Detection of environmental DNA of the invasive red-eared slider in ponds for evaluating their distribution with comparison to water quality

Abstract

Environmental DNA (eDNA) is a powerful tool for monitoring the distribution of aquatic macro-organisms. However, environmental factors, including the water temperature and water quality, can affect the inhibition and/or degradation of eDNA, which prevents accurate estimations of eDNA concentrations and the detection of the presence/absence of species in natural habitats. Also, very few eDNA studies have been conducted for reptiles, especially with respect to estimating their biomass and/or abundances. Here we examined the relationship between the visually-observed number of red-eared sliders (Trachemys scriptaelegans) and the eDNA concentrations. Additionally, we evaluated the effect of water quality on the eDNA concentration in 100 ponds. We found that there was a significant positive correlation between the observed number of red-eared sliders and the eDNA concentration in the ponds. On comparing various water quality indicators, including dissolved nitrogen, dissolved phosphorous, organic matter, and chlorophyll a (Chl. a), we found that only Chl. a had a negative correlation with the red-eared slider eDNA concentration, while we did not find any inhibitions in the quantitative PCR. We conclude that concentrations of eDNA can potentially be used for estimating the abundance of the red-eared slider. Additionally, Chl. a might indirectly influence the degradation of eDNA through the microorganisms bonded to the phytoplankton in the ponds, which microbial activity thought to be decreasing eDNA.

Comparing the efficiency of open and enclosed filtration systems in environmental DNA quantification for fish and jellyfish

“…For quantification using eDNA analysis, there was a positive correlation between eDNA concentration and fish biomass in ponds [9,10] and tanks [11,12]. The concentration of eDNA was also positively correlated with the size of fish [13], density [14][15][16] and wet mass [17]. Previous studies comparing spatiotemporal change in abundance or biomass in aquatic species, based on traditional methods and eDNA concentration, found a significantly positive correlation between biomass and the amount of eDNA in visual observations via land or vessel based surveys [18], using commercial fish landing data [19], via captures by bottom trawl [6], and by monitoring using echo sounder technology [20] in marine environments.…”