Distinct Bacterial Communities in Wet and Dry Seasons During a Seasonal Water Level Fluctuation in the Largest Freshwater Lake (Poyang Lake) in China.

Ze Ren,Wenqi Peng,Min Zhang,Xiaodong Qu,Yang Yu

doi:10.3389/fmicb.2019.01167

Ze Ren, Wenqi Peng + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2019.01167

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Abstract

Water level fluctuations (WLFs) are an inherent feature of lake ecosystems and have been regarded as a pervasive pressure on lacustrine ecosystems globally due to anthropogenic activities and climate change. However, the impacts of WLFs on lake microbial communities is one of our knowledge gaps. Here, we used the high-throughput 16S rRNA gene sequencing approach to investigate the taxonomic and functional dynamics of bacterial communities in wet-season and dry-season of Poyang Lake (PYL) in China. The results showed that dry-season was enriched in total nitrogen (TN), nitrate (NO3-), ammonia (NH4+), and soluble reactive phosphorus (SRP), while wet-season was enriched in dissolved organic carbon (DOC) and total phosphorus (TP). Bacterial communities were distinct taxonomically and functionally in dry-season and wet-season and the nutrients especially P variation had a significant contribution to the seasonal variation of bacterial communities. Moreover, bacterial communities responded differently to nutrient dynamics in different seasons. DOC, NO3-, and SRP had strong influences on bacterial communities in dry-season while only TP in wet-season. Alpha-diversity, functional redundancy, taxonomic dissimilarities, and taxa niche width were higher in dry-season, while functional dissimilarities were higher in wet-season, suggesting that the bacterial communities were more taxonomically sensitive in dry-season while more functionally sensitive in wet-season. Bacterial communities were more efficient in nutrients utilization in wet-season and might have different nitrogen removal mechanisms in different seasons. Bacterial communities in wet-season had significantly higher relative abundance of denitrification genes but lower anammox genes than in dry-season. This study enriched our knowledge of the impacts of WLFs and seasonal dynamics of lake ecosystems. Given the increasingly pervasive pressure of WLFs on lake ecosystems worldwide, our findings have important implications for conservation and management of lake ecosystems.

Highlights

Lakes fluctuate intra- and inter-annually in response to seasonal and long-term hydrologic imbalance, respectively
Given the increasingly pervasive pressure of Water level fluctuations (WLFs) on lake ecosystems worldwide, in this study, we examined the microbial communities in wet-season and dry-season of Poyang Lake (PYL) using high-throughput 16S rRNA gene sequencing and assessed the functional potentials in carbon (C-), nitrogen (N-), and phosphorus (P-) cycles
In dry-season, NO3− and NH4+ accounted for 72 and 12% of total nitrogen (TN), and soluble reactive phosphorus (SRP) accounted for 81% of total phosphorus (TP) on average

Summary

Introduction

Lakes fluctuate intra- and inter-annually in response to seasonal and long-term hydrologic imbalance, respectively. WLFs might have an overriding effect on the health and integrity of some lake ecosystems (Leira and Cantonati, 2008). These natural hydrological regimes are increasingly impacted by anthropogenic activities on local and global scales through dam construction, water extraction, as well as on-going climate change (Poff and Zimmerman, 2010; Haddeland et al, 2014)

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