Effects Of Procambarus Clarkia Biotuibation On The Degradation And Utilization Of Organic Matter In Pond Sediments

This study used the Procambarus clarkia as research object.Six glass tanks were set in this experiment,and divided into treatment group and control group.Each group had 3 replicates.The effect of bioturbation derived from the Procambarus clarkia on the degradation of sedimentary organci matter was investigated through the spatial distribution and occurence forms of organic matter in sediment.The ecological mechanism or pathway of the Procambarus clarkia bioturbation affecting the sedimentary organic matter was analyzed based on the physical properties of sediment,extracellular hydrolase activity,and the heterotrophic bacteria community.Finally,the restoration effect of the Procambarus clarkia bioturbation on the organic matter in sediment was determined.The main findings are as follows:During the test,the redox potential decreased with time,but the bioturbation group was significantly higher than the control group,indicating that bioturbation can increase the redox potential in the sediment.At the end of the experiment,the total organic matter(TOM),light organic matter(LFOM),recombinant organic matter(HFOM),total phosphorus(TP),organic phosphorus(TOP),total nitrogen(TN)and organic nitrogen(TON)in the sediment of the bioturbation group.The contents are(0.048±0.0006)g/g,(7.17±0.50)mg/g,(40.67±0.51)mg/g,(1.32±0.013)mg/g,(0.24±0.024)mg/g,(0.83±0.025)mg/g,(0.65±0.03)mg/g,and the control group are(0.061 ±0.005)g/g,(9.23±0.15)mg/g,(51.43±5.12)mg/g,(1.36±0.007)mg/g,(0.34±0.01)mg/g,(1.09±0.09)mg/g,(0.84±0.046)mg/g,the bioturbation group was lower than the control group.It is proved that the bioturbation of Procambarus clarkia has obvious degradation effect on the organic matter in the sediment.In this experiment,the alkaline phosphatase and urease activity of bioturbation group were significantly lower than the control group,and the nitrate reductase and peroxidase activity of bioturbation group was higher than the control group.It indicates that the reduction of organic phosphorus and organic nitrogen content due to the bioturbation of Procambarus clarkia is mainly caused by ingestion and by increasing the redox potential to promote the degradation,but not by affecting alkaline phosphatase and urease.This activity promotes its degradation;while the bioturbation of Procambarus clarks enhances the peroxidase activity and promotes the degradation of organic matter;in addition,the bioturbation of Procambarus clarks accelerates the degradation rate of organic matter in pond sediments.This leads to an increase in nitrate reductase activity.The bioturbation of Procambarus clarkii significantly increased the abundance of Nitrosomonadales and Ktedonobacteria.Nitrosomonas belonging to nitrifying bacteria whose abundance promoted nitrification and denitrification,increased ammonium nitrogen content,and inhibits URE activity reduction Also it reduced the abundance of Gammaproteobacteria,Deltaproteobacteria,Pseudomonadaceae,Chloroflexales,Acidimicrobiales,and Legionellaceae.The reduction in Chloroflexales indicated that the perturbation of Procambarus clarkii can effectively reduce the total nitrogen content in the sediment.Acidimicrobiales and Legionellaceae are indicator bacteria for the degree of contamination in sediment.The reduction of abundance proved that the disturbance of Procambarus clarkia has reduced the degree of contamination of the sediment and has obvious repairing effect on the substrate.The reason for the decrease in the abundance of Ktedonobacteria,Gammaproteobacteria,Deltapooteobacteria and Pseudomonadaceae is not clear,and futher research is needed.From the perspective of using the bioremediation to restore the aquaculture pond bottom environment,this experiment explored the restoration effect of Procambarus clarkii bioturbation on the organic matter in pond sediments,and analyed the corresponding ecological mechanism or pathway of the Procambarus clarkia bioturbation affecting the sedimentary organic matter.The purpose of this research is to apply bioremediation and provide a theoretical basis for pond culture production in the future.