MEPS - Vol. 562 - FEATURE ARTICLE

Flow cytometric sorting of 14C-radiolabeled cells allowed quantification of primary productivity by specific picophytoplankton in the North Pacific subtropical gyre. Images: Flow cytogram and shipboard operations at Station ALOHA (Photo & diagram: Y. Rii).

Rii YM, Karl DM, Church MJ

 

Temporal and vertical variability in picophytoplankton primary productivity in the North Pacific Subtropical Gyre

Photosynthetic picoeukaryotes (PPE) and unicellular cyanobacteria Prochlorococcus and Synechococcus account for a substantial proportion of phytoplankton biomass and production in low-nutrient subtropical gyres. Rii and colleagues examined cell- and group-specific rates of 14C-primary productivity over a two-year period in the subtropical North Pacific Ocean. Prochlorococcus dominated picophytoplankton productivity and biomass, with PPE exhibiting high cell-specific rates of productivity. Synechococcus displayed large fluctuations in productivity with smaller fluctuations in biomass, suggesting tight coupling between production and removal processes. Results from this study highlight the importance of picophytoplankton productivity to carbon cycling in the North Pacific subtropical gyre, and emphasize the tight coupling between cellular production and removal in this oligotrophic habitat.

 

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