CARBON FLUX BY SEASONAL VERTICAL MIGRANT COPEPODS IS A SMALL NUMBER

The abundant species of Calanus that dominate the mesozooplankton of high North Atlantic latitudes overwinter at depths >500 m, when the population loses 70-80% of its biomass by predation and physiological stress. This represents an annual flux of carbon, obtained in the photic zone, into the interior of the ocean of 274.5 mg C m-2 year-1, or 0.001 8 Gt C year-1 for the North Atlantic. This is a small value compared with the flux of respiratory carbon by diel migrants in warmer oceans and, when extrapolated to a global flux (0.012-0.018 Gt C year-1) over areas where winter migrations are important is also small compared with computations of the global sinking flux of particles through 200 m (1.6-3.8 Gt C year-1), or other relevant global carbon fluxes in the oceans.