eDNA‐based detection reveals invasion risks of a biofouling bivalve in the world's largest water diversion project

Abstract

Environmental DNA (eDNA) has increasingly been used to detect rare species (e.g., newly introduced nonindigenous species) in both terrestrial and aquatic ecosystems, often with distinct advantages over traditional methods. However, whether water eDNA signals can be used to inform invasion risks remains debatable owing to inherent uncertainties associated with the methods used and the varying conditions among study systems. Here, we sampled eDNA from canals of the central route of the South‐to‐North Water Diversion Project (hereafter SNWDP) in China to investigate eDNA distribution and efficacy to inform invasion risks in a unique lotic system. We first conducted a total of 16 monthly surveys in this system (two sites in the source reservoir and four sites in the main canal) to test if eDNA could be applied to detect an invasive, biofouling bivalve, the golden mussel Limnoperna fortunei. Second, we initiated a one‐time survey in a sub‐canal of the SNWDP using refined sampling (12 sites in ~22 km canal) and considered a few environmental predictors. We found that detection of target eDNA in the main canal was achieved up to 1100 km from the putative source population but was restricted to the warmer months (May–November). Detection probability exhibited a significant positive relationship with average daily minimum air temperature and with water temperature, consistent with the expected spawning season. eDNA concentration in the main canal generally fluctuated across months and sites and was generally higher in warmer months. Golden mussel eDNA concentration in the sub‐canal decreased significantly with distance from the source and with increasing water temperature and became almost undetectable at ~22 km distance. Given the enormity of the SNWDP, golden mussels may eventually expand their distribution in the main canal, with established “bridgehead” populations facilitating further spread. Our findings suggest an elevated invasion risk of golden mussels in the SNWDP in warm months, highlighting the critical period for spread and, possibly, management.

Analysing spatio‐temporal patterns of non‐native fish in a biodiversity hotspot across decades

“…We can prioritize the following areas of work. First, enhancing monitoring and early detection systems for translocated species is imperative, as they are morphologically similar to native species and are at a higher risk of being overlooked (Blackwell et al, 2021; Xia et al, 2023). Second, it is necessary to strengthen communication to foster consensus among stakeholders, including scientists, government agencies, conservation organizations and local communities, that translocated species are also harmful non‐native species (Jarić et al, 2021).…”

Risk Screening of Invasive Aquatic Species and a Survey of Fish Diversity Using Environmental DNA Metabarcoding Analysis in Shanghai

“…Filters were stored in 2 mL cryotubes (S Biotech, Shanghai, China) and kept in a laboratory at −20 °C until eDNA extractio filtration equipment was soaked in a 10% sodium hypochlorite solution for five m before and after use to remove residual DNA, followed by thorough rinsing with t ter and a final rinse with commercially available distilled water (Hangzhou wahaha co., LTD, Hangzhou, China). Disposable gloves were used for each sample filtratio processing of eDNA was carried out according to Xia et al [46]. After pre-processin eDNA was extracted from the filters using the DNeasy Blood and Tissue kit (Q Dusseldorf, Germany).…”

“…Disposable gloves were used for each sample filtration. Pre-processing of eDNA was carried out according to Xia et al [46]. After pre-processing, total eDNA was extracted from the filters using the DNeasy Blood and Tissue kit (Qiagen, Dusseldorf, Germany).…”

Perspectives of invasive alien species management in China

“…The use of eDNA has gained increasing popularity as an effective high‐throughput approach for detecting aquatic IAS. Following the opening of the South‐to‐North Water Diversion Project, Xia et al (2023) conducted intensive field eDNA surveys to assess the invasion risk of the golden mussel ( Limnoperna fortune ), an invasive biofouling bivalve, in this world's largest water diversion project. Their findings established an “eDNA concentration‐flowing distance” relationship, confirming the creation of an “invasion highway” that facilitated the spread of this invader to the northern invasion front.…”