关键词: 干湿交替, 草地生态系统, 土壤呼吸, 微生物响应机制

Abstract: From November 2008 to April 2009, an investigation was conducted to understand the feeding traits of Gambusia affinis and their relations with the dynamics of zooplankton population, water temperature, and light intensity in the Minghu pond in Jinan University campus in autumn (November), winter (December-February), and spring (March-April). In the pond, G. affinis mainly fed zooplankton, especially cladocera and copepod. The daily mean temperature and daily mean abundance of the zooplankton changed significantly with the three seasons, but the repletion index of the alimentary canal of G. affinis had little change. The repletion index had no significant relationships with the zooplankton abundance, water temperature, and light intensities in the three seasons. No matter what season, the G. affinis had a day-night feeding rhythm, and its repletion index in the daytime (10:00-18:00) was higher than that in the nighttime (22:00-6:00). The diurnal feeding rhythm of G. affinis was significantly affected by light intensity, but not by the diurnal changes of zooplankton abundance and water temperature.

Key words: drying and rewetting, grassland ecosystem, soil respiration, microorganism response mechanism.