In conclusion, this is the first time that direct in situ measure-
ments of both autotrophic and heterotrophic processes have been
conducted in the North Atlantic oligotrophic gyre to estimate the
plankton microbial metabolic balance over short time scales allowed
by a Lagrangian sampling design. Our results demonstrate the
importance of using the confidence interval as a tool to adequately
characterize the metabolic balance of the microbial plankton com-
munities. The microbial plankton metabolism in the unproductive
open ocean may be more balanced than previously reported, as NCP
was not different from 0 in 83% of the sampling days.