Mesocosm and laboratory investigations for the effects of current velocity, dilution, pH, and temperature on eDNA persistence in an aquatic environment.

Environmental DNA (eDNA) sampling is a relatively new methodology for indirect detection of organisms and is often used in conservation research of rare or endangered species. Most eDNA research has focused on aquatic organisms and involves the collection of water samples in which the target eDNA particles may be suspended. Past studies have shown that environmental variables such as current velocity, pH, and water temperature can influence both the rate at which organisms shed eDNA into the environment, as well as how long the eDNA molecules persist in water before breaking down and becoming undetectable. Most studies have used fish or invertebrates as study organisms. In this study, we used two captive alligator snapping turtles (Macrochelys temminckii), a species of conservation concern, as a source of eDNA to examine the influence of different abiotic conditions on the shedding and persistence of eDNA. We used two artificial stream mesocosms to examine eDNA shedding in current versus no-current conditions, and later performed laboratory dilutions and manipulations of pH and temperature to evaluate detection of eDNA in water samples. Our findings suggest high stability of eDNA molecules with shortterm exposure to pH and temperature extremes with relation to typical field observations of these abiotic factors. These results are most informative within the context of field collection of eDNA samples, which may experience increases and fluctuations in temperature during transport. [ABSTRACT FROM AUTHOR]