| In view of the limited self purification capacity of the water body in aquaculture pond,the high stocking density farming will lead to the increase of nutrients in water body,and cause endogenous and exogenous pollution.It is of great significance to develop an ecological sustainable aquaculture mode.Macrobrachium rosenbergii is an important economic crustacean of aquatic products,which has the characteristics of wide appetite,fast growth and good meat quality.It's traditional culture model is pond monoculture.The M.rosenbergii pond–paddy field aquaponics combines the characteristics of in-situ remediation and ex-situ remediation,which provides a new idea for shrimp culture.It is mainly divided into two parts:ponds and paddy fields?50%for each part?,which are independent and interconnected.In this paper,a combined model of M.rosenbergii and paddy field was developed to explore the feasibility of applying this model in the production of M.rosenbergii,and to provide theoretical and practical basis for the development of a new ecological breeding model for M.rosenbergii.This paper mainly studied the water pond environment under the M.rosenbergii pond-paddy field aquaponics through the following aspects:Effects of Giant Fresh Water Prawn Pond–Paddy Rice Field Aquaponics on water qualityThe dynamics of major water environment factors was monitored in a trial pond?combined with paddy field?and the control pond?M.rosenbergii monoculture?.The effects of this new farming model on water quality was analyzed.The results showed:During the culture period,the trial pond had a better water temperature environment,and the average water temperature was 0.82?lower than that of the control pond.During the whole sampling period,the concentrations and variation coefficients of ammonium nitrogen?NH4+-N?,nitrate nitrogen?NO3--N?,nitrite nitrogen?NO2--N?,active phosphate phosphorus?PO43--P?,total particulate matter?TPM?,particulate organic matter?POM?,particulate inorganic matter?PIM?and chemical oxygen demand?COD?in the trial pond water were all lower than those in the control pond,and the differences in NH4+-N and COD were significant?P<0.05?.In general,the experimental pond has a better physical and chemical environment.2. Community structure of plankton in pond–paddy rice field aquaponicsThe plankton samples in the early,middle and late stages of pond water were identified and analyzed,and the community structure of plankton and and its changes in the M.rosenbergii-rice pond water were discussed.The results showed:During the culture period,there were 17 genera and 26 species of phytoplankton in the water inlet,trial pond and control pond,which belonged to Cyanophyta,Chlorophyta,and Bacillariophyta etc.The Cyanophyta species were the most in the whole cultivation period.In terms of dominant species,Microcystis aeruginosa and Oscillatoria maxima dominated at all stages in control pond;Green algae dominated in the early stage of the trial pond,and diatom species appeared in the dominated group of the middle stage;In the later period,blue-green algae and green algae were the dominant species.The number of dominant species in the trial pond were less than that in the control pond.The phytoplankton diversity index was much higher than that of the control pond after the first stage,but lower during the first stage,and phytoplankton diversity was highest at the middle stage in trial pond.There are 30 species of zooplankton in these two ponds,most of which are cladocera and copepoda.The dominant species of zooplankton in the two ponds were different in each period,and Noctiluca spintillans dominanted in the later period of the control pond.The abundance and biomass of zooplankton in both ponds showed a decreasing trend;the abundance and biomass of zooplankton in each period of the trial pond were lower than that of the control pond,and the average value was significantly lower than that of the control pond?P<0.05?.The redundant analysis showed that nitrogen and phosphorus were the main factors which affected the composition of plankton dominant species in the trial pond.Indicators such as POM also affect the density of dominant zooplankton species.3. The effect of giant fresh water prawn pond–paddy rice field aquaponics on the sedimentary environmentIn order to study the effect of shrimp pond-paddy field combined farming on the pond sedimentary environment,the samples of pond sediment were tested and analyzed.The results showed:The p H of sediment in these two ponds were similar and barely changed during the trial,and the oxidation-reduction potential?ORP?showed a downward trend.ORP in the middle stage of the trial pond was slighty higher than that of the control pond.During the breeding periods,the TN and TP of the sediment in two ponds generally increased.The increase values of TN and TP in trial pond and control pond were 0.471%,0.518%and-0.024%,0.012%,respectively.In addition,the TC content in the test pond was lower during the sampling period.4. Analysis of microbial community structure in pond–paddy rice rield aquaponics pondsIllumina Mi Seq sequencing technology was used to analyze the microbial structure in water of the pond-paddy field aquaponics pond?MR?and the shrimp monoculture pond?MS?.The results showed:The microorganisms detected in this study belong to160 genus,123 families,82 orders,31 classes and 15 phyla.The dominant bacteria in these two ponds were similar during the experiment.At phylum level:Proteobacteria,Cyanobacteria,Actinobacteria and Bacteroides were advantage bacteria.At class level:Oxyphotobacterium,Actinobacteria,Proteomycetes and Bacteroidia were advantage bacteria.At genus level:Planktothricoides?SR001,hgc I?clade were advantage.In each period,the proportion of bacteria in the trial pond,such as proteobacteria,actinomycetes which related to water quality regulation were gradually decreased,and the cyanobacteria showed an upward trend,it's proportion in the later period was relatively high;The proportion of flora in the control pond was relatively small in each period.In the diversity analysis,ACE index showed similar result to the Chao 1 index,both reached the maximum value in the middle period.Shannon index and Simpson index showed a different result,which were MR2>MS3>MR1>MS1>MS2>MR3vs.MR2>MR1>MS1>MS3>MS2>MR3?1.Prophase;2.Metaphase;3.Anaphase?.In the trial pond,the similarity of the microbial composition in the early and middle stages was high,but the differences in microbial composition among the three stages were greater than that of the control pond.5. Analysis of the culture benefit of pond-paddy field aquaponicsDuring the cultivation,the growth curve of M.rosenbergii in the two ponds was normal.The specific growth rate and the relative growth rate of body weight of M.rosenbergii in the trial pond were 3.07%·d-1and 459.40%respectively,and those in the control pond were 2.86%·d-1and 397.44%respectively.The measured yield per unit area of M.rosenbergii in the trial pond was 3825 kg·hm-2,the survival rate was 68.8%,and the bait coefficient was 1.4;while the local level of per unit area was about 2250kg·hm-2,the survival rate was about 30%and the bait coefficient was about 2.5.The culture profit of the trial pond is higher than of the local monoculture model.The results showed that the M.rosenbergii pond-paddy rice field aquaponics had a better development prospect. |
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