How Indigenous peoples and European settlers transformed terrestrial ecosystems in the Americas is well evidenced in the literature, but far less is known about how aquatic ecosystems changed. This study examined diatom records from sediment cores from paleoclimate studies in mountain lakes of Guatemala, Panama, and Colombia, in order to clarify the long-term human influences on the ecology of these lakes. We focused on two aspects of beta diversity in identified diatom zones: species turnover and variation in relative abundances of species. All records displayed a single diatom zone or cluster of zones with assemblages that had no close analogues in the past. The ages of these distinctive assemblages varied from post-European to 5000 cal yr BP. Most novel assemblages comprised moderately motile, non-planktonic, single-celled diatoms, associated with disturbed, productive environments. Archaeological data and pollen records pointed to the onset of intensification of human activities as the main driver behind the changes in diatoms. Maximum depth exerted control on how diatom communities responded to anthropogenic stressors. In shallower lakes, diatom assemblages transitioned gradually over time into their current novel composition. In deeper lakes, assemblages displayed slight fluctuations before shifting to their current condition. Differences between the two lake groups likely resulted from a more complete water-column mixing and higher rates of nutrient cycling in the shallow lakes, which led to a more rapid response of the diatoms to environmental changes. The shift to novel recent diatom assemblages suggests that these lakes now display ecosystem characteristics with no past analogues, and that they have lost their capacity to resist change or recover from stressors, jeopardizing the future of mountain water resources.

文献充分证明了土著人民和欧洲定居者如何改变美洲的陆地生态系统，但是对水生生态系统如何变化的了解却很少。这项研究检查了危地马拉，巴拿马和哥伦比亚山区湖泊古气候研究中沉积物核心的硅藻记录，以阐明人类长期对这些湖泊生态的影响。我们关注于已确定的硅藻区中β多样性的两个方面：物种更新和物种相对丰度的变化。所有记录都显示了一个单一的硅藻区域或区域簇，这些区域的集合过去没有相似的类似物。这些独特的组合的年龄从后欧洲时代到5,000 cal yr BP不等。大多数新颖的组合都包含适度运动的，非浮游性的单细胞硅藻，与受干扰的生产环境相关联。考古数据和花粉记录指出，人类活动加剧是硅藻变化背后的主要驱动力。最大深度控制了硅藻群落对人为应激源的反应。在较浅的湖泊中，硅藻组合物随着时间的推移逐渐转变为它们当前的新颖成分。在更深的湖泊中，鱼群显示出轻微的波动，然后才转变为当前状态。两组湖泊之间的差异很可能是由于水柱混合更完全，浅水湖泊中养分循环的速率更高，从而导致硅藻对环境变化的反应更加迅速。