Do Phaeocystis colony blooms affect zooplankton in the Belgian coastal zone

The ability of herbivorous zooplankton to control phytoplankton blooms, and to efficiently transfer primary production towards higher trophic levels such as invertebrates, fish larvae and planktivorous fish, is considered as a sign of equilibrium in marine ecosystems. This is not the case in the Southern Bight of the North Sea where massive Phaeocystis colony spring blooms sustained by anthropogenic nitrates, are suggested to be the consequence of a high resistance to losses, in particular grazing (Lancelot et al., 1994; 2002). To which extent Phaeocystis colony blooms are negatively impacting zooplankton dynamic is investigated in this chapter, based on available information on zooplankton in the Belgian coastal zone (BCZ).