Benthic diatom assemblages on the natural substrata at Balikhli River (northwest Iran) were investigated monthly. A total of 96 samples were collected from epilithic and epipelic substrata. A total of 110 taxa from 49 genera were identified. The most abundant diatom species were Cyclotella meneghiniana, Diatoma moniliformis, Nitzschia inconspicua, Planothidium lanceolatum and Gomphonema olivaceum. Non-metric multidimensional scaling (nMDS) analyses revealed explicit differences between diatom communities of stony and sediment substrates. Although common diatom taxa were not restricted to single substrates, some taxa had higher tendencies to every substrate. The nMDS analysis also showed differences between summer and autumn samples. Canonical correspondence analysis (CCA) of groups resulted from cluster analysis, showed that the nutrient concentration gradient, pH were the most important factors affecting the composition of diatom assemblages and species distribution. In our study orthophosphates had greater effect than nitrates, and Gomphonem parvulum and Navicula recenswere found in phosphate rich samples. Anthropogenic input including agricultural and domestic wastes may be responsible for high levels of these parameters. Alkali volcanic rocks and limestone sediments underlying the watershed could explain the high pH in the Balikhli River. In total 67.5% of the identified species in the river are considered as alkaliphilous. The findings of this study denote that the main determinants of variation in benthic diatom communities of Balikhli River result from a combination of land use patterns caused by human activities, river hydrology and natural phenomena including geology.

每月对巴厘赫里河（伊朗西北部）天然基质上的底栖硅藻组合进行调查。总共从上层和上层地下收集了96个样品。共鉴定出49个属的110个分类单元。最丰富的硅藻种类是Cyclotella meneghiniana，硅藻Diatoma，Nitzschia conconspicua，Planothidium lanceolatum和Gomphonema olivaceum。非度量多维标度（nMDS）分析显示，石质和沉积物基底的硅藻群落之间存在明显差异。尽管普通的硅藻类群不限于单个基质，但某些类群对每种基质都有较高的趋向。nMDS分析还显示了夏季和秋季样品之间的差异。聚类分析得出的各组典型对应分析（CCA）表明，营养物浓度梯度，pH是影响硅藻集合体组成和物种分布的最重要因素。在我们的研究中有正磷酸盐比硝酸盐更大的作用，并Gomphonem parvulum和舟形recens在富含磷酸盐的样品中被发现。这些参数的高水平可能是人为因素造成的，包括农业和生活垃圾。流域下面的碱火山岩和石灰岩沉积物可能解释了巴厘克里河的高pH值。在河流中，总计67.5％的已识别物种被认为是碱性的。这项研究的结果表明，巴厘克里河底栖硅藻群落的主要变化因素是人类活动，河流水文学和自然现象（包括地质学）造成的土地利用方式的综合结果。