STRUCTURE AND SPACIAL DISTRIBUTIONAL PATTERN OF MACROZOOBENTHOS IN BAO'ANLAKE

Investigation of macrozoobenthos was carried out in Bao’ an Lake in August 2001. All total, 70 taxa were identified from forty-two sampling sites, of which, 15 Oligochaeta 29 Chironomidae, 11 Gastropoda, two Bivalva, 9 other Insecta and 4 other forms. Mollusks constituted the most dominant group and accounted for more than 80% of the total abundance. Among which, Parafossarulus striatulus, Gyraulus albus, Alocinma longicornis, Semisulcospira libertine and Bellamya aeruginosa were the dominant species. The richness and Shannonπs diversity per site were all relatively low (7.1 and 1.34 respectively). Assemblages were composed mainly of scrapers (80. 0%) and collector2gatherers (11%), and to a lesser extent to other functional feeding groups. The investigation data were compiled and a GIS database of macrozoobenthos was established. A vector boundary map of the lake was digitized and georeferenced, then used to introduce sampling sites. Under the support of GIS software Arcview 3.2 and the relative extension modules (Spatial Analyst Extension 2.0 and Kringing Interpolator Extension 3.22 SA), the GIS database was employed to simulate spacial distribution patterns of parameters of macrozoobenthos. The simulation process was based on the principle of Kringing interpolation technique. The simulated results were stored as Arcview Grid format with a grid precision of 20m. The simulated patterns of macrozoobenthos showed that these patterns were relatively high spatial heterogeneity, and distributions of most parameters of macrozoobenthos had usually 2-4 high value distributed zones in the whole lake. Comparison of patterns of total macrophytes biomass with different macrozoobenthos parameters showed that the total density, densityof mollusks and Shannon2Wiener index were overlapped in most highly distributed zone. The results indicated that macrophyte was the most important factor influencing the distribution of macrozoobenthos in the macrophyte2type lakes.