Postgraduate Program in Environment and Water Resources (POSMARH), Federal University of Itajubá (Unifei), Itajubá 37500-903, Minas Gerais, Brazil; Institute of Exact Sciences, Federal University of Southern and Southeastern Pará (Unifesspa), Marabá 68507-590, Pará, Brazil.
Postgraduate Program in Environmental Technology, Fluminense Federal University (UFF), Volta Redonda 27255-125, Rio de Janeiro, Brazil.
Chemosphere. 2024 Aug;361:142492. doi: 10.1016/j.chemosphere.2024.142492. Epub 2024 Jun 1.
The Amazon rivers constitute the largest river basin in the world, with a high level of biodiversity. The Tocantins River is one of the most important rivers in this region, which has been impacted by different land uses. The objective of this study was to carry out a multi-evidence analysis focusing on the water quality of the Tocantins River, close to the municipality of Marabá-PA. We analyzed forest cover and water quality and, using the model organism Danio rerio, performed toxicity tests for histopathological effects, as well as the habitat selection approach by exposing fish to different river water samples in a multi-compartment device. The results showed that the studied area has already lost almost 30% of its forests in recent decades. Regarding water quality, the upstream (C1) and downstream (C5) points are the least impacted. On the other hand, the other points (C2-C4), closer to the city, greater input of pollutants was detected. Fish exposed to water samples from the most impacted sites showed several oedemas and hyperplastic cells in the gills. Regarding habitat selection behavior, there was a marked avoidance by samples with the highest contamination load. The results of this study lead to the understanding of the potential negative effects of human activities on local Amazonian biodiversity, since the potential toxicity of the environment, in conjunction with changes in the habitat selection process, could lead to a decline in populations of aquatic organisms, altering the environmental balance.
亚马逊河流域是世界上最大的河流流域之一，拥有高度的生物多样性。托坎廷斯河是该地区最重要的河流之一，它受到了不同土地利用方式的影响。本研究的目的是进行多证据分析，重点关注帕拉州马拉巴市附近的托坎廷斯河的水质。我们分析了森林覆盖和水质，并使用模式生物斑马鱼进行了毒性测试，以研究组织病理学效应，以及通过在多隔室装置中使鱼类暴露于不同的河水样本来进行栖息地选择方法。结果表明，在最近几十年，研究区域已经失去了近 30%的森林。关于水质，上游（C1）和下游（C5）点的污染程度最低。另一方面，其他靠近城市的点（C2-C4）检测到更多的污染物。暴露于污染最严重的水样中的鱼类显示出鳃部水肿和增生细胞。关于栖息地选择行为，受污染负荷最高的样本有明显的回避现象。本研究的结果使人们了解到人类活动对当地亚马逊生物多样性的潜在负面影响，因为环境的潜在毒性以及栖息地选择过程的变化可能导致水生生物种群减少，从而改变环境平衡。
