Nutrients Drive the Structures of Bacterial Communities in Sediments and Surface Waters in the River-Lake System of Poyang Lake

Abstract

Lake and its inflow rivers compose a highly linked river-lake system, within which sediment and water are also closely connected. However, our understanding of this linked and interactive system remains unclear. In this study, we examined bacterial communities in the sediments and surface waters in Poyang Lake and its five tributaries. Bacterial communities were determined while using high-throughput 16S rRNA gene sequencing. The results showed significant differences of bacterial communities between sediments and surface waters, as well as between Poyang lake and its tributaries, suggesting that the river-lake system of Poyang Lake provides diverse and distinct habitats for bacterial communities, including lake water, lake sediment, river water, and river sediment. These biomes harbor distinct bacterial assemblages. Sediments harbor more diverse bacterial taxa than surface waters, but the bacterial communities in surface waters were more different across this river-lake system than those in sediments. In this eutrophic river-lake ecosystem, nitrogen and phosphorus were important drivers in sediment bacterial communities. Nitrogen, phosphorus, and dissolved organic carbon, as well as their stoichiometric ratios affected bacterial communities in surface waters. Moreover, network analysis revealed that the bacterial communities in surface waters were more vulnerable to various disturbances than in sediments, due to lower alpha diversity, high complexity of network, and a small number of key taxa (module hubs and connectors). Nutrient variables had strong influences on individual operational taxonomic units (OTUs) in the network, especially in bacterial network in surface waters. Different groups of taxa responded differently to nutrients, with some modules being more susceptible to nutrient variations. This study increased our current knowledge of linked river-lake ecosystems and provided valuable understanding for effective management and protection of these ecosystems by revealing bacterial communities in sediments and surface waters in Poyang Lake and its tributaries, as well as their responses to nutrients variation.

Functional properties of bacterial communities in water and sediment of the eutrophic river-lake system of Poyang Lake, China

“…Samples were collected from the surface water and sediment of Poyang lake and its fiver tributaries (Xiushui, Ganjiang, Fuhe, Xinjiang, and Raohe). This figure was modified from Ren et al (2019).…”

“…Lakes and their tributaries are highly linked ecosystems in multiple ways, especially through materials transported from the watershed to the lake through river systems (Cole et al, 2006; Marcarelli & Wurtsbaugh, 2009; Jones, 2010; Ylla et al, 2013). Microbial communities in lake and its tributaries have different taxonomic compositions (Ren et al, 2017a, 2019). In lake ecosystems, water and sediment are two distinct realms and interact closely through biogeochemical processes (Parker et al, 2016).…”

“…In lake ecosystems, water and sediment are two distinct realms and interact closely through biogeochemical processes (Parker et al, 2016). These two habitats host tremendous diversity of microorganisms (Lozupone & Knight, 2007; Röeske et al, 2012; Huang et al, 2016), which constitute distinct microbial communities in sediment and water column (Briée, Moreira & López-García, 2007; Nishihama et al, 2008; Ren et al, 2019). However, the functional differences of bacterial communities in sediment and water column of lake-river systems were not well studied.…”

“…The increase in nutrient inputs caused by agriculture, urbanization, and industry has significantly degraded water quality and ecological integrity of Poyang Lake with serious eutrophication (Wang et al, 2015; Zhang et al, 2015; Liu, Fang & Sun, 2016). In the river-lake systems of Poyang Lake, our previous study has shown that the taxonomic composition of bacterial communities in lake sediment (SL), river sediment (SR), lake water (WL), and river water (WR) had distinct spatial distribution patterns and close relationships with nutrients (Ren et al, 2019). However, our understanding of the functions mediated by the bacterial communities in the sediment and water of this linked river-lake ecosystem is still limited.…”

Impact of Nutrient and Stoichiometry Gradients on Microbial Assemblages in Erhai Lake and Its Input Streams

“…The most likely mechanism for synergistic effects of N and P is that a single nutrient quickly induces limitation by the alternative nutrient [64]. Additionally, previous studies have shown that organic carbon plays an important role in regulating microbial assemblages and the food web of aquatic ecosystems [65][66][67]. In the present study, synergistic effects of C-factor and P-factor (C:P) and N-factor and P-factor (N:P) played crucial roles in regulating bacterial communities in Erhai Lake (Figure 7 and Figure S1).…”