The Relationship Between the Spatial Distribution of Common Carp and Their Environmental DNA in a Small Lake

Environmental DNA (eDNA) is hypothesized to accumulate in surface water and sediment; however, the distribution of eDNA within a lentic environment and its relationship to fish spatial distribution is not well-known. We developed a quantitative PCR assay for the cytochrome b gene of the common carp (Cyprinus carpio), an ubiquitous invasive fish, and used it to measure eDNA in a small (65 ha) lake, in which both the density of carp and their spatial distribution were monitored for several years. Surface water, sub-surface water, and sediment were sampled from 22 locations in the lake, including areas frequently used by the carp. The detectability and concentration of eDNA in surface and sub-surface water were not significantly different (p > 0.05). In water, areas of high carp use had higher detectability and eDNA concentration, but there was no effect of fish use on sediment. Detectability followed the trend: high use water > low use water > sediment. Concentration of eDNA was highest in sediment on a per mass basis. These results suggest that eDNA sampling schemes should be informed by expected fish distribution patterns. This research is funded by Environment and Natural Resources Trust Fund.