Abstract: Metabolism of organic carbon of plankton community in shrimp cultural enclosure ecosystems was studied from May 30 to August 23,1997 in the shrimp farm of Huanghai Fishery Group corporation.The results indicated that the plankton community respiration rate fluctuated from 0.07 to 2.28mg C·L^-1·d^-1 with an average of 0.82±0.42mgC·L^-1·d^-1;in which,phytoplankton respiration rate averaged 0.34mgC·L^-1·d^-1,while zooplankton and bacteria respiration rates averaged 0.48 mgC·L^-1·d^-1,constituting 41% and 59% of the plankton community respiration rates respectively.Phytoplankton production rates fluctuated from 0.08 to 4.41 mgC·L^-1·d^-1 with an average of 1.68±0.80mgC·L^-1·d^-1.Its average ratio to plankton community respiration rate was 1∶0.49.The rate of plankton community respiration correlated positively with particular organic carbon concentration,but negatively with dissolved organic carbon concentration and water transparency.About 35% of the total organic carbon income was mineralized through the process of plankton community metabolism during the cultural period.

Key words: soil fungi, N₂O production mechanism, N transformation processes, N₂O emission.