Abstract We evaluated the response of diatom community relative to environmental changes with the aim of characterizing and comparing, along a linear gradient, three environments across the Cascavel River microbasin with distinct land-uses. In June 2016, 10 substrates were collected for periphyton extraction in locations with different land-uses (conservation, urban, and agriculture respectively). One-hundred and nine infrageneric taxa and 30 genera were found. Eunotia and Gomphonema presented elevated and representative taxa richness at all stations, with totals of 14 and 11 respectively. Pinnularia and Navicula (12 and 8 taxa respectively) were significant indicators at the more upstream points; while Encyonema, Achnanthidium and Navicula (5, 5, and 6 taxa respectively) occurred primarily downstream. The sampling stations were quite distinct in their densities, species richness, and physical, chemical, and biological characteristics. The tests showed a significant difference among the stations based on the species abundance matrix. Upstream points, within the conservation area, revealed high Eunotia density, high nitrate concentrations and low pH. The urbanized area was characterized by greater exposure to light associated with elevated electrical conductivity and high ammoniacal nitrogen concentration, favoring the cosmopolitan species development such as Gomphonema lagenula, Gomphonema exilissimum and Fragilaria gracilis. The agricultural area exhibited elevated flow, a factor limiting the colonization of species and favoring the development of Achnanthidium and Fragilaria species. The distribution of the community across the microbasin were related to flow, dissolved oxygen, electrical conductivity, nitrate, ammonia, and total coliforms, confirming the distinctiveness among the environments. Except for spatial autocorrelation, there wasn’t a single environmental filtering explanation for the diatom community variation. The abiotic variables differentiated the environment in conjunction with the spatial variation. Along the river, physical characteristics such as depth, water volume, flow, solar incidence, concentration of solids, and temperature varied, directly interfer with the periphytic community’s primary production.

中文翻译：

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环境变量可能影响亚热带环境中的附生硅藻群落

摘要 我们评估了硅藻群落对环境变化的响应，目的是沿着线性梯度表征和比较卡斯卡维尔河微流域中具有不同土地用途的三种环境。2016 年 6 月，收集了 10 种基质，用于在不同土地用途（分别为保护、城市和农业）的地点提取附生生物。发现了一百零九个属下分类群和30个属。Eunotia 和 Gomphonema 在所有站点都呈现出较高和具有代表性的类群丰富度，分别为 14 和 11。Pinnularia 和 Navicula（分别为 12 个和 8 个分类群）是更上游点的重要指标；而 Encyonema、Achnanthidium 和 Navicula（分别为 5、5 和 6 个分类群）主要发生在下游。采样站的密度、物种丰富度和物理、化学和生物特征都非常不同。测试表明，基于物种丰度矩阵的站点之间存在显着差异。保护区内的上游点显示出高桉树密度、高硝酸盐浓度和低 pH 值。城市化地区的特点是更多地暴露在与高电导率和高氨氮浓度相关的光照下，有利于世界性物种的发展，如 Gomphonema lagenula、Gomphonema exilissimum 和 Fragilaria gracilis。农业区表现出较高的流量，这是一个限制物种定殖并有利于针螟属和脆弱属物种发展的因素。微流域中群落的分布与流量、溶解氧、电导率、硝酸盐、氨和总大肠菌群有关，证实了环境之间的独特性。除了空间自相关外，硅藻群落变异没有单一的环境过滤解释。非生物变量将环境与空间变化相结合。沿着河流，深度、水量、流量、太阳入射、固体浓度和温度等物理特征的变化直接干扰了附生群落的初级生产。对于硅藻群落变异，没有单一的环境过滤解释。非生物变量将环境与空间变化相结合。沿着河流，深度、水量、流量、太阳入射、固体浓度和温度等物理特征的变化直接干扰了附生群落的初级生产。对于硅藻群落变异，没有单一的环境过滤解释。非生物变量将环境与空间变化相结合。沿着河流，深度、水量、流量、太阳入射、固体浓度和温度等物理特征的变化直接干扰了附生群落的初级生产。