Quantifying the Role of Heterotrophic Bacteria in the Carbon Cycle: A Need for Respiration Rate Measurements

During the past two decades, microbial studies have convincingly demonstrated the existence of a diverse, numerous, and active heterotrophic bacterial community, However, due to methodological uncertainties and limitations, these studies do not accurately constrain the role of the bacterial community in determining the fate of organic carbon in aquatic systems. This is, in part, because most studies have focused solely on biomass production as the primary measure of bacterial metabolic activity. In addition, many investigators have not fully appreciated the magnitude of the uncertainties associated with biomass production measurements and respiration rates derived from them. The incorporation of the bacterial community into quantitative models of carbon cycling would be accelerated if future research efforts placed greater emphasis on the determination and interpretation of respiration rates.