Microbial Observatory at North Temperate Lakes LTER Time series of bacterial community dynamics in Lake Mendota 2000 - 2009

With an unprecedented decade-long time series from a temperate eutrophic lake, we
analyzed bacterial and environmental co-occurrence networks to gain insight into seasonal
dynamics at the community level. We found that (1) bacterial co-occurrence networks were
non-random, (2) season explained the network complexity and (3) co-occurrence network
complexity was negatively correlated with the underlying community diversity across
different seasons. Network complexity was not related to the variance of associated
environmental factors. Temperature and productivity may drive changes in diversity across
seasons in temperate aquatic systems, much as they control diversity across latitude. While
the implications of bacterioplankton network structure on ecosystem function are still
largely unknown, network analysis, in conjunction with traditional multivariate techniques,
continues to increase our understanding of bacterioplankton temporal dynamics.