longitudinal trends and coupling with primary production

Abstract. Spatial variation of heterotrophic bacterial pro-duction and phytoplankton primary production were inves-tigated across the eastern South Pacific Ocean (−141 ◦ W, −8 ◦ S to −72 ◦ W, −35 ◦ S) in November–December 2004. Bacterial production (3H leucine incorporation) integrated over the euphotic zone encompassed a wide range of val-ues, from 43 mg C m−2 d−1in the hyper-oligotrophic South Pacific Gyre to 392 mg C m−2 d−1 in the upwelling off Chile. In the gyre (120 ◦ W, 22 ◦ S) records of low phytoplankton biomass (7 mg Total Chla m−2) were obtained and fluxes of in situ 14C-based particulate primary production were as low as 153 mg C m−2 d−1, thus equal to the value considered as a limit for primary production under strong oligotrophic conditions. Average rates of 3H leucine incorporation rates, and leucine incorporation rates per cell (5–21 pmol l−1 h−