Conservationists may be unintentionally spreading pathogens between threatened animal populations

Conservationists may be unintentionally spreading pathogens between threatened animal populations - University of Cambridge

At-risk species of river mussel (David Aldridge)

Moving endangered species to new locations is often used as part of species conservation strategies, and can help to restore degraded ecosystems. But scientists say there is a high risk that these relocations are accidentally spreading diseases and parasites.

The new report published today in the journal Conservation Letters focuses on freshwater mussels, which the researchers have studied extensively, but is applicable to all species moved around for conservation purposes.

Mussels play an important role in cleaning the water of many of the world’s rivers and lakes, but are one of the most threatened animal groups on Earth. There is growing interest in moving mussels to new locations to boost threatened populations, or so they can be used as ‘biological filters’ to improve water quality.

A gonad-eating parasitic worm, Rhipidocotyle campanula, which can leave mussels completely sterile, was identified as a huge risk for captive breeding programmes where mussels from many isolated populations are brought together.

“We need to be much more cautious about moving animals to new places for conservation purposes, because the costs may outweigh the benefits,” said Dr David Aldridge in the Department of Zoology at the University of Cambridge, senior author of the report.

He added: “We’ve seen that mixing different populations of mussels can allow widespread transmission of gonad-eating worms – it only takes one infected mussel to spread this parasite, which in extreme cases can lead to collapse of an entire population.”

Pathogens can easily be transferred between locations when mussels are moved. In extreme cases, the pathogens may cause a population of mussels to completely collapse. In other cases infections may not cause a problem unless they are present when other factors, such as lack of food or high temperatures, put a population under stress leading to a sudden outbreak.