Preservation of filtered environmental DNA samples at ambient high temperatures.

Environmental DNA (eDNA) analysis is widely applied for biological monitoring; however, its use in tropical environments remains limited due to rapid eDNA degradation under high temperatures. This study evaluated the feasibility of storing eDNA samples at high-temperatures using Buffer ATL, a lysis buffer included in a commonly used extraction kit. After water filtration, 1 mL of Buffer ATL was added directly to Sterivex cartridge filters, which were stored at 20 °C and 40 °C for up to one week. The effectiveness of this method was evaluated using a tank experiment and natural river water samples. Fish eDNA concentration changes were quantified by species-specific qPCR, and changes in detected species richness were assessed by eDNA metabarcoding using MiFish primers. Adding Buffer ATL prevented eDNA decline during high-temperature storage and maintained fish species detection even after one week at 40 °C. This method provides a practical solution for preserving filtered eDNA samples during tropical fieldwork and transport under high-temperature conditions where cold storage is unavailable.