Dougherty Matthew M, MacDonald Andrew, York Geneva, Post David M
Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America.
Biology, Saint Norbert College, De Pere, Wisconsin, United States of America.
PLoS One. 2025 May 23;20(5):e0324385. doi: 10.1371/journal.pone.0324385. eCollection 2025.
Keystone species are important drivers of ecological processes. Their ecological importance makes them prime candidates for biological monitoring, both to preserve and restore their populations when facing decline, and to limit their spread as invasive species. To monitor species well requires cost and labor efficient methods that are capable of detecting the target species at low abundances. Traditional sampling methods, or methods of direct capture, can be labor intensive when trying to monitor large areas or species at low abundances. Another method, environmental DNA (eDNA), has emerged as a more cost and time efficient supplement to traditional monitoring methods. Environmental DNA techniques and strategies continue to be developed, but face limitations for some taxonomic groups within certain habitats. Here, we propose a novel method for monitoring keystone species: environmental effects sampling. Keystone species have large effects on their environment relative to their abundance. Measuring their environmental effects-or quantifiable changes in the biotic or abiotic environment due to organism-environment interactions-has potential as a low-effort and low-cost method for detecting keystone species. In this study, we compare the effectiveness of traditional sampling, eDNA methods, and environmental effects sampling as an alternative low cost and time efficient method for monitoring the presence and abundance of an ecologically important keystone species, the alewife, Alosa pseudoharengus, in freshwater lakes. The alewife is a zooplanktivorous fish managed as a species of conservation concern along coastal New England, USA, and an invasive or non-native species throughout the Laurentian Great Lakes watershed. We sampled lakes throughout Michigan and Connecticut from 2018-2020 and compared the three monitoring methods along four axes: alewife presence/absence, alewife abundance, financial cost, and time efficiency. Our results suggest that monitoring alewife with environmental effects is more accurate, more cost efficient, and more time efficient than purse seining and eDNA. Our environmental effects results also led to the discovery that two historically recognized alewife lakes no longer contained alewife, as confirmed by traditional sampling. However, environmental effects monitoring was only useful for determining alewife presence/absence, and was not reliable for determining alewife relative abundance. Environmental effects monitoring presents novel opportunities for efficiently and effectively monitoring keystone species such as alewife for the purpose of restoration or management.
关键物种是生态过程的重要驱动因素。它们的生态重要性使其成为生物监测的主要候选对象，既能在面临数量下降时保护和恢复其种群，又能限制其作为入侵物种的扩散。要很好地监测物种需要成本和劳动力高效的方法，这些方法要有能力在低丰度时检测到目标物种。传统的采样方法，即直接捕获的方法，在试图监测大面积区域或低丰度物种时可能会耗费大量劳动力。另一种方法，环境DNA（eDNA），已成为传统监测方法中一种更具成本效益和时间效率的补充方法。环境DNA技术和策略仍在不断发展，但在某些栖息地内对一些分类群存在局限性。在此，我们提出一种监测关键物种的新方法：环境效应采样。关键物种相对于其丰度而言，对其环境有很大影响。测量它们的环境效应——即由于生物与环境相互作用导致的生物或非生物环境中可量化的变化——有潜力成为一种低工作量和低成本的检测关键物种的方法。在本研究中，我们比较了传统采样、eDNA方法和环境效应采样作为一种替代的低成本且省时的方法来监测淡水湖泊中一种具有生态重要性的关键物种——美洲西鲱（Alosa pseudoharengus）的存在和丰度的有效性。美洲西鲱是一种以浮游动物为食的鱼类，在美国新英格兰沿海地区被作为受保护物种进行管理，在整个劳伦琴五大湖流域则是入侵物种或非本地物种。我们在2018年至2020年期间对密歇根州和康涅狄格州的湖泊进行了采样，并从四个方面比较了这三种监测方法：美洲西鲱的存在与否、美洲西鲱的丰度、财务成本和时间效率。我们的结果表明用环境效应监测美洲西鲱比围网捕捞和eDNA更准确、更具成本效益且更省时。我们的环境效应结果还发现，经传统采样证实，两个历史上公认有美洲西鲱的湖泊已不再有美洲西鲱。然而，环境效应监测仅对确定美洲西鲱的存在与否有用，对于确定美洲西鲱的相对丰度并不可靠。环境效应监测为有效且高效地监测关键物种（如美洲西鲱）以进行恢复或管理提供了新的机会。
