暴雨期前后库里泡底栖硅藻群落结构变化及其环境因子相关性

为探究库里泡底栖硅藻群落结构在暴雨期前后的变化特征,深入分析底栖硅藻群落对连续强降雨的响应模式,本研究于2019年夏季暴雨前(7月27日)和暴雨后(8月11日)分别对其进行定性、定量分析,并基于多元统计分析阐述暴雨期前后水体理化因子变化对底栖硅藻群落结构的环境过滤作用。研究期间共鉴定底栖硅藻71种,隶属于2纲6目10科30属。其中,暴雨期前共记录24属55种;暴雨期后共记录26属58种。底栖硅藻丰度、优势种丰富度以及物种多样性指数整体上呈现出暴雨期前高于暴雨期后的规律。单因素交叉相似性分析(One-way crossed ANOSIM)指出,暴雨期前后底栖硅藻群落结构差异显著(R=0.279,P=0.001)。相似性百分比分析(SIMPER)指出,梅尼小环藻(Cyclotella meneghiniana)、系带舟形藻(Navicula cincta)和谷皮菱形藻(Nitzschia palea)是暴雨期前后底栖硅藻群落结构差异的主要贡献物种。运用Margalef物种丰富度指数、Shannon-Weaver物种多样性指数和Pielou均匀度指数并结合水体理化指标对水体营养状态进行初步评价,发现库里泡水体由暴雨期前的中度富营养状态转变为中营养状态。典范对应分析(CCA)结果显示,pH和总氮(TN)是影响底栖硅藻群落结构变化的主要因素(P0.01),此外浊度(Tur.)以及水温(WT)也是底栖硅藻群落发生变化的重要驱动因子(P0.05)。

CHANGES IN COMMUNITY STRUCTURE OF BENTHIC DIATOM AND THE ENVIRONMENTAL FACTORS BEFORE AND AFTER RAINSTORM SEASON IN THE KULIPAO LAKE

To understand the changes of the benthic diatom communities before and after the rainstorm season and the response patterns, the community structure of benthic diatoms in the Kulipao Lake was analyzed based on data collected on Jul.27th (before rainstorm season) and Aug.11th (after rainstorm season). The environmental filtering effects by physical and chemical factors on benthic diatom community assembly were scrutinized in multivariate statistics. Seventy-one species of benthic diatoms including 2 classes, 6 orders, 10 families, and 30 genera were identified. Twenty-four genera covering 55 species were recorded before the rainstorm, and 26 genera comprising 58 species were recorded after the rainstorm. The benthic diatom density, dominant taxa richness, and diversity index were greater before rainstorm season. In addition, the benthic diatom community structure varied significantly (R=0.279, P=0.001) before and after the rainstorm season as revealed in single-factor cross-similarity test (ANOSIM), and the major contributors to the differences in structure of the benthic diatom communities were from Cyclotella meneghiniana, Navicula cincta, and Nitzschia palea as disclosed in similarity percentages (SIMPER) analysis. Water quality was assessed with the Margalef Species Richness Index, Shannon-Weaver Index, and Pielou Evenness Index, and combined with physical and chemical parameters. Results show that the lake water was changed from moderate eutrophic status before rainstorm to mesotrophic status after, and pH and total nitrogen were the key factors driving the changes in the benthic diatom community structure (P<0.01), water turbidity, and water temperature (P<0.05) as indicated in the canonical correspondence analysis.