Mesoscale variability in the metabolic balance of the Sargasso Sea

Net community production (NCP) experiments based on in vitro changes in dissolved oxygen were carried out in three mesoscale eddies investigated in the Sargasso Sea in the summer of 2004. NCP estimates ranged from negative to positive values, and the age and type of the sampled eddy were important factors responsible for this variability. Positive rates occurred in younger cyclones and in areas of eddy-eddy interactions, whereas negative NCP rates were observed in anticyclones and older cyclone features that were decaying. This information was combined with a nine-year data set from the BATS program and satellite altimeter data to assess the role of mesoscale eddies in the metabolic balance of the Sargasso Sea. Indirect NCP estimates (NCPe) were obtained by calculating the difference between C-14 phytoplankton production and bacterial carbon demand rates. The results showed highly variable NCPe rates that spanned the range of direct NCP observations.