The low density of cladocera wase observed in Hulun Lake. The absence of cladocera was observed
could be due to the effects of fish predation. Zooplankton is influenced strongly by both bottom-up and
top-down processes and is often used as models for ecological paradigm. In order to effectively utilize
water resources, some fish fries (including carp and silver carp) are released by relevant government
department. It is likely that fish predation limits the biomass of macro-zooplankton in productive lakes.
Lakes with intense fish predation typically have only small species of cladocera, which was found to be
the major factor structuring zooplankton assemblages in several studies [38-40]. The above conclusion
was also observed substantial reductions in macrozooplankton biomass with gradients of fish predation
[41]. In winter, it is biotic interaction operating through feeding pressure rather than water quality. It
seems to affect the zooplankton diversity and density particularly the stocked fish species which play an
important role in harvesting species of zooplankton, thereby reducing their predatory pressure on other
groups.