A Preliminary Study On Plankton Community And Early-Stage Fish Resources In Fuhe River,Jiangxi Province,China

As the second largest river in Poyang Lake system,Fuhe River has very important economic and ecological value.In recent years,influenced by domestic pollution and human activities such as water conservancy projects,the water environment has undergone complex changes.from September 2020 to August 2021,plankton was collected from 9 sampling points in Fuhe River,and the early fish resources in Linchuan River were investigated from May to July 2021.The results were as follows:A total of 304 species of phytoplankton were identified which belonged to 99genera,45 families,24 orders and 8 phyla in the Fuhe River.Among them,Bacillariophyta and Chlorophyta phylum account for the major part.The species number of Nancheng was the largest,and the seasonal change was:summer>autumn>spring>winter.The cluster analysis divided nine sampling points into three groups when the similarity was 54.05%.There were 27 dominant species,they were Aphanizomenon sp.,Tribonema sp.,Cyclotella sp.,N.wullerstorffii,Chlamydomonas sp.,C.vulgaris,Ankistrodesmus sp.etc.There were 30 functional groups,and the dominant functional groups were C,D,G,H1,M,MP,W1,X2 and Y.The phytoplankton densities ranged from 1.29 to 49.86×10~5cells/L and the biomass varied from 2.05 to 131.71mg/L.The species and functional diversity index of phytoplankton was highest in Dongxiang,and the highest in spring in the quarter.The environmental factors affecting the phytoplankton were temperature(WT),transparency(TS),redox potential(ORP)and dissolved oxygen(DO).A total of 158 species of zooplankton were collected,belonging to 62 genera in 31families,14 orders and 4 phyla.Among them,the highest number of species in the Rotifera and Protozoa phylum.Similarly,there were the most kinds of Nancheng,and the quarterly changes were:summer>spring>winter>autumn.The nine sampling points were divided into three groups when the similarity is 44.85%.There were 8dominant species,they were D.oblonga,D.balbianii,S.gyrans,B.calyciflorus,T.bicristata etc.The main functional groups of zooplankton were PF,PC,RF,RC,SCF,MCF,MCC and LCF.The densities ranged from50.00 to 4950.00ind/L and the biomass varied from 0.0013 to 6.39 mg/L.Species diversity index of zooplankton was higher in Lichuan,species diversity was higher in spring,functional divergence(FDiv)was higher in winter,and functional evenness(FEve)and functional richness(FRic)were higher in spring.The main effects on zooplankton were temperature(WT),potential of hydrogen(p H),redox potential(ORP)and dissolved oxygen(DO).There were 581 fish eggs and 5797 fish larvae collected in Linchuan reach,and 41species(10 fish eggs and 40 fish larvae)were identified,belonging to 6 orders,8families and 31 genera.Among them,Carpiformes had the most,with 31 species.The dominant species were H.tchangi,R.giurinus,P.simoni,S.curriculus,H.bleekeri,S.argentatus,M.terminalis,P.dispar,P.sinensis etc.The reproductive peaks appeared several times in mid-May,early June and late June respectively.The spawning ground of drifting eggs was concentrated in the middle reaches.The spawning ground of drifting eggs was concentrated in the middle reaches.The variation trend of Margalef richness index(D)and Shannon-Wiener diversity index(H)of larvae was May>June>July,and Pielou evenness index(J)was May<June<July.The diversity index of fish eggs all showed May<June.The main influencing factors were temperature(WT),dissolved oxygen(DO),transparency(TS)and water flow rate(FR).