Speaker
Description
Environmental DNA (eDNA) has become a powerful tool for monitoring freshwater biodiversity. However, its reliability remains strongly influenced by methodological choices throughout the analytical workflow and by the degradation and transport of environmental nucleic acids (eNAs) after their release. Within the PEPR One-Water ALIQUOT project, we aim to better understand the eNA life cycle and improve freshwater biomonitoring. Because these questions are difficult to study in the field, we conducted two complementary experiments at the SETE Aquatic Metatron (Moulis, France), an AnaEE experimental infrastructure dedicated to freshwater ecology.
The first experiment focused on optimizing targeted eDNA workflows. To do so, a lentic mesocosm contained a semi-controlled community of fishes and isopods, supplemented with synthetic amphibian DNA at different concentrations. We compared three filtration approaches (Waterra capsules, Sylphium capsules, and open membrane filters), two membrane pore sizes, and various eDNA preservation protocols. Each combination was tested in triplicate, and analysed by species-specific digital PCR. We then identified workflows maximizing detection. Our results also challenge the general assumption that filtering larger water volumes always improves eDNA recovery.
The second experiment investigated eDNA and environmental RNA (eRNA) degradation in flowing water, with the Metatron's controlled lotic platform, to experimentally test eDNA degradation expected models. Five artificial streams combined contrasting organism biomass, water temperature and sediment conditions. Various assemblages of Phoxinus phoxinus and Asellus aquaticus were exposed to ambient summer temperatures (25–30°C) or cooled conditions (-3°C and -7°C), with or without sediment. eNAs were sampled repeatedly over one week to quantify them and identify how these parameters drive their degradation. According to degradation models we expect eNA production to increase with biomass, whereas higher temperatures accelerate enzymatic and thermal eNA degradation, and sediment enhances the removal of eNAs from the water column through adsorption and physical settling.
Together, these experiments demonstrate how controlled freshwater infrastructures can improve both eDNA methodologies and our understanding of eNAs dynamics.
| Are you participating to the "AnaEE Environmental Rising Star Award "? | No |
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