We investigated microcrustaceans inhabiting arsenic contaminated and non-contaminated freshwater to identify potential bioindicators of arsenic contamination in the tropical freshwater of Matehuala in northern Mexico. We collected water, sediment, and zooplankton, at five sampling points during three sampling campaigns. We determined water temperature, pH, electrical conductivity, dissolved oxygen, alkalinity, salinity, and total arsenic concentration in water. Additionally, we determined total arsenic and arsenic speciation in sediment samples. We identified microcrustaceans and determined abundance, richness, and Shannon Index. We also investigated relationships and correlations between physiochemical and ecological variables. Results showed that arsenic concentrations in freshwater ranged from 0.001 to 53.23 mg/L, while total arsenic in sediments ranged from 10.37 to 2472.84 mg/kg as As + 5. Six microcrustacean species were found in highly and moderately contaminated water (Latonopsis australis, Eucyclops chihuahuensis, Acanthocyclops americanus, Pleuroxus (Picripleuroxus) quasidenticulatus, Macrocyclops albidus, and Paracyclops chiltoni), while five species were found in arsenic-free water (Simocephalus punctatus, Alona glabra, Eucyclops leptacanthus, M. albidus, and P. quasidenticulatus). An inverse relationship was observed between microcrustacean richness and arsenic. However, the scope of the data did not allow for a strong and significant correlation. Nevertheless, among the species inhabiting As-free water, S. punctatus showed potential to be further tested as a bioindicator of As contamination in Matehuala. Identification of potential bioindicators could help monitor water quality and increase understanding of the incorporation and toxicity of As in freshwater-sensitive and freshwater-metallotolerant microcrustaceans, which, in turn, might help us to understand As incorporation in the food web.

我们调查了栖息在砷污染和未污染淡水中的微型甲壳类动物，以确定墨西哥北部马特瓦拉热带淡水中砷污染的潜在生物指标。在三个采样活动中，我们在五个采样点收集了水、沉积物和浮游动物。我们测定了水温、pH、电导率、溶解氧、碱度、盐度和水中的总砷浓度。此外，我们确定了沉积物样品中的总砷和砷形态。我们确定了微型甲壳类动物并确定了丰度、丰富度和香农指数。我们还研究了物理化学和生态变量之间的关系和相关性。结果表明，淡水中的砷浓度范围为 0.001 至 53.23 mg/L，（Latonopsis australis、Eucyclops chihuahuensis 、Acanthocyclops americanus、Pleuroxus (Picripleuroxus) quasidenticulatus、Macrocyclops albidus和Paracyclops chiltoni），而在无砷水中发现了 5 个物种（Simocephalus punctatus、Alona glabra、Eucyclops leptacanthus、M. albidus 和 P . quasidenticulatus）。观察到微甲壳动物丰富度与砷之间存在反比关系。然而，数据的范围不允许强和显着的相关性。然而，在生活在无砷水中的物种中，S. punctatus表明有可能作为 Matehuala 中砷污染的生物指标进行进一步测试。识别潜在的生物指示物有助于监测水质并增加对淡水敏感和耐淡水金属微甲壳类动物中砷的掺入和毒性的了解，这反过来可能有助于我们了解砷在食物网中的掺入。