赤水河春季浮游植物群落结构变化及其优势种生态位分析

Spring Phytoplankton Community Structure and Niche Analysis of Dominant Species in Chishui River

基于2011-2016年春季对赤水河4个断面浮游植物的调查,分析其群落结构变化及优势种生态位,揭示浮游植物群落变化规律、优势种的生态位分化及其环境适应性,可为赤水河浮游植物群落结构特征研究提供基础资料。结果显示,6年间在赤水河共采集到浮游植物7门、68属、233种(变种),主要为硅藻,占比超过60%;浮游植物细胞密度在(17.28~136.68)×10^(4)个/L,各段面浮游植物密度年际间变化无显著差异,群落组成时间异质性较空间异质性明显,时空方差分解显示,时间变异可解释总变异的24.5%,空间变异仅解释总变异的2.0%;浮游植物多样性指数显示,2014年和2016年赤水河处于轻污或无污染状态,2011-2013年和2015年受到中度人为影响。2011-2016年春季赤水河共出现优势种31种(变种),主要为广生态位和中生态位种,生态位重叠指数在同一门类物种中最高,在不同门类物种中最小。研究表明,赤水河春季浮游植物对水生态环境的适应能力强,对水环境变化有较好的适应性。

Chishui River is an important part of the national nature reserve for rare and endemic fish in the upper Yangtze River. A better understanding of the relationships between phytoplankton species will support the conservation and management of Chishui River ecology. In this study, phytoplankton community structure and the niches of dominant species were analyzed based on spring surveys of phytoplankton in Chishui River from 2011 to 2016. Phytoplankton community changes during spring and our investigation of niche differentiation and environmental adaptation of dominant species provides basic data for characterizing phytoplankton community structure in Chishui River. Sampling of phytoplankton for quantitative and qualitative analysis was carried out each spring(March-May) at four transects on the main stem of Chishui River. During the investigation, a total of 233 phytoplankton species(variants) from 68 genera and 7 phyla were collected in Chishui River, with absolute dominance by Bacillariophyta(141 species, 60% of total species). From 2011 to 2016, the numbers of species collected each year were, respectively,105, 105, 100, 122, 132 and 133. The range of phytoplankton density was(17.28-136.68)×10^(4) cells/L and, among sampling transects, there were no significant differences in inter-annual phytoplankton density. The temporal heterogeneity of the phytoplankton community composition was more obvious than the spatial heterogeneity. Analysis of variance showed that temporal variability accounted for 24.5% of the total, while spatial variability accounted for only 2.0%. Water quality evaluation, based on phytoplankton diversity indices, indicated that Chishui River was in a light to no-pollution state in 2014 and 2016, and was moderately affected by humans during 2011-2013 and 2015. A total of 31 dominant species(variants) occurred in Chishui River in spring during 2011-2016. The dominant species of phytoplankton in Chishui River were species that primarily inhabit broad and moderate breadth niches. The average niche overlap index of dominant species was highest among species in the same category and minimum among species in different categories. Our research shows that phytoplankton in the Chishui River are strongly adaptable to the seasonal changes of the water environment that occur during spring.