Structure And Spatial Temporal Distribution Of Macrobenthic Communities In Huangshui River

From 2015 to 2019,taking the macrobenthos in the main stream of the upper reaches and five tributaries(Yaoshui River,Xinachuan River,Shatangchuan River,Nanchuan River and Beichuan River)of Huangshui River as the research object,river were divided into dry season(the end of April and the beginning of May)and the wet season(the end of July and the beginning of August).This paper analyzed the basic situation of macrobenthos,community distribution characteristics and their relationship with environmental factors,and studied the influence of different land use types and bottom material composition on the community composition of macrobenthos.The results are as follows:(1)In this study,118 taxa(43 families,103 genera,11 orders,4 classes)of macromacrobenthic were collected from huangshui river,with a total of 81,827(excluding 2019),including arthropods,mollusks,annelids,insects,crustaceans,gastropods and oligochaeta.Among them,there are 36 dominant benthic species,36 rare species and 28 sensitive species.The species and quantity of macromacrobenthic collected from the main stream of huangshui river were higher than other five tributaries.In the tributaries,the species and quantity of macrobenthos were the highest in Shatangchuan river and the lowest in Yaoshui river.(2)The total nitrogen,total phosphorus,nitrate nitrogen and ammonium nitrogen in the water samples of the upper reaches of Huangshui River were analyzed: As time goes by,the total nitrogen concentration in the upper reaches of huangshui river tends to increase,while the total phosphorus concentration tends to decrease.The total nitrogen,total phosphorus,nitrate nitrogen and ammonium nitrogen were higher than other places when the samples were located near towns and villages.(3)Taking the upper stream of the Huangshui River and the source of each tributary as reference points: The reference point of the main stream of Oushui River(sample(4)point 1),5 tributaries: the reference point of Yaoshui River(sample point 25),the reference point of Xinachuan River(sample point 28),the reference point of Beichuan River(sample point 1)Sample point 31),Nanchuan River reference point(Sample point 38),Shatang River reference point(Sample point 43).A total of 8378 macrobenthic were collected from the reference sample,and the richness in descending order was: Xinachuan River,Huangshui River Main Stream,Beichuan River,Shatangchuan River,Nanchuan River,and Yaoshui River.(5)Analysis of reference points in the upper reaches of the Huangshui River:(1).PCA analysis shows that the reference sample is affected by a variety of environmental factors.The environmental factors with a higher degree of influence are: Temperature(T),Dissolved Oxygen(DO),Ammonium Nitrogen(NH4 +-N),and Maximum flow rate(Max),Turbidity(TURB),Soluble Phosphorus(SRP),etc.(2)General situation of benthos: totally 8378 benthos were collected,including 1249 benthos of 18 species in Huangshui River Main Stream,919 benthos of 12 species in Yaoshui River,1603 of 25 species in Xinachuan River,1577 of 18 species in Beichuan River,375 of 12 species in Nanchuan River and 2655 of 16 species in shatangchuan river.(3)The functional predators of macrobenthos can be divided into four groups: ripper,collector,scraper and predator.The dominant groups of each reference sample point are the collector,followed by the Ripper and scraper,and the functional predators of macrobenthos are 14 for ripper,19 for collector,5 for scraper and 5 for predator.(IV)(4).CCA analysis of macrobenthic,environment,and sampling points: macrobenthic such as Chiroptera Tanypus Meigen sp.(Tan)and other macrobenthic have a higher degree of contribution to sample number 38,and Togoperla sp.And biopsy moth Psendostonophylax sp.(Pse),etc.,have a higher contribution to the sample point 43.Most of the macrobenthic appear in the sample points 1 and 28,and some of the macrobenthic are relatively discrete and the correlation degree is not obvious.(6)Analysis of sample points of Huangshui river upstream:(1)In combination with PCA sequencing analysis and cluster analysis of abiotic indexes,sample points in the Huangshui river upstream main stream were divided into four groups: the first group:sample points 1,2,3,4;the second group: sample points 5,6,7,9,10,11;the third(7)group: sample points 12,13,14,15,16;and the fourth group: 17,18,19.(2).There were 15 dominant species of macromacrobenthic: 1 species of mayoptera,8species of diptera,4 species of trichoptera,and 5 species of rare species.(3).Classification of land use types: The land use type of sample points 1 to 7 is Grassland,the land use type of sample points 8 to 15 is Farm land,and the land use type of sample points 16 to 19 is Urban land.Distribution of insects in the order Hymenoptera%: Grassland> Farm land> urban area,distribution of insects in the order Diptera:% of Urban areas> Farm land> Grassland,distribution of insects in the order Chaetoptera%: Farm land> Grassland> Urban area,insect distribution in a order : Farmland> Urban Land> Grassland.(4)total nitrogen,total phosphorus,ammonium nitrogen,soluble phosphorus bubble map,benthic animal bubble map and benthic animal abundance map show that the four hydrochemical indexes of sample points 1-19 are significantly increased,and when the nitrogen and phosphorus indexes in the river or water are too high,the eutrophication degree of the river will increase,and the benthic animal diversity will decrease,accompanied by the community succession phenomenon.(5).CCA analysis showed that most macrobenthic were negatively correlated with environmental factors such as total phosphorus(TP),total nitrogen(TN),turbidity(NTU),and positively correlated with maximum flow velocity(MAX),average flow velocity(AVG),and elevation(Alt),etc.Macrobenthic were mostly close to the sample points in the middle and upper reaches and basically appeared in the left half axis of CCA double-sequence diagram.The physical and chemical indexes of the upper reaches of the Huangshui River River increased,the diversity of macrobenthos decreased,the species tended to be unitary,the river ecosystem was disturbed and damaged to a certain extent,the number and length of artificial river channels increased,and the number of pollution-resistant species increased,since this article investigates the research has not seen the effective governance and the improvement measure.