Crayfish Study May Hold Key to Invasive Species Control

An MSc student in the Department of Life Sciences at Imperial College London, working in collaboration with leading ecology consultancy Thomson Ecology, has successfully shown that eDNA, which is used to detect organisms in water, can potentially be used to detect early signs of aquatic invasive species.

When monitoring the American signal crayfish, a non-native alien species in the UK, which is threatening our native crayfish species, the student found that levels of eDNA rose dramatically if the crayfish was bearing eggs. In contrast, when the animals were not carrying eggs, the correlation between eDNA and numbers of invasive crayfish was lost. This indicates that detecting and estimating crayfish numbers appears to be more effective during the breeding season. If the research is proven successful, it will help to change how some species populations are measured.

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Paul Franklin, Principal Ecological Consultant at Thomson Ecology, said: “This is potentially very exciting news. Although we already use eDNA to help us in surveying aquatic environments, once this new technique is validated by scientific research and approved by statutory bodies like Natural England, it has the potential to speed things up significantly, and could allow us to detect problems even earlier.

“Invasive species can decimate native wildlife by outcompeting them for food and damaging local environments. Therefore, early detection is important to prevent their spread. Studies such as this really help us in developing new techniques for detecting presence or likely absence of protected or invasive species in aquatic environments. Often, we need to gather ecological data over large areas or long linear routes and the use of new techniques such as this enables us to do it more quickly and efficiently. If this method and use of eDNA can be used to find out which invasive species are present, it could allow for the eradication of invasive species before they cause harm to any native species present.”

Nick Dunn, lead author on the research paper, said: “I hope that my work will be able to help with the management of invasive species so that our native species stand the best chance of survival. It would be exciting if my work has opened the door for further research to be undertaken by future students.”

“Behavior and season affect crayfish detection and density inference and environment DNA” by Nicholas Dunn, Victoria Priestley, Alba Herraiz, Richard Arnold and Vincent Savolainen is published in Ecology and Evolution Journal.

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