| 摘要: |
| 样品重复数设计是环境DNA(eDNA)监测技术标准化中最靠前的一个关键环节，对特定站位或断面进行eDNA监测，采样中应该设置多少个样品重复先前已有研究探讨，而这种小时空尺度的样品重复应该是在空间上设置系列样点，还是在时间上设置连续采样尚未有研究仔细探讨，但这对于eDNA监测实践十分重要。为解决大型河流eDNA监测中重复采样策略的优化问题，本研究在长江武汉段设计了以样品重复方式为单一变量的对照实验，通过比较不同重复方案下eDNA监测检出的物种组成差异，提出适用于小时空尺度eDNA监测的采样建议。结果显示，细菌和后生动物的eDNA监测空间序列样品比时间序列样品所检出的累计物种数多，所检出物种组成的空间异质性比时间异质性大，而真菌、藻类、原生动物3个细分类群相反。因此，我们建议在大型河流小时空尺度的eDNA监测中，监测细菌和后生动物时，样品重复的设计优先关注空间重复采样；监测真菌、藻类、原生动物时，样品重复的设计优先关注时间重复采样，考虑到可能存在的河流特异性、断面特异性、时间特异性，本结论可能需要进行异时异地验证。特别强调，采取空间重复采样应注意采样时间的选择，采取时间重复采样应注意采样点位的选择，针对细分类群的监测采样应注意保证样品重复数量。 |
| 关键词: eDNA监测 小尺度时空差异 重复采样 16S rRNA基因 COI基因 长江 |
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| Is multi-day sampling or multi-point sampling suitable for eDNA monitoring in large rivers at a small spatiotemporal scale? |
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Yang Haile, Xu Lanxin, Wu Jinming, Du Hao
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Key Laboratory of Freshwater Biodiversity Conservation,SMinistry of Agriculture and Rural Affairs,Yangtze River Fisheries Research Institute,Chinese Academy of Fishery Sciences
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| Abstract: |
| The design of duplicated samples constitutes the primary stage in the standardisation of eDNA monitoring processes. A plethora of studies have hitherto investigated the optimal number of duplicated samples required for the purpose of ascertaining the precise eDNA information at a given sampling site or transection. However, the question of whether duplicated samples should be collected at a series of sites or in continuous moments remains unresolved in the context of eDNA monitoring at this scale. This issue is of particular significance for the practice of eDNA monitoring. To optimize the sampling strategy of duplicated samples in eDNA monitoring of large rivers, the present study employed a single-variable controlled experiment in the Wuhan section of the Yangtze River. A total of 16 eDNA samples were obtained from 27 June to 14 July 2022 on a daily basis (temporal group samples) and 16 eDNA samples were collected across the Yangtze River on 28 June and 12 July 2022 (spatial group samples). The composition of the detected species and OTUs in each eDNA sample was then analyzed. The following steps were taken in order to provide suitable suggestions for how to set duplicated samples in a small spatiotemporal scale eDNA monitoring practice in a large river. Firstly, the species and OTU compositions, temporal heterogeneity of temporal group samples, and the species and OTU compositions, spatial heterogeneity of spatial group samples, were quantified. The findings demonstrated that, for bacteria and metazoa, the total number of species detected in spatial group eDNA samples exceeded that detected in temporal group eDNA samples. Furthermore, the spatial heterogeneity of species detected in eDNA monitoring was found to be greater than the temporal heterogeneity of the same. In contrast, an antithetical status was observed for the three taxonomies of fungi, algae and protozoa. In essence, the study proposed that in the context of monitoring environmental bacteria and aquatic metazoa within a specified sampling site or transection of a substantial river, the implementation of spatial duplicated sampling of eDNA monitoring should be accorded priority in the design of duplicated samples. With regard to the monitoring of fungi, algae and protozoa, the implementation of temporal duplicated sampling of eDNA monitoring should be prioritised within the framework of duplicated samples design. It is evident that the conclusions drawn must be subject to verification, given the potential variations in the community structure of aquatic organisms across different rivers, sections and temporal periods. It is imperative to emphasise that particular attention must be allocated to the selection of sampling time when implementing spatial duplicated sampling, and the selection of sampling point when executing temporal duplicated sampling. Furthermore, it may be necessary to consider the replication of samples when the focus is on the monitoring of a subdivision taxonomy. |
| Key words: environmental DNA monitoring small-scale temporal and spatial heterogeneity duplicated sampling 16S rRNA gene COI gene Yangtze River |
