BIOASSESSMENT OF SEDIMENT QUALITY USING MACROFAUNA IN THE WETLANDS OF LAKE BUFFER ZONE OF ZIIUSHAN BAY, TAIHU LAKE, CHINA

With the rapid urban and industrial development, Taihu Lake and its adjacent wetlands had suffered serious pollution due to human activities. In order to assess sediment quality of the lake buffer zone of Zhushan Bay, Taihu Lake, macrofauna and sediment chemicals were analyzed at 33 sites from August 2013 to May 2014. A total of 79 macrofaunal species were identified, belonging to 3 phyla, 14 orders and 20 families. The most two dominant taxa were Oligochaeta (78%) and Chironomidae larva (19%). In terms of species richness, Chironomidae larva were the largest group (43 species), followed by Oligochaeta, Mollusca, Hirudinea, Decapoda and Polychaeta. Limnodrilus hoffmeisteri (accounting for 26.2%) was the most dominant species, which was one of the heavy pollution indicators in the study area. According to Biotic Index (BI), sediment quality was under serious pollution during August 2013 to March 2014, ranging from 7.98 to 8.81 while there was a declining trend for BI from March 2014 to May 2014, which indicated that sediment quality was under recovery. However, chemical indices showed that a continuous amelioration of sediment quality from December 2013 to March 2014, which was not consistent with biological assessment. This result indicated that there was a delay of the recovery for macrofauna compared with sediment chemicals. Correlation analysis showed that BI had significant relationship with sediment total nitrogen. The present study showed that in sediment quality assessment, macrofauna should be involved, which could provide more accurate results than sediment chemicals.