Abstract: Moss-epiphytic diatom is one of the important microbial groups in peatland. The population composition of the diatom in peatland is quite sensitive to water level change, but little is known about the relationships between the diatom morphology and the peatland water level change. In this paper, two dominant species of mossepiphytic diatom (Eunotia steineckei and E. paludosa var. paludosa) were taken as the objects, with their individual lengths measured under microscope. The Pearson correlation analysis on the relationships between the average diatom individual length and the peatland environmental factors (e.g., water table, water content, pH, conductivity, and total phosphorus and nitrogen contents) revealed that the average individual length of the two diatom species had highly significant negative correlations with the changes of water table, and positive correlations with the peatland water content. Except that the individual length of E. steineckei was significantly negatively correlated with water pH, the individual length of the two diatom species had little correlations with the other environmental factors, indicating that the individual length of the two diatom species was mainly affected by the peatland water level change. The diatoms at their vegetative reproduction stage had a successive diminution in cell size, but the cell size was restored at sexual reproduction stage via the gamete production and anxosporulation. Peatland water level change could regulate the diatom reproduction pattern, and then, affect the diatom individual morphology. This study demonstrated that the individual length of moss-epiphytic diatom could be used as a sensitive indicator reflecting the water level change of peatland.

Key words: Arid regions, Oasis, Corridor landscape