Agribusiness is one of the main economic activities in Brazil, which caused the removal of much of its natural vegetation for the expansion of monoculture areas. Once aquatic environments have a direct relationship with the surrounding terrestrial environment, it is essential to understand the monocultures’ impact on adjacent streams and, especially, how aquatic communities react to these impacts. Our aim was to verify the effects of different monoculture types on stream benthic macroinvertebrate and fish communities’ structure. We compared the environmental characteristics and these communities’ structure in four streams located in native vegetation areas and four in each of three monoculture types (sugarcane, citrus, and eucalyptus), all belonging to the Paranapanema River basin, Southeastern Brazil. We found lower pH and dissolved oxygen and higher total phosphorus and fine substrate values in monoculture streams and these variables were also related to the lower abundance of macroinvertebrate groups more sensitive to environmental impacts. However, we did not find differences in fish communities or in their relationship with the different environmental characteristics observed. We also did not observe differences between the monoculture types in all comparisons made, which demonstrate that these plantations, although have different cultivation characteristics, cause similar negative impacts in the streams. Our study demonstrates the physical and chemical impacts of monoculture development on stream headwater communities. Regulatory measures such as increased riparian vegetation and contour farming and terracing may be critical to protect and restore headwater streams from monoculture impacts.

农业综合企业是巴西的主要经济活动之一，导致其大部分自然植被被砍伐，从而扩大了单一种植面积。一旦水生环境与周围的陆地环境直接相关，就必须了解单一养殖对邻近河流的影响，尤其是水生社区对这些影响的反应。我们的目的是验证不同单一养殖类型对河流底栖无脊椎动物和鱼类群落结构的影响。我们比较了位于巴西南部帕拉纳帕内玛河流域，位于原生植被区的四个溪流和三种单一栽培类型（甘蔗，柑桔和桉树）中的四种中的四种的环境特征和这些群落的结构。我们发现单一养殖流中的pH值和溶解氧较低，总磷和底物值较高，这些变量还与对环境影响更为敏感的大型无脊椎动物种群数量较低有关。但是，我们没有发现鱼类群落的差异或它们与观察到的不同环境特征之间的关系。我们也没有在所有比较中观察到单一栽培类型之间的差异，这表明这些人工林虽然具有不同的栽培特性，但在溪流中也会产生相似的负面影响。我们的研究表明了单一养殖发展对溪流上游社区的物理和化学影响。