Bioturbation Effect of Misgurnus anguillicaudatus on Nitrogen Dynamic in Surface Water of Paddy Field

Bioturbation effect of benthic fish,e.g.Misgurnus anguillicaudatus,on nitrogen dynamic in paddy field surface water and its mechanism was investigated through a simulation experiment analyzing comparatively nitrogen contents in waters with and without Misgurnus anguillicaudatus.Misgurnus anguillicaudatus showed strong bioturbation effect.Throughout the experiment,NH⁺₄-N and NO^-₃-N concentrations remained higher in the bioturbation group than in the control group,while NO^-₂-N concentration did not show any obvious rules.In the early stage of the experiment NH⁺₄-N/TN ratio was higher in the bioturbation group than in the control group,while in the middle and late stages of the experiment it turned reversely.DIN/TN ratio was markedly higher in the bioturbation group than in the control group.Misgurnus anguillicaudatus bioturbation increased remarkably DIN and TN concentrations in paddy field surface water.