Spatio-temporal variability of periphytic protozoa related to environment in the Niyang River, Tibet, China

• Published in: Chinese journal of oceanology and limnology 2017-05, Vol.35 (3), p.489-500
• Main Author: 刘海平 叶少文 杨学峰 郭传波 张惠娟 范丽卿 张良松 Sovan Lek 李钟杰
• Format: Article
• Language: English
• Subjects: Abundance; Alkalinity; Alveolata; Aquatic ecosystems; Autumn; Biology; Correlation analysis; Cyphoderia; Difflugia; Dissolved oxygen; Diversity indices; Earth and Environmental Science; Earth Sciences; Enchelydium; Enchelys; Environmental factors; Freshwater; Genera; Glaucoma; Limnology; Living resources; Marine; Oceanography; Protozoa; Regression analysis; River ecology; Rivers; Species diversity; Species richness; Summer; Sustainable development; Taxonomy; Temporal variations; Water hardness; Water temperature; Winter; 中国; 动物多样性; 周丛原生动物; 尼洋河; 时空变异性; 河流生态系统; 环境相; 西藏高原
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-017-5274-7

The Niyang River, a main tributary of the Yarlung Zangbo River, is an important and typical plateau fiver ecosystem in Tibet, China. At present, few studies have focused on its aquatic living resources and fiver ecology. In this study, the composition, abundance, and diversity of periphytic protozoa were investigated across four seasons from 2008 to 2009 to better understand their spatio-temporal patterns and relationship to the environment. Our investigation shows that periphytic protozoa in the Niyang River contained 15 genera, belonged to Tubulinea, Alveolata, Discosea and Rhizaria, Alveolata possessed most genera, up to nine, with highest share in abundance, exceeding 50%, Difflugia and Glaucoma were dominant genera. Moreover, four diversity indices of periphytic protozoa, including species richness, total abundance, Shannon-Wiener diversity index and Pielou＇s evenness index, displayed a significant descending trend as the seasons continued, in the order of winter, spring, summer and autumn; with a significant difference existing between winter and summer （or autumn） for Shannon-Wiener diversity index and species richness （P〈0.05）. Four of these diversity indices also presented a V-shaped pattern between the upper middle course of the Niyang River and the confluence of the Niyang River and Yarlung Zangbo River, with the lowest value occurred in the middle course of the Niyang River. However, no significant variation was found through the Niyang River （P〉0.05）. In addition, canonical correlation analysis （CCA） shows that the densities of Difflugia, Glaucomais, Enchelydium, Cyphoderia, and Enchelys correlate with water temperature, alkalinity, hardness, pH, and dissolved oxygen, respectively. Lastly, the relationship between periphytic protozoa diversity and the environmental factors of the Niyang River can be predicted using classification and regression trees （CART） annalysis, which suggests that the total abundance and Shannon-Wiener diversity index would be higher when the elevation is above 3 308 m. On the other hand, the Shannon-Wiener diversity index and Pielou＇s evenness index would be lower when pH and ammoniacal nitrogen have lower or higher values. Finally yet importantly, close attention should be paid to periphytic protozoa and its environment to ensure sustainable development of the Niyang River ecosystem.