胡家溪中华新米虾种群动态、周年生产量及营养基础分析

POPULATION DYNAMICS,ANNUAL PRODUCTION AND TROPHIC BASIS ANALYSIS OF THE DOMINANT SPECIES NEOCARDINA DENTICULATA SINENSIS (KEMP) IN HUJIAXI STREAM

2006年4月至2007年3月间对清江流域二级河流-胡家溪大型底栖动物群落的优势种中华新米虾[Neocaridina denticulata sinensis(Kemp)]进行为期1周年的调查研究。结果表明,中华新米虾的生活史为1年2代,中华新米虾的种群密度峰值分别出现在7月(31ind/m2)、10月(35ind/m2)、12月(20ind/m2)和次年的2月(20ind/m2),生物量峰值则出现在4月(1.76g/m2)、7月(4.74g/m2)和次年2月(2.38g/m2)。采用体长频率法(Size-frequency method)测算的周年生产量和P/B分别为67.40g/m2(湿重)和4.7。通过对中华新米虾前肠内含物组成的分析测定了各类食物类型的比例及对生产量的贡献率,结果表明,无形态碎屑和动物组织为其主要食物类型,分别占前肠内含物的79.9%和12.5%,对生产力的贡献率分别为62.50%和34.18%。

Macrozoobenthos community plays an important role in material cycle and energy flow in riverine ecosystem. During the period of April 2006 to March 2007, an investigation on population dynamics, annual production, and trophic basis analysis of a dominant macrozoobenthic species Neocardina denticulata sinensis （Kemp） in a second order river （Hujiaxi Stream） of Qingjiang River Basin was conducted. From the upper to the lower reach of Hujiaxi Stream, we chose six types of habitats to collect quantitative samples. Station 1 （S1） was in the middle of a peaceful flowing section with grit bottom, station 2 （S2） was at a branch away with silver sand, station 3 （S3） was under a waterfall of the riffle with large boulders, station 4 （S4） was at the lower reach of a weir with slowly flowing water and cornbrash, station 5（S5） was at a riffle with much litter and many cobbles on the bed, station 6 （S6） was at the lower reach of a sewage outlet with gravel-sand bottom. At each station, samples were taken with a Surber net （60 mesh）, and the specimens were kept in 10% formalin for later processing. The life cycle of N. denticulata sinensis was analyzed by the monthly size-class frequency distribution, the annual production were estimated by size-frequency method, the trophic basis analysis followed the method employed by Wallace and Benke （1997）. The results showed that N. denticulata sinensis appeared to develop two generations per year. The density of its population reached its peaks in July （31 ind/m^2）, Octo-ber （35 ind/m^2）, December （20 ind/m^2） and February （20 ind/m^2） of next year. The biomass reached its peaks in April （1.76 g/m^2）, July （4.74 g/m^2） and February （2.38 g/m^2） of next year, respectively. The annual production and the annual P/B ratio of N. denticulata sinensis estimated with size-frequency method were 67.40g/m^2, 4.72. The proportions of various food types as well as their contribution to production with foregut content analysis were also examined. The results showed that amorphous detritus and animal materials were the most important food types, accounting for 79.9% and 12.5 % of foregut content, and contributing 62.50% and 34.18% of the production, respectively.