ABSTRACT
S. AGUSTI, J. I. GONZÁLEZ-GORDILLO, D. VAQUÉ, M. ESTRADA, M. I. CEREZO, G. SALAZAR, J. M. GASOL, and C. M. DUARTE
6.1 INTRODUCTION
The role of the ocean as a sink for anthropogenic CO2 is critically dependent on the transport of carbon to depths below 1,000 m, where it is removed from ventilating back to the atmosphere over centennial timescales [1, 2]. Ocean plankton contributes to remove CO2 through sinking of particles, transporting organic carbon at depth, the so-called biological pump [3, 4]. Sinking rates of individual phytoplankton cells are very slow, at ~1.5 m d−1 (ref. 5) expected for diatom cells [6]. However, Smayda [7] suggested that a range of physical and biological (aggregation, downwelling and density inversion currents, packaging of cells in faecal pellets) mechanisms can accelerate phytoplankton-sinking rates in situ [8, 9] beyond the rates expected for single cells.
