Potential Role\nof Photochemistry in Environmental\nDNA Degradation

Given the severe loss of species richness across diverse\necosystems,\nthere is an urgent need to assess and monitor biodiversity on a global\nscale. The analysis of environmental DNA (eDNA), referring to any\nDNA extracted from environmental samples and subsequently sequenced,\n is a promising method for performing such biodiversity related studies.\nHowever, a comprehensive understanding of the factors that drive distinct\neDNA degradation rates under different environmental conditions is\ncurrently missing, which limits the spatiotemporal interpretations\nthat are possible from the eDNA-based detection of species. Here,\nwe explore what role photochemistry may play in the fate of eDNA in\naquatic ecosystems. Since few eDNA photodegradation studies have been\nperformed, we extrapolate measured photochemical degradation dynamics\nfrom dissolved organic matter (DOM) and cellular DNA to what is expected\nfor eDNA. Our findings show that photochemistry may dominate eDNA\ndegradation under certain environmental conditions (e.g., DOM-rich\nwaters with no light-limitation) and that photochemical alteration\nof eDNA may impact microbial respiration rates and the quantitative\npolymerase chain reaction (qPCR)-based detection of eDNA. We therefore\nencourage future studies to analyze the impact of photochemistry on\neDNA degradation and provide suggested research directions that could\nhelp improve the accuracy of spatiotemporal inferences from eDNA analyses.