Studies On Chrysophyta From China

Chrysophyta is the major part of algae, which primarily are characterized by their golden color. Majority of the species live in freshwater, therefore, Chrysophyta hold the important status in the freshwater algae.The studies in this thesis dealt with the species of Chrysophyta from China, including their morphological diversity, systematics, silica-scaled Chrysophyta, biogeography, ecology, and Chrysophyta as ecological indicators.It was deeply studied in the research history and the classification system of Chrysophyta. And the taxonomy of Chrysophyta of China was revised based on the Chrysophyta classification system (revised by Kristiansen & Priesig in 2001), combining the research history and current situation in China.In this thesis, 5 classes, 7 orders, 15 families, 29 genera and 119 species were described in detail, and the taxa of China was completely listed. They were Chrysophyceae (3 orders, 8 families, 22 genera, 70 species), Bicosoecophyceae (1 order, 1 family, 1 genus, 1 species), Phaeothamniophyceae (1 order, 1 family, 1 genus, 1 species), Synurophyceae (1 order, 2 families, 2 genera, 44 species) , and (Prymnesiophyceae) (1 order, 3 families, 3 genera, 3 species).Several genera with many species carried silica scales and other silica structures were recorded in China. They were deeply studied by both light microscope (LM) and scanning electron microscope (SEM), especially in Mallomonas, which was the most species of Synurophyceae of silica-scaled Chrysophyta. Also, the taxonomy of the Mallomonas, was studied by Furtherest neighbor classification and Ward's method classification. Although M. costata and M. portae-ferreae belong to the different sections in different methods, the results of Furtherest Neighbor Classification and Ward's Classification were similar. However, when compared with the results of the traditional classification method, the results showed some differences in some branches. Taken the results of morphological classification, the numeral taxonomy and the molecular biology taxonomic together, a more objective taxonomy could be established.The distribution of 116 species of Chrysophyta recorded in China was studied. Species were abundant in East China, Central China and Southwest China, especially for silica-scaled Chrysophyta, but poor in Northeast China, North China, and Northwest China among 27 provinces recorded.The ecology of freshwater Chrysophyta had been studied in China. Many different species distributed widely in different nutritional water such as plankton of lakes, ponds, reservoir and cold running water. Most of them were recorded once since they were difficult for collection.The main external factors affecting the occurrence of Chrysophyta included water temperature, seasonality, pH etc. In freshwater, Chrysophyta predominantly occured in clear-water lakes and pounds with low nutrient contents, low temperature, and high transparence. Because it was sensitive to the water temperature, Chrysophyta showed the maximal reproduction during early spring and late autumn.The occurrence and ecological ranges of some Chrysophyta restrictedly distributed could be as important ecological indicators for the special ecological range they lived and relevant ecological parameters. Firstly, Chrysophyta with silica-scaled could be used as an indicator of paleolakes, which could provide theories for reconstructions of lake history. Secondly, as the producer and custom in the water, especially as a multiple function mixotrophic plant, Chrysophy played an important role in water ecosystem. Therefore, it was essential for systematic research in Chrysophyta.