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Wang C.,Chinese Academy of Fishery Sciences | Wang C.,Fishery Eco environment Monitoring and Evaluation Function Laboratory of the Pearl River Valley | Li X.H.,Chinese Academy of Fishery Sciences | Li X.H.,Fishery Eco environment Monitoring and Evaluation Function Laboratory of the Pearl River Valley | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

The Pearl River Delta (PRD) in Guangdong province is one of the most prosperous areas of China. At the same time, a large increase in the production of domestic and industrial waste occurred because of this economic development, and a 10% increase in waste production is estimated to have occurred in the past few years. The complicated river delta system, characterized as criss-cross and multiple river channels, is the primary location at which the Pearl River reaches the South China Sea. Many studies have focused on physical and chemical factors functioning in this region, especially in recent years, but few have investigated their effects on aquatic organisms. To understand the temporal and spatial distribution patterns of Euglenophyta, a riverine phytoplankton community, seasonal investigations were carried out in the river delta area in 2012. Thirteen representative sampling sites settled cover almost the whole river delta area. The correlation between the species richness and the biomass of each genus, and environmental factors is also analyzed in order to identify the key components of the interaction mechanism, using the PCA method. Moreover, the regional characteristics of the phytoplankton biodiversity pattern were evaluated at the genus level, using these results. During the investigation, 84 taxonomic species (including variant and derivative) from 12 genera of Euglenophyta were identified. The high biodiversity in this area is the result of its characteristic geographic features and high rate of eutrophication due to human activities. Of all the genera of Euglenophyta, Euglena contributed most to species richness and biomass, followed by Phacus and Trachelomonas. Although euglenoids in rivers are mainly dependent on exterior supplements from the influx of lentic waters into the river ecosystems, the present results revealed that euglenoids could grow along the river flows. Seasonal variation patterns of species richness and biomass were high in wet seasons and low in dry seasons. Besides the exterior supplementation by water flows during flood periods, simultaneous augmentation of organisms by flows could also promote the growth of euglenoids. Moreover, the corresponding high temperatures present during flood periods also benefit the growth of euglenoids. The spatial distribution pattern of euglenoids showed apparent seasonal differences. During flood periods, the values of the outer sites were significantly higher than those of inner sites, a dynamic mainly associated with variations in flow conditions. In drought periods, the differences among the rural sites were not so significant, but the extremely high values in urban sites were the result of high nutrient influx. The contribution of different genera indicated that Phacus and Trachelomonas could only co-dominate with Euglena during drought periods, and exhibited the K-selection strategy, which is generally characterized by a slower nutrient gathering capacity. In addition, the relationship between the biomass and species richness of euglenoids was analyzed, and it had an incline to the ascending curve part of the unimodal function of global phytoplankton biodiversity patterns. © 2016, Ecological Society of China. All rights reserved.


Wang C.,Chinese Academy of Fishery Sciences | Wang C.,Fishery Eco environment Monitoring and Evaluation Function Laboratory of the Pearl River Valley | Wang C.,CNRS Biological Evolution and Diversity Laboratory | Li X.H.,Chinese Academy of Fishery Sciences | And 12 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2014

The Pearl River Delta (PRD) in Guangdong province is one of the most economically prosperous areas in China. A large number of domestic and industrial wastes are produced together with the economic development and 10% of wasteoutput in growth rate has been estimated in the past few years. The complicated river web of the delta, which is characterized as criss-cross and multiple river channels, is the essential entrance for the Pearl River water entering into the South China Sea. Many studies have been focusing on physical and chemical factors of this region, but few referred to aquatic organisms, especially in recent years. To understand the temporal and spatial distribution pattern of Scenedesmus, a common green algal group of riverine phytoplankton community, seasonal investigation has been carried out in the river web area in 2012. The thirteen representative sampling sites settled covered almost the whole area and shaped in umbrella-type. The coherence between the biomass of each taxa and environmental factors was also analyzed using PCA method to evaluate the key factors for explaining the interaction mechanisms. Also, the regional characteristics of phytoplankton biodiversity pattern were evaluated from the genus level based on the results. During the investigation, the total 24 taxonomic species (including variant and derivative) were identified, including 11 taxa with spines and 13 taxa none. Although several species showed high occurrence rate, their contribution to total phytoplankton biomass was low, and less than 1% in terms of averages. However, relative abundance between different taxa was closely related to their occurrence rate. Three species (S. armatus var. armatus, S. armatus var. boglariensis f. bicaudatus, S. dimorphus) showed relatively high values in both occurrence and biomass, which was assumed related to their special morphological features. Seasonal variation pattern of both species richness and biomass indicated high in wet seasons and low in dry seasons, water temperature and discharge have been found to be responsible for this through the PCA analysis. Water temperature mainly influenced the growth and physiological conditions of Scenedesmus, while discharge mainly determined the exterior supplement of the algae. The spatial distribution pattern of total species richness showed high in outside stations and low in central stations, but this pattern had apparent seasonal differences. The patterns of May and August were in accordance with that of the total, and the patterns of March and December just showed high values in sampling sites close to Guangzhou. Through the PCA analysis, discharge, water temperature and nutrients have been found to be the key factors to influence this spatial pattern. The spatial distribution pattern of biomass showed extremely higher in ZJQ than those in other stations. Nutrients, water stability and salinity have been found to be the key factors for the spatial pattern through the PCA analysis. In addition, the relationship between Scenedesmus biomass and species richness was analyzed, and it was in consistent with the global phytoplankton biodiversity pattern, and had an incline to ascending part of the model, which also promotes the grading and regional understanding of the global diversity pattern.

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