| Guangdong Province is located in the southernmost part of the motherland,with many islands and certain freshwater resources.Guangxi Zhuang Autonomous Region is located in the south Asian subtropical monsoon region,with abundant freshwater resources.In this study,diatom specimens were collected from 10 coastal islands in Guangdong and Guangxi provinces in February 2021,including Xunzhou Island,Haishan Island,Nan’ao Island,Dahao Island,Sanmen Island,Qi ’ao Island,Shangchuan Island,Hailing Island,Donghai Island,Weizhou Island,a total of 10 islands.The habitats include: ponds,reservoirs,wells,rivers,swamps,waterfalls,lakes,streams,wetlands,rivers,wet stone walls.205 specimens were collected and more than 410 slides were made.Light microscope(ZEISS Imager.A2)and scanning electron microscope(Hitachi S-4800)were used to observe and study the diatoms in the specimens.The main results are as follows:1.The species of freshwater diatoms are abundant in the coastal islands of Guangdong and Guangxi provinces are abundant 446 taxa of diatom plants were found,belonging to 3 classes,29 families and 81 genera,with including 1 new genera and 11 newly recorded in China.The morphological characteristics and distribution information of each unit were described in detail.All species were accompanied by light microscope pictures,and some species were accompanied by scanning electron microscope pictures.2.The composition characteristics of freshwater diatoms in the coastal islands of Guangdong and Guangxi provinces were preliminarily analyzed.From the perspective of the species studied,it has the characteristics of more species and less quantity.Most of them are common freshwater species,with some seawater species;In the collection area,there were obvious differences in the composition of diatom species between different habitats.Compared with the mainland,the difference in species number is small,but the distribution of genera is limited;The diatom species in different temperature zones were compared.In terms of the number of species,the species found in subtropical islands were more abundant,but there were more endemic groups in tropical islands,indicating that the temperature zone had a certain influence on the distribution of diatom species.3.In this paper,29 sampling sites were selected to count diatom plants.By analyzing the distribution of diatom plants in 10 islands and the similarity of diatom plants between islands,it can be seen that Hailing Island and Weizhou Island have the highest similarity,Nan ’ao Island and Hailing Island,Nan ’ao Island and Weizhou Island also have high similarity.4.Based on the two-way clustering method of the sum of squares of deviations,the islands in the study area were divided into three groups according to the difference of species.The diatom plants in Shangchuan Island were rich in species.The diatom plants in Nan ’ao Island,Hailing Island and Weizhou Island were relatively rich.The diatom plants in Dahao Island,Sanmen Island,Qi ’ao Island,Donghai Island,Xunzhou Island and Haishan Island were significantly less.5.According to the analysis of the co-occurrence network of diatom communities between islands based on the relative abundance of diatom species,the relationship between diatom communities and dominant species in each island is mutually beneficial and synergistic,among which Achnanthidium minutissimum Kützing is the central specie.6.The analysis of the relative abundance of island diatom species and environmental factors shows that the main factors affecting the relative abundance of freshwater diatom plants in coastal islands of Guangdong and Guangxi are the nearest distance from the mainland,the length of the coastline and the conductivity.7.The β diversity of freshwater diatoms in coastal islands of Guangxi Province was studied based on frequency and relative abundance.The results showed that the βdiversity of freshwater diatom communities in coastal islands of Guangdong and Guangxi provinces was mainly composed of spatial turnover. |
PDF Full Text Request