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APEM Group - Case Study
Invasive non-native species (INNS) are one of leading causes of biodiversity loss worldwide and there is a demand for more efficient detection methods. Relatedly, there is increasing interest in using eDNA for INNS detection and monitoring.
Global biodiversity is in crisis and invasive non-native species (INNS) are amongst the leading cause of species losses. There is increasing pressure on industries to monitor and improve their direct environmental impact. This includes increasing INNS monitoring and, where required, mitigation. Early detection is key to minimising the impact of invasive non-native species (INNS) on recipient ecosystems increasing demand for more efficient detection methods. This has led to a growing interest in the use of eDNA (or environmental DNA) for detecting INNS, particularly in freshwater environments.
What is environmental DNA (eDNA)?
Environmental DNA (eDNA) refers to the genetic material that can be obtained from an environmental sample such as water, sediment, soil, snow or air. This DNA can originate from a several sources including urine, faeces, shed skin cells and gametes. A range of molecular analyses can be used to identify the species from which the DNA originated. Results from eDNA analysis can be used to infer the presence of the species detected in the sampled environment, although it should be noted that eDNA methods are very sensitive and can detect DNA introduced from elsewhere (e.g., in the faeces of predators that move between locations). Because of the high sensitivity of eDNA methods there is potential for species to be detected in very low population densities. This is especially compelling for the detection of invasive non-native species (INNS) early in the invasion process.
What do we need to know about eDNA analysis?
As a relatively novel method, there are several uncertainties around the use of eDNA which need further investigation. Detectability can vary between species and molecular assays, as well as with environmental conditions and population size. For most species influences on detectability, and the overall reliability of eDNA for species detection, is relatively poorly understood. To help build this knowledge base APEM Group, working with Yorkshire Water and Cardiff University, undertook baseline investigations into the use of this innovative technique for invasive non-native species (INNS) detection.
Written by APEM Group scientists Dr Emily Moore (Senior Water Quality Scientist), Dr Paul Stebbing (Associate Director, INNS), and Dr Jo James, (Principal Freshwater Scientist) and collaborators at Yorkshire Water and Cardiff University, insights from the paper ‘Using eDNA to detect freshwater invasive non-native species under controlled conditions’ will inform decisions around the use of commercially-available eDNA assays and improve interpretation of the results generated.
This work used a series of laboratory experiments to investigate the ability of commercially-available eDNA assays to detect two high priority freshwater INNS in the UK, killer shrimp (Dikerogammarus villosus) and signal crayfish (Pacifastacus leniusculus), at different population densities.
The findings demonstrated the potential for using eDNA as a detection method for killer shrimp and signal crayfish but also highlighted that detectability was species/assay specific and dependant on population density. The insights gained will help practitioners make informed decisions about the use of eDNA for detecting/monitoring these high priority INNS.
The future of eDNA
The demand for more effective means of detecting INNS, especially at low population densities (i.e. at early stages of the invasion process) is increasing. There is a potential use for eDNA to meet this demand, but an increased understanding of its application is required. Whilst earlier uses of eDNA focussed on detecting species in freshwater environments, recent innovations have looked at the use of eDNA for monitoring in marine and terrestrial habitats. Most recently this has involved capturing air DNA to detect bat species, and research with air DNA is also underway to see if it can be used for ecosystem level monitoring.
Within freshwater environments the main uses of eDNA are likely to be in the detection of rare protected species and invasive non-native species (INNS) as well as in the conduction of biodiversity assessments for key taxonomic groups.
There are many potential benefits of using eDNA including detection at lower population densities, less impact to the environment being sampled, and allowing sampling of locations where using conventional methods would not be feasible. There are, however, also still several uncertainties surrounding the use of this technology. The many factors that can influence eDNA detectability and the lack of standardised methods mean that surveys incorporating eDNA need to be designed carefully and results critically evaluated. APEM Group are using eDNA analysis as part of a considered approach, designing bespoke eDNA field surveys and analysing data. In conjunction with conventional sampling techniques, and with an expert analysis of the circumstances of species detected, eDNA as an innovative species detection technique is certainly one to watch.
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