镜湖常见臂尾轮虫(Brachionus)种群周年动态及生活史对策

对镜湖臂尾轮虫种群的周年动态进行了研究,测量和分析了它们的个体大小、卵大小和相对卵大小及其与水温和叶绿素a浓度等生态因子间的关系。结果表明,镜湖常见的7种臂尾轮虫中,仅萼花臂尾轮虫(Brachionus calyciflorus)、角突臂尾轮虫(B.angularis)、裂足臂尾轮虫(B.diversicornis)和剪形臂尾轮虫(B.forficula)的种群密度和出现频率较高;前两者种群密度高峰期均出现在2~3月份,4月份后均较低;后两者种群密度在6~9月份较高,而在10月份后很快下降。除剪形臂尾轮虫外,其它3种臂尾轮虫的个体体积均与水温间具有显著的相关性,平均卵体积均与各自的平均被甲长度呈显著的正相关关系。角突臂尾轮虫和萼花臂尾轮虫个体大小与水体叶绿素a浓度间呈显著的负相关关系,它们的卵体积分别与水温和叶绿素a浓度之间具有显著的负相关性,且水温是影响它们卵体积的主要因子。4种臂尾轮虫中,仅角突臂尾轮虫的相对卵体积与水温间表现出显著的正相关关系。

Population dynamics and life history strategy of the common Brachionus species (Rotifera) in Lake Jinghu

The annual dynamics of Brachionus (Rotifera) populations in Lake Jinghu of Anhui Province, China was studied in the year 2003, and the relationships between their body volumes, egg volumes as well as relative egg volumes and the ecological factors including water temperature, Chl-a concentration were regressively analyzed. Seven Brachionus species in Lake Jinghu were found, of which Brachionus calyciflorus, B.angularis, B.diversicornis and B.forficula were determined as common species due to their higher population densities and occurrence frequency. The population density of both B. calyciflorus and B. angularis reached the peak in February and March and decreased rapidly after April, while that of both B. diversicornis and B. forficula remained high during June-September and decreased sharply after October. The body volumes of the four common Brachionus species excluding B. forficula were significantly correlated to water temperature, and their mean body size was positively correlated with their mean egg volume. The body volumes of B. calyciflorus and B. angularis were both negatively correlated with Chl-a concentration, and their egg volumes were negatively associated with water temperature and Chl-a concentration, respectively, with water temperature being the greatest effect. The relative egg volume of only B. angularis was positively correlated with water temperature.