Distribution patterns of the abundance of major bacterial and archaeal groups in Patagonian lakes

Abstract

We explored the distribution patterns of bacterial and archaeal abundances at the phylum and class level using cata-lyzed reporter deposition-fluorescencein situhybridization (CARD-FISH), examining the among (across 35 waterbodies) and within-lake (intra-annual seasonality) patterns in Patagonia (Argentina).Alphaproteobacteria,BetaproteobacteriaandActinobacteriaglobally dominated the bacterioplankton, whereasGammaproteobacteriaandArchaeanever exceeded 3and 6% of the community, respectively. The different groups showed seasonality, with simultaneous peaks of all bacter-ial group absolute abundances during late winter or spring, and with peaks ofArchaeaduring winter, late spring andsummer. The bacterial groups presented roughly similar relative abundances in all seasons, whereasArchaeavaried intheir relative contribution to community structure. Multivariate analyses showed that dissolved organic carbon was animportant variable structuring the community at the studied taxonomic resolution (using absolute and relative abun-dances), in both among and within-lake patterns. The absolute abundance of most bacterial groups was significantlyhigher in mesotrophic and eutrophic systems than in oligotrophic ones (exceptActinobacteria), whereas their relativeabundances did not change among trophic states (exceptBacteroidetes). The lake grouping obtained from CARD-FISHwas consistent with previous work using polymerase chain reaction-denaturing gradient gel electrophoresis data: deepoligotrophic lakes clustered together, whereas small and shallow water bodies grouped separately