Effects of abiotic variables on DNA degradation in a limnic environment

Environmental DNA (eDNA) has emerged as a powerful tool for biodiversity monitoring, yet the environmental factors influencing its persistence and degradation remain poorly understood. This study assessed the effects of light intensity, water column depth, turbidity, transparency, temperature, and exposure time on eDNA persistence under field conditions in a limnic environment. Two experiments were conducted. Experiment I used bottles containing DNA extracts of Limnoperna fortunei, whereas Experiment II used bottles containing reservoir water with naturally occurring eDNA from Cordylophora sp. and L. fortunei. Sampling units consisted of sterile glass tubes subjected to two treatments: transparent tubes exposed to sunlight and tubes covered with black tape to block light. Units were arranged in triplicate and attached to a guide rope positioned vertically in the water column at different depths, remaining submerged for 24, 72, 168, and 264 hours. eDNA remained detectable after 12 days under varying environmental conditions, although degradation was most pronounced during the first 24 hours. The rapid breakdown of eDNA in aquatic habitats highlights its potential for near real-time biodiversity monitoring, suggesting that detected DNA primarily reflects recent biological activity. These findings contribute to understanding eDNA dynamics and may improve interpretation of detection results in freshwater monitoring.