The efficiency of the biological pump transferring carbon from the
surface to deep waters can be reduced to a large extent due to the
demineralization of sinking material in the upper layers (Buesseler
et al., 2007). In such cases, the contribution of zooplankton to the biological
pump would be mainly mediated by its capacity to perform
diel vertical migrations (DVMs), releasing during the day, at depth,
part of the material taken up at surface waters when migrating upward
at nighttime (Longhurst and Harrison, 1989). Zooplankton DVMis generally
thought as an antipredatory response (e.g. Frost and Bollens,
1992). This process is triggered by changes in light intensity, although