Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, United States of America.
PLoS One. 2021 Jun 4;16(6):e0245314. doi: 10.1371/journal.pone.0245314. eCollection 2021.
Environmental DNA (eDNA) is increasingly used to measure biodiversity of marine ecosystems, yet key aspects of the temporal dynamics of eDNA remain unknown. Of particular interest is in situ persistence of eDNA signals in dynamic marine environments, as eDNA degradation rates have predominantly been quantified through mesocosm studies. To determine in situ eDNA residence times, we introduced an eDNA signal from a non-native fish into a protected bay of a Southern California rocky reef ecosystem, and then measured changes in both introduced and background eDNA signals across a fixed transect over 96 hours. Foreign eDNA signal was no longer detected only 7.5 hours after introduction, a time substantially shorter than the multi-day persistence times in laboratory studies. Moreover, the foreign eDNA signal spread along the entire 38 m transect within 1.5 hours after introduction, indicating that transport and diffusion play a role in eDNA detectability even in protected low energy marine environments. Similarly, native vertebrate eDNA signals varied greatly over the 96 hours of observation as well as within two additional nearby fixed transects sampled over 120 hours. While community structure did significantly change across time of day and tidal direction, neither accounted for the majority of observed variation. Combined, results show that both foreign and native eDNA signatures can exhibit substantial temporal heterogeneity, even on hourly time scales. Further work exploring eDNA decay from lagrangian perspective and quantifying effects of sample and technical replication are needed to better understand temporal variation of eDNA signatures in nearshore marine environments.
环境 DNA（eDNA）越来越多地用于测量海洋生态系统的生物多样性，但 eDNA 的时间动态的关键方面仍然未知。特别有趣的是 eDNA 信号在动态海洋环境中的原地持久性，因为 eDNA 降解率主要通过中观研究来量化。为了确定原地 eDNA 居留时间，我们将非本地鱼类的 eDNA 信号引入南加州多岩石礁生态系统的一个保护区湾，然后在 96 小时内跨固定横断面测量引入和背景 eDNA 信号的变化。在引入后仅 7.5 小时，外来 eDNA 信号就不再被检测到，这一时间明显短于实验室研究中的多日持续时间。此外，在引入后 1.5 小时内，外来 eDNA 信号沿着整个 38 米的横断面传播，表明即使在受保护的低能量海洋环境中，运输和扩散也会影响 eDNA 的可检测性。同样，在 96 小时的观察期间以及在另外两个在 120 小时内采样的附近固定横断面内，本地脊椎动物 eDNA 信号也发生了很大变化。虽然群落结构随着一天中的时间和潮汐方向的变化而显著变化，但没有一个因素可以解释观察到的大部分变化。综合结果表明，即使在小时时间尺度上，外来和本地 eDNA 特征也可以表现出显著的时间异质性。需要进一步从拉格朗日角度探索 eDNA 衰减并量化样本和技术复制的影响，以更好地了解近岸海洋环境中 eDNA 特征的时间变化。
