Instituto de Biofísica Carlos Chagas Filho, Laboratório de Estudos Ambientais Olaf Malm, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-900, Brasil.
Instituto de Ciências Biológicas, Laboratório de Limnologia, Ecotoxicologia e Ecologia Aquática, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brasil.
Ecotoxicology. 2024 Sep;33(7):762-771. doi: 10.1007/s10646-024-02776-6. Epub 2024 Jul 10.
Reservoir construction promotes many environmental impacts, including the enhancement of mercury concentrations in fish. The processes that can influence mercury concentrations in fish in Amazonian reservoirs are still little explored in depth, especially when we consider the possible particularities of the ecosystems in question. This study aims to investigate how mercury concentrations in fish could be influenced by the Tucuruí dam, considering possible changes in their feeding and trophic position according to the dam position (up or downstream). Fish were sampled upstream and downstream of the Tucuruí reservoir, and total mercury (THg) and stable isotopes of carbon and nitrogen (δN and δC) were measured in muscles. We observed three different Hg bioaccumulation patterns influenced by the dam. These differences occurred due to species trophic niche changes corroborated by the isotope analysis. Higher THg concentrations downstream compared to those upstream ones were only observed for Geophagus proximus. On the contrary, Plagioscion squamosissimus, from downstream, presented lower concentrations than upstream ones. The isotopic niche of these two species presented different changes according to the sampled site. THg biomagnification was higher upstream compared to downstream, considering that the regression slope was approximately two times higher upstream versus downstream. THg concentrations in fish were explained by the differences in their feeding habits according to their location in relation to the dam. The difference in THg biomagnification was able to reflect differences in structure of the food web chain in ecosystems under the dam's influence.
水库建设会带来许多环境影响，包括鱼类中汞浓度的增加。在亚马逊水库中，影响鱼类汞浓度的过程仍未得到深入探讨，尤其是在考虑到所涉及生态系统的可能特殊性时。本研究旨在调查图库里蒂巴大坝如何影响鱼类中的汞浓度，同时考虑到根据大坝位置（上游或下游），其摄食和营养位置可能发生的变化。在图库库里蒂巴水库的上游和下游采集了鱼类样本，并测量了肌肉中的总汞（THg）和碳、氮稳定同位素（δN 和 δC）。我们观察到了三种不同的汞生物累积模式，这些模式受到大坝的影响。这些差异是由于物种营养生态位的变化所导致的，这一点得到了同位素分析的证实。只有在近缘锯脂鲤（Geophagus proximus）中，下游的 THg 浓度高于上游。相反，在下游的副棘鳍鱼（Plagioscion squamosissimus）中，THg 浓度低于上游。这两个物种的同位素生态位根据采样地点的不同而发生了不同的变化。与下游相比，上游的 THg 生物放大倍数更高，因为上游的回归斜率大约是下游的两倍。鱼类中的 THg 浓度可以根据其在与大坝相关的位置的摄食习惯的差异来解释。THg 生物放大倍数的差异能够反映出大坝影响下的生态系统中食物网链结构的差异。
