Abstract
Bacterial communities have been described as early indicators of both regional and global climatic change and play a critical role in the global biogeochemical cycle. Exploring the mechanisms that determine the diversity patterns of bacterial communities and how they share different habitats along environmental gradients are, therefore, a central theme in microbial ecology research. We characterized the diversity patterns of bacterial communities in Pipahai Lake (PPH), Mayinghai Lake (MYH), and Gonghai Lake (GH), three subalpine natural lakes in Ningwu County, Shanxi, China, and analyzed the distribution of their shared and unique taxa (indicator species). Results showed that the species composition and structure of bacterial communities were significantly different among the three lakes. Both the structure of the entire bacterial community and the unique taxa were significantly influenced by the carbon content (TOC and IC) and space distance; however, the structure of the shared taxa was affected by conductivity (EC), pH, and salinity. The structure of the entire bacterial community and unique taxa were mainly affected by the same factors, suggesting that unique taxa may be important in maintaining the spatial distribution diversity of bacterial communities in subalpine natural freshwater lakes. Our results provide new insights into the diversity maintenance patterns of the bacterial communities in subalpine lakes, and suggest dispersal limitation on bacterial communities between adjacent lakes, even in a small local area. We revealed the importance of unique taxa in maintaining bacterial community structure, and our results are important in understanding how bacterial communities in subalpine lakes respond to environmental change in local habitats.
Highlights
Aquatic bacteria are important components of lake ecosystems, having a high level of species diversity and playing essential roles in global biogeochemical cycles
The concentration of total organic carbon (TOC) was higher in Pipahai Lake (PPH) than in Gonghai Lake (GH) and Mayinghai Lake (MYH); the other eight factors were highest in GH (p < 0.05)
We found that the abundance of the dominant shared operational taxonomic unit (OTU) was different among the three lakes (Figure 3B), and this was significantly related to electric conductivity (EC), carbon (TC and inorganic carbon (IC)), and nitrogen (TN, NO-3, and NH+4 ; Supplementary Table S2)
Summary
Aquatic bacteria are important components of lake ecosystems, having a high level of species diversity and playing essential roles in global biogeochemical cycles. It is clear that bacteria are active and potentially significant players in water biological processes This means that understanding the diversity of aquatic bacteria and their biogeographical patterns will help to explain the variations in ecosystem functioning, and to predict ecosystem responses to current and future environmental changes (Hanson et al, 2012). Biogeographical patterns of shared and unique bacterial taxa in different habitats have been under-researched compared with the abundant and rare bacterial taxa in lakes and reservoirs (Baltar et al, 2015; Wu et al, 2016; Xue et al, 2018). Unique taxa are more restricted in habitat range, and their distribution is strongly affected by habitat conditions and distance between habitats (Mckenzie et al, 2012; Miura et al, 2019) It seems that both rare and unique taxa are mainly affected by environmental factors, but unique taxa have strict habitat specificity. Little is known about the biogeographical basic patterning of shared and unique bacterial taxa, and to what extent lakes share bacterial taxa in a local area
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