Nutrient limitation of cyanobacteria in the Tropical Pacific

Thomas Browning1, Mak A Saito2, Xuechao Wang3, Alessandro Tagliabue4, Anja Engel5 and Eric P Achterberg1, (1)GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, (2)WHOI, Woods Hole, MA, United States, (3)GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, (4)University of Liverpool, Liverpool, United Kingdom, (5)GEOMAR, Helmholtz-Zentrum für Ozeanforschung, Kiel, Germany
Assessments of oceanic nutrient limitation are method dependent. On the one hand, identifying in situ phytoplankton physiological stress via observation of their proteome potentially provides the least ambiguous measure of how in situ nutrient availability might be impacting resource use efficiency and therefore specific growth rate. On the other, directly observing the response of phytoplankton groups to experimental supply of a nutrient is potentially an easier way to connect nutrient availability with growth in a quantitative way. We have attempted to pair both approaches in nitrogen and iron limited regions of the tropical Pacific Ocean. In this presentation I will present these observations and discuss how they could provide insight into modelling nutrient limited phytoplankton growth in the ocean.