Common frog populations have seen numbers tumble by more than 80 per cent in the face of a virus spreading through the UK, scientists warned today.
Populations infected with the disease Ranavirus, which is thought to be relatively new to the UK, suffered an average 81 per cent decrease in adult frogs over a 12-year period.
Using data collected from the public by the frog mortality project and charity Froglife, the research from the Zoological Society of London (ZSL) showed long-term declines in numbers in the face of the virus.
Disease: Common frog populations have seen numbers tumble by more than 80 per cent in the face of a virus spreading through the UK
The study also found sudden mass die-offs of frogs, which the disease is known to cause.
But the research, which was published in the ZSL journal Animal Conservation, found that while some populations of frogs suffered from infection year-on-year, others bounced back from mass mortality events.
The research suggests some frogs may be immune to infection by the virus, the scientists said.
Dr Amber Teacher, lead author of the study from ZSL, said: ‘Our findings show that Ranavirus not only causes one-off mass mortality events, but it is also responsible for long-term population declines.
‘We need to understand more about this virus if we are to minimise the serious threat that it poses to our native amphibians.’
The origins of non-native disease, which causes a range of symptoms in common frogs including skin ulceration and haemorrhaging of internal organs, are unknown but is thought to be relatively new to the UK and is closely related to viruses found in North American amphibians.
Common frog populations around the UK have seen numbers tumble by more than four-fifths in the face of a virus spreading through the country
In the 1980s and 1990s, the disease was associated with the south-east of England but in recent years new pockets of virus have turned up in Lancashire, Yorkshire and along the south coast.
The study’s co-author Dr Trent Garner, from ZSL, said: ‘It is very difficult to treat wildlife diseases and so the mystery that we desperately need to solve is how the disease spreads.
‘Understanding more about the ecology of the disease will allow us to offer advice to the public on how to limit the spread of infection, which could also prevent the movement of other frog diseases in the future.’
Lucy Benyon, of Froglife, said the discovery of populations which seemed to have some form of immunity to the virus was good news.
She said: ‘The discovery of persistent populations in the face of disease emergence is very encouraging and offers hope for the long-term future of this species.
‘However, we still need regular information from the public on what is happening in their ponds to continue this essential research.’
