Abstract：
Estuarine ecosystems face increasing anthropogenic pressures, necessitating effective monitoring methods to mitigate their impacts on the biodiversity they harbour. The use of environmental DNA (eDNA) based detection methods is increasingly recognized as a promising tool to complement other, potentially invasive monitoring techniques. Integrating such eDNA analyses into monitoring frameworks for large ecosystems is still challenging and requires a deeper understanding of the scale and resolution at which eDNA patterns may offer insights in species presence and community composition space and time. The Scheldt estuary, characterized by its diverse habitats and complex currents, is one of the largest Western European tidal river systems. Until now, it remains challenging to obtain accurate information on fish communities living in and migrating through this ecosystem, consequently confining our knowledge to specific locations. To explore the potential of eDNA based monitoring, we simultaneously combine stow net fishing with eDNA metabarcoding, to assess spatiotemporal shifts in the Scheldt estuary\'s fish communities. In total, we detected 71 fish species in the estuary using eDNA metabarcoding, partly overlapping with historic fish community data gathered at the different study locations and in contrast to only 42 species using stow net fishing during the same survey period. Community compositions found by both detection methods varied among sampling locations, driven by a clear correlation to the salinity gradient. Limited effects of sampling depth and tide were observed on the eDNA metabarcoding data, allowing a significant reduction of the eDNA sampling effort for future eDNA fish monitoring campaigns in this study system. Our results further demonstrate that seasonal shifts in fish species occurrence can be detected using eDNA metabarcoding. Combining eDNA metabarcoding and stow net fishing further enhances our understanding of this vital waterway\'s diverse fish populations, allowing a higher resolution and more efficient monitoring strategy.
摘要：
河口生态系统面临着越来越大的人为压力，需要有效的监测方法来减轻它们对它们所拥有的生物多样性的影响。使用基于环境DNA(eDNA)的检测方法越来越被认为是一种有前途的工具,潜在的侵入性监测技术。将这种eDNA分析整合到大型生态系统的监测框架中仍然具有挑战性，需要更深入地了解eDNA模式可能提供对物种存在和群落组成空间和时间的见解的规模和分辨率。Scheldt河口,以其多样化的栖息地和复杂的水流为特征，是西欧最大的潮汐河流系统之一。直到现在,获取有关在该生态系统中生活和迁移的鱼类群落的准确信息仍然具有挑战性，因此将我们的知识限制在特定的位置。探索基于eDNA的监测的潜力，我们同时将装料网捕鱼和eDNA元编码结合起来，评估谢尔特河口鱼类群落的时空变化。总的来说,我们使用eDNA元转录编码在河口检测到71种鱼类，与在不同研究地点收集的历史鱼类群落数据部分重叠，而在同一调查期间，只有42种使用集装网捕鱼。两种检测方法发现的群落组成因采样地点而异，由与盐度梯度的明显相关性驱动。采样深度和潮汐对eDNA元编码数据的影响有限，在此研究系统中，可以显着减少未来eDNA鱼类监测活动的eDNA采样工作量。我们的结果进一步表明，使用eDNAmetabarcoding可以检测到鱼类物种发生的季节性变化。结合eDNA元编码和堆网捕鱼进一步增强了我们对这一重要水道的不同鱼类种群的理解，允许更高的分辨率和更有效的监控策略。
