Data from: Environmental DNA surveillance for invertebrate species: advantages and technical limitations to detect invasive crayfish Procambarus clarkii in freshwater ponds

1. The introduction of non-native species is a major threat to
biodiversity. While eradication programs of well-established invaders are
costly and hazardous for non-target species, the early detection of a
non-native species at low density is critical for preventing biological
invasions in recipient ecosystems. Recent studies reveal that
environmental DNA (eDNA) is a powerful tool for detecting target species
in aquatic ecosystems, but these studies focus mostly on fish and
amphibians. 2. We examine the reliability of using eDNA to detect the
presence of an invasive freshwater crustacean species, the red swamp
crayfish Procambarus clarkii. Species-specific primers and probes were
designed; their specificity was tested using in silico PCR simulations and
against tissues of other crayfish species. Limits of detection and
quantification were specified for the target DNA sequence by means of
quantitative PCR amplifications on dilution series of known amount of P.
clarkii DNA. 3. The method was applied to water samples collected in 158
ponds in a French Nature Park, and results were compared to a traditional
method using food-baited traps. eDNA has a better detection efficiency but
predominantly leads to divergent results compared with the trapping
method. While habitat features partly explain the failure of crayfish
detection by trapping, detection by eDNA is problematic at low crayfish
abundances. When P. clarkii is detected, the estimated concentrations of
crayfish DNA in water samples are always below the limit of quantification
for the target DNA sequence. 4. Synthesis and applications. The
combination of eDNA and conventional trapping methods is recommended to
monitor the invasion by the red swamp crayfish P. clarkii in small
waterbodies such as ponds. However, the risk of mortality for non-targeted
species, notably amphibians, has to be carefully evaluated before the
deployment of traps at large scale. Contrary to fish and amphibians, low
amount of extracellular DNA in water is suspected to be the major
limitation for crayfish detection by molecular approaches. Current
advancements in PCR technology, together with optimization of the water
sampling method, promise upcoming developments of eDNA detection for
aquatic invertebrate species.