Dryland river systems support a diverse aquatic biota in semi-arid and arid landscapes, but they are increasingly vulnerable to natural and human impacts. This study provides the first modern diatom training set (n = 38) from three dryland rivers in northern Patagonia, Argentina. The relationship between surface-sediment diatoms and contemporary environmental variables was explored using multivariate analyses. The results showed that surface-water chemistry varies among rivers in accordance with local-scale factors such hydro-climatic variability and anthropic activities. A total of 378 diatom taxa were identified but only 45 taxa occurred with relative abundances higher than 2% in at least one sediment sample. The Colorado and Negro rivers were characterized by high abundances of small tychoplanktic fragilarioids whereas the Chubut River was dominated by epiphytic and planktic taxa. The canonical correspondence analyses (CCA) showed that conductivity, pH and HCO₃⁻ were the main environmental variables governing diatoms distributions. A transfer function was developed for water conductivity using unimodal methods because of partial CCA and λ₁/λ₂ ratio revealed that this variable had the largest unique effect on diatom variance. A weighted averaging (WA) model with tolerance downweighting and classic deshrinking provided a reasonably robust model (r²_jack = 0.94 and RMSEP = 0.249 log₁₀ μS cm⁻¹). However, the diatom-inferred conductivity values should be carefully interpreted because of the uneven distribution of sampling sites and the dominance of small araphid diatoms belonging to the genera Staurosira, Pseudostaurosira and Punctastriata. By their benthic habitat, the distribution of these taxa could be influenced by other factors as light and substrate in addition to water chemistry. The autoecological information achieved through this study will provide the basis for a better insight into the hydrological responses of the dryland rivers in northern Patagonia to climate and environmental changes.

旱地河流系统在半干旱和干旱景观中支持多样化的水生生物群，但它们越来越容易受到自然和人类影响。本研究提供了第一个现代硅藻训练集（n = 38) 来自阿根廷巴塔哥尼亚北部的三个旱地河流。使用多变量分析探讨了地表沉积硅藻与当代环境变量之间的关系。结果表明，不同河流的地表水化学成分因水文气候变异和人类活动等局部尺度因素而异。总共确定了 378 个硅藻类群，但在至少一个沉积物样品中，只有 45 个类群的相对丰度高于 2%。科罗拉多河和内格罗河的特点是小浮游类脆弱类群的丰度高，而丘布特河则以附生类和浮游类群为主。典型对应分析 (CCA) 表明电导率、pH 值和 HCO ₃ ^-是控制硅藻分布的主要环境变量。由于部分 CCA 和λ ₁ / λ ₂比率表明该变量对硅藻方差具有最大的独特影响，因此使用单峰方法开发了用于水电导率的传递函数。具有容差降低权重和经典去收缩的加权平均 (WA) 模型提供了相当稳健的模型（r ² _jack  = 0.94 和 RMSEP = 0.249 log ₁₀ μS cm ^-1）。然而，硅藻推断的电导率值应该仔细解释，因为采样点分布不均，并且属于Staurosira属的小型蜘蛛硅藻占主导地位。、Pseudostaurosira和Punctastriata。由于它们的底栖栖息地，除了水化学之外，这些分类群的分布还可能受到光和基质等其他因素的影响。通过这项研究获得的自生态信息将为更好地了解巴塔哥尼亚北部旱地河流对气候和环境变化的水文响应提供基础。