The use of environmental DNA (eDNA) has recently been employed to evaluate the distribution of various aquatic macroorganisms. Although this technique has been applied to a broad range of taxa, from vertebrates to invertebrates, its application is limited for aquatic insects such as aquatic heteropterans. Nepa hoffmanni (Heteroptera: Nepidae) is a small (approx. 23 mm) aquatic heteropteran that inhabits wetlands, can be difficult to capture and is endangered in Japan. The molecular tool eDNA was used to evaluate the species distribution of N. hoffmanni in comparison to that determined using hand-capturing methods in two regions of Japan. The eDNA of N. hoffmanni was detected at nearly all sites (10 eDNA-detected sites out of 14 sites), including sites where N. hoffmanni was not captured by hand (five eDNA-detected sites out of six captured sites). Thus, this species-specific eDNA technique can be applied to detect small, sparsely distributed heteropterans in wetland ecosystems. In conclusion, eDNA could be a valuable technique for the detection of aquatic insects inhabiting wetland habitats, and could make a significant contribution to providing distribution data necessary to species conservation.

Environmental DNA (eDNA) has recently been used for detecting the distribution of macroorganisms in various aquatic habitats. In this study, we applied an eDNA method to estimate the distribution of the Japanese clawed salamander, Onychodactylus japonicus, in headwater streams. Additionally, we compared the detection of eDNA and hand-capturing methods used for determining the distribution of O. japonicus. For eDNA detection, we designed a qPCR primer/probe set for O. japonicus using the 12S rRNA region. We detected the eDNA of O. japonicus at all sites (with the exception of one), where we also observed them by hand-capturing. Additionally, we detected eDNA at two sites where we were unable to observe individuals using the hand-capturing method. Moreover, we found that eDNA concentrations and detection rates of the two water sampling areas (stream surface and under stones) were not significantly different, although the eDNA concentration in the water under stones was more varied than that on the surface. We, therefore, conclude that eDNA methods could be used to determine the distribution of macroorganisms inhabiting headwater systems by using samples collected from the surface of the water.

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 complicates accurate estimations of eDNA concentrations and the detection of the presence/absence of species in natural habitats. Further 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 scripta elegans) and eDNA concentrations across 100 ponds. Additionally, we evaluated the effect of water quality on red-eared slider eDNA concentration in these 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 inhibition 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, as microbial activity is thought to decrease eDNA persistence.

Four genera of Philopotamidae (Trichoptera) are known from Japan: Chimara, Dolophilodes, Kisaura, and Wormaldia. Among them, adults of the genus Kisaura are known in the Oriental and East Palearctic region; but until now, larvae of this genus have not been observed. In this study, molecular evidence is presented to support the relationship between adults and larvae of Kisaura minakawai Arefina 2005 from hyporheic zones of Japanese rivers. Morphological features of the larva of K. minakawai, which include very small eyes and somewhat dorsoventrally flattened (depressed) head capsules, compared with those of other philopotamid species, are also suggested to be adapted to the hyporheic zone. Detailed morphology of K. minakawai larval characters are provided.

1. Environmental DNA (eDNA) has recently been developed for detecting the distribution of macroorganisms in aquatic systems and for estimating biomass/abundance. Although positive relationships between eDNA concentrations of species and biomass/abundance have been observed in previous studies, estimation of total biomass in a particular ecosystem based on eDNA concentration has not been investigated. 2. To test this, we sampled eDNA from the littoral and pelagic zones of eight small ponds in Japan. Then, we drained ponds to capture all fish inhabiting each pond.We compared the eDNA copies measured by quantitative real-time polymerase chain reaction analysis with the captured biomass of three dominant fish species (common carp, bluegill sunfish, and largemouth bass) obtained by direct capture.Differences in eDNA concentrations were compared between the littoral and pelagic zones of each pond.3. We found positive relationships between the eDNA copies and the whole captured biomass of all target species using Type II logarithmic equations, and the eDNA copies appeared to be saturated at a higher total biomass. 4. We found positive correlations between the total number of eDNA copies and the total captured biomass of three fish species. This demonstrated the first step in estimating the population biomass of target fish species under natural conditions using eDNA measurement.