N. minor exudates can inhibit the growth of phytoplankton mono- specific species, whether it also has the potential to inhibit natural phytoplankton assemblages in lake water is not known. So, we col- lected the phytoplankton assemblages from eutrophic lake water and measured their response to N. minor exudates. As expected, the chlorophyll a and TFP contents decreased significantly, which in- dicated that N. minor exudates stress resulted in a decrease in the phytoplankton biomass and an inhibition in the total dehydroge- nase activity.