UV degradation
Although a heavy rainstorm terminated the UV experiment at day 6, we
found extracellular eDNA in our full sun treatment was not detectable
beyond day four, with very few detections within the first four days of
sampling (Table 2 ). For the full sun and half sun conditions,
we found intracellular eDNA was detectable throughout all six days of
sampling, with full shade only detectable up to day five (Table
2 ). DNA from our no sun treatment was detectable across all six days,
with all samples and qPCR replicates providing positive results
(Table 2 ). Our non-linear least squares models of copy number
decay performed similarly based on AICc, whether the independent
variable was cumulative UV exposure or time elapsed for both
intracellular and extracellular eDNA (Table 3 ). We estimated
that extracellular eDNA, under the full sun treatment, had a decay rate
of 18.7% per hour and was detectable for 22.7 and 26.8 hours for the
two thresholds, respectively (Figure 4a ), and
intracellular eDNA had a decay rate of 3.0% per hour and was detectable
for 88.1 and 111.6 hours, respectively (Figure 4b,
Table 4 ). The decay rate of eDNA for our half sun treatment was 2.1%
per hour and was detectable up 118.3 and 152.2 hours, respectively, and
our full shade treatment had a decay rate of 1.6% per hour and was
detectable for 143.3 and 186.6 hours, respectively (Figure4b, Table 4 ). We found no evidence of a significant decrease in
copy number for intracellular or extracellular eDNA over the 144 hour
experiment in our no sun treatment (Table 4 , Figure5 ), indicating time alone did not contribute to the decay of
eDNA across UV treatments and our observed eDNA degradation was likely
due to cumulative UV exposure.