Mining operations can cause environmental alterations that have a major impact on aquatic organisms. In the present study, we analyzed the effects of mining operations on the environmental heterogeneity of streams in the eastern Brazilian Amazon, and the beta diversity (and components) of the local communities of the order Ephemeroptera. We tested three hypotheses: (a) mining activities reduce the environmental variation of streams; (b) altered streams have lower beta diversity, and (c) environmental variables influence the genus richness and abundance of ephemeropterans. The ephemeropterans were sampled in the Carajas National Forest in the dry season over 3 years. Streams were sampled in areas near the extraction of iron ore (16) and in pristine environments (8). The beta diversity was estimated based on the occurrence and abundance approaches. We recorded 2259 individuals and 32 genera. The comparative assessment of environmental variables indicated that environments altered by mining have higher total manganese and iron concentrations than preserved environments. Environmental variables influenced ephemeropteran communities, and the analysis of the components of the beta diversity indicated a higher turnover of ephemeropterans in preserved streams, which implies that species substitution rates are higher in preserved streams than in altered streams. These results indicate that the substitution of species in preserved streams is limited spatially, probably linked to the sensitivity of the organisms to oscillations in the environmental variables occurring in impacted environments. The results indicated that possibly the changes brought about by mining activities restrict the turnover of species between the preserved and altered areas, and only species tolerant to these changes were established. Over time and with the advancement of mining activities may occur the local exclusion of the most sensitive species and homogenization of the composition formed by more tolerant and less relevant conservation species.

中文翻译：

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巴西东部亚马逊河流中蜉蝣（昆虫纲）的开采和减少营业额的影响

采矿作业可能导致环境变化，对水生生物产生重大影响。在本研究中，我们分析了采矿作业对巴西亚马逊东部河流环境异质性的影响，以及蜉蝣目当地群落的 Beta 多样性（和组成部分）。我们测试了三个假设：(a) 采矿活动减少了河流的环境变化；(b) 改变的溪流具有较低的 beta 多样性，以及 (c) 环境变量影响蜉蝣的属丰富度和丰度。蜉蝣在 3 年多的旱季在 Carajas 国家森林进行采样。在靠近铁矿石开采区 (16) 和原始环境 (8) 的地区对溪流进行采样。β 多样性是根据发生率和丰度方法估计的。我们记录了 2259 个个体和 32 个属。环境变量的比较评估表明，采矿改变的环境比保存环境具有更高的总锰和铁浓度。环境变量影响了蜉蝣群落，对β多样性组成部分的分析表明，保存溪流中蜉蝣类的周转率更高，这意味着保存溪流中的物种替代率高于改变溪流中的物种替代率。这些结果表明，保存下来的溪流中物种的替代在空间上是有限的，这可能与生物体对受影响环境中发生的环境变量振荡的敏感性有关。结果表明，采矿活动带来的变化可能限制了保存区和改造区之间物种的周转，只有能够耐受这些变化的物种才能建立。随着时间的推移和采矿活动的进展，最敏感的物种可能会被局部排斥，并且由更耐受和相关性较低的保护物种形成的组成会发生同质化。