Effect of artificial barriers on the distribution of the invasive signal crayfish and Chinese mitten crab

Abstract

The role of river obstacles in preventing or facilitating the dispersal and establishment of aquatic invasive species is controversial. Novel detection tools like environmental DNA (eDNA) can be used for monitoring aquatic invasive species (AIS) such as the American signal crayfish ( Pacifastacus leniusculus ) and the Chinese mitten crab ( Eriocheir sinensis ), providing information on the effect of barriers on their distribution. We analysed eDNA from both water and surface sediment in three river catchments (Medway, Dee and Stour; Great Britain), with differing levels of connectivity, to determine spatial distribution of the two species, and assessed the effect of barriers on their eDNA detection. Positive eDNA detections were obtained within confirmed sites for both species in all catchments, with evidence of species overlap in the River Medway. Upstream barriers in the Medway positively influenced detection success of mitten crab lower in the catchment while detection success of signal crayfish was higher in the highly fragmented catchment (River Medway). This information on the role of river barriers on AIS distribution and eDNA detection is important for management strategies and for predicting both future dispersal and likelihood of new colonisations in previously uninvaded fragmented catchments.

To invade or not to invade? Exploring the niche-based processes underlying the failure of a biological invasion using the invasive Chinese mitten crab

“…Environmental DNA (eDNA) is capable of detecting invasive species at low densities; this enables the rapid implementation of eradication programs, thereby increasing the success of eradication efforts (Ficetola et al, 2008;Zhan et al, 2015). Recently, Robinson et al (2019) used the eDNA technique to study the spatial distribution of E. sinensis within three rivers in Great Britain. We encourage researchers to develop species-specific eDNA markers for E. sinensis and E. japonica and consider the use of eDNA for the early detection of E. sinensis in Japan.…”

Lateral and longitudinal fish environmental DNA distribution in dynamic riverine habitats

“…Rivers and streams contain, absorb, and transport eDNA from aquatic and terrestrial species and are thus ideal for cross‐habitat species detection (Deiner et al., 2016; Sales et al., 2020), although the dynamic nature of these ecosystems leads to constantly changing conditions during sampling (Shogren et al., 2017; Willett et al., 2014). Nevertheless, aspects such as a species' upstream distribution limits (Carim et al., 2019; Robinson et al., 2019) or local abundance and its change over time (Doi et al., 2017; Levi et al., 2019; Thalinger et al., 2019) have been successfully examined in lotic systems via eDNA. Often, these efforts are combined with traditional monitoring techniques to confirm molecular results and facilitate their interpretation (Evans et al., 2017; Wilcox et al., 2016), and there is generally a good consensus between molecular and nonmolecular data.…”

Predator recognition and anti-predatory behaviour in a recent aquatic invader, the killer shrimp (Dikerogammarus villosus)

“…In this sense, behavioural profiling of anti-predatory strategies, using perhaps some of the simple assays shown in our study, could be incorporated into risk assessments. Knowledge of how invasive species might respond to resident predators can inform the development of more efficient management actions, as these seldom consider biotic resistance (Robinson et al 2019; Robinson et al 2018). Given its strong aggregation behaviour, we also suggest that even when complete eradication is not possible, control measures that aim to reduce the density of killer shrimp might be beneficial, as a lower relative abundance and a smaller group size can make them more vulnerable to fish predators, potentially reducing their impact on native communities.…”