Annual production and its dynamics of four dominant mayflies in Hujiaxi Stream of Qingjiang River catchment,Yangtze River Basin

Abstract

2006年4月至2007年3月对长江支流清江二级支流——胡家溪的大型底栖动物群落结构和生产量进行为期一周年的调查和研究.结果表明,主要蜉蝣优势种小裳蜉(Leptophlebia sp.)、扁蜉(Electrogena sp.)、四节蜉(Indobaetis sp.)的生活史为一年三代,细蜉(Caenis sp.)为一年两代;小裳蜉的年均密度和年均生物量分别为407 ind./m²、1.00 g/m²;扁蜉为150 ind./m²、0.37 g/m²,四节蜉为232 ind./m²、0.30 g/m²,细蜉为91 ind./m²、0.17 g/m².采用龄期频率法测算的周年生产量和P/B分别为:小裳蜉为441.42 g/m²(WW),14.3;扁蜉为434.88 g/m²(WW),7.6;四节蜉为747.21 g/m²(WW),15.0;细蜉为40.52 g/m²(WW),7.2.四种蜉蝣生产量的时间重叠比例相似系数较高,均大于0.55,这可能与四种蜉蝣的生境及食物资源较为相似有关.;During the period of April 2006 to March 2007,secondary production and its dynamics of the dominant species of mayfly community in a second order river (Hujiaxi Stream) of Qingjiang River,Yangtze River Basin were investigated.From the upper to the lower reach of the stream,we sampled at six sites of different habitats quantitatively.The life cycles of the four dominant mayflies, namely Leptophlebia sp.,Electrogena sp.,Indobaetis sp.,and Caenis sp.,were analyzed by the monthly size-class frequency distribution,the cohort and annual production were estimated by size frequency method,and the production dynamics were examined by the method sensu Benke and Wallace (1997).The results show that Leptophlebia sp.,Electrogena sp.,and Indobaetis sp.appear to develop three generations per year,while Caenis sp.completed two generation a year.Their average annual standing stocks were: for Leptophlebia sp.,407 ind./m²,1.00 g/m²;for Electrogena sp.,150 ind./m²,0.37 g/m²;for Indobaetis sp., 232 ind./m²,0.30 g/m²;and for Caenis sp.,91 ind./m²,0.17 g/m²,respectively.The annual production (g/m² (WW)) and the annual P/B ratio of four mayflies were: for Leptophlebia sp.,441.42 g/m² (WW),14.3;for Electrogena sp.,434.88 g/m² (WW),7.6;for Indobaetis sp.,747.21 g/m² (WW),15.0;and for Caenis sp.,40.52 g/m² (WW),7.2.Temporal overlap of secondary production dynamics of the four species,which measured with the proportional similarity index as 0.55,indicates that they utilize similar or same food resources along time dimension.