Summary
Environmental DNA (eDNA) is used for monitoring the occurrence of
freshwater organisms. Various studies show a relation between the amount
of eDNA detected and target organism abundance, thus providing a
potential proxy for reconstructing population densities. However,
environmental factors such as water temperature and microbial activity
are known to affect the amount of eDNA present as well In this study, we
use controlled aquarium experiments using Gammarus pulex L.
(Amphipoda) to investigate the relationship between the amount of
detectable eDNA through time, pH, and levels of organic material. We
found eDNA to degrade faster when organic material was added to the
aquarium water, but that pH had no significant effect. We infer that
eDNA contained inside cells and mitochondria is extra resilient against
degradation, though this may not reflect actual presence of target
species. These results indicate that, although estimation of population
density might be possible using eDNA, measured eDNA concentration could,
in the future, be corrected for local environmental conditions in order
to ensure accurate comparisons.