LAUSR

The Zhalong wetland is located in the western portion of the Heilongjiang Province, downstream of the Wuyuer River, which is the most complete wetland in north China at similar latitudes. It is an important habitat for cherish cranes and waterfowl. Recently, water in the Zhalong wetland became more saline. In 2012, algae samples were collected from six sites in spring, summer, and autumn. In total, 140 diatom taxa were observed, including 121 species, 19 varieties belonging to 2 classes, 6 orders, 9 families, and 30 genera. Pennatae diatoms were rich in species and accounted for 95% of the total number. Diatom community showed seasonal succession, with the richness and relative abundance of diatom species in autumn higher than during spring and summer. Most of the dominant species were freshwater, brackish, or weakly alkaline water species. Dominant species occurred in response to salinity and pH of water; an obvious correlation with environmental conditions. Navicula cryptocephala was the dominant species of the Zhalong wetland in spring, summer, and autumn. Meanwhile, Amphipleura pellucida, Gomphonema micropus, and Nitzschia palea were abundant in alkaline water. This indicated that the Zhalong wetland was affected by soil salinization. Environmental parameters, including pH, water temperature( WT ), conductivity ( SpCond.), chemical oxygen demand ( CODCr ), permanganate index ( CODMn ), biochemical oxygen demand ( BOD5 ), dissolved oxygen ( DO), total phosphorus ( TP ), and total nitrogen ( TN) were measured. The relationships between environmental factors and the variation in diatom community structure were analyzed by