The ecology of terrestrial eDNA: Its state, transport, and fate on
aboveground surfaces
Abstract
Environmental DNA (eDNA) has become a valuable tool for monitoring
species of concern or site biodiversity, including expanded use of
surveys designed to detect fully terrestrial species. However, if
aboveground terrestrial eDNA surveys are to be widely adopted, it is
necessary to first understand how terrestrial conditions affect the
state, transport, and ultimate fate (or ‘ecology’) of terrestrially
deposited eDNA. Many of the processes that affect eDNA’s state,
transport, and fate in aquatic environments may not be applicable in
aboveground systems, warranting an exploration of the terrestrial
processes that likely do affect eDNA. Here we explore ecology
terrestrial eDNA through a series of experiments exploring the optimal
filter pore size for eDNA collection, how eDNA is affected by rain
events, and its degradation rate under different solar radiation
conditions. We found that the capture concentration of intracellular
eDNA was not significantly affected by an increase in filter pore size,
suggesting there is a wide range of viable pore size options for
targeting intracellular eDNA. We also found extracellular eDNA degrades
more rapidly than intracellular forms when exposed to solar radiation,
indicating the latter is a more viable target for collection. Finally,
we identified that rainfall or mist will remove most terrestrial eDNA
present on vegetation substrate. This study provides researchers and
managers key insights into successfully designing and carrying out
terrestrial eDNA surveys that maximize detection probability and reduce
production of false positive survey results.