Quantitative Relationship Between Benthic Macroinvertebrate Community Biodiversity And Environmental Driving Factors In The Taizi River Basin

In recent years,human activities have more and more serious impact on the stability of river ecosystem.A series of problems have emerged such as eutrophication of river ecological environment water body,loss of habitat diversity and damage of biological integrity.Human life,industrial and agricultural production are closely related to river ecological environment.To study the evaluation method of river ecological health,analyze the spatial distribution of aquatic communities and its relationship with water environmental factors,quantitatively analyze the relationship between species diversity of aquatic organisms and environmental factors,and quantitatively analyze the relationship between functional groups of aquatic organisms and environmental factors is of great importance to the protection of river ecosystems.This study based on the taizi river basin in the spring of 2012,three times in the fall 2016 and spring 2016 136 stance water ecological investigation,with benthic macroinvertebrate sample collection and determination of the water environmental factors,analysis of taizi river basin in benthic macroinvertebrate community species composition,spatial distribution and taizi river basin ecological health assessment,benthic macroinvertebrate species diversity and its feeding function group of river habitat main driving factors of the turmoil and the threshold.The research results show that:(1)A total of 120 genera(species)of benthic macroinvertebrate,belonging to 6 classes,12 orders,43 families,were collected from 136 stations for 3 times in the taizi river basin.Benthic macroinvertebrate community structure(species abundance,individual number,species density,Shannon-Wiener diversity index)shows high spatial heterogeneity,which is characterized by higher community diversity in the eastern upstream,mid-stream mountain and hilly areas than the downstream plain areas,and higher tributaries than the main stream.CCA analysis showed that aquatic insects of Ephemeroptera,Plecoptera and Trichoptera(EPT)and environmental factors such as dissolved oxygen(DO)were positively correlated The environmental factors TN and NH3-N have positive correlation with Neocaridina denticulata sinensis,Cybister and chironomus.Bellamya purificata is positively correlated with environmental factor conductivity(COND).This study used benthic macroinvertebrate biodiversity index and the index of biological integrity of taizi river basin water quality evaluation,the uneven distribution of taizi river basin ecosystem condition,overall performance is from the source of taizi river waters to the taizi river downstream water ecological health lined for good health and,in general,a bad trend,a good environmental conditions in the river water,branch source is higher than in the middle and lower reaches;The habitat quality of forest land area is the best,followed by agricultural land area,industrial and agricultural concentration area and urban land area is the worst;The source water area,drinking water protection area and fishery water use area are better,and the water quality in the areas where industry and agriculture are relatively concentrated is poor.(2)CCA analysis of benthic macroinvertebrate and environmental factors showed that dissolved oxygen(DO),conductivity(COND)and total nitrogen(TN)were more correlated with species than ammonia nitrogen(NH3-N).Benthic macroinvertebrate community habitat environment major driving factors in the weighted average,according to the results of regression analysis(WA)benthic macroinvertebrate habitats,conductivity,dissolved oxygen,and total nitrogen is the most nearly range is 9.08-14.71 mg/L,147.08-574.77 ?s/cm,0.57-8.36 mg/L,benthic macroinvertebrate fauna present a sensitive kind of the most nearly high dissolved oxygen,and low fouling resistant species,sensitive kind of conductivity and the lower of total nitrogen is the most nearly,fouling resistance is higher;The benthic macroinvertebrate shannon-wiener diversity index(0-1] group has the lowest dissolved oxygen,10.13mg/L,the highest conductivity and total nitrogen,375.56 ?s/cm and 3.49 mg/L,respectively.The dissolved oxygen in group(3-4] was the highest,13.80 mg/L,while the conductivity and total nitrogen were the lowest,155.23 ?s/cm and 2.10 mg /L,respectively.TITAN analysis showed that there were 11 species,9 species and 6 species of dissolved oxygen,9 species of conductivity and 6 species of total nitrogen,respectively.The Shannon-Wiener diversity index(0-1] group had a negative response to the dissolved oxygen threshold,but a positive response to the conductivity and total nitrogen threshold.The Shannon-Wiener diversity index(1-2] group,(2-3] group and(3-4] group showed a positive response to the dissolved oxygen threshold,and a negative correlation with the conductivity and total nitrogen.Groups is diversity index indicated the dissolved oxygen(0-1] group,conductivity is the instructions of the groups(0-1] group and the group(3-4],and the Shannon-Wiener diversity index(0-1] group and conductivity were positively response relationship,the threshold is 272.00 ?s/cm,namely river habitat conductivity is higher than 272.00 ?s/cm,benthic macroinvertebrate diversity index is low,the shannon-wiener diversity index(3-4] group and negative response relationship between conductivity,threshold of 135.40 ?s/cm,namely river habitat conductivity is lower than 135.40 ?s/cm,benthic macroinvertebrate community Shannon-Wiener diversity index is higher.(3)51 species of gatherer-collectors(GC),10 species of filter-collectors(FC),21 species of scraper(SC),8 species of shredders(SH)and 30 species of predator(PR)were found in the taizi river basin from three water ecological surveys,accounting for 42.5%,8.3%,17.5%,6.7% and 25%,respectively.CCA analysis showed that SH was negatively correlated with DO in most species.A few species are positively correlated with it;Scraper(SC)is positively correlated with TN and COND.WA analysis of the optimal values of the main driving factors of feeding functional groups showed that the optimal values of different feeding functional groups of benthic macroinvertebrate were significantly different.Among them,the optimal values of dissolved oxygen of the gatherer-collectors(GC)were the lowest among the five groups of feeding functional groups,while the optimal values of conductivity and total nitrogen were the highest.Shredders(SH)had the highest value of dissolved oxygen in the five functional groups,while the highest value of conductivity and total nitrogen was relatively low.TITAN analysis showed that dissolved oxygen indicated that the feeding functional group of benthic macroinvertebrate was shredders(SH),which was positively correlated with the dissolved oxygen threshold with a frequency of 37 and a threshold of 10.14mg/L.when the dissolved oxygen in the habitat of the basin was higher than 10.14mg/L,the group density of large benthic animal predators mutated and decreased relatively.The conductivity indicates that the feeding function groups of large benthic animals are filter-collector(FC),scraper(SC),shredders(SH),predator(PR),and are negatively correlated with the conductivity thresholds,which are 60,91,37,and 84,respectively.The thresholds are 253.00 ?s/cm,446.03 ?s/cm,253.00 ?s/cm,and 222.00 ?s/cm,respectively.Total nitrogen indicates that the feeding function groups of benthic macroinvertebrate are filter-collector(FC),scraper(SC),shredders(SH),and are negatively correlated with the total nitrogen thresholds,the frequencies are 60,91,37 microns,the thresholds are 2.19 mg/L,2.96 mg/L,2.20 mg/L,respectively.That is,the total nitrogen concentration is lower than 2.19 mg/L.The total nitrogen concentration of river basin habitats is lower than 2.96 mg/L.The total nitrogen concentration is lower than 2.20 mg/L.