在种与属两个级别评价太子河硅藻群落与环境因子的关系

Evaluation of relationship between environmental factors and diatom assemblages at genus and species levels in the Taizi River Basin,China

2009年8—9月,对辽宁省太子河流域67个点位进行采样调查,以硅藻群落为研究对象,比较硅藻属级水平与种级水平相对多度、物种丰富度以及生物多样性指数间的相关性,并比较硅藻属级与种级属性与环境因子的相关性。实验结果表明,太子河流域硅藻属级水平的相对多度、丰富度和多样性指数与硅藻种级水平都极显著相关。Pearson相关性分析表明,硅藻属级水平的丰富度与环境显著相关的因子与种级水平丰富度与环境显著相关的因子相一致。Mantel-Test相关性分析表明,硅藻属级水平的相对多度与环境因子的相关性弱于种级水平与环境因子相关性。典范对应分析结果显示,影响硅藻属级和种级群落结构分布的主要环境因子均为悬浮物。基于硅藻生物评价指数的流域健康评价结果表明,应用硅藻属级和种级属性对太子河流域进行健康评价,其评价结果相一致。

Benthic diatoms are generally used to assess stream conditions, however most of the methods and diatom indices are based on the identification at species levels, which requires a lot of training because of its extreme diversity. Compared with species level, identification at genus level can save amount of time and money to assess river pollution, however it may lose some ecological information. In this paper, we investigated 67 samples sites in the Taizi River basin to investigate the relationship between diatom assemblages and environmental characteristics at both species and genus levels. Ten diatom assemblage attributes： relative abundance, richness, Shannon-Wiener diversity index, Pielou diversity index, Margalef diversity index, Berger-Parker diversity index, Simpson diversity index, Hill diversity index and Mackintosh diversity index were chosen to evaluate concordance correlations between genus and species level. We assessed relationship between diatom assemblages and environment base on the Pearson Correlation Test, Mantel-Test, Canonical Correspondence Analysis and Diatom Bioassessment Index. The results showed that 15 genera and 141 species of diatoms were observed in the Taizi River basin. The most abundant species was Navicula, followed by Nitzschia, presenting 32.6% and 13.5% of the sample sites, respectively. The Diploneis and Stauroneis were represented by a single species. Genus richness ranged from 2 to 13 and the species richness ranged from 3 to 40. The relative abundance and richness had strong correlations between species and genus resolution. Eight biology diversity indexes had strong correlations between species and genus resolution, of which the strongest coefficient was Mackintosh diversity index. Moreover the Berger-Parke diversity index was no related with the other biology diversity indexes. Both genus and species richness exhibited strong correlations with the suspended solid, total dissolved solid, total nitrogen, Cl^-, NH4^＋-N, PO4^3-, sand, total phosphorus, biochemical oxygen demand, chemical oxygen demand and permanganate index. Dissolved oxygen and NO3--N variables were significantly correlated with genus richness, however there were no significant correlation between species richness and dissolved oxygen or NO3^--N. Correlations between major-ions, nutrients and organic matter with species relative abundance were significant, which was also observed at genus level. Based on principal component analysis, dissolved oxygen, conductivity, suspended solid, NO2^--N and biochemical oxygen demand were the main environmental factors in Taizi River basin. Canonical correspondence analysis showed that suspended solid had significant influence on the community structure of genus and species diatom in Taizi River basin. Assessment of river condition was made using the Diatom Bioassessment Index （DBI） at species and genus levels. The results at both levels （species and genus） showed same trend, indicating that upstream area of Taizi River basin was in excellent and good ecological integrity, while the stream condition of downstream area was in severe pollution. In conclusion, genus resolution may be used to replace the species resolution to evaluate the river conditions in China.