Taxonomical And Ecological Studies On Diatoms From Zoige Wetland And Its Nearby Waters In Sichuan Province

Diatoms are unicellular, eukaryotic algae with silicon cell walls. Which are primary producers of aquatic ecosystem. They have wide distribution in time and space. Furthermore, different species have different habitats. Therefore they play an important role in ecology, environmental monitoring, paleoecology and so on. Zoige Wetland is located in the northeast edge of the Qinghai-Tibet Plateau. Zoige alpine wetland is one of the three Tibetan Plateau grass wetlands, which is a typical area of alpine ecosystems. There is rare report of diatoms which are abundant in Zoige wetland.In this study,712 diatoms samples are systermatically collected for 3 times which are during the August,2011, May,2012 and October,2012 on survey of Zoige Wetland and its nearby water. The area include Zoige County, Hongyuan County, Songpan County and Mao County which located in Sichuan Province, Maqu County and Diebu County which located in Gansu Province. This paper focuses on the taxonomical and ecological characters of diatoms distributed here.1. We use LM and SEM to research the diatom of Zoige wetland and its nearby water and photograph. Taxonomical work is based on Round et al.1990’s system. There are 309 species,46 varieties and 2 forma which belong to 3 classes,15 order, 29 families and 74 genera. There are 21 new species,2 genera and 29 species are new records in China among them. Each species is described and are illustrated with light electron microscopy and some of them illustrated with scanning electron microscopy.2.21 new species are observed in Zoige wetland. Among them 17 species belong to Neidium Pfitzer:N. baoae, N. qia, N. suboblongum, N. angustatum, N. tortum, N. rostratum, N. apiculatoides, N. convexum, N. zoigeaeum, N. lacusflorum, N. avenaceum, N. medioconstrictum, N. tibetianum, N. bacillum, N. aequum, N. ligulatum, N. dicephalum; 1 species belong to Neidiomorpha Lange-Bertalot & Cantonati:N. sichuaniana;1 species belong to Muelleria (Frenguelli) Frenguelli:M. pseudogibbula and 2 species belong to Prestauronei Bruder & Medlin 2:P. nenwai, P. lowei. Neidiomorpha and Prestauroneis are new records genera in China. We detailed these genus and all new species characteristic. We also confirmed the type species, the sample number of type species, etymology and discussed with similar species.3. The characteristic of diatom flora and the composition features of diatoms in different water bodies of Zoige Wetland and its nearby waters were studied. We observed 357 species (including varieties and forms) in this area. There are 308 species belong to Bacillariophyceae which is 85.8% of the total species. Coscinodiscophyceae and Fragilariophyceae have 13 species and 38 species separately which is 3.6% and 10.6% of the total. Neidium, Pinnularia, Nitzschia, Gomphonema, Navicula, Cymbella, Cymbopleura and Luticola are dominant genera account for 40.7% of overall species, most of them are epiphytic and benthic. Compare with 47 casual species, only 19 common species in this area. Most of common species are dominant species in each microhabitat.4. The ecological distribution characteristics of Zoige Wetland and its nearby waters was summarized. Lotic ecosystem and lentic ecosystem have different diatoms flora. Because of alkaline water here, most diatoms are alkaliphilous species. There are 15 representative species can indicate alkaline habitat. Common species are observed and found out:they live on moss with different bottom materials which have different diatom flora. Variety and quantity of diatoms are high which live in moss with nutrient rich soil, however, diversity and quantity of diatoms are low when they live in moss with less nutrient rocks. Most of diatoms in Zoige Wetland and its nearby waters distribute in north hemisphere and alpine and some of them are typical of cold and alpine water, Luticola nivalis, Luticola murrayi, Mulleria pseudogibbula, Gomphosinica hedinii, Gomphosinica chubichuensis.