| As an important part of the paddy water ecosystem,zooplankton has important reference value for the monitoring of the paddy water ecological environment and the analysis of the structure and function of the farmland food web.Based on the research group’s previous research on the ecosystem service function of paddy fields in northern Jiangxi,this paper systematically investigated the diversity of zooplankton in paddy fields and the influencing factors affecting the diversity of zooplankton in paddy fields in northern Jiangxi.In order to analyze the community characteristics of zooplankton in paddy fields in northern Jiangxi,13 plots with obvious landscape heterogeneity in 3 cities and 6 counties were selected in 2020 and 2021,and the zooplankton samples were collected,identified and analyzed one by one,in order to investigate and analyze the zooplankton diversity and community characteristics of paddy water bodies,and to set up sprayed pesticide areas and unsprayed pesticide areas in various plots to comprehensively compare the differences in the number of zooplankton species and individual richness,and compare the high standards of different areas.Differences in the number and abundance of zooplankton species in paddy fields and non-high-standard paddy fields;the community structure of zooplankton in different growth stages of rice and the differences in the composition of zooplankton in different landscape plots during the flowering stage of rice were analyzed to clarify the indication role of zooplankton on water environment and farmland management measures in each landscape plot.The research results have theoretical and practical significance for evaluating the zooplankton structure of the regional paddy water ecosystem and the management measures of water,fertilizer and pesticides in the paddy field.1.Community structure of zooplankton in paddy fields in northern JiangxiA two-year zooplankton survey on rice fields in northern Jiangxi shows that there are119 species of zooplankton in 58 genera in 13 paddy fields in northern Jiangxi,and 46 genera and 96 species of rotifers are the main groups,accounting for 80.67% of the total number of species.The main dominant species 13 sampling sites are Copepod nauplii,widely distributed Daphnia mesilius,Cystic monodactyly,Tendactyl rotifer,Longilonga rotifer and Brachypodium,and the dominant species are basically the same in different years.The two-year averages of zooplankton species number,density,biomass and diversity indices showed no significant inter-annual differences.By comparing the density and biomass of zooplankton in different places,it was found that there was obvious spatial heterogeneity in the abundance of zooplankton.Using univariate linear regression to analyze the relationship between the density of zooplankton in paddy field and the diversity index of landscape fragrance,the large-scale range of 2000 m radius shows that the density of zooplankton tends to increase with the increase of the diversity index of fragrance in 2020,but the correlation did not reach a significant level.In 2021,with the increase of the landscape fragrant diversity index,the density of zooplankton decreased with a very significant decrease(P<0.01).2.Effects of different farmland management measures on zooplankton in paddy fieldsThe impact of farmland management measures on zooplankton has not yet been explored.This paper is the first time to compare the zooplankton community characteristics of high-standard rice fields and non-high standard rice fields in 13 sites of two years in the region,and found that the overall trend in 2020 and 2021 is the number of zooplankton species,zooplankton density and biomass,and zooplankton diversity index in high-standard rice fields were higher than those in non-high-standard rice fields,but there was no significant difference.The survey results of zooplankton in the sprayed and unsprayed areas of the paddy fields for two years showed that the number of zooplankton species,diversity index,richness index and uniformity index in the sprayed pestieide areas were generally higher than those in the unsprayed pesticide areas in 2020.The result indicates that most of the pesticides have obvious toxic effects on zooplankton.In the 2021 sampling sites,the number of species,diversity index,richness index and evenness index in half of the sprayed areas were lower than those in the unsprayed area,while the other half were the opposite.There are many reasons for this result,and its mechanism needs to be deeply explored.3.Zooplankton diversity in different growth stages of riceThere are obvious time differences in zooplankton.In order to explore the impact of time differences in small water bodies such as paddy fields on zooplankton,in 2021,the zooplankton samples of 11 different paddy water bodies were collected during the tillering,jointing and flowering stages these three key growth stages of rice.Tthe species composition,density,biomass and diversity of zooplankton(rotifers,cladocerans and copepods)in different growth stages were systematically analyzed.The results showed that in the comparison of zooplankton density,the total density of zooplankton in the flowering stage was significantly higher than that in the other two growth stages.Among the three groups of zooplankton,the density peaks of rotifers and copepods all appeared in the flowering stage.In terms of biomass comparison,the zooplankton biomass in the tillering stage was significantly larger than that in the other two stages.However,there were no significant differences in the number of species,aromatic diversity index(H’),richness(ds)index and evenness index(J’)in the three growing stages of rice.4.Effects of farmland landscape sites of different scales on water zooplankton community during flowering periodIn order to explore zooplankton community changes under the influence of landscape plots at different scales in two years,the 500 m small-scale and 1000 m large-scale landscape factors and zooplankton community characteristics of 9 plots in 2020 and 11 plots in 2021 were analyzed.The results show that within a small scale range of 500 m in radius,with the increase of landscape fragrance diversity index,zooplankton density,biomass and zooplankton diversity show a downward trend in two years,but there is no significant difference,while zooplankton density and biomass were positively correlated with cultivated land area,and zooplankton diversity was negatively correlated with cultivated land area.Within a large scale of 1000 m,the landscape aroma index and cultivated land area had a significant positive correlation with zooplankton density and biomass,while the water area had a negative correlation with zooplankton biomass. |
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