Linking Bacterial Community Structure to Carbon Fluxes in Marine Environments

Microbial oceanography is undergoing a dramatic revolution thanks to the rapid development of novel techniques that allow the examination of microbial diversity and functions via molecular methods, including genomic and metagenomic analyses. During the past decade, studies have revealed previously unknown and surprisingly diverse bacterial communities in marine waters. These studies have radically changed our understanding of spatiotemporal patterns in marine bacterial community composition and the distribution of specific genes. However, our knowledge of the role of individual bacterial subgroups in oceanic food webs and biogeochemical cycles remains limited. To embed the internal dynamics of bacterial communities into marine biogeochemistry models, the characteristic parameters of individual bacterial subgroups (i.e., growth, mortality, and utilization of dissolved organic matter) must be determined. Here, we survey the approaches used to assess variation in and factors controlling bacterial communities in marine environments, emphasizing the importance of quantitative studies that examine growth and grazing parameters of bacterial subgroups.