Preliminary Taxonomical Study Of Benthic Diatoms From Songhua River Basin

The Songhua River Basin is one of the seven major river basins in China,located in the northeast of China.There are many tributaries,lakes and swamps,and rich water resources.During our investigation,algal samples were collected in June 2018,April,June2019,and July 2021 from the Songhua River Basin.The collection areas included: the East Stream of Songhua River,the West Stream of Songhua River,the Nen River,the main lakes and wetlands in the basin.A total of 145 samples were collected and 290 permanent slides were made.The habitats include: rivers,lakes and wetlands.Light microscope(ZEISS Imager.A2)and scanning electron microscope(Hitachi S-4800)were used to observe the diatom.The main results were as follows:1.The benthic diatom biodiversity in this basin are really high.A total of 309 taxa,belong to 3 classes,13 orders,30 families,81 genera were identified.Habitats information and morphological characteristics of each taxon was described.Light microscope photos are provided to all species.SEM pictures were given to some taxa.Eleven taxa were newly recorded in China: Placoneis ellipticorostrata Metzeltin,Lange-Bertalot ? Nergui?Diadesmis laevissima(Cleve)Mann?Luticola cuspidata Levkov,Metzeltin ? Pavlov?Luticola sparisipuncata Levkov,Metzeltin ? Pavlov?Luticola wulffii(Petersen)Levkov,Metzeltin ? Pavlov?Neidium septentrionale Cleve-Euler?Hippodonta coxiae LangeBertalot?Nitzschia brunoi Lange-Bertalot?Nitzschia rectirobusta Lange-Bertalot?Psammodictyon rudum(Cholnoky)Mann?Surirella spendida(Ehrenberg)Kützing.2.The benthic diatom species in the Songhua River Basin are dominated by Bacillariophycidae,including 57 genera and 244 taxa,accounting for 79% of the total species,followed by Fragilariophyceae,including 13 genera and 41 taxa,accounting for13.3% of the total species,Coscinodiscophyceae is the least,including 9 genera and 24 taxa,accounting for 7.7% of the total species.3.Among the 81 genera,Nitzschia had the most species,21 taxa were observed,followed by Gomphonema,Navicula,Surirella,and 26 genera were only found 1taxon respectively.4.In the basin,the more numerous and dominant species were observed,namely:Cyclotella meneghiniana Kützing?Discostell astelligera(Cleve ? Grunow)Houk ? Klee?Melosira varians Agardh?Aulacoseira granulata(Ehrenberg)Simonsen?Fragilaria tenera(Smith)Lange-Bertalot?Cymbella excise Kützing?Achnanthidium latecephalum Kobayasi?Nitzschia palea(Kützing)Smith?Surirella angusta Kützing.5.Most species were distributed in rivers,with a total of 266 taxa observed;lakes were next,with 204 taxa observed;and wetlands were the least,with 126 taxa observed.95 species appear in all three habitats,171 species appear in both rivers and lakes,113 species appear in both rivers and wetlands,and 98 species appear in both lakes and wetlands.6.The river habitats of the Songhua River Basin collected in 2021 were divided into three parts,including the East Stream of Songhua River,the West Stream of Songhua River and the Nen River.A total of 202 taxa of benthic diatoms were observed,118 taxa were observed in the West Stream of Songhua River,95 taxa were observed in the East Stream of Songhua River,and 94 taxa were observed in the Nen River.26 taxa were observed in the East Stream of Songhua River,the West Stream of Songhua River and the Nen River.7.According to statistics,from 1992 to 2020,a total of 1032 taxa of diatoms were reported in the Songhua River Basin,198 species of them were observed in this study,and 111 species were newly discovered.