Spatial patterns in picoplankton communities along a cascade reservoir system (Limay River, Patagonia) in relation to environmental factors

LU LUNHUI ; VERA M. SOLANGE; LI ZHE; BERNAL MARÍA CAROLINA; SANCHEZ M.L; PORCEL S.; SABIO Y GARCÍA, C.; SINISTRO R.; IZAGUIRRE I.

Ciudad del Cabo

Congreso; ISME Virtual Microbial Ecology; 2020

ISME

We explored how picoplankton community structure and diversity varied along three cascade oligo-mesotrophic reservoirs (Alicura, Piedra del Águila and Ramos Mexía) along the Limay River and an affluent (Collon Cura-CC), covering lotic and lentic stretches and a 262 km landscape gradient from Andes to steppe (Patagonia, Argentina). Subsuperficial samples were taken at 12 sites during summer 2019. Main limnological variables were measured. Picoplankton abundances were obtained through flow cytometry, and cytometric populations were identified. Bacterial samples were sequenced by Illumina MiSeq and Ribosomal Database Project classifier retrained with Greengenes was used for taxonomical assignment of Operational Taxonomic Units (OTUs).The slight increase in trophic status downstream coincided with higher picoplankton abundance in that direction, and was also associated to the spatial distribution of sites based on their bacterial OTU composition. Cytometric populations present in the overall system were typical of oligotrophic environments. Behaviour of Actinobacteria and Bacteroidetes as well as HNA and LNA abundances at CC and S8 may suggest a shift in ecological function related to hydrology. Evenness and richness patterns of bacterial OTUs agree with previous studies where lentic environments promoted species sorting and lotic systems provided new species from immigrant pools.