Multiple metals and agricultural use affects oxidative stress biomarkers in freshwater Aegla crabs

Abstract Metals and agrochemicals are among the main aquatic contaminants, being able to trigger oxidative stress in exposed organisms. The objective of this work was to evaluate the correlation between the level of oxidative stress biomarkers in Aegla crabs (Crustacea, Anomura) with (i) the set of metals present in the streams sediment and (ii) with land uses of three hydrographic basins. The study was carried out in streams (≤ 2nd order) of hydrographic basins in southern Brazil (Basins of Rio Suzana, Rio Ligeirinho-Leãozinho and Rio Dourado). In these streams were quantified the land uses and Cu, Cr, Cd, Fe, Mn and Zn concentrations in the sediment. The enzymes Catalase (CAT) and Glutathione Reductase (GR), as well as the level of membrane lipid peroxidation (TBARS), were analyzed in adult females. The PCA analysis showed that the distribution of metals was different between the basins. Cd, Cr and Fe were correlated positively with CAT and negatively with TBARS and GR. The Dourado basin had the lowest concentrations of these three metals and the highest levels of TBARS. However, in Dourado basin there is predominance of agriculture land use, and TBARS was positively correlated with agricultural land use. Besides in Dourado basin, GR activity was higher than in the others basins, indicating a compensatory response in relation to CAT inhibition. The basins of Suzana and Ligeirinho-Leãozinho rivers had lower TBARS values, which may be due to the induction of CAT in response to metals accumulated in sediment. In summary, this work indicates that in the basins with a higher concentration of toxic metals there is an adaptive response of CAT induction, which reduces TBARS in Aegla. On the other hand, in the basin with lower metallic contamination, TBARS occurrence was primarily influenced by agricultural land use.

摘要：金属与农用化学品是主要的水生污染物之一，可对暴露生物体引发氧化应激。本研究旨在评估瓷蟹（Aegla crabs，甲壳纲、异尾下目）体内氧化应激生物标志物水平与（i）溪流沉积物中所含金属组分，以及（ii）三个水文流域的土地利用类型之间的相关性。本研究选取巴西南部的等级≤2级溪流作为研究对象，涉及苏珊娜河（Rio Suzana）、利热里尼奥-莱昂济纽河（Rio Ligeirinho-Leãozinho）以及多拉多河（Rio Dourado）三大水文流域。本研究对上述溪流的土地利用类型，以及沉积物中铜（Cu）、铬（Cr）、镉（Cd）、铁（Fe）、锰（Mn）与锌（Zn）的浓度进行了定量检测，并对成年雌性瓷蟹体内的过氧化氢酶（CAT）、谷胱甘肽还原酶（GR）活性，以及膜脂过氧化水平（TBARS）开展了分析。主成分分析（PCA）结果显示，不同流域间的金属分布存在显著差异。镉、铬与铁与CAT活性呈正相关，而与TBARS水平及GR活性呈负相关。多拉多河流域的这三种金属浓度最低，但其TBARS水平最高。但该流域以农业用地占主导，且TBARS水平与农业用地占比呈正相关。此外，多拉多河流域的GR活性高于其余两个流域，表明其存在针对CAT活性受抑制的代偿性响应。苏珊娜河与利热里尼奥-莱昂济纽河流域的TBARS水平更低，这可能是由于沉积物中累积的金属诱导了CAT活性的表达。综上，本研究表明，在有毒金属浓度更高的流域中，瓷蟹体内会产生CAT诱导的适应性响应，从而降低TBARS水平；而在金属污染程度更低的流域中，TBARS水平主要受农业用地类型的影响。