泥炭地苔藓附生硅藻个体大小对水位变化的响应

Individual size of moss-epiphytic diatoms in response to water level change in peatland

苔藓附生硅藻是泥炭地中重要的微生物种群,其种群组成对泥炭地水位变化响应敏感,但其形态特征与水位变化的关系还不清楚。本文选取苔藓附生硅藻中2个主要优势属种Eunotia steineckei和Eunotia paludosa var.paludosa,在显微镜下测量其个体长度。硅藻个体长度均值与水位、含水量、pH、电导率、总磷和总氮等环境因子的Pearson相关分析结果表明,2个种的个体长度均值都与水位变化呈极显著负相关关系,而与含水量呈显著正相关。除E.steineckei个体长度与pH值呈显著负相关外,硅藻个体长度与其他环境因子相关性都不显著。表明这2种硅藻个体的长度主要响应于泥炭地水位变化。硅藻在无性繁殖阶段个体分裂变小,有性繁殖阶段产生复大孢子个体恢复。泥炭地水位变化可能调控硅藻繁殖方式,从而影响硅藻的个体形态。本研究表明,苔藓附生硅藻个体大小可作为反映泥炭地水位变化的敏感指标。

Mossepiphytic diatom is one of the important microbial groups in peatland. The popu lation 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 mossepiphytic 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 in dividual 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 lev el 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 mossepiphytic diatom could be used as a sensitive indicator reflecting the water level change of peatland.