Abstract: Macrobenthos is an important part of freshwater ecosystem, playing an important role in material cycling and energy utilization. The changes in community structure of macrobenthos are indicators for the stability for freshwater ecosystem, because macrobenthos have slow mobility, long life history, and stable habitat requirements. For this reason, the macrobenthos has great significance for freshwater environmental monitoring and evaluation. Previous researchs show that macrobenthos in salt ponds were scarce. Few studies were investigated the macrobenthos in salt ponds except Huangshui River of Qinghai Province, salt ponds of Shandong Province, DaLi Lake of Inner Mongolia and SalineAlkaline wetland of Ordos Plateau. In these studies, fewer were involved the community structure of macrobenthos and their relationship with environmental factors. In order to better understand community structure of macrobenthos and environmental factors in salt ponds, the paper explored the species composition, density, biomass of macrozoobenthos and their relationships between macrobenthos and environmental factors in high flow period (June), normalwater period (July) and low water level period (October) in five salt ponds of northern Xinjiang from July 2008 to May 2009. A total of 23 species of macrobenthos were identified, of which 18 species were Aquatic insects (78.3%), 4 species were Mollusca(17.4%), 1 species were Aneuelida (4.3%). The dominant species were Chironomus plumosus (IV=59.00%), Ephydrasp. (IV=6.86%), Planorbidae sp. (IV=6.67%), Diplocladius sp. (IV=4.69%) and Radix ovata (IV =4.34%). The average density and biomass were 316.36±117.27 ind / m2 and 4.09±2.73 g/m2. Density was highest in Baqian Salt Pond (436.00±84.00 ind / m2) and lowest in Yinongchang Salt Pond (103.11±26.90 ind / m2). Biomass has the same trend that with highest in Baqian Salt Pond (10.89±5.94 g/m2) and lowest in Yinongchang Salt Pond (0.27±0.10 g/m2). Ponds with different salinity have different community structure of macrobenthos. In general, the salinity between 5 ‰-8 ‰ is an important ecological barrier to the spatial distribution of macrobenthos. In this salinity, the species number, density and biomass of macrobenthos would be in the lowest lever. Species number, density and biomass showed a decreasing tendency with the rising of salinity. However, when the salinity higher than 8‰, this tendency have been changed. Sanqian Salt Pond have the highest salinity, but its species number, density and biomass of macrobenthos are not the least. The relationships between macrobenthos and environmental factors were studied by canonical correspondence analysis (CCA) and the results showed that species-environment correlations were both higher than 99%, which indicated the distribution of macrobenthos in salt ponds was strongly affected by environmental factors measured. Salinity and conductivity were the two major factors affecting macrobenthos distribution. More over, altitude, pH and temperature were also influential on macrobenthos distribution.

Key words: salt pond, macrobenthos, environmental factors, community structure, canonical correspondence analysis