Diatom Diversity And Spatio-temporal Changes In Manghe Nature Reserve

Diatom is a kind of eukaryotic algae with silicified cell wall,single cell.Single cell or group living,2 m-500 m long.Diatom is an important primary producers in aquatic ecosystems,benthic diatoms are the advantages of benthic microalgae groups,as they respond to changes in the environment rapidly,can at the community level response the change of environment and ecological system,thus has become an important indicator of river environmental monitoring,in the ecological environment has played a very important role.In September 2017,March 2018 and July 2018(representing autumn,spring and summer respectively),more than 162 samples were collected from diatoms in Manghe river nature reserve,and detailed records were made on the collection information.The collected diatom plants were observed,identified and described,and their diversity and community structure were analyzed.The main results are as follows:1.In this paper,the classification system of Round et al.(1990)was used to classify and identify diatoms in the area of Manghe.A total of 175 diatoms were identified,belonging to 51 genera,21 families,11 orders,3classes.Two new species and four new records from China.In this paper,the morphology of all diatom species observed is described and are illustrated with light electron microscopy.2.Diatoms are rich in species diversity.Coscinodiscophyceae observed4 species of 2 genera belonging to 2 orders and 2 families.Fragilariophyceae has been observed in 17 species of 7 genera belonging to 1 order and 1 family.Bacilluariophyceae has been observed to possess 154 species of 42 genera belonging to 18 families of 8 orders.The dominant genera are Navicula,Cymbella and Gomphonema,with 16,15 and 15 species each observed,accounting for 26 % of the total taxonomic unit.Only one species was observed in 23 genera: Merdion,Achanthes,etc.3.Spatio-temporal changes in Manghe national nature reserve.(1)Time distribution characteristics: reflect the structure characteristics of the community in spring,summer and autumn.The largest number of samples collected in autumn was 60,followed by 57 in spring and 45 in summer.There were 171 species of diatoms observed in autumn,158 species in spring and 145 species in summer.The species and quantity of diatoms in spring and autumn were higher than that in summer,which was corresponding to the life habits of diatoms.The dominant species and common species were similar in different seasons.SPSS clustering analysis and similarity analysis showed that season had little effect on the structure of diatom community.(2)Spatial distribution characteristics: benthic habitat,adherent habitat,planktonic habitat,community structure characteristics of Manghe river diatom in different habitats.Benthic habitat: mainly stream benthic and river benthic,55 samples were collected,p H 7.72-8.69,water temperature13.4-24.8 ?;Adherent habitat: mainly water grass adherent,grass leaf adherent,et al.100 samples collected in total,p H 7.72-8.69,and water temperature 13.4-24.8 ?;Planktonic habitats: mainly lakes,streams and river wetlands,7 samples collected.This habitat has a small number of samples,p H 8.28-8.68,and water temperature 14.7-21.2 ?;Attachment type habitat: mainly aquatic grass attachment,grass leaf attachment,et al.Compared with other habitats,more specimens were collected,a total of 100,p H 7.72-8.69,water temperature of 13.4-24.8 ?;Plankton-type habitat:mainly in lakes,streams,rivers and wetlands,the number of specimens collected is 7,and the number of specimens in this habitat is small,with a p H of 8.28-8.68 and a water temperature of 14.7-21.2 ?.The main group of the three habitats is the Bacillariophycidae,followed by the Fragilariophycidaeclass and Coscinodiscophyceae.Through similarity analysis,it was found that the benthic and attached diatom communities were moderately similar,while the planktonic and attached diatom communities were moderately different.4.In this paper,the species diversity of diatoms in the area of Manghe river was calculated and analyzed,and the water body was preliminarily evaluated by shannon-weaver diversity index,Simpson index,Margalef diversity index and Pielou evenness index,combined with the species composition and community structure of diatoms.According to the evaluation results of diversity index,the data showed that the water quality in the area of Manghe river was slightly polluted,the water quality in spring and autumn was slightly polluted,the shannon-weaver diversity index in summer showed moderate pollution,and other data showed mild pollution.