Environmental DNA analysis provides the potential to detect new spawning ground for rare and endangered species: an example from Chinese Sturgeon

Abstract:

Environmental DNA (eDNA) is a high-efficiency sampling method that has been widely used for detecting various species. Less stressful for the target organisms seems likely make it more appropriate for detecting the endangered species, which usually occupied extremely low abundance and was rare in natural environments. Here, we monitored the spatiotemporal patterns of Chinese Sturgeon (Acipensor sinensis) during the propagation period. Samples were collected from the spawning ground (18 sites) as well as the surrounding water bodies (i.e. the Qingjiang River; 8 sites) from 10, Nov to 30, Dec (2019). Using the droplet digital PCR (ddPCR) technology, we positively identified Chinese Sturgeon DNA in all sampling dates and sites, respectively. As expected, the mean DNA concentrations across all sampling sites significantly increased with time (R² = 0.67, P << 0.05). Similar trend was also observed for the frequency of positive identification, which, however, decreased in the late propagation period. It is also interesting to note that, in terms of the DNA concentration, there was no significant difference between the spawning ground and the surrounding water bodies (One-way ANOVA, P>0.05), which highlights the importance of Qingjiang River to be a new spawning ground for Chinese Sturgeon. Further studies should focus on two questions: i) how to improve the eDNA-based identification quality (e.g. individual level identification), and ii) how to combine the eDNA results with the background datasets.