Ecological characteristics of dominant phytoplankton community in Lake Nanhai (Baotou) during freezing-thawing period

Abstract

为了探究包头南海湖浮游植物群落特征和物种与生境之间的关系，于2018年11月和2019年1月、3月分别对南海湖浮游植物群落结构进行调查分析，得出南海湖冻融期浮游植物群落结构为绿藻-硅藻-蓝藻型.使用改进的Levins公式和Petraitis指数测定了南海湖冻融期优势种的生态位量度.结果显示：在不同生境条件下，物种生态位宽度存在季节性变化，同样，生态位重叠也随季节变化而变化.随着湖面冰冻，多数浮游植物生态位宽度有所下降；结冰期生态位重叠程度最高，融冰期生态位重叠程度最低.综合冻融过程优势藻种生态特征，绿藻门的四尾栅藻（Scenedesmus quadricauda）是冻融过程中最主要优势种，优势度、密度、生态位量度均优于其他优势藻种，能充分利用环境资源，更具竞争力.优势种与环境因子的灰关联分析显示，pH是影响浮游植物优势种数量的主要相关因子.;This study investigated the phytoplankton community structure and their relationship with habitats in Lake Nanhai of Baotou city, based on the data from November 2018 and January and March 2019 respectively. It found that the phytoplankton community comprised of Chlorophyta-Bacillariophyta-Cyanophyta in the freezing-thawing period. The niche traits of the dominant species in the freezing-thawing period were determined by using the improved Levins Niche Breadth Index and Petraitis Index. Results showed that there were seasonal changes in the niche breadth of the species under different habitats. Similarly, the niche overlap also changed with the seasons, with highest values during the icing period and lowest during the ice-melting period. Scenedesmus quadricauda was the most dominant species in the process of freezing and thawing. It's dominance degree, density, niche breadth and niche overlap are superior to other dominant phytoplankton species, and it can make full use of environmental resources, and be more competitive. Grey correlation analysis between dominant species and environmental factors showed that pH was the main factor affecting the density of dominant species of phytoplankton.