that their bacterial communities are less resilient than those of periglacial rivers.
Highlights
Glacial ecosystems, at the interface of the cryosphere, hydrosphere, pedosphere, and the biosphere, cover approximately 10% of the Earth’s surface [1] and store approximately 75% of the world’s freshwater [2]
Our results showed that the aquatic environments were inherently distinct between melt ponds and periglacial rivers (Figure 2)
dissolved total phosphorus (DTP) was below the detection limitation in both habitats
Summary
At the interface of the cryosphere, hydrosphere, pedosphere, and the biosphere, cover approximately 10% of the Earth’s surface [1] and store approximately 75% of the world’s freshwater [2]. Owing to rapid population growth, water demand exceeds supply worldwide, making glacial meltwater a crucial resource [3,4]. Research to date on the practical and scientific fields has focused largely on the glacial ecosystems [5,6]. Distributed over glacial landscapes and key components of glacial ecosystems are melt ponds, which collect meltwater on the glacial surface in visible pools [7]. The mechanisms of their formation and maintenance have been widely explored. Topographic depressions in the surface exert a first-order control on the formation of melt ponds, followed by a positive albedo-feedback that the lower albedo of surface waters enhances radiative-driven melting [8]. Despite the harsh and pristine environment, melt ponds are not lifeless, but support a remarkable biodiversity, including archaea, bacteria, as well as microeukaryotes [9,10,11,12]
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