The contribution of zooplankton DVM to the vertical flux was estimated
only for the largest size class (Bongo samples) due to the lack
of diel differences for the rest of the fractions. The flux of carbon respired
below 500 m was estimated as in Zhang and Dam (1997), by applying
the equation F = B ∗ M ∗ T, where B is the diel-migrating zooplankton
biomass (in mg DW m−2) calculated as the difference between day
and night samples;M is the hourly metabolic rate; and T is the average
number of daylight hours (12, 14 and 11.5 in March, May and