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Research article - Peer-reviewed, 2023

Temperature moderates eDNA-biomass relationships in northern pike

Ogonowski, Martin; Karlsson, Erik; Vasemägi, Anti; Sundin, Josefin; Bohman, Patrik; Sundblad, Göran


Support for eDNA as a quantitative monitoring tool is growing worldwide. Despite ad-vances, there are still uncertainties regarding the representability of the eDNA signal over varying spatiotemporal scales, the influence of abiotic forcing, and phenological changes affecting the behavior of the study organism, particularly in open environ-ments. To assess the spatiotemporal variability and predictive power of quantitative eDNA analysis, we applied species-specific real-time quantitative PCR on water fil-trates during two visits to 22 coastal bays in the Baltic Sea. Within bays, we col-lected water along four transects across each bay and compared the pooled eDNA concentration to temporally matched catches from standardized angling targeting the northern pike (Esox lucius), a species for which reliable monitoring data is lacking. We found the variability in eDNA concentrations between transects to be moder-ate (21%) but still considerably lower than across bays and visits (52%), suggesting small-    scale spatial differences are of less importance during spring when pike spawn. Standardized angling catches, bay area, and water temperature together explained 48% of the variance in eDNA concentrations. DNA concentrations decreased with the increasing bay area, likely indicating a dilution effect. Notably, the relationship be-tween eDNA and standardized catches was positive but varied with temperature and the eDNA-abundance relationship was only significant at higher temperatures, which also coincided with a higher proportion of spawning/spent fish. We conclude that temperature is a key moderating factor driving changes in pike behavior and spring DNA-    dynamics. We recommend that future surveys focus on larger spatiotemporal scales during times when the influence of changing temperatures is minimized.


abundance; angling; Baltic Sea; biomass; coast; CPUE; eDNA; environmental DNA; Esox lucius; spawning; temperature

Published in

Environmental DNA
2023, Volume: 5, number: 4, pages: 750-765