Spatiotemporal Dynamics Of Aquatic Insects Communities In The Guangzhou Area,with Emphases On The Key Driving Factors

Aquatic insect assemblages collected from 23 sites from Guangzhou Metropolis across four different ecological zones were studied for analysis of spatiotemporal dynamics and species abundance distributions?SAD?.In the meantime,the canonical correspondence analysis?CCA?was also applied into detecting environmental drivers for shaping the current community structures.The major results are as follows:1.The conductivity,salinity,TN,TP and COD_Mn varied dramatically among different ecological zones,such pattern was not observed in the seasonal samples.The water health condition declined gradually from Northeastern area to Southwestern area.Seasonally,the best water quality occurred in the somewhat stable season,such as December,while the worst occurred the dry season,March.2.A total of 14806 individuals were sorted,identified and enumerated.229 taxa?morphotypes?belonging to 139 genera which allied to 49 families and 9 orders were yield.The diverse groups are Diptera?138 taxa?,EPT?35 taxa?,dragonflies?21 taxa?and water beetles?23taxa?.The major categories of feeding functional groups?FFGs?,are those collector-gatherers?101 taxa?and predators?70 taxa?.The top four dominant species in the whole year community is Cloeon marginale,Cricotopus polyannulatus,Cladotanytarsus paratridorsum and Conchapelopia togamaculatus,while seasonally variation of dominant species is dramatically.3.The fluctuation of spatiotemporal changes were observed clearly.The average richness and abundance in the stable season is higher than that in the flooding season.The community metrics,such as H',D and HBI,indicated that the health condition of forest zone is best,while worst in the costal wetland zone.The ordination of all sampling sites by NMDS showed those sites in the same zone are clustered together,separaing each other by relative clear boundaries,while no clear pattern was found when running the seasonal ordination.The mapping of aquatic insects diversity based on Geographic Information System?GIS?showed that the similar trends as the above physiochemical parameters did.The overall performance of Northeast mountain forest area is much better than the middle and south zones.4.Three well-accepted models,geometric series,log series and log normal series,were tested by Kolmogorov-Smirnov method,the result showed that among all studied sites,most sites of forest and agriculture-shrub zone were accepted by the log-normal models,while sites coming from the urban and coastal wetland zones were mostly accepted by the geometric series?partially fitted to logarithmic series distribution?,some sites were accepted by the 2 models at the same time.This indicated that the SADs is a dynamical procession along the different size of community,different slope,relative position and posterior tails which were very useful to determine and compare the different ecological states among the sampling sites,even that could not be easily distinguished by environmental variable and community metrics.5.CCA analysis showed some hydraulic parameters,substrate composition and certain water quality parameters?DO,TN and TP?play a key role in the whole procession.