Abstract
AbstractDam‐mediated biological invasions are a serious problem all over the world. Once established in reservoirs, the invasive species have catastrophic impacts on the river ecosystems downstream, and thus, rapid monitoring of invasive species is an urgent issue for the effective removal of them and the conservation management of native ecosystems. Here, we verified the utility of environmental DNA (eDNA) analysis as a tool to effectively monitor three invasive fish species (bluegill, largemouth bass, and smallmouth bass) in reservoirs using multiplex real‐time PCR. First, to determine the optimal sampling location and season to detect eDNA from these species, we analyzed the eDNA in water samples from shore and offshore sites in three reservoirs all year around. We found that eDNA detection rates either did not differ between sampling locations or were higher for shore than offshore sites. In addition, eDNA detection rates were higher in spring (breeding season of target species) and/or summer than winter. Second, we extensively surveyed the distribution of the three species in 30 reservoirs in Japan using eDNA analysis. Consequently, a single eDNA‐based surveillance in summer allowed to match approximately 90% of the presence/absence of the invasive fish species known from 27 yr of administrative capture‐based surveillances. Given these results, we recommend collecting the replicated water samples from shore sites in summer or the breeding season for the effective detection of invasive fish eDNA in reservoirs. Our eDNA assays with multiplex real‐time PCR enable the rapid and sensitive monitoring of invasive fish distribution in reservoirs.
Highlights
License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited
Effects of sampling location and seasonality on Environmental DNA (eDNA) detection rates In Miharu reservoir, the detection rate of largemouth bass eDNA was significantly higher in shore than in offshore sites (P < 0.001; Fig. 2)
Smallmouth bass eDNA was only detected in May and June at low detection rates, and no eDNA was detected in other months in Miharu (Data S1)
Summary
License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. By the programmed water level drawdown (Azami et al 2008, Tanida et al 2014, Matsuzaki et al 2019) These traditional methods for fish fauna surveys in reservoirs require substantial effort and cost due to their huge surface areas and water depth and are disruptive for native fauna (Darling and Mahon 2011). EDNA analysis has been applied to various taxa and natural environments (Fukumoto et al 2015, Minamoto et al 2017, Ushio et al 2017, Carraro et al 2018), the application of eDNA analysis for biodiversity assessment and ecological monitoring in reservoirs is relatively limited (Lim et al.2016, Perez et al 2017, Hayami et al 2020). We verified the utility of eDNA analysis as a tool in monitoring representative invasive fish species (bluegill, largemouth bass, and smallmouth bass) in reservoirs in Japan
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