Secondary Production And Trophic Basis Analysis Of Benthic Macrozoobenthos In Shenglihe Stream

Water is crucial for life, but it is not inexhaustible. Nowadays, water pollution is becoming serious, though firm measures have been taken to hold pollution. However, the consequence is not optimistic. Resaerches have comfirmed that the macroinvertebrate community can sensitively reflect the variation of water quality, and they play an important role in the water quality monitoring. Meanwhile, study on macroinvertebrate community in the clean waters can accumulate useful data in Chinese rivers and also provide standards for evaluation of restoration of the polluted streams and rivers.From March 2009 to March 2010, an investigation was conducted on Shenglihe Stream (a 4-order river in upper reach of Bahe River, which is a main tributary of Yangtze River) for one year. 12 sampling sites were selected in consideration of different habitats. Major work was study on the species composition and biodiversity, analysis of anaual variations of standing stock and life history of the dominant species in different order rivers, calculation of the secondary production and analysis of its trophic basis. The main results were as follows:1. Altogether 123 species of benthic zoobenthos were collected in the Shenglihe Stream, among which, 2 species were Annelida, 5 species were Mollusca, 2 species were Arachnida, 3 species were Crustacea, 2 species were Pisces and 109 species were Insecta. The analyses of spatial and temporal dynamics of the macrozoobenthos community showed that the species number had its peak in January and March, 2010, the least species number occurred in August 2009. For microhabitats, Station 2 and Station 3 (S2 and S3) had the the largest species number, and Station 1 and Station 6 had the least ones.2. The macrozoobenthos biodiversity in different order stream were calculated. The Pielou index and Shannon-wiener index were rather stable, and the Margalef index was relatively fluctuated, the three indexes in the 4 order streams were both steady. The biodiversity indexes can be used as biological monitoring parameters, Margelf and Pielou indexes showed that the water quality is clean in Shenglihe Stream, and the water was sometimes slightly polluted by Shannon-Wiener index. 3. Compared the species similarity between sampling sites in Shenglihe Stream, the similarity indexes generally were in the range of 0.6 to 0.8, the minimal one was 0.472, and the maximum was 0.819.4. The annual variations of standing stock of dominant species in different order stream in Shenglihe Stream were examined,including annual mean density (ind/m~2) and biomass (mg/m~2 wet weight). There were nine dominant species: Georthocladius sp., Larsia sp., Hydropsyche sp., Heptagenia sp., Isonychia sp., E. rufamaculata, Simulium sp., N. denticulata sinensis, S. teritism.5. The life histories of the dominant species were analyzed. E. rufamaculata, Simulium sp. developed 2 generations per year, Georthocladius sp., Larsia sp., Hydropsyche sp., Heptagenia sp., Isonychia sp. N. denticulata sinensis had 3 generations a year, while S. teritism developed one generation every four years.6. Secondary production of dominant species in Shenglihe Stream was calculated, including P/B ratio and annual production(g/m~2) in different order stream.7. The daily production of the dominant species in Shenglihe Stream was also calculated. The peak of biomass (mg/m~2)and daily production(mg/m~2.d) of the dominant species were as follows: Georthocladius sp. 3.59, 0.20,Larsia sp. 19.51,0.66, Hydropsyche sp. 19.51, 655.03, Heptagenia sp. 1526.16, 363.56, Isonychia sp. 1872.58, 282.76, E. rufamaculata 227.94, 33.36, Simulium sp. 802.32, 72.48, N. denticulata sinensis 6.61 g/m~2, 493.55 mg/m~2.d and S. teritism 8.71 g/m~2, 95.83 mg/m~2.d, respectively.8. The trophic bases of seven dominant species were analyzed in Shenglihe Stream. The results showed that the stream was a detritus-based river, except E. rufamaculata, amorphous detritus composed more than 60% of their diets, and its contribution to production also excelled 60%. The total ingestions (g/m~2.a) of the species were: for Larsia sp. 4.60, Hydropsyche sp. 309.53, Heptagenia sp.1922.48, Isonychia sp. 789.04, E. rufamaculata 129.20, Simulium sp. 287.03, N. denticulata sinensis 3598.34.