Abstract
Climate change has given rise to salinization and nutrient enrichment in lake ecosystems of arid and semiarid areas, which have posed the bacterial communities not only into an ecotone in lake ecosystems but also into an assemblage of its own unique biomes. However, responses of bacterial communities to climate-related salinization and nutrient enrichment remain unclear. In September 2019, this study scrutinized the turnover of bacterial communities along gradients of increasing salinity and nutrient by a space-for-time substitution in Xinjiang Uyghur Autonomous Region, China. We find that salinization rather than nutrient enrichment primarily alters bacterial communities. The homogenous selection of salinization leads to convergent response of bacterial communities, which is revealed by the combination of a decreasing β-nearest taxon index (βNTI) and a pronounced negative correlation between niche breadth and salinity. Furthermore, interspecific interactions within bacterial communities significantly differed among distinct salinity levels. Specifically, mutualistic interactions showed an increase along the salinization. In contrast, topological parameters show hump-shaped curves (average degree and density) and sunken curves (modularity, density, and average path distance), the extremums of which all appear in the high-brackish environment, hinting that bacterial communities are comparatively stable at freshwater and brine environments but are unstable in moderately high-brackish lake.
Highlights
In arid and semiarid areas, lake ecosystems are typically unproductive, and external disturbances dominate in-lake processes, making these systems ideal sentinels of environmental disturbance
Based on the above hypothesis, we addressed the following questions: (1) Which climate-related disturbance primarily regulates the bacterial community dynamics? (2) What are the adaptive strategies of bacterial communities? (3) How does bacterial community stability respond to environmental disturbances? By addressing these issues, we attempt to provide new insights into the future responses of bacterial communities in relation to climate change
The principal component analysis (PCA) results indicated that these four lakes were significantly heterogeneous, there was overlap between Lake R1 and Lake Bosten (Figure 2A)
Summary
In arid and semiarid areas, lake ecosystems are typically unproductive, and external disturbances dominate in-lake processes, making these systems ideal sentinels of environmental disturbance. Nutrient enrichment is regarded as another most urgent environmental problem in arid and semiarid areas. In the context of climate change, the combination of salinization and nutrient enrichment renders the biotic communities of lake ecosystems in arid and semiarid areas not just as an ecotone but rather an assemblage with unique biomes and biotic processes (Lozupone and Knight, 2007; Tang et al, 2021). A flurry of research about the responses of lake ecosystems to climate change has led to an increasing interest in how communities respond to salinization and nutrient enrichment in arid and semiarid areas
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