Dinâmica espaço – temporal do bacterioplâncton em um sistema de várzea Amazônico
Resumo
Amazonian floodplains are complex networks that play relevant roles in global
biogeochemical cycles, and the bacterioplankton degradation of organic matter is key in
regional carbon budget in these systems. The Amazon undergoes seasonal variations in water
level, which produces changes in landscape and in sources of organic inputs into floodplain
systems. Although these changes should affect bacterioplankton, no studies have addressed
the question of which factors drive spatial and temporal patterns of bacterioplankton in these
systems. We used high-throughput (Illumina MiSeq) sequencing of the V3-V4 region of the
16SrRNA gene to investigate the spatiotemporal patterns of bacterioplankton community at
different diversity layers and size fractions, and their correlation with environmental variables
in an Amazon floodplain lake. Overall, four phyla dominated the community throughout the
study: Actinobacteria, Cyanobacteria, Proteobacteria and Planctomycetes, but their
abundance were different between size fractions, hydrologic periods and influence area. The
rare biosphere had an important contribution for the composition patterns of all community
and showed be more influenced by the spatial complexity. We found that the floodpulse was
the mainly drive force of community composition patterns for the free-living fraction, and the
distance from the Amazon river was the main driver for the particle-attached fraction. We
also found differences between the combination of local and regional factors across space and
time shaping the community. This is the first detailed characterization of the bacterioplankton
community composition in an Amazon floodplain lake and we demonstrated that the spatial
and temporal complexity of this system were reflected in bacterioplankton community
composition.