Spatio‐temporal monitoring of lake fish spawning activity using environmental DNA metabarcoding

Abstract

Determining the timing and location of fish reproductive events is crucial for the implementation of correct management and conservation schemes. Conventional methods used to monitor these events are often unable to assess the spawning activity directly or can be invasive and therefore problematic. This is especially the case when threatened fish populations are the study subject, such as the Arctic charr (Salvelinus alpinus L.) populations in Windermere (Cumbria, UK). Arctic charr populations have been studied in this lake since the 1940s, and the locations and characteristics of spawning grounds have been described in detail using techniques such as hydroacoustics, as well as physical and visual surveys of the lake bottom. Here, in conjunction with established netting surveys, we added an environmental DNA (eDNA) metabarcoding approach to assess the spatial distribution of Arctic charr in the lake throughout the year to test whether this tool could allow us to identify spawning locations and activity. Sampling was carried out between October 2017 and July 2018 at three locations in the lake, covering putative and known spawning .

eDNA metabarcoding from aquatic biofilms allows studying spatial and temporal fluctuations of fish communities from Lake Geneva

“…Our study is not the only that detected fish spawning events trough metabarcoding. Di Muri et al (2022) observed peaks or Arctic char (Salvelinus alpinus) during spawning seasons at specific locations of known spawning sites as we did in our study for some fish species (i.e., C. lavaretus, P. fluviatilis, T. tinca, and G. aculeauts). Even though the information obtained through metabarcoding is not as accurate as that obtained using species-specific PCR assays, metabarcoding allows to have an overview of the trend of the community composition.…”

Arctic char occurrence and abundance using environmental DNA

“…A second major consideration regarding eDNA natural dynamics for this study is to ensure eDNA samples are taken where eDNA has accumulated within each lake. Accumulation of fish eDNA can occur either through shedding of scales, excrement, gametes, or decaying bodies (Di Muri et al, 2022; Wang et al, 2021). As such, it is important to include sufficient spatial sampling to avoid false negatives when conducting eDNA surveys (Di Muri et al, 2022).…”

“…Accumulation of fish eDNA can occur either through shedding of scales, excrement, gametes, or decaying bodies (Di Muri et al, 2022; Wang et al, 2021). As such, it is important to include sufficient spatial sampling to avoid false negatives when conducting eDNA surveys (Di Muri et al, 2022). Here the spatial distribution of eDNA was found to be randomly distributed with no clear spatial structure within individual lakes.…”

Beyond species detection—leveraging environmental DNA and environmental RNA to push beyond presence/absence applications

“…Di Muri et al (2023) assess the effectiveness of eDNA metabarcoding for inferring the spatiotemporal distribution of the spawning activity of Arctic char ( Salvelinus alpinus ) in Windermere, UK, and observe corresponding peaks of relative read numbers with conventional netting survey. They show that eDNA metabarcoding may accurately and efficiently define the spatial and temporal characteristics of fish spawning activity in lentic environments.…”