Influence of Water Pollution on Species Diversity of Freshwater Benthic Macro-invertebrates in the Yellow River Delta

Continuous monitor was carried out from 1993 to 1997 on the water quality of 8 rivers,3 reservoirs and 1 lake in the Yellow River Delta.In pace with the monitor,a systematic investigation about the species diversity of freshwater benthic macroinvertebrates was performed from 1996 to 1997.The result of the water quality evaluation is as following: 2 rivers are severely polluted,7 rivers are heavily polluted and Mada Lake is severely polluted.69 species of freshwater benthic macroinvertebrates are identified.They are subordinate to 38 families and 62 genera.Water pollution has decreased the species diversity of benthic.