Flood pulse regulation of bacterioplankton community composition in an Amazonian floodplain lake

Abstract

Understanding spatial and temporal dynamics of microbial communities is a central challenge in microbial ecology since microorganisms play a key role in ecosystem functioning and biogeochemical cycles. Amazonian aquatic systems comprise a dynamic mosaic of heterogeneous habits but are understudied and there is limited information about the mechanisms that shape bacterial community composition (BCC). There is a consensus that environmental selection (species sorting) and dispersal processes (source–sink dynamics) act in concert to shape the composition of these communities, but the relative importance of each mechanism may vary dramatically through time and between systems. Applying 16S rRNA gene amplicon high‐throughput sequencing, we studied factors and processes that modulate BCC in an Amazonian floodplain lake and used source‐tracking models to trace the main dispersal sources of microorganisms in the whole floodplain system during a full hydrological cycle. Our source‐tracking models indicated that dispersal processes were predominant, explaining most of the BCC variability throughout the study period. We observed more sources contributing to the sink community during the falling water than rising water period, when contributions from the Solimões River dominated. There was a clear seasonal pattern in BCC, closely related to environmental variables, suggesting that the successful establishment of dispersing bacteria also depends on environmental filtering that is linked to water flow. In summary, source–sink dynamics and species sorting were strongly affected by water exchange and connectivity with the main river that varied throughout the flood pulse cycle. Our results demonstrated the influence of lateral transport and temporal dynamics on BCC in Amazonian floodplain lakes that could ultimately impact regional carbon budgets and biogeochemical cycles.

Linking dissolved organic matter composition and bacterioplankton communities in an Amazon floodplain system

“…Floodplain lake Janauacá (3°23′S, 60°18′W; altitude 32 m) is located in the central Amazon basin, on the south margin of Solimões River, being permanently connect to it year‐round by a 12‐km long channel (more details can be found in de Melo et al ). We performed seasonal sampling between June 2015 and May 2016, for a total of five campaigns in different phases of the annual hydrological cycle (Fig.…”

“…To track changes in DOM composition, we used samples from all of these campaigns; but to specifically assess the BCC‐DOM coupling, we used samples for only four campaigns (excluding the LW campaign). Samples were collected just below the water surface (50 cm depth) at five sites ( see de Melo et al ): (1) drainage basin—a region of the lake draining upland areas, characterized by seasonally variable clear and humic waters; (2) open lake Janauacá—an open water area in the northern region of the floodplain lake, strongly influenced by Solimões waters during high water periods; (3) macrophyte bank—site located near to the lake margin, dominated by different aquatic grass species throughout the year ( Paspalum repens P.J. Bergius, Oryza rufipogon Griff, Luziola spruceana Benth.…”

“…DNA was extracted from filters using the phenol‐chloroform method followed by purification with Amicon Ultra‐4 centrifugal filters (Millipore® 100 kDa) (Ganesh et al ). Using primers 341F (5′‐CCTACGGGNGGCWGCAG‐3′) and 805R (5′‐GACT ACHVGGGTATCTAATCC‐3′), we amplified the V3/V4 region of the 16rRNA gene (Herlemann et al ) and then performed PCR reactions and purifications (more details in de Melo et al ). High‐throughput sequencing was performed on an Illumina Miseq2000 instrument using a paired‐end approach and 2 × 250 bp chemistry.…”

Bacterial community composition and function along spatiotemporal connectivity gradients in the Danube floodplain (Vienna, Austria)

“…Also, hydrology-related parameters, like water level, water age and electrical conductivity were among the potential drivers of BCC, emphasizing the impact of hydrological connectivity on BCC (Besemer et al 2005). Hydrology has also been found to be an important regulator of the BCC in an Amazonian floodplain lake and alpine floodplains (Freimann et al 2015;Melo et al 2019).…”

Eukaryote microbes potential for bioflocs in the swamp aquaculture

“…The aquatic microorganisms play an important role in the water ecosystem and biogeochemical cycles (De Melo et al, 2018). The eukaryote microbes, comprising microalgae, fungi, and microzooplankton, are important components of water productivity.…”