Purification Effect Of In-situ Ecological Restoration On Yellow Catfish Pond Environment

Yellow catfish(Pelteobagrus fulvidraco)belongs to Chordate phylum,Silocyformes,genus Pelteobagrus;Is a small freshwater famous and excellent aquaculture varieties.Because of its high economic value,coupled with the breakthrough of artificial breeding technology,large-scale breeding of yellow catfish has been all over the country.However,at present,problems such as high-density soil pond breeding,large area of land,unable to collect and remove feces in time,and high fishing cost persist.In this study,bioflocs restoration(P1),water cabbage ecological floating bed restoration(P2),peppermint ecological floating bed restoration(P3)and control pond(P0)were compared.Water quality evaluation,phytoplankton,aquaculture water,gills and intestinal microorganisms were used to comprehensively evaluate the remediation effects of different remediation schemes on aquaculture ponds of yellow catfish.The results are as follows:1.The analysis of physicochemical indexes of P1,P2,P3 and P0 showed that there were significant differences between P0 and P1,P2 and P3 in total nitrogen,total phosphorus,nitrite nitrogen,n-phosphate and chlorophyll a(P<0.05).The comprehensive nutrient state index of aquaculture ponds showed that P1 was significantly lower than P0(P<0.05)during the experiment period.Results of P2 were significantly different from P0 except for October 9(P<0.05).The results of P3 on August 14,September 11 and 25 showed significant differences with P0(P<0.05).In conclusion,P1,P2 and P3 absorbed more nutrients such as nitrogen and phosphorus in the aquaculture water,which indicated that the in-situ three-dimensional remediation technology had certain efficacy,and P1 had a better effect.2.To investigate the effects of P1,P2 and P3 on phytoplankton community composition in breeding ponds.The results showed that a total of 6 phyla,66 genera and 133 species of phytoplankton were identified in the autumn water of the aquaculture pond,including 55 species of Chlorophyta,33 species of Cyanophyta,28 species of Diatoms,8 species of Euglesophyta,6 species of Dinoflagellates and 3species of Cryptosophyta.There were significant differences in the densities of P2,P22,P3,P33 and P0 in cyanobacteria(P<0.05).P1,P3,P33 and P0 had significant differences in chlorophyta densities(P<0.05).Pearson correlation results showed that diversity,evenness and transparency were significantly positively correlated(P<0.05).The diversity index and evenness were significantly negatively correlated with total nitrogen(P<0.05).Chlorophyll a was significantly negatively correlated with diversity index(P<0.05).There was a significant positive correlation between total nitrogen and chlorophyll a and density(P<0.05).There was a significant negative correlation between total phosphorus and chlorophyll a and evenness(P<0.05).There was a significant negative correlation between richness and transparency and nitrogen(P<0.05),and a significant positive correlation between richness and total nitrogen(P<0.05).These results indicate that bioflocs and combined ecological floating beds can affect the population structure of algae in the water by reducing the concentration of physical and chemical indexes of species in the aquaculture water,especially the cyanophyta and chlorophyta.3.The analysis of the composition of the water,gill and intestinal microbial community and its relationship with environmental factors in the aquaculture ponds showed that the number of microorganisms in the water was P3>P2>P0>P1 in terms of species composition,and there were some differences in the dominant species in each pond.Compared with P0,the proportion of Proteobacteria in P1,P2 and P3 increased,while the proportion of Fusobacteria decreased.The number of intestinal microorganisms showed P3>P0>P1>P2.Alpha analysis showed that the microbial richness and diversity in P1 water were significantly lower than those in P0(P<0.05).P0 indices were higher than those of P2 and P3,but the difference was not significant(P>0.05).The diversity of P0 microorganism in gills was significantly higher than that in P1 and P2(P<0.05),but was not significantly higher than that in P3(P>0.05),while the richness of P0 microorganism in gills was lower than that in P1,P2 and P3(P>0.05).The richness of intestinal microorganism P0 was higher than that of P1,P2 and P3,and the diversity was higher than that of P1,P2 and lower than that of P3,but the differences were not significant(P>0.05).Beta analysis showed that P1,P2 and P3 were far from P0.Chlorophyll a was the most important environmental factor,followed by nitrate nitrogen and total phosphorus.Nitrite nitrogen,transparency and dissolved oxygen in the environmental factors on the gill microorganisms ranked the first three.Nitrite nitrogen and ammonia nitrogen in environmental factors had significant effects on the distribution of intestinal microflora(P<0.05).These results indicated that P1,P2 and P3 could influence the microbial community structure,with P1 "inhibiting" the microbial community structure,while P2 and P3 "promoting" the microbial community growth.