| 摘要: |
| 样品重复数设计是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。针对此问题，本研究在长江武汉段开展了以样品重复方式为单一变量的实验研究，通过分析不同样品重复方式所获得的eDNA监测检出的物种组成，探讨大型河流中小时空尺度eDNA监测的重复采样建议。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、原生动物三个细分类群相反。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，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，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: |
| Design of duplicated samples is the first key step for standardizing the eDNA monitoring processes. Previous works have studied how many duplicated samples should be sampled for identifying the detailed eDNA information at a definite sampling site or sampling transection. However, in this small spatiotemporal scale eDNA monitoring, whether the duplicated samples should be sampled in a series of sites or in continuous moments has not been carefully studied, although this question is very important for an eDNA monitoring practice. To answer this question, the current work took a single variable controlled experiment in Wuhan section of Yangtze River. We got 16 eDNA samples from June 27 to July 14, 2022 day by day (temporal group samples) and 16 eDNA samples across the transection of Yangtze River in June 28 and July 12, 2022 (spatial group samples), and analyzed the detected species and OTUs compositions of each eDNA samples. Then we quantified the species and OTUs compositions temporal heterogeneity of temporal group samples and the species and OTUs compositions spatial heterogeneity of spatial group samples, so as to provide suitable suggestions for how to set duplicated samples in a small spatiotemporal scale eDNA monitoring practice in a large river. The results showed that, for bacteria and metazoa, the total number of species detected in spatial group eDNA samples was more than that detected in temporal group eDNA samples, and the spatial heterogeneity of species detected in eDNA monitoring was greater than the temporal heterogeneity of which. While for the three taxonomies of fungi, algae and protozoa, there was an opposite status. In other words, it suggested that to monitor environmental bacteria and aquatic metazoa in a definite sampling site or sampling transection of a large river, spatial duplicated sampling of eDNA monitoring should be given priority in duplicated samples design. To monitoring fungi, algae, protozoa, temporal duplicated sampling of eDNA monitoring should be given priority in duplicated samples design. Of course, considering the possible variation on community structure of aquatic organisms from different rivers, sections and times, the current conclusions may need to be verified at different times and locations. It needs to be particularly emphasized that attention should be paid to the selection of sampling time when taking spatial duplicated sampling, and the selection of sampling point when taking temporal duplicated sampling. Moreover, maybe, more duplicated samples are needed when one focuses 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 |
