The Andean Altiplano is characterized by its isolation, high altitude (> 3,600 m.a.s.l.), and a unique biodiversity, contains water systems such as lakes, rivers, wetlands, and salt flats. Near the southernmost area of the Andean Altiplano are two salt flats, Carcote and Ascotán, the former almost undisturbed by human intervention, and the latter historically intervened by brine-mining. These mining activities deplete, pollute, and alter waterflow, suggesting a significant threat to ecosystem functions. To identify the main factors promoting biotic community differentiation in these salt flats under different levels of human intervention, the aim of this study was to compare diatom community indices by guilds (high-profile, low-profile, and motile) between these systems, with a functional perspective, their relationship to environmental conditions, and the potential anthropic impact on their community structures. Diatom guilds were compared between salt flats based on their diversity, species richness, and abundance relative to ionic concentrations and granulometry. Beta diversity and the percentages of nestedness and turnover for each guild were also estimated. Results showed significant differences in ecological variables between the two salt flats. The largest values of species abundance, richness, and diatom diversity were measured in Carcote, suggesting greater primary productivity and diversity. The results also showed that the species composition of the motile guild was more differentiated between salt flats than other guilds (with the greatest diversity and richness), suggesting that motile diatoms are a key guild in maintaining the diatom community and that species from this guild are more sensitive to local conditions from each salt flat. Additionally, beta diversity by all guilds was mainly explained by turnover rather than nestedness, and the turn-over was highest for motile and low profile. A more heterogeneous community was observed in Ascotán, showing that the mechanisms of diversity maintenance, such as dispersion abilities, were salt flat-dependent. This suggests that the highest diversity could be related to human use, which challenges us to reexamine the effectiveness of past conservation activities in the area and to develop future strategies including both connected basins.

中文翻译：

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安第斯高原极端环境中硅藻群的分化

安第斯高原的特点是与世隔绝、海拔高（> 3,600 masl）和独特的生物多样性，包含湖泊、河流、湿地和盐滩等水系。靠近安第斯高原最南端的地区有两个盐滩，Carcote 和 Ascotán，前者几乎不受人为干预的干扰，而后者在历史上通过卤水开采进行了干预。这些采矿活动消耗、污染和改变水流，表明对生态系统功能构成重大威胁。为了确定在不同程度的人为干预下促进这些盐滩生物群落分化的主要因素，本研究的目的是比较这些系统之间的行会（高调、低调和活动性）的硅藻群落指数，其中功能性观点，它们与环境条件的关系，以及对其社区结构的潜在人为影响。根据其多样性、物种丰富度以及相对于离子浓度和粒度的丰度，对盐滩之间的硅藻群进行了比较。还估计了每个公会的 Beta 多样性以及嵌套和周转率。结果显示两个盐滩之间的生态变量存在显着差异。在 Carcote 测量了物种丰度、丰富度和硅藻多样性的最大值，这表明初级生产力和多样性更高。结果还表明，与其他类相比，活动类群的物种组成在盐滩之间的差异更大（多样性和丰富度最大），表明活动硅藻是维持硅藻群落的关键公会，并且来自该公会的物种对每个盐滩的当地条件更敏感。此外，所有公会的 Beta 多样性主要是由周转而不是嵌套来解释的，并且流动性和低调的周转率最高。在阿斯科坦观察到一个更加异质的群落，表明多样性维持的机制，如分散能力，是盐滩依赖的。这表明最高的多样性可能与人类使用有关，这要求我们重新审视该地区过去保护活动的有效性，并制定包括两个相连盆地在内的未来战略。所有公会的 Beta 多样性主要是由周转而不是嵌套来解释的，并且流动性和低调的周转率最高。在阿斯科坦观察到一个更加异质的群落，表明多样性维持的机制，如分散能力，是盐滩依赖的。这表明最高的多样性可能与人类使用有关，这要求我们重新审视该地区过去保护活动的有效性，并制定包括两个相连盆地在内的未来战略。所有公会的 Beta 多样性主要是由周转而不是嵌套来解释的，并且流动性和低调的周转率最高。在阿斯科坦观察到一个更加异质的群落，表明多样性维持的机制，如分散能力，是盐滩依赖的。这表明最高的多样性可能与人类使用有关，这要求我们重新审视该地区过去保护活动的有效性，并制定包括两个相连盆地在内的未来战略。