DNA state influences the uptake and persistence of environmental DNA by
marine sponge natural samplers
Abstract
1. Marine sponges as natural samplers of environmental DNA (eDNA) are
receiving growing attention as an untapped source of biodiversity data.
However, little is known about the state of the DNA that is represented
by these samples and how this compares to conventional aquatic eDNA
samples. 2. Here, we present an artificial spiking experiment where DNA
in cellular and extracellular states was added into tanks containing two
sponge species. Aquatic eDNA samples and sponge (natural sampler DNA
(nsDNA)) samples were collected over 7 days and DNA from the two states
was quantified using qPCR. 3. We found that there was a significant
interaction between DNA state and sample type (eDNA and nsDNA), with
lower detection and concentration of extracellular DNA, compared to
cellular DNA, found in nsDNA samples. We also found that detection
probability and concentration of DNA were significantly lower in nsDNA
than eDNA overall. 4. During methodological testing, PCR inhibition was
observed in both sponge species; this was prohibitive in one of the
species. Further work to investigate the degree of PCR inhibition during
nsDNA metabarcoding is important to understand it’s impact on the
communities resolved using these nsDNA methods. 5. Synthesis and
applications. We show that nsDNA may originate from a subset of the DNA
present in environmental media, potentially resolving a more stable
picture of local communities. Natural samplers provide a promising
option for hard-to-reach environments and for analysing archived
samples; however, further work and optimisation is required to
understand what is and isn’t well represented by this sample type
compared to widely applied aquatic eDNA approaches.