黄洲河流域浮游植物的季节变化及其环境影响因子

为了解贵州白云岩喀斯特世界自然遗产地浮游植物群落结构及其与环境因子的关系，于2017年秋季(10月)、2018年冬季（1月）、2018年春季（4月）、2018年夏季（8月）对遗产地境内黄洲河流域的浮游植物群落种类组成、优势种、丰度以及多样性的时空变化进行研究，并应用Pearson相关性分析和冗余分析（RDA）探究环境因子总氮（TN）、氨氮（NH3-N）、总磷（TP）、叶绿素a（Chl-a）、溶解氧（DO）、高锰酸盐指数（CODMn）、水温（WT）对黄洲河浮游植物群落结构的影响。结果表明，调查共鉴定出藻类6门、29科、37属、38种,以硅藻门和绿藻门居多。按季节划分，黄洲河流域优势种共9种，其中硅藻门5种,?绿藻门1种,?蓝藻门3?种；按空间划分，黄洲河流域优势种共19种，其中硅藻门9种，绿藻门4种，蓝藻门6种。浮游植物年均丰度为36.45×104个/L，夏季的丰度最高，达到89.7×104个/L，春秋季次之，冬季最低，仅8.9×104个/L。全年Margalef丰富度指数（D）、Shannon多样性指数（H）及Pielou均匀度指数（J）分别为0.34 ~0.51、1.18~1.4及0.72~0.84。Pearson相关性分析和冗余分析(RDA) 表明，影响遗产地浮游植物丰度和分布的主要环境因子为WT、CODMn、Chl-a。

Seasonal Variation of Phytoplankton Community and Driving Environmental Factors in the Huangzhou River Basin

The Huangzhou River basin is within the South China Karst, a UNESCO World Heritage Site in Guizhou Province. In this study, we explored the spatial and temporal variation of phytoplankton community structure in Huangzhou River, focusing on species composition, dominant species, abundance and diversity of the phytoplankton community. In addition, the effects of TN, NH3-N, TP, Chl-a, DO, CODMn and WT on phytoplankton community structure in the heritage sites were analyzed by Pearson correlation analysis and redundancy analysis (RDA). The study aimed to provide a reference for conserving and treating the aquatic ecological environment of the South China Karst heritage site in Shibing County. The phytoplankton survey and water quality investigation were conducted at eight sampling sites in October 2017 (autumn), January 2018 (winter), April 2018 (spring) and August 2018 (summer) and included both the buffer zone and core area of the heritage site. A total of 38 phytoplankton species from 37 genera, 29 families and 6 phyla were identified during the survey, with dominance by Bacillariophyta and Chloraphyta. Phytoplankton species were rich during the heat of summer and, through the four seasons, there were 9 dominant species: 5 Bacillariophyta species, 1 Chlorophyta species and 3 Cyanophyta species. Spatially, there were 19 dominant species in the Huangzhou River basin: 9 Bacillariophyta species, 4 Chlorophyta species and 6 Cyanophyta species. The average annual abundance of phytoplankton in the basin was 36.45×104 cells/L, with the highest value (89.7×104 cells/L) in summer and the lowest value (8.9×104 cells/L) in winter. The ranges of Margalef richness (D), Shannon diversity (H) and Pielou evenness (J) indices for the phytoplankton community were 0.34-0.51, 1.18-1.4 and 0.72-0.84, respectively. Pearson correlation analysis and redundancy analysis showed that WT, CODMn and Chl-a were the primary environmental factors affecting phytoplankton abundance and distribution. The comprehensive trophic state index for the Huangzhou River averaged at 34.85, indicating mesotrophic conditions and was consistent with the phytoplankton community characteristics. Water quality was highest in winter, and differences in water quality among the other seasons was not evident. Spatially, water quality in the buffer zone of the upper Huangzhou River was lower than in the core area.