汉江流域黑竹冲河五种优势摇蚊的周年生产量及营养基础分析

Secondary production and its trophic basis of five dominant chironomids in Heizhuchong Stream, Hanjiang River Basin

2003年6月至2004年6月间对汉江流域2级河流——黑竹冲河大型底栖动物群落优势种类的生产力进行为期一周年的调查研究,其中主要优势摇蚊中粗腹摇蚊(Pentaneura sp．)和多足摇蚊(Polypedilum sp.)的生活史为一年三代, 小摇蚊(Microtendipes sp．)和帕摇蚊(Pagastia sp．)为一年两代,刺突摇蚊(Chaetocladius sp．)为一年一代．粗腹摇蚊种群生物量和多度在一年中出现两次峰值,多足摇蚊则出现三次,小摇蚊在6月份达到最大峰值,刺突摇蚊在1月份达到最大峰值,帕摇蚊在10月份和次年1月份分别达到次峰值和主峰值．采用龄期频率法(instar-frequency method)测算的周年生产量(鲜重)分别为:粗腹摇蚊,19．9233g/(m2·a),P/B为8．7;多足摇蚊,7．2177g/(m2·a),P/B为8．1;小摇蚊, 0．8996g/(m2·a),P/B为6．0;刺突摇蚊,3．2533 g／(m2·a),P／B为3．4;帕摇蚊,8．5132g/(m2·a),P／B为8．4．除粗腹摇蚊外,其它四种摇蚊的前肠内含物中无形态碎屑所占比例均高于90％,对生产量的贡献率达到77％-96％;粗腹摇蚊的动物性食物所占比例达到14．73％,其对生产量的贡献率高达46．04％．

Macrozoobenthos community plays an important role in material cycle and energy flow in riverine ecosystem. During the period of June, 2003 to June 2004, an investigation on the llfe cycle and production of the dominant species of macrozoobenthos community in a second-grade river of Hanjiang River Basin was carried out. From the upper reach to the lower reach of Heizhuchong stream, we chose six types of habitats to sample. At each station, two quantitative samples were taken with a 1671μm D-frame kick net or a Surber net, and the samples were sieved with a 1671μm net, sorted in a porcelain dish with naked eye. The specimens were kept in 10% formalin for later processing. The life cycles of the two dominant chironomids were analysed by the monthly size-class frequency distribution, the cohort and annual production were estimated by size frequency method. The results showed that the Pentaneura sp. and Polypedilurn sp. appeared to develop 3 generations for one year, Microtendipes sp. and Pagastia sp. had two generations one year, while Chaetocladius sp. just developed one generation per year. The standing stocks of Pentaneura sp. and Pagastia sp. had two peaks, that of Polypedilurn sp. had three, while that of Microtendipes sp. and Chaetocladius sp. only had one. The estimated annual production of Pentaneura sp. by size-frequency method was 19. 9233 g/（ m^2 · a） （FW） , and the P/B ratios was 8.7. The annual production of Polypedilurn sp. was 7. 2177 g/（ m^2 · a） , and the P/B ratios was 8.1. Annual productiont of Microtendipes sp. was 0. 8996g/（ m^2 · a） , and P/B was 6.0 ; production of Chaetocladius sp. was 3. 2533 g/（ m^2 · a） ,and P/B was 3.4 ; and that of Pagastia sp. was 8.5132 g/（ m^2 ·a） and 8.4, respectively. By analyzing their fore-gut contents, it was found that all species except Pentaneura sp. consumed a large portion of amorphous detritus, constituting more than 90% of their diets, and contributing 77% -90% to their secondary production.