Natural fluctuations in ecosystems, such as those associated with climate, are a fundamental factor structuring macroinvertebrate assemblages. Given that macroinvertebrates are widely used in biomonitoring of aquatic systems, it is necessary assess the potential effects of seasonality on this group to avoid confusing its effects with the effects of anthropogenic impacts. In the present study, the richness, assemblage composition, and abundance of macroinvertebrates of Amazonian streams (n = 23) were compared among four periods—the start and apex of dry period, and the start and apex of rainy period. For these comparisons, were considered the conditions of the streams in three categories: (i) pristine, (ii) impacted by deforestation, and (iii) impacted by deforestation and pollution with raw sewage. The results indicate no significant variation among periods in the richness (p = 0.397), abundance (p = 0.420), and assemblage composition (p = 0.274) of the macroinvertebrates, which respond to anthropogenic impact irrespective of the seasonal period. Given this, representative samples can be obtained during any given period of the year, reducing field costs and sample processing time, enabling the reliable and rapid diagnosis of streams.

生态系统的自然波动（例如与气候有关的波动）是构成无脊椎动物集合体的基本因素。鉴于大型无脊椎动物广泛用于水生系统的生物监测，有必要评估季节性对这一群体的潜在影响，以避免将其影响与人为影响相混淆。在本研究中，亚马逊河流域的大型无脊椎动物的丰富度，组合组成和丰度（n = 23）在四个时期之间进行了比较-干旱时期的开始和顶点，以及雨季的开始和顶点。为了进行这些比较，考虑了三类河流的状况：（i）原始，（ii）受到森林砍伐的影响，（iii）受到森林砍伐和原始污水污染的影响。结果表明 ，大型无脊椎动物的丰富度（p  = 0.397），丰度（p  = 0.420）和组合物组成（p = 0.274）的时间段之间无显着变化，这些响应对人为影响的响应与季节无关。鉴于此，可以在一年中的任何给定时间段内获取有代表性的样本，从而减少了现场成本和样本处理时间，从而能够可靠，快速地诊断流。